JPH08194458A - Character processing device - Google Patents

Abstract

PURPOSE: To improve memory efficiency of a font cache memory by reducing compression processing judging time, and compressing only dot form data having a compression processing effect. CONSTITUTION: A character processing device is provided with a judging part 4 to judge whether or not finally developing processing-performed dot form data must be compressed on the basis of developing information obtained in order in a developing processing process in which a developing processing part 2 performs developing processing into dot form data on the basis of vector form data, for example, a contour plotting processing process by a contour plotting part 2a or a painting-out processing process by a painting-out processing part 2b, that is, information such as a number of change points when a run length is coded, a compressing-elongating part 3 to compress developing processing-performed dot form data and a whole control part 10 to control so as to make a font cache memory part 6 hold this compression processing- performed data by making the compressing-elongating part 3 perform compression processing on this judged dot form data when the judging part 4 judges that it must be compressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vector format data (hereinafter referred to as "vector font") indicating the outline of a figure such as a character.
Say. ) Is expanded into dot format data, and the expanded dot format data is output to an output device. In particular, the expanded dot format data is temporarily stored in a temporary storage means such as a font cache memory. However, the present invention relates to a character processing device that can efficiently perform expansion processing by reusing dot format data that has been expanded once in the subsequent expansion processing.

[0002]

2. Description of the Related Art Conventionally, an input drawing command is interpreted, and based on the interpretation result, a dot format data represented by a dot format is developed using a vector font indicating the outline of a figure such as a character, There is a character processing device that outputs the expanded dot format data to an output device such as a printer.

Since this character processing device uses a vector font, it has the advantage that high-quality character output can be performed regardless of the character size. On the other hand, unlike the dot font, expansion processing is performed for each character size. Therefore, there is a problem that it takes a long time to develop the dot format data.

In order to solve this problem, once the dot format data expanded using the vector font is temporarily stored in the font cache memory and the command for drawing the same character is input, Without performing this character expansion processing, the dot format data of the same character stored in the font cache memory can be reused, so that the expansion processing of the document data corresponding to the drawing command can be performed at high speed. A character processing device based on the above was conceived.

However, in order to temporarily store all the dot format data of a character that has been expanded once, the memory capacity of the font cache memory is finite and the cost is high. is there.

Therefore, a character processing device has been considered in which the dot format data of a character to be temporarily stored is compressed and stored in the font cache memory as compressed data.

For example, in Japanese Patent Laid-Open No. 4-133091, compression processing is performed once before temporarily storing the expanded dot format data in the font cache memory.
If the data amount of the compressed data by this compression process is smaller than the data amount of the dot format data before the compression process, the compressed data after the compression process is temporarily stored in the font cache memory. There is described a character processing device that can temporarily store dot format data in a font cache memory and thereby improve the memory efficiency of the font cache memory.

Further, in Japanese Laid-Open Patent Publication No. 4-133091, the dot format data of a character having a certain reference size or more is
Based on the assumption that the amount of data will decrease when compressed, the standard size of characters is set in advance, and when the size of the characters to be expanded is equal to or larger than the reference size, the expanded dot format data is compressed. Described is a character processing device that processes and temporarily stores the compressed data that has been compressed in the font cache memory, and temporarily stores the expanded dot format data as it is in the font cache memory when the size is not larger than the reference size. .

[0009]

However, in the character processing device described in Japanese Unexamined Patent Publication No. 4-133091, it is necessary to determine the effect of compression by the compression process, that is, whether or not the data amount is reduced by the compression process. Since the compression process is performed once every second, the compression process must always be performed. Therefore, even if there is no compression effect, it is necessary to perform compression processing once, and this compression processing has a problem that the final output of character processing is delayed.

Further, in the character processing device disclosed in Japanese Patent Laid-Open No. 4-293093, compression processing is performed on the assumption that the dot format data of a character having a certain reference size or more has a compression effect. However, this assumption holds for relatively simple characters such as alphabets and symbols, but may not hold for complicated characters such as Chinese characters. If compression processing is applied to characters for which this assumption does not hold, the amount of data after compression processing will increase compared to the amount of data before compression processing, resulting in a decrease in memory efficiency of the font cache memory. However, there is a problem in that the original purpose of improving the memory efficiency by the compression process may not be achieved.

Therefore, the present invention eliminates such problems and reduces the time required for determining the effect of the compression process, and compresses only the dot format data which has the effect of the compression process to perform the font cache memory. It is an object of the present invention to provide a character processing device that can truly improve the memory efficiency of the above.

[0012]

According to a first aspect of the present invention, when vector format data indicating a figure such as a character is expanded into dot format data and the expanded dot format data is output to an output device, In a character processing device that temporarily stores the expanded dot format data in a storage unit and reuses the dot format data, the expansion processing is performed based on the expansion information sequentially acquired in the process of the expansion processing. If the determination means determines whether or not the dot format data should be compressed, the compression means for compressing the dot format data, and the determination means determines that the dot format data should be compressed, the compression processing of the determined dot format data is performed. If the compression means is caused to store the compressed data in the temporary storage means, and the determination means determines that compression should not be performed,
And a control means for controlling the temporary storage means to store the determined dot format data.

A second aspect of the invention is characterized in that the expansion information is expansion information that is sequentially acquired in the process of filling processing.

A third aspect of the invention is characterized in that the expansion information is expansion information sequentially acquired in the course of the contour drawing process.

A fourth aspect of the invention is characterized in that the expansion information is the number of change points of the dot format data and the data amount of the dot format data in the course of the expansion processing.

In a fifth aspect based on the fourth aspect, the data amount of the dot format data is the number of lines of the dot format data and the number of dots per line.

In a sixth aspect of the present invention, the determining means calculates a predicted data amount when the compression means compresses the compressed data based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. When it is equal to or larger than a reference value indicating a predetermined reduction amount with respect to the data amount, the compression means determines that the data should be compressed.

In a seventh aspect of the invention, the determining means calculates a predicted data amount when the compression means compresses the compressed data based on the expansion information, and the predicted data amount is a reference value indicating a predetermined data amount. In the following cases, the compression means determines that compression should be performed.

According to an eighth aspect of the invention, the judgment means calculates a predicted data amount when the compression means compresses the compressed data based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. It is characterized in that the compression means decides that the data should be compressed when it is equal to or larger than a reference value indicating a predetermined reduction rate with respect to the data amount.

A ninth invention is characterized in that, in the sixth invention to the eighth invention, the judging means changes the reference value based on a free storage area state of the temporary storage means.

A tenth aspect of the invention is characterized in that the compression means compresses the dot format data by performing run length coding.

[0022]

In the first aspect of the present invention, the determination means first determines whether or not the expanded dot format data should be compressed, based on the expansion information sequentially acquired during the expansion processing. When the determination means determines that the compression should be performed, the control means causes the compression means to perform the compression processing of the dot format data determined by the determination means, and stores the compressed data in the temporary storage means. Let On the other hand, when the determination means determines that the compression should not be performed, the control means stores the dot format data determined by the determination means in the temporary storage means as it is.

In the second invention, the expansion information in the first invention is sequentially acquired during the filling process in the expansion process, that is, during the filling process.

In the third invention, the expansion information in the first invention is sequentially acquired during the contour drawing process in the expanding process, that is, during the contour drawing process.

In the fourth invention, the expansion information is the number of change points of the dot format data and the data amount of the dot format data in the process of the expansion processing.

In the fifth invention, the data amount of the dot format data in the fourth invention is the number of lines of the dot format data and the number of dots per line.

In the sixth invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. When it is equal to or larger than a reference value indicating a predetermined reduction amount with respect to the data amount of, the compression unit determines that compression is to be performed, and when the determination unit determines that compression is to be performed, the control unit applies the dot format data to the compression unit. A compression process is performed, and the compressed data is stored in the temporary storage means. When the determination means determines that the compression should not be performed, the control means controls the dot format data to be stored in the temporary storage means as it is.

In the seventh invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is a reference value indicating a predetermined data amount. In the following cases, the compression means determines that the compression means should be compressed, and when the determination means determines that the compression means should be compressed, the dot format data is compressed by the compression means, and the compressed data is processed. It is stored in the temporary storage means. When the determination means determines that the compression should not be performed, the control means controls the dot format data to be stored in the temporary storage means as it is.

