JP2013169763A - Image forming apparatus, and character drawing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of improving utilization efficiency of a memory, regarding a font cache.SOLUTION: An MFP (Multifunction Peripheral) secures a font cache on a RAM individually in accordance with a font type of characters, a font size and resolution (S134), and when a bit map image of the characters is stored in the font cache (S140; YES), the bit map image is acquired from the font cache (S137), and an expansion unit as a unit for expanding the font cache is determined in accordance with the font size of the characters, the resolution and a number of kinds of the characters (S133), and when a capacity for storing the bit map image of the characters does not remain in an unused part of the font cache (S142; NO), the font cache is expanded by the expansion unit (S143).

Description

  The present invention relates to an image forming apparatus that utilizes a font cache, which is an area on a memory that temporarily stores a bitmap image of a drawn character.

  2. Description of the Related Art Conventionally, as an image forming apparatus that uses a font cache, an apparatus that secures a font cache having a fixed size in advance and stores a bitmap image of characters in the font cache is known (see Patent Document 1). ).

JP-A-10-202963

  However, in the conventional image forming apparatus, since a font cache having a fixed size is secured in advance, an unnecessarily large area may be secured as the font cache, and there is a problem that the memory usage efficiency is poor. .

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of improving the use efficiency of a memory with respect to a font cache.

  The image forming apparatus of the present invention is a memory, a character drawing unit that draws a bitmap image of characters included in print data, and an area that temporarily stores the bitmap image drawn by the character drawing unit. Cache management means for managing a font cache, wherein the cache management means secures the font cache separately on the memory according to at least the typeface and font size of the characters, and the character drawing means includes: When the bitmap image of the character is stored in the font cache, the bitmap image is acquired from the font cache, and the cache management unit sets an extension unit that is a unit for extending the font cache as the font. Decide at least according to size The cache management unit expands the font cache by the expansion unit when a capacity for storing the bitmap image drawn by the character drawing unit does not remain in an unused part of the font cache. It is characterized by.

  With this configuration, the image forming apparatus according to the present invention is configured in an appropriate expansion unit corresponding to at least the font size of the character when the capacity for storing the bitmap image of the character does not remain in the unused portion of the font cache. Since the font cache can be expanded, unnecessary expansion of the font cache in the memory can be suppressed. Therefore, the image forming apparatus according to the present invention can improve the use efficiency of the memory with respect to the font cache.

  The cache management unit of the image forming apparatus of the present invention may release the unused portion of the font cache before expansion when expanding the font cache.

  With this configuration, when the font cache is expanded, the image forming apparatus of the present invention releases the unused portion of the font cache before expansion, so that it is possible to further improve the memory use efficiency with respect to the font cache.

  The cache management means of the image forming apparatus of the present invention separately secures the font cache on the memory at least further according to the resolution of the character, and the cache management means at least further according to the resolution. The extension unit may be determined.

  With this configuration, the image forming apparatus according to the present invention can expand the font cache in an appropriate expansion unit at least further according to the resolution of the character, so that it is possible to further improve the memory use efficiency with respect to the font cache.

  Further, the cache management unit of the image forming apparatus of the present invention sets the expansion unit at least further according to the number of types of the characters to be stored in the same font cache among the characters included in the print data. You may decide.

  With this configuration, the image forming apparatus of the present invention expands the font cache by an appropriate expansion unit at least further according to the number of character types to be stored in the same font cache among the characters included in the print data. Therefore, the memory use efficiency can be further improved with respect to the font cache.

  The character drawing program of the present invention is a character drawing program executed by an image forming apparatus provided with a memory, and includes a character drawing step for drawing a bitmap image of characters included in print data, and the character drawing step. A cache management step for managing a font cache, which is an area for temporarily storing the rendered bitmap image, and the cache management step according to at least a typeface and a font size of the character. Securing the font cache separately on the memory, and the character drawing step, when the bitmap image of the character is stored in the font cache, stores the bitmap image from the font cache. Take The cache management step is a step of determining an expansion unit, which is a unit for extending the font cache, according to at least the font size, and the cache management step is rendered by the character rendering step. When the capacity for storing the bitmap image does not remain in an unused part of the font cache, the font cache is expanded by the expansion unit.

  With this configuration, the image forming apparatus that executes the character drawing program of the present invention at least responds to the font size of the character when the capacity for storing the bitmap image of the character does not remain in the unused portion of the font cache. Since the font cache can be expanded by an appropriate expansion unit, it is possible to suppress unnecessary expansion of the font cache in the memory. Therefore, the image forming apparatus that executes the character drawing program of the present invention can improve the memory use efficiency with respect to the font cache.

  The printer driver of the present invention is a printer driver for generating the print data transmitted to the image forming apparatus, and should be stored in the same font cache among the characters to be included in the print data A character type calculating step for calculating the number of character types for each font cache, and a print data generating step for generating the print data including information on the number of character types calculated by the character type calculating step. And having a computer execute.

  With this configuration, the computer that executes the printer driver according to the present invention allows the print data transmitted to the image forming apparatus to include the types of characters to be stored in the same font cache among the characters scheduled to be included in the print data. Since the number information is included, the font cache can be expanded in the image forming apparatus by an appropriate expansion unit corresponding at least to the number of character types to be stored in the same font cache among the characters included in the print data. .

  The image forming apparatus of the present invention can improve the use efficiency of the memory with respect to the font cache.

1 is a block diagram of a network system according to an embodiment of the present invention. FIG. 2 is a block diagram of the MFP shown in FIG. 1. It is a figure which shows an example of the kind of font cache shown in FIG. It is a figure which shows the function of the control part shown in FIG. It is a block diagram of PC shown in FIG. It is a flowchart of operation | movement of PC shown in FIG. 5 in the case of transmitting print data. FIG. 6 is a diagram showing an example of the number of character types calculated by the character type calculating unit shown in FIG. 5. 3 is a flowchart of the operation of the MFP shown in FIG. 2 when drawing a character. FIG. 5 is a diagram illustrating an example of an expansion unit table determined by the cache management unit illustrated in FIG. 4. FIG. 3 is a diagram showing an example of print data printed on a recording medium by the MFP shown in FIG. 2. (A) is a diagram showing a state of a font cache secured by the MFP shown in FIG. FIG. 11B is a diagram illustrating a state of the font cache after FIG. (C) is a diagram showing a state of the font cache after FIG. 11 (b). FIG. 12D is a diagram showing a state of the font cache after FIG. (A) is a figure which shows the state of the font cache after FIG.11 (d). FIG. 13B is a diagram illustrating a state of the font cache after FIG. (C) is a diagram showing a state of the font cache after FIG. 12 (b). 3 is a flowchart of the operation of the MFP shown in FIG. 2 when a font cache expansion unit is determined for each print data.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the network system according to the present embodiment will be described.

  FIG. 1 is a block diagram of a network system 10 according to the present embodiment.

  As shown in FIG. 1, the network system 10 includes an MFP (Multifunction Peripheral) 20 as an image forming apparatus and a PC (Personal Computer) 50 that is a computer external to the MFP 20. The MFP 20 and the PC 50 are connected to be communicable with each other via a network 11 such as a LAN (Local Area Network).

  FIG. 2 is a block diagram of the MFP 20.

  As shown in FIG. 2, the MFP 20 is a display device such as an operation unit 21 that is an input device such as buttons for inputting various operations by the user and an LCD (Liquid Crystal Display) that displays various information. Fax communication via a display unit 22, a printer 23 that is a printing device that prints an image on a recording medium such as paper, a scanner 24 that is a reading device that reads an image from a document, and a communication line such as a public telephone line A fax communication unit 25 that is a fax device that performs communication, a network communication unit 26 that is a network communication device that performs communication via the network 11, and an EEPROM (Electrically Erasable Programmable Read On) that stores various data. y Memory), an HDD (Hard Disk Drive) storage unit 30 is a storage device such as, and a control unit 40 which controls the entire MFP 20.