In the eighth invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. If the determination means determines that the compression is to be performed, and the determination means determines that the compression is to be performed, the dot format data is compressed by the compression means. The compressed data is processed and stored in the temporary storage means. When the determination means determines that the compression should not be performed, the control means controls the dot format data to be stored in the temporary storage means as it is.

In the ninth invention, the reference value in the sixth invention to the eighth invention is changed based on the empty storage area state of the temporary storage means. This flexible change of the reference value allows the temporary storage means to be utilized to the maximum extent, and is particularly effective because the storage area of the temporary storage means is almost empty in the initial state.

In the tenth aspect of the invention, the compression means compresses the dot format data by performing run length coding.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a functional block diagram showing the configuration of a character processing apparatus according to the first embodiment of the present invention.

In FIG. 1, the character processing device is roughly composed of an overall control unit 10, an output control unit 11, and a storage unit 12. The overall control unit 10 includes a reception unit 1, an expansion processing unit 2, and a compression / expansion unit. The storage unit 12 includes the unit 3 and the determination unit 4.
Has a font storage unit 5, a font cache memory unit 6, and a page memory unit 7.

The acceptance unit 1 accepts the input drawing command C and sequentially outputs it to the expansion processing unit 2.

The expansion processing unit 2 executes expansion processing of characters and the like in response to the drawing command C input from the reception unit 1 to generate final dot format data (bitmap data) page by page. However, the page-by-page bitmap data is stored in the page memory unit 7. Here, the contour drawing unit 2a performs a contour drawing process which is one step of the expansion process, and the filling unit 2b performs a filling process which is one step of the expansion process. Generally, in the process of expanding characters and the like, coordinate conversion processing such as enlargement / reduction or transformation is performed based on the vector font data stored in the font storage unit 5, and the data subjected to the coordinate conversion processing is also processed. Then, a contour drawing process for drawing the final outline of the bitmap data is performed, and finally, a filling process for filling the outline is performed.

The compression / expansion unit 3 performs a compression process on the bitmap data that needs to be compressed, and temporarily stores the compressed compressed data in the font cache memory unit 6. Also, the compressed data temporarily stored in the font cache memory unit 6 is expanded to the bitmap data before the compression processing. The compression process is performed by run length coding.

The determination unit 4 determines, after the compression processing, from the number of change points of the dot format data sequentially acquired in the process of the filling processing of the filling section 2b, the number of lines of this dot format data and the number of dots per line. The data amount of is predicted, the predicted data amount (predicted data amount) is compared with the generated bitmap data amount, and when the predicted data amount is smaller than the bitmap data amount, Determine that it should be compressed. If the result of this determination is that the data should be compressed, the determined bitmap data is run-length encoded by the compression / decompression unit 3 and compressed, and this compressed data is reused for subsequent reuse in the font cache memory. It is temporarily stored in the unit 6.

The font storage unit 5 stores vector font data of characters corresponding to character codes defined in character sets such as ASCII, JIS first level, and JIS second level.

The font cache memory unit 6 temporarily stores the bitmap data expanded by the expansion processing unit 2 or the compressed data compressed by the compression / expansion unit 3. By temporarily storing this bitmap data or compressed data in the font cache memory unit 6, the expansion processing unit 2 expands the same character as the character corresponding to the temporarily stored bitmap data or compressed data. No processing needed. If the bitmap data itself is temporarily stored, the corresponding bitmap data need only be retrieved from the font cache memory unit 6 as it is. If the compressed data is temporarily stored, the font cache memory unit 6 The same bitmap data as the expanded bitmap data can be obtained by only extracting the corresponding compressed data from 6, and expanding the compressed data by the compression / expansion unit 3. Generally, since the expansion process takes time, the entire document process can be performed at high speed. In addition,
The compression / decompression process takes less time than the decompression process.

The page memory unit 7 stores the pit map data for each page which is expanded by the expansion processing unit.

The output control unit 11 receives the expansion processing end notification from the expansion processing unit 2 and controls the transfer of the bitmap data in page units to an output device (not shown).

FIG. 2 is a diagram showing a hardware configuration of a document processing system including the character processing device shown in FIG. 1. The CPU 21, the ROM 22, the RAM 23, the host interface 26, the hard disk device 28, and the printer interface 30. Are connected to the bus B. A host workstation 27 is connected to the host interface 26, and a printer engine 31 is connected to the printer interface 30.

The CPU 21 receives a drawing command relating to a document input from the host workstation 27 via the host interface 26 and the bus B, generates bit map data in page units indicated by the drawing command, and the generated bit map data. Are stored in the page memory 25 in the RAM 23. And the CPU 21
Outputs the bitmap data in page units stored in the page memory 25 via the printer interface 30 to the printer engine 31, which is an output device.

The printer engine 31 prints out the input bitmap data in page units.

The ROM 22 stores various control programs executed by the CPU 21, a development processing program for developing the bitmap data, and the like.

The RAM 23 has a font cache memory 24 and a page memory 25, and the CPU 2
One work area is secured.

Vector font data 29 is stored in the hard disk device 28.

The correspondence between the character processing device of FIG. 1 and the document processing system of FIG. 2 will be described. The overall control unit 10 of FIG. 1 includes the CPU 21 and the ROM 22 of FIG. 2 and the output control unit 11 of FIG. Is the CPU 21 and the ROM 2 of FIG.
2, the font storage unit 5 in FIG. 1 is in the hard disk device 28 in FIG. 2, and the font cache memory unit 6 and page memory unit 7 in FIG. 1 are in the font cache memory 24 and page memory 25 in FIG. 2, respectively. Equivalent to. The character processing device of FIG. 1 functionally shows the state of the document processing system of FIG. 2 after startup.

Next, the management of the font cache memory unit 6 will be described.

FIG. 3 is a diagram for explaining the configuration of the font cache memory unit 6 and the cache data management system. In FIG. 3, the font cache memory unit 6 is
It has a character search table TA, a character management table TB, and a bitmap data storage area 40. The font cache memory unit 6 uses a FIFO (First In First Out) method as a cache data management method.

The character search table TA is used to know whether or not the character designated by the drawing command is registered in the font cache memory unit 6. The character search table TA stores a character code and a pointer that specifies the link destination of this character. When the registered character is represented by ASCII code, the ASCII code itself is stored as the search character code of the character search table TA, and in the case of the character of JIS 1st level or JIS 2nd level, these characters are stored. The lower byte of the character code is stored as the search character code in the character search table TA. Therefore, when the character search table TA is indexed by the search character code corresponding to a certain character, the pointer corresponding to this character is obtained, and the storage address of the search character in the character management table TB is obtained by the value of this pointer. can get. When the character corresponding to a certain search character code is not registered, the value of the pointer is set to "null (none)", and the corresponding character is registered in the font cache memory unit 6 by the value of this pointer. You can confirm that it has not been done.

The character management table TB is a table for holding the attributes of characters registered in the font cache memory, and is composed of a plurality of table groups for different characters. Here, the different characters include not only different character codes but also different typefaces, sizes, etc. even if the character codes are the same, and the character attributes are held as different tables. Then, the bitmap data of the character corresponding to each of these tables is individually stored in the bitmap storage area 40. That is, the character management table TB is a table for managing each character stored in the bitmap data storage area 40.

In FIG. 3, three tables TB1 to TB3 are shown as an example of the character management table TB. The tables TB1 and TB2 are the character search table T
The table TB3 is a table corresponding to the code "40" of A, and the table TB3 is a table corresponding to the code "48" of the character search table TA. Here, tables TB1 and T
B2 is "10 points" and "12 points" respectively
Corresponds to characters of different sizes.

Each table forming the character management table TB has eight entries. These eight entries are the "Next character code pointer (Code Next
CharPtr) ”,“ Previous character code pointer (Code Prev Cha
r Ptr), “Font”, “Code (Cod
e) ”,“ Char Size ”,“ Compress Flag ”,“ Bitmap pointer (Bitma
p Ptr) ”and“ Bitmap Size ”. "Next character code pointer" and "previous character code pointer" are tables that have the same code in the case of 1-byte code character and the same lower 1 byte in the case of 2-byte code character. It is a pointer for bidirectionally linking between. In the “font” entry, fonts of characters such as Gothic font and Mincho font are stored. The "character size" entry stores the size of the character indicated by the number of points. The character code is stored in the “code” entry. The “compression flag” entry includes the bitmap data storage area 4
A flag indicating whether or not the bitmap data stored in 0 is compressed data is stored. If the value of the flag is “TRUE”, the stored bitmap data is compressed. It indicates that the
"E)" indicates that the stored bitmap data is not compressed. The “bitmap pointer” indicates the address of the area of the bitmap data storage area 40 in which the bitmap data is stored. The “bitmap size” entry indicates the number of bytes on the memory occupied by the bitmap data in the bitmap data storage area 40. This "bitmap size" indicates the actual number of bytes, and when the "compression flag" is "true", it indicates the value of the compressed bitmap data.

Here, the character codes of the tables forming the character management table TB are the same (lower 1 byte).
The character table group is linked by the "next character code pointer" and the "previous character code pointer",
It is managed by the LRU (Latest Recently Used) method. That is, the table of the character whose reference time is the latest in the table group of the same character code is the head of the link (directly linked to the character search table TA),
The table of the character with the oldest reference time is managed as the end of the link. Therefore, the "next character code pointer" indicates the address of the character of the "next character code pointer" referenced at the next oldest time from the time when the character of the "next character code pointer" is referenced, and The "code pointer" indicates the address of the character of the "previous character code pointer" that was referenced one time before the time when the character of the "previous character code pointer" was referenced. Then, the address of the table itself at the head of the link becomes the same as the pointer of the code of the corresponding character in the character search table TA. The values of the "previous character code pointer" of the table at the beginning of the link and the "next character code pointer" of the table at the end of the link are "NULL" because there is no corresponding table. In the case of a table that does not have the same character code like the table TB3, there is no corresponding table for both the "next character code pointer" and the "previous character code pointer", so that the value is "NUL
It is "L".

The bit map data storage area 40 stores bit map data corresponding to each table constituting the character management table TB. Then, in the bitmap data area for each character, table pointers P1 to P3 that point to the corresponding tables in the character management table TB.
have. The table pointer makes it possible to refer to the corresponding table in the character management table TB, and when the bitmap data is deleted, the corresponding table is used to delete the corresponding table. The address of the area in which the bitmap data of each character is stored is indicated by the "bitmap pointer" in the character management table TB. Further, in the bitmap data storage area 40, a "top pointer (Top Ptr)" indicating the start address, a "bottom pointer (Bottom Ptr)" indicating the address of the last byte, and an address of an unused area of the bitmap data Has a "Free Ptr" indicating that the recording area is managed.

Next, an example of a drawing command for instructing the drawing of a document will be described.

FIG. 4 is a diagram showing an example of the drawing command. In the drawing command of FIG. 4, the drawing instruction of the document is described in the page description language. The page description language includes a position designation command, a font designation command, a character string drawing command, a page printing command, and the like. The position designation command is a command for designating the position where the drawing of the character string is started, and the font command command is a command for setting the font and size of the character drawn by the character string drawing command. The character string drawing command is a command for drawing a character string using the font (current font) set by the font command command with the latest processed time. The character string is a series of character codes, and the character code is a 1-byte or 2-byte code. The character string drawing command “character string drawing (3F26 3648)” in FIG. 4 instructs drawing of the two 2-byte codes (3F26) and (3648) expressed in hexadecimal. The page print command is a command to output image data for one page as output data D to an output device such as a printer. The page description language has various other commands, but the description thereof will be omitted.

Next, a character processing procedure of the character processing apparatus will be described.

FIG. 5 is an overall flowchart showing the overall processing procedure of the document processing system shown in FIG. In FIG. 5, the CPU 21 performs predetermined initialization at system startup (step 101) and maintains an idle state until a print request is input from the host workstation 27 (step 102). Step 10
When a print request is input in 2, the CPU 21 receives a drawing command from the host workstation 27 (step 103), and temporarily stores this drawing command in the RAM 23. Then, the CPU 21 activates the expansion processing program stored in the ROM 22 and performs expansion processing based on the temporarily stored drawing command to generate image data (bitmap data) for one page (step 104). ), The bitmap data for one page is stored in the page memory 25. Then, the bitmap data as the image data stored in the page memory 25 is transferred to the printer engine 31 via the printer interface 30 in page units, and is output.
The printer engine 31 prints out the transferred bitmap data (step 105). After that, it is determined whether or not the output of all the bitmap data indicated by the drawing command has been completed (step 106). When all the output has been completed, the process proceeds to step 104, and the process from the expansion process to the process described above is continued. repeat. On the other hand, if all the outputs are completed in step 106, step 1
The process shifts to 02, and the printer enters the idle state until the next print request is input from the host workstation 27.

Now, the expansion processing in step 104 will be described with reference to the flowchart of FIG. 6 and FIG.

FIG. 6 is a flowchart showing the expansion processing procedure in step 104 of FIG. In FIG. 6, the expansion processing unit 2 first reads one drawing command from the reception unit 1 (step 201). Then, it is determined whether the read drawing command is a page print command (step 20).
2) If the command is a page print command, step 1 in FIG.
Return to 04.

On the other hand, if it is determined in step 202 that it is not a page print command, it is further determined whether the read drawing command is a font designating command (step 20).
3) If the command is a font designation command, a process for updating the current font is performed (step 204) and the process proceeds to step 201.

If it is determined in step 203 that it is not a font designation command, it is further determined whether the read drawing command is a position setting command (step 205). If it is a position setting command, a character string is drawn. Perform the processing to update the position (current point) (step 20
6) and then to step 201.

If it is determined in step 205 that it is not a position setting command, it is further determined whether the read drawing command is a character string drawing command (step 207). If it is a character string drawing command, this character is drawn. A process of drawing a column is performed (step 208), and the process proceeds to step 201. If the command is not a character string drawing command, the process directly proceeds to step 201.

Next, the processing of the character string drawing command in step 208 will be described with reference to the flowchart shown in FIG.

In FIG. 7, first, the character code indicated by the character string drawing command is extracted (step 301). Here, if the current font has a 2-byte code system, 2 bytes are extracted, and if the current font is a 1-byte code system, 1 byte is extracted. Next, it is judged whether or not the extraction of the character code in step 301 has succeeded (step 302),
If it succeeds, a process of generating a bitmap of the character at the position of the current point is performed (step 303)
After that, a process of moving the current point by the width of the character string is performed (step 304), and the process proceeds to step 301. On the other hand, if the extraction of the character code is not successful in step 302, the process returns to step 208. In addition,
The character output process of step 303 will be described later.

In this way, the processing is repeated for each drawing command of the drawing commands constituting the drawing command, and the desired character string is output.

For example, in the case of the drawing command shown in FIG. 4, the first drawing command "position designation (100, 60
0) "is read, it is determined in step 205 that it is a position setting command, and in step 206, the process of setting the current point to the coordinate (100, 600) is performed. When the next font designation command "font designation (12 po, Gothic) is read, it is determined in step 203 that it is a font designation command, and in step 204 the process for setting the current font to 12-point Gothic is performed. The next character string drawing command "character string drawing (3F26
3648) ”is determined to be a character string drawing command in step 207, and character string drawing command processing is performed in step 208. That is, according to the procedure shown in FIG. 7, the first character code (3F26) in the character string drawing command is extracted (step 301), and the character code is successfully extracted (step 302). A process for outputting a map is performed (step 303),
The current point is moved by the character width (step 30)
4). After this process, the next character code (364
8) is taken out in step 301, character output processing is performed in the same manner, and the current point is moved by the character width. Then, since the extraction of the next character code fails (step 302), the process returns to step 208 and proceeds to step 201. Hereinafter, the position designation command “position designation (200, 600)”, the font designation command “font designation (12, Mincho)”, and the character string rendering command “character string rendering (4750)
4D25) ”and the like are read one by one according to the description order of the page description language, and the processing is executed.

Next, referring to the flowcharts of FIGS. 8 to 10 for the character output processing procedure of step 303, the character string drawing command “character string drawing (3F26 36
The character output process for the character code "3F26" of "48)" will be described as an example of the character output process.

FIG. 8 is a flow chart showing the character output processing procedure of step 303. First, the size and font name of the current font are acquired (step 40).
1). Here, as shown in FIG. 4, "character string drawing (3F26 3
648) ”, the current font size is“ 12 points ”and the font name of the current font is“ 12 points ”by executing the font designation command“ font designation (12, Gothic) ”. Gothic "
Is. Next, the character search table TA of the font cache memory unit 6 and the character management table TB are searched using the font name, size and character code as keys (step 402). Here, since no character is currently registered in the font cache memory unit 6, the search for the character code "3F26" fails. Then, in step 403, it is determined whether or not the search in step 402 is successful. If the search is successful, the process proceeds to step 408. If the search is unsuccessful, step 4 is performed.
Move to 04.

If the font cache memory unit 6 is successfully searched in step 403, it is determined whether the searched bitmap data is run-length compressed by referring to the "compression flag" in the character management table TB. Information is acquired (step 408), it is judged based on the acquired information whether or not it is run-length compressed (step 409), and if it is run-length compressed, it is a bitmap data storage area. The corresponding bit map data is taken out from 40, and the decompressed bit map data is transferred to the position on the page memory in the page memory unit 7 indicated by the current point, while being expanded by the compression / expansion unit 3 (step 410). And
The process returns to step 303. On the other hand, step 409
If it is determined that the file is not run length compressed,
The corresponding bitmap data is extracted from the bitmap data storage area 40, and the extracted bitmap data is stored in the page memory unit 7 indicated by the current point.
Transfer to a location on the page memory within (step 41
1). Then, the process returns to step 303.

On the other hand, if the search in the font cache memory unit 6 fails in step 403, the bit map data of this character is generated (step 40).
4). The detailed processing procedure of this bitmap data generation processing will be described with reference to the flowchart of FIG.

In FIG. 9, the expansion processing section 2 first reads the outline data from the font storage section 5 using the font name and character code as keys (step 501).
Here, in the case of character string drawing of the character code "3F26",
Outline data corresponding to the font name "Gothic" and the character code "3F26" is acquired. Next, processing for converting the acquired outline data into a designated size is performed (step 502). Here, in the case of the character code “3F26”, the coordinates of the acquired outline data are converted into a size of 12 points. Further, the size of the bitmap data after the expansion processing is calculated (step 503). The size can be calculated by the additional information of characters included in the acquired outline data. Here, the character code "3F2
In the case of 6 ", the bitmap data after the expansion processing is vertically 6
The size is 512 bytes with 4 dots and 64 dots horizontally. Thereafter, the expansion processing unit 2 determines the bitmap data storage area 40 of the font cache memory unit 6 based on the size of the bitmap data calculated in step 503.
Area is secured (step 504). And
In the secured area, the contour drawing section 2a draws the edge of the character based on the outline data coordinate-converted in step 502 (step 505). Here, FIG. 11 shows the result of the edge drawing processing in step 505 in the case of the character code “3F26”.
In FIG. 11, the edge of the character “work” with the character code “3F26” is drawn.

Next, when the edge drawing processing in step 505 is completed, the painting section 2b carries out the painting processing based on the drawn edges (step 50).
6). For the detailed procedure of this filling processing, see FIG.
A description will be given based on the flowchart.

First, referring to FIG. 15 and FIG. 16 before explaining the filling processing procedure, the data in the bitmap data storage area 40 of the font cache memory unit 6 and the bitmap image drawn from this data will be described. The relationship will be described.

FIG. 15 shows the bitmap data storage area 4
FIG. 16 is a diagram showing a data storage state at 0, and FIG.
It is a figure which shows the bitmap image drawn by the data of No. 5. FIG. 15 shows an actual data storage state, and shows, as a simple example, bitmap data after the edge drawing process of the character “H” of 16 × 16 dots is performed. This bit map data is converted from word address "E0000000" to word address "E
It is stored in the area up to 000001C ".
FIG. 16 shows an image of the bitmap data after the edge drawing process of the character “H” of 16 × 16 dots is performed.
It is shown as a dimensional array. The dot array in FIG. 16 is a two-dimensional array of a line index (Line Index) and a dot index (Dot Index).
It can be represented as [M, N], which allows the dot array to be represented as the Mth dot in the Nth line. For example, Dot [14,15] indicates the 14th dot of the 15th line. The bitmap data shown in FIG. 15 is sequentially stored in the order from the bottom to the top of the character “H” in the bitmap image after the edge drawing processing of the character “H” shown in FIG. 16. For example, the dot data (Dot [0,0] -D) of the bottom line of the bitmap image in FIG.
ot [15,0]) is "42" (indicating dot data of 01000010) and "42" (01000010) in hexadecimal notation in the first half of the area of the word address "E0000000" of the bitmap data shown in FIG. (Indicates the dot data of).

Now, FIG. 10 is a detailed flow chart showing the procedure of the filling process of step 506. This filling process uses the edge flag algorithm,
Filling processing is performed line by line from the lower part to the upper part of the character of the edge-mapped bitmap image, and from the left to the right of the character in the processing of each line.
Here, the filling process will be described by taking the above-mentioned character “job” whose font name is “Gothic” and whose character code is “3F26” as an example.

First, the variables necessary for performing the filling process are initialized (step 601). That is, the number of lines in the bitmap data LineNum, the number of dots per line DotPerLine, the start address Dot of the area secured in step 504, the number of bytes in the bitmap RawBy
te is initialized respectively. In the example of the character code “3F26”, LineNum = 64, DotPerLine = 64, Dot = For example, E000000
It is set as 0, RawByte = 514. Further, a predetermined counter variable is initialized (steps 602 and 603).
Here, as the counter variables, there are a variable i for counting the number of lines subjected to the filling processing, a variable ChangeNum for counting the change points of the bitmap, and a variable j for counting the number of dots subjected to the filling processing. The variable i is
The variable j is incremented every time the filling process for one line is performed, the variable j is initialized to "0" for each line, and incremented each time one dot is processed. The change point means a point where the values of adjacent dots are different.

Next, the exclusive OR of adjacent dots, that is, Dot [j + 1, i] = xor (Dot [j, i], Dot [j + 1, i]) is taken (step 604). As a result, it is determined based on the following equation whether or not the values of adjacent dots have different values (step 605). That is, the judgment is made based on Dot [j, i] = Dot [j + 1, i] ?. If the adjacent dots have the same value (equal to each other) in step 605, the variable Chan
Increment the value of geNum (step 606),
If the adjacent dots have different values (not equal to each other), the process proceeds to step 507 as it is.

Then, in step 607, the value of the variable j is reduced by 2 from the number of dots per line (DotPerLin
Determine whether it is less than or equal to the value of e-2). Where the variable j
Is less than or equal to the value of (DotPerLine-2) means that there are still dots to be filled. Therefore,
When it is determined in step 607 that the variable j is less than or equal to the value of (DotPerLine-2), the value of the variable j is incremented (step 608) and the process proceeds to step 604.

On the other hand, in step 607, the variable j is (DotPerLi
If it is judged that it is not less than the value of (ne-2), further variable i
Is less than or equal to the number of lines LineNum (step 609). Here, the fact that the variable i is equal to or less than the number of lines LineNum means that the number of lines to be filled still remains. Therefore, if it is determined in step 609 that the variable i is less than or equal to the number of lines LineNum, the variable i
Is incremented (step 610) and the process proceeds to step 603.

On the other hand, in step 609, the variable i is the number of lines L
If it is determined that it is not less than or equal to ineNum, it means that the filling process for all the lines is completed. Here, FIG. 12 shows a bitmap image obtained as a result of performing the filling processing on the bitmap image subjected to the edge drawing processing shown in FIG. 11.

Therefore, if it is determined in step 609 that the variable i is not equal to or less than the number of lines LinNum, run length encoding is performed based on the value of ChangeNum, which is the number of change points in the bitmap, and the value of LineNum, LineNum. The value of the total number of bytes RleByte required to store the bitmap data when the compression processing is performed is calculated by the following formula (step 6).
11). That is, RleByte = ChangeNum + LineNum is calculated.

Here, the compression processing by the run length coding will be described.

FIG. 13 shows an example of the data structure of one line when the compression processing by the run length coding is performed. In FIG. 13, it is assumed that the compression process by the run length encoding is performed for each line, and the data structure subjected to the compression process is the type of the dot pattern that appears first, that is, the first byte (black dot). If so, "1" is used as a flag, and if it is a white dot, "0") is used as a flag, and the number of consecutive dots of the same type is sequentially configured as data in the remaining bytes following this flag. For example, an example of the run-length compressed data shown in FIG. 13 is 62 of the bitmap image shown in FIG.
The data structure of the line (from the lower side of the character "Job") is shown. In this case, the compressed data of one line has a 4-byte structure. That is, since the first dot is a white dot, the first 1 byte is 1-byte data indicating "0", and the next 1 byte is 45 "dots" of white dots "0" in succession. 1-byte data indicating a value is stored. This indicates that the first 45 bits are white dots. Furthermore, in the next 1 byte, the black dot "1" changed from the white dot to the black dot is "4".
Indicates that the bits are continuous, and in the next 1 byte, a white dot "0" that has changed from a black dot to a white dot is "1".
It is shown to be 6 "consecutive.

Therefore, the value of the total number of bytes RleByte calculated in step 611 indicates the sum of the number of bytes ChangeNum for storing the number of change points in all lines and the number of bytes LineNum for storing the flags of each line. Therefore, the value of the total number of bytes RleByte indicates the number of bytes required to store the bitmap data.

Now, returning to FIG. 10, in step 612,
The determination unit 4 determines whether the value of the total byte count RawByte of the bitmap data when not compressed is smaller than the value of the total byte count RleByte of the bitmap data when compressed. As a result, when the value of the total number of bytes RawByte is smaller than the value of the total number of bytes RleByte, the value of the compression flag in the character management table TB is set to "true" (step 613), and the total number of bytes RawByte is set. Is the total number of bytes Rle
If the value is not smaller than the value of Byte, the value of the compression flag in the character management table TB is set to "false" (step 614), and the process returns to step 506. Here, in the case of the character code “3F26”, the value of the total number of bytes RawByte without compression is 512, and the value of the total number of bytes RleByte with compression is 733. It is determined that there is no effect, and the compression flag in the character management table TB is "false".
Is set to

Further, after returning to step 506, the process directly returns to step 404 in FIG. Then, in step 405, the bitmap data generated from the bitmap data storage area 40 in the font cache memory unit 6 is transferred to the position on the page memory in the page memory unit 7 indicated by the current point. Then, it is judged whether or not the compression flag is "true" (step 406). If the compression flag is "true", the bitmap data generated in the bitmap data storage area 40 is subjected to run length encoding. The compression process is performed (step 407) and the process returns to step 303. On the other hand, when the compression flag is not “true”, that is, “false” in step 406, the compression process is not performed by the run-length encoding, and the process directly returns to step 303.

In the case of the character code "3F26", since the compression flag is "false", the compression processing by the run length encoding is not performed, and the uncompressed bitmap data is the bitmap data. It is held in the storage area 40.

In the font cache memory unit 6, the bit map data generated by the expansion processing unit 2 or the bit map data further compressed by the run length coding by the compression / decompression unit 3 may be bit data in any case. It is held in the map data storage area 40. However, as described above, since the management method in the font cache memory unit 6 adopts the FIFO method, when there is no storage area to be stored, old bitmap data is automatically stored in the bitmap data storage area. The table in the character management table TB corresponding to the deleted bitmap data is deleted.

In this way, for example, the character code "3F"
The 26 "character is output, and the bitmap data generated in the font cache memory unit 6 is retained as it is, and is then reused.
The character code "3F26" does not become smaller than the case where the data amount is not compressed even if the compression process by the run length encoding is performed, and therefore the bitmap data that is directly expanded without the compression process is the bitmap data. Although the data is held in the data storage area 40, step 3 is similarly performed for the character code “3648” in the character string drawing command “character string drawing (3F26 3648)”.
A character output process is performed by 03.

That is, the outline of the character output process of the character "work" indicated by the character code "3648" is as follows.
In step 3, the process proceeds to the process shown in FIG.
In the processing of, the character code "3F26" is searched for, and the contents are the same. Also in the search process in step 403, the same character is not registered yet, so the search fails, and the process proceeds to step 404, and the process proceeds to the bitmap data generation process shown in FIG. In the judgment of step 612 in the filling processing of step 506 of this bitmap data generation processing, the value of the total byte number RleByte when the compression processing is performed is 390, which is smaller than the value 512 of the total byte number RawByte when the compression processing is not performed. Therefore, it is determined that the compression processing by the run length encoding has an effect, and the compression flag is set to “true” in step 613. After that, returning to FIG. 9 and FIG. 8, since the compression flag is set to “true” in step 407 of FIG. 8, the compression / expansion unit 3 performs the compression processing by the run length encoding, and this compression As a result, the processing result is stored and held in the bitmap data storage area 40 in the font cache memory unit 6.

Here, FIG. 14 shows the management state in the font cache memory unit 6 at the time when the processing of the character string drawing command "character string drawing (3F26 3648)" is completed.

In FIG. 14, the character search table TA2
The character string drawing command “character string drawing (3F26 364
8) ”indicates the character codes“ 3F26 ”and“ 364
"26" and "4", which are the lower 1 bytes of 8 ", respectively
8 "is registered, and tables TB21 and T in the character management table TB2 corresponding to these character codes, respectively.
B22 has been generated. Tables TB21 and TB2
No. 2 is not linked to each other because the bitmap data relating to the same character code is not stored in the bitmap data storage area 41. The table TB21 corresponds to the character code “3F26”, the compression flag is set to “false” as described above, and the bitmap size is set to the number of bytes “512” when compression processing is not performed. This 512-byte bitmap data is temporarily stored in the bitmap data storage area 41. On the other hand, the table TB22 corresponds to the character code “3648”, the compression flag is set to “true” as described above, and the bitmap size is the bitmap data compressed by the run length encoding. Are temporarily stored in the bitmap data storage area 41.

As described above, in the first embodiment described above, whether or not the effect of the compression processing by the run length coding is effective is determined based on the information sequentially obtained during the filling processing shown in FIG. The amount of data when compressed by length coding is predicted, and based on this predicted value, the effect of compression processing, that is, when it is determined that the amount of data does not decrease, compression processing of bitmap data after expansion processing If it is determined that the compression processing is effective without performing the compression, the compression processing of the bitmap data after the expansion processing is performed, and as a result, the storage of the bitmap storage area 40 in the font cache memory unit 6 is performed. The efficiency can be increased.

Next, the second embodiment will be described. In the first embodiment, the acquisition of information as a criterion for predicting whether or not to perform compression processing by run-length coding is acquired during the filling processing in the expansion processing, but in the second embodiment. Then, the acquisition of this information is to be acquired during the edge drawing processing (contour drawing processing) in the expansion processing.

The configuration of the second embodiment is similar to that of the first embodiment, but the operation processing of the expansion processing section 2 in the first embodiment is different. That is, the bitmap data generation process shown in the flowchart of FIG. 9 and the filling process shown in the flowchart of FIG. 10 are different. In particular, the edge drawing process in step 505 and the filling process in step 506 of FIG. 9 are different.

In the first embodiment, in step 505, only the edge drawing processing is performed, but in the second embodiment
In the embodiment of the present invention, along with this edge drawing process, a process of acquiring information (bitmap change point) for determining whether or not there is an effect of the compression process by the run length coding is performed in parallel. In addition, in the first embodiment, step 5
In 06, along with the filling process, the information for determining whether or not the compression process is effective is obtained by the run-length coding. However, in the second embodiment, the compression is already performed during the edge drawing process. Since the information for determining whether or not the processing is effective is acquired, only the filling processing is performed. In both the first embodiment and the second embodiment, the result information for determining the effect of the compression processing supplied to the determination unit 4 is the same result information.

Therefore, in the second embodiment, the same processing as in the first embodiment is performed until the character output processing shown in FIG. Therefore, the bitmap data generation process of step 404 in FIG. 8 will be described.

FIG. 17 is a flow chart showing a bitmap data generation processing procedure in the second embodiment corresponding to the flow chart of FIG. 17, steps 701 to 704 include steps 501 to 701 shown in FIG.
The same processing as 504 is performed.

In step 705, the bitmap data in which the edge of the character is drawn is stored in the reserved area in the bitmap data storage area 40 of the font cache memory unit 6. An example of the bitmap image resulting from the edge drawing process is as shown in FIG. At this time, the change point of the bitmap is measured together with the edge drawing process. The process of step 705 will be described in detail later.

Further, in step 706, the edge-drawn bitmap is filled. This filling processing is performed using the edge flag algorithm as in the first embodiment. However, as described above, only the filling process is performed. In step 506, that is, the change point of the bitmap shown in FIG. 10 is measured to calculate the predicted data amount when the compression process by the run length coding is performed. No processing is done.

Next, the edge drawing processing procedure in step 705 will be described with reference to the flowchart in FIG.

First, similarly to steps 601, 602 in FIG. 10, variables required for edge drawing processing are initialized (steps 801, 802). That is, the number of lines in the bitmap data LineNum, the number of dots per line D
otPerLine, the start address Dot of the area secured in step 504, and the byte count RawByte of the bitmap are initialized in step 801, respectively, and in step 802,
A variable ChangeNum that counts the change points of the bitmap is initialized to "0".

Thereafter, the drawing command is fetched (step 8
03), it is determined whether or not this drawing command is an end command (step 804), and if it is not the end command, it is further determined whether or not this drawing command is a curve drawing command (step 8).
05). If the drawing command is the end command in step 804, the process proceeds to step 812. This step 81
The case of shifting to 2 is the case where the edge drawing of one character is completed. The drawing command referred to here is a command for drawing a straight line or a curve indicated by a segment forming the outline data.

If it is determined in step 805 that it is not a curve drawing command, one straight line may be drawn, so the value of the variable Counter indicating the number of straight lines is set to "1" (step 807), and step 809 Move to. On the other hand, if it is determined in step 805 that the command is a curve drawing command, the corresponding curve is divided into a plurality of curves by a predetermined process (step 806), and the value of the number of the plurality of divided straight lines is calculated. Was set to the value of the variable Counter (step 8
After 08), the process proceeds to step 809. Then, in step 809, straight line drawing processing is performed. This straight line drawing process will be described in detail later, but at the time of this process, the value of the variable ChangeNum that counts the change points of the bitmap is measured.

When the straight line drawing process for one straight line is completed in step 809, the value of the variable Counter indicating the number of straight lines is set to "1".
Reduction processing (Counter = Counter-1) is performed (step 81).
0). Thereafter, it is determined whether or not the value of the variable Counter is larger than “0”, that is, whether or not a straight line remains (step 811). If a straight line remains, step 809
And the straight line drawing process is repeated. If no straight line remains, the process moves to step 803 and the drawing command for the next edge drawing is taken out and the above-described process is repeated.

On the other hand, if the drawing command is the end command in step 804, the variable Chan acquired in step 809
The value obtained by adding the value of geNum and the value of the number of lines LineNum is set as the value of the total number of bytes RleByte of the bitmap image expected when the compression processing by the run length encoding is performed (step 812). Then, the determination unit 4
Determines whether the value of the total number of bytes RleByte when compressed is smaller than the value of the total number of bytes RawByte when not compressed (step 813), and the total number of bytes when compressed
When it is determined that the value of RleByte is less than the total number of bytes of RawByte when not compressed, the character management table TB
Set the corresponding compression flag in each to "true" (step 8
14) If it is determined that the value of the total number of bytes RleByte when compressed is not smaller than the value of the total number of bytes RawByte when not compressed, set the corresponding compression flag in the character management table TB to “false”. (Step 815) and returns to step 705. As a result, when the subsequent filling process ends and the bitmap data corresponding to the final bitmap image is generated, step 81
4 or the compression flag is set by the run length encoding based on the compression flag set in step 815, or the compression process is not performed and the data is held in the bitmap data storage area 40 as it is.

Next, the straight line drawing processing procedure in step 809 will be described with reference to the flowchart shown in FIG. 19 and the diagram for explaining the edge drawing method shown in FIG.

First, referring to FIG. 20, a general edge drawing method will be described. Usually, a vector font such as an outline font is composed of a plurality of straight lines and a plurality of curves (a plurality of segments) that define the outline of a character. If it is a straight line segment, it has a flag indicating that the segment is a straight line, a start point coordinate, and an end point coordinate. Also, a curve segment also has a flag indicating the type of curve, start point coordinates, and end point coordinates. In the case of this curve, by dividing the drawn curve into a plurality of straight lines (step 808), all straight lines or segments of the curved line can be expressed as straight lines. It should be noted that circles and the like are also included in the curves, and by dividing these into a plurality of straight lines, all the curves can be expressed as straight lines. Therefore, the edge drawing of the character can be performed by performing the straight line drawing process.

FIG. 20 is a diagram for explaining this straight line drawing processing. As a straight line drawing algorithm, a horizontal scanning method (horizontal scanning method) is used. In the horizontal scan method, intersections CH1 to CH3 of the straight line L to be drawn and the half scan lines HY1 to HY3 in the Y direction are obtained in the puxel coordinate system shown in FIG.
When the intersections CH1 to CH3 are on the right side (X direction) of the half scan line in the X direction of the pixel including the intersection, a pixel adjacent to this pixel on the right side, for example, P1 is selected as a pixel forming an edge. , If the intersection is not on the right side of the half-scan line in the X direction of the pixel including this intersection (in the center of the pixel or in the −X direction), this pixel is set as, for example, pixels P2 and P3 that form an edge. As a result, the edge of the character is drawn as a straight line by the pixels P1 to P3.

Next, the process based on this straight line drawing algorithm and the process of measuring the value of the variable ChangeNum of the change point which is performed at the same time will be described in detail with reference to the flowchart of FIG. First, for each of the X coordinate and Y coordinate of the starting point and the X coordinate and Y coordinate of the ending point of the target straight line,
The value obtained by adding 0.5 is converted into an integer, and the integerized values are obtained as StartX, StartY, EndX, and EndY, respectively (step 901). That is, StartX = Integer (start point X coordinate + 0.5) StartY = Integer (start point Y coordinate + 0.5) EndX = Integer (end point X coordinate + 0.5) EndY = Integer (end point Y coordinate + 0.5) In addition, the absolute value of the difference between EndY and StartY is the distance Le
It is defined as ngth, and the value obtained by dividing the difference between EndX and StartX by the distance Length is defined as the difference DX of X, EndY and StartY
The difference DY of Y is "1" if the difference is positive, "0" if 0, and "-1" if negative. That is, Length = Abs (EndY-StartY) DX = (EndY-StartY) / Length DY = Sign (EndY-StartY) is obtained. Note that Sign (X) is a function that returns "1" if X is positive, "0" if X is 0, and "-1" if X is negative.

Next, the difference D of Y obtained in step 902
It is determined whether X is 0 (step 903). And
If the difference DY of Y is 0, step 80 is left as it is.
Return to 9. This is because the straight line drawing algorithm uses the horizontal scanning method, and therefore, if the distance of the Y component of the straight line is not present, it is not necessary to process.
On the other hand, when the difference DY of Y is not 0, the value X obtained by further adding the value StartX to the value obtained by multiplying the difference DX of X by 0.5 is obtained, and the value obtained by multiplying Sign (DY) by 0.5 is obtained. A value Y obtained by adding StartY is obtained (step 904). Then, the variable i required for the iterative process is initialized and set to "0" (step 9).
05), it is determined whether or not the variable i is less than or equal to the value of the distance Length (step 906). As a result, the variable i is the distance Len
If it is less than or equal to gth, the process directly returns to step 809. On the other hand, if the variable i is not equal to or less than the distance Length, the value IX obtained by rounding up the decimal point of the value X and the value IY obtained by rounding down the decimal point of the value Y are obtained, and Dot [X, Y] is set to "1", and the change point The value of the variable ChangeNum that counts the number of is incremented (step 907). That is, IX = Ceil (X) IY = Floor (Y) Dot [X, Y] = 1 ChangeNum = ChangeNum + 1. Ceil (X) is a function that rounds up the decimal point of X, and Floor (X) is a function that rounds down the decimal point of X.

After that, the value X is updated to the value obtained by adding the difference DX of X, and the value Y is updated to the value obtained by adding the difference DY of Y (step 908), and the variable i is incremented (step 908). 909), and moves to step 906,
The number of change points associated with edge drawing is measured.

When the measurement of the value of the number of change points, ChangeNum, is completed, the process returns to step 809, and it is finally determined in steps 812 to 815 whether or not there is a compression effect, and the compression flag is set accordingly. Then, only those having a compression effect will be compressed.

As described above, in the second embodiment, unlike the first embodiment, the number of change points is measured at the same time as the edge drawing processing by the contour drawing section 2a, and the number of change points is measured. Based on the result, it is determined whether or not there is a compression effect as compared with the bitmap data after the filling process, and the same effect as the first embodiment can be obtained.

In the second embodiment, it is possible to determine whether or not the compression process is effective before performing the filling process for generating the final bitmap image. Since the compression processing is possible, the overall character processing efficiency is further improved as compared with the first embodiment.

Next, application examples common to the first and second embodiments will be described. In this application example, the judgment criteria of step 612 in the first embodiment and step 813 in the second embodiment are changed.

That is, step 612 by the judgment unit 4
Alternatively, the determination in step 813 is performed by simply calculating the total number of bytes of predictive bitmap data RleByt
e is compared with the total number of bytes of bitmap data, RawByte, when compression processing is not performed, and based on this judgment result,
The compression flag is set so that the compression process is performed only when the total number of bytes RleByte is smaller than the total number of bytes RawByte.

Therefore, in the first application example, step 61
2 or the criterion in step 813 is determined by the following equation. That is, the determination unit 4 makes a determination based on RleByte + E1 <RawByte. Where E1 is
It is a positive integer and indicates the threshold value of the number of bytes that is reduced by compression. For example, if the total number of bytes when compression processing is performed is "390" and the total number of bytes when compression processing is not performed is "514", and the value of the threshold E1 is "100", 390
Since +100 <512 ”is satisfied and the condition is satisfied, compression processing will be performed. However, when the value of the threshold value E1 is “200”, “390 + 200 <512” is satisfied, and the condition is not satisfied, so that the compression process is not performed.

That is, in the first application example, the threshold value E1 is provided so that the compression process is performed only when the number of bytes reduced by the compression process is equal to or larger than the predetermined number of bytes.

This case is especially effective when the font cache memory has a sufficient memory capacity.

Next, the second application example will be described. In the second application example, the total number of bytes RleB when compressed
The judgment criterion is set so that yte is equal to or less than a predetermined absolute threshold value E2. In this case, it is assumed that the value of the total number of bytes RleByte when compressed is less than the total number of bytes RawByte when not necessarily compressed. Therefore, a criterion is set so as to satisfy the following logical expression. That is, set RleByte <RawByte and RleByte <E2.

According to the second application example, the compression process reduces the data amount as compared with the data amount when the compression process is not performed, and the data amount after compression processing (total number of bytes) is smaller than the threshold value E2. In this case, it can be determined that the compression processing was effective.

Next, a third application example will be described. Thresholds E1 and E2 in the first application example or the second application example
Respectively indicate the number of bytes, but in the third application example, the threshold value E3 with no dimension, which is a ratio number, is used.
Is set as the criterion value. That is, when the ratio of the value of the total number of bytes RleByte when the compression process is performed to the value of the total number of bytes RawByte when the compression process is not performed is smaller than the threshold value E3, it is determined that the compression process is effective. . That is, when RleByte / RawByte <E3 is satisfied, it is determined that the compression processing has been effective. In this case, the value of the threshold value E3 is set to a real number less than or equal to 1. For example, if the threshold value E3 is set to "0.5", the compression process is performed when the data amount becomes less than half by the compression process. .

As described above, according to the third application example, the threshold value E3 indicating the reduction rate of the data amount when the compression process is performed with respect to the case where the compression process is not performed is used, and the compression process is performed with respect to the data amount when the compression process is not performed. In this case, the relative compression effect can be used as a criterion.

Next, a fourth application example will be described. The values of the threshold values E1 to E3 set by the first to third application examples are
Although the fixed threshold value is set in advance in the character processing device, in the fourth application example, the values of these threshold values E1 to E3 can be made variable at the time of document processing.

For example, when the character processing device is started up, since no characters are registered in the font cache memory, the memory area is empty. Therefore, immediately after starting up the character processing device,
Many characters can be registered in the font cache memory. Therefore, when the character processing device is started up, for example, the value of the threshold value E1 is set to a large value, and the threshold value is set as the time elapsed after the character processing device starts up, that is, the registration state in the font cache memory becomes dense. The threshold value E1 at which the stable state is finally reached may be set as a fixed threshold value thereafter, so that the value of E1 can be set to be small. That is, an attempt is made to improve the memory efficiency of the font cache memory by making the maximum use of the characteristic that the registered state of the font cache memory is a transitional state that changes significantly with the passage of time from the startup of the character processing device. It is a thing.

Further, regardless of the passage of time, the above thresholds E1 to E3 are made variable according to the character registration state of the font cache memory, so that the finite memory capacity is optimally utilized to the maximum. Character registration may be possible. In other words, if the memory has a small amount of free space, the threshold is variably set so that the compression process can be performed if there is even a small amount of compression effect. The threshold value that enables compression processing is variably set. As a result, when there is a relatively large free area in the memory, the compression processing is not performed, so the time for performing the compression processing is reduced and the processing speed of the entire document processing is improved. In addition, when the free space in the memory is small, the compression process is relatively large, so the number of characters registered in the font cache memory increases, so the hit ratio of the characters registered in the font cache memory increases. This also improves the processing speed of the entire document processing. Of course, a means for detecting the character registration state of the font cache memory is required in order to be able to variably set the threshold value regardless of the passage of time. This detection processing may be performed by the expansion processing unit 2 or the overall processing unit 10.

In the fourth application example, the threshold value is set with the passage of time or the registered state of characters in the font cache memory. A setting unit that can arbitrarily set the values of the threshold values E1 to E3 in the application example may be provided, or a selection unit that selects any one of the threshold values E1 to E3 may be provided. . Furthermore, a changing means for changing the variable setting may be provided according to the fourth application example. Further, an instruction means for instructing an appropriate combination of the first application example to the fourth application example may be provided. For example, after the character processing device is started up, a predetermined time indicates a variably set threshold value according to the fourth application example, and then, a fixed threshold value E1 according to the first application example or a fixed threshold value according to the third application example. E3 can be directed.

The threshold values in the first to fourth application examples described above are optimal depending on the character hit ratio and the time required for compression processing, the storage capacity of the font cache memory, and the type of document. The threshold varies, and this threshold can be obtained by experience or simulation.

The edge drawing processing in the above-mentioned first and second embodiments performs edge drawing in the horizontal direction (X direction), and based on the result of this edge drawing, the filling processing is also performed in the horizontal direction. However, the edge drawing process is performed in the vertical direction (Y direction) without being limited to this.
Alternatively, a vector font expansion method in which the filling process is performed in the vertical direction may be adopted.

In particular, in the first and second embodiments,
Although the effect of the compression processing by the run length encoding in the horizontal direction (X direction) of the character is determined, in the first and second embodiments, the vector font expansion method in the vertical direction (Y direction) is adopted. In that case, the effect of the compression process can be determined by run length encoding in the vertical direction of the character.

Further, in the first and second embodiments, the total number of bytes when the compression processing by the run length coding for each line is performed, the effect of the compression processing is determined, and the compression processing is performed. However, the total number of bytes after compression processing when each line is regarded as continuous data instead of each line and run length encoding is performed, and the effect of compression processing is judged based on this total number of bytes. When performing compression processing, each line may be subjected to run-length coding compression that considers continuous data. In this case, the number of the first byte required for each line, that is, the flag indicating whether the first dot is "1" or "0" is only one as a whole, and the data amount after the compression processing by the run length encoding is It has the effect of further reducing.

[0137]

As described above in detail, in the first aspect, whether the determination means should compress the expanded dot format data based on the expansion information sequentially acquired in the expansion processing. Determine whether or not. When the determination means determines that the compression should be performed, the control means causes the compression means to perform the compression processing of the dot format data determined by the determination means, and stores the compressed data in the temporary storage means. Let On the other hand, when the determination means determines that the compression should not be performed, the control means stores the dot format data determined by the determination means in the temporary storage means as it is.

Therefore, the information necessary for determining the compression processing is
It is acquired at the same time as the decompression process, and since it is not necessary to actually perform the compression process to determine whether or not the compression process is effective, the time required for the compression process determination is reduced and the overall document processing is improved. In addition to speeding up, only the characters that have the effect of compression processing are compressed, so the memory efficiency of the temporary storage means, which is the font cache memory, is improved and the character hit rate is also improved. This has the advantage of speeding up the general document processing.

In the second invention, the expansion information in the first invention is sequentially acquired during the filling process in the expansion process, that is, during the filling process.

Therefore, there is an advantage that it is not necessary to actually perform the compression process to determine whether or not the compression process is effective, and the time required for the determination of the compression process is reduced.

In the third invention, the expansion information in the first invention is sequentially acquired during the contour drawing process in the expanding process, that is, during the contour drawing process.

Therefore, similarly to the second invention, there is an advantage that the time required for determining the compression processing is reduced.

Particularly, the contour drawing process in the third invention is
This is a process performed before the filling process, which is the final expansion process to dot format data, and it is possible to determine whether or not the compression process is effective when the contour drawing process is completed. There is an advantage that the compression processing of the characters having the effect of the processing can be performed at the same time and the time required for the compression processing can be reduced.

In the fourth invention, the expansion information is the number of change points of the dot format data and the data amount of the dot format data in the process of the expansion processing, and the compression processing is performed based on this specific data amount. The effect of can be determined.

In the fifth invention, the data amount of the dot format data in the fourth invention is the number of lines of the dot format data and the number of dots per line, and based on this more specific data amount It is possible to determine the effect of the compression process.

In the sixth invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. When it is equal to or larger than a reference value indicating a predetermined reduction amount with respect to the data amount of, the compression unit determines that compression is to be performed, and when the determination unit determines that compression is to be performed, the control unit applies the dot format data to the compression unit. A compression process is performed, and the compressed data is stored in the temporary storage means. Further, when the determination means determines that the compression should not be performed, the control means performs control to store the dot format data as it is in the temporary storage means, thereby flexibly determining the target to be compressed. It can be carried out.

In the seventh invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is a reference value indicating a predetermined data amount. In the following cases, the compression means determines that the compression means should be compressed, and when the determination means determines that the compression means should be compressed, the dot format data is compressed by the compression means, and the compressed data is processed. It is stored in the temporary storage means. Further, when the determination means determines that the compression should not be performed, the control means performs control to store the dot format data as it is in the temporary storage means,
As a result, it is possible to flexibly determine the target to be compressed.

In the eighth invention, the judging means calculates a predicted data amount when compressed by the compressing means based on the expansion information, and the predicted data amount is the dot format data after the expansion processing. If the determination means determines that the compression is to be performed, and the determination means determines that the compression is to be performed, the dot format data is compressed by the compression means. The compressed data is processed and stored in the temporary storage means. Further, when the determination means determines that the compression should not be performed, the control means performs control to store the dot format data as it is in the temporary storage means, thereby making it possible to flexibly determine the compression processing. You can

In the ninth invention, the reference value in the sixth invention to the eighth invention is changed based on the free storage area state of the temporary storage means. Therefore, by flexibly changing the reference value, the temporary storage means can be utilized to the maximum, and in particular, the storage area of the temporary storage means is an empty area in the initial state, which is effective.

In the tenth aspect of the invention, the compression means compresses the dot format data by performing run-length encoding, and by doing so, a specific compression process can be performed.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of a character processing device that is a first embodiment of the present invention.

FIG. 2 is a diagram showing a hardware configuration of a document processing system including the character processing device shown in FIG.

FIG. 3 is a diagram illustrating a configuration of a font cache memory unit 6 and a cache data management system.

FIG. 4 is a diagram showing an example of a drawing command.

5 is an overall flowchart showing an overall processing procedure of the document processing system shown in FIG.

FIG. 6 is a flowchart showing the expansion processing procedure in step 104.

FIG. 7 is a flowchart showing a processing procedure of a character string drawing command in step 208.

FIG. 8 is a flowchart showing a character output processing procedure of step 303.

FIG. 9 is a flowchart showing a detailed processing procedure of bitmap data generation processing.

FIG. 10 is a flowchart showing a detailed procedure of a filling process.

FIG. 11 is a diagram showing an example of a result of edge drawing processing in step 505.

12 is a diagram showing a bitmap image obtained as a result of performing a filling process on the bitmap image subjected to the edge drawing process shown in FIG.

FIG. 13 is a diagram showing an example of a data configuration of one line when a compression process by run-length coding is performed.

FIG. 14 is a character string drawing command “character string drawing (3F263
648) ”is finished, the diagram shows the management state in the font cache memory unit 6.

FIG. 15 is a diagram showing a data storage state in the bitmap data storage area 40.

16 is a diagram showing a bitmap image drawn by the bitmap data shown in FIG.

FIG. 17 is a flowchart showing the procedure of bitmap data generation processing in the second embodiment.

FIG. 18 is a flowchart showing an edge drawing processing procedure in step 705.

FIG. 19 is a flowchart showing a straight line drawing processing procedure in step 809.

FIG. 20 is a diagram illustrating an edge drawing method.

[Explanation of symbols]

1 ... Reception unit 2 ... Expansion processing unit 2a ... Contour drawing unit 2b
... Filling section 3 ... Compression / expansion section 4 ... Judgment section 5 ... Font storage section 6 ... Font cache memory section 7 ... Page memory section 10 ... Overall control section 11 ... Output control section 12 ... Storage section C ... Drawing command
D ... Output data

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Claims (10)

[Claims] 1. When the vector format data indicating a figure such as a character is expanded into dot format data and the expanded dot format data is output to an output device, the dot format data expanded into a temporary storage means. In the character processing device for temporarily storing the dot format data and reusing the dot format data, it is determined whether the expanded dot format data should be compressed based on the expansion information sequentially acquired in the expansion process. Judgment means for judging, compression means for compressing the dot format data, and when the judgment means judges that the data should be compressed, the compression means is caused to perform compression processing of the judged dot format data and the compression processing When the determination means determines that the compressed data should not be compressed, the determined dot format data is stored in the temporary storage means. A character processing device, comprising: a control unit that performs control for storing the data in a column. 2. The character processing apparatus according to claim 1, wherein the expansion information is sequentially acquired during a filling process. 3. The character processing apparatus according to claim 1, wherein the expansion information is sequentially acquired during the contour drawing process. 4. The expansion information is the number of change points of dot format data and the data amount of the dot format data in the process of the expansion processing. Character processing unit. 5. The data amount of the dot format data is
The character processing device according to claim 4, wherein the number of lines of dot format data and the number of dots per line are included. 6. The determination means calculates a predicted data amount when compressed by the compression means based on the expansion information, and the predicted data amount corresponds to the data amount of the dot format data after the expansion processing. 2. The character processing device according to claim 1, wherein when it is equal to or larger than a reference value indicating a predetermined reduction amount, it is determined that the compression means should compress. 7. The determination means calculates a predicted data amount when compressed by the compression means based on the expansion information, and when the predicted data amount is equal to or less than a reference value indicating a predetermined data amount. The character processing device according to claim 1, wherein the compression unit determines that the character should be compressed. 8. The determination unit calculates a predicted data amount when compressed by the compression unit based on the expansion information, and the predicted data amount corresponds to the data amount of the dot format data after the expansion processing. The character processing device according to claim 1, wherein the compression unit determines that the compression should be performed when the value is equal to or larger than a reference value indicating a predetermined reduction rate. 9. The character processing device according to claim 7, wherein the determination unit changes the reference value based on a free storage area state of the temporary storage unit. 10. The character processing device according to claim 1, wherein the compression means compresses the dot format data by performing run length encoding.