  The storage unit 30 stores a character drawing program 31 for drawing characters. The character drawing program 31 may be installed in the MFP 20 at the manufacturing stage of the MFP 20, may be additionally installed in the MFP 20 from a storage medium such as a USB (Universal Serial Bus) memory, an SD memory card, or the network 11. It may be additionally installed in the MFP 20 from above.

  The control unit 40 includes, for example, a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42 that stores programs and various data, and a RAM (RAM) as a memory of the present invention used as a work area of the CPU 41. Random Access Memory) 43. The CPU 41 is configured to execute a program stored in the ROM 42 or the storage unit 30.

  The RAM 43 can store a plurality of font caches 43a, which are areas for temporarily storing bitmap images drawn by a character drawing means 40a described later.

  FIG. 3 is a diagram illustrating an example of the type of the font cache 43a.

  As shown in FIG. 3, the font cache 43a is stored in the RAM 43 separately according to the typeface of characters such as Arial and Courier, the font size of characters such as 12 points and 16 points, and the resolution of characters such as 300 dpi and 1200 dpi. Secured. The font cache 43a includes information on the typeface, font size, and resolution of the characters to be stored in the header, and is determined based on the information.

  FIG. 4 is a diagram illustrating functions of the control unit 40.

  As shown in FIG. 4, the control unit 40 executes a character drawing program 31 stored in the storage unit 30, thereby drawing a character drawing unit 40a for drawing a bitmap image of characters included in the print data, and It functions as a cache management means 40b for managing the font cache 43a, which is an area for temporarily storing the bitmap image drawn by the character drawing means 40a.

  FIG. 5 is a block diagram of the PC 50.

  As shown in FIG. 5, the PC 50 includes an operation unit 51 that is an input device such as a mouse and a keyboard for inputting various operations by a user, and a display unit 52 that is a display device such as an LCD that displays various information. A network communication unit 53 that is a network communication device that performs communication via the network 11, a storage unit 60 that is a storage device such as an HDD that stores various data, and a control unit 70 that controls the entire PC 50. I have.

  The storage unit 60 stores a printer driver 61 for controlling printing in the MFP 20.

  The printer driver 61 may be installed in the PC 50 at the manufacturing stage of the PC 50, or may be additionally installed in the PC 50 from a storage medium such as a USB memory, a CD (Compact Disc), a DVD (Digital Versatile Disc), or the like. Alternatively, it may be additionally installed on the PC 50 from the network 11.

  The control unit 70 includes, for example, a CPU, a ROM that stores programs and various data, and a RAM that is used as a work area of the CPU. The CPU is configured to execute a program stored in the ROM or the storage unit 60.

  The control unit 70 executes the printer driver 61 stored in the storage unit 60 to thereby determine the number of types of characters to be stored in the same font cache 43a (hereinafter ““ Character type calculation means 70a for each font cache 43a, and print data generation means for generating print data including information on the number of character types calculated by the character type calculation means 70a. It functions as 70b.

  Next, the operation of the network system 10 will be described.

  The user can instruct the PC 50 to print an image on the MFP 20 via the operation unit 51 of the PC 50. Upon receiving this instruction, the control unit 70 of the PC 50 executes the process shown in FIG.

  FIG. 6 is a flowchart of the operation of the PC 50 when printing data is transmitted.

  As shown in FIG. 6, the character type calculating unit 70 a of the control unit 70 of the PC 50 determines the type of character to be stored in the same font cache 43 a among characters scheduled to be included in the print data transmitted to the MFP 20. The number, that is, the number of character types is calculated for each font cache 43a (S101). That is, the character type calculating unit 70a determines how many characters having the same typeface, font size, and resolution combination are to be included in the print data transmitted to the MFP 20, based on the typeface, font size, and resolution. Calculate for each combination.

  FIG. 7 is a diagram illustrating an example of the number of character types calculated by the character type calculating unit 70a.

  In the process of S101, the character type calculating unit 70a calculates the number of character types as shown in FIG. 7, for example.

  As shown in FIG. 6, the print data generation unit 70b of the control unit 70 of the PC 50 generates print data including information on the number of character types calculated in S101 after the process of S101 (S102). The print data is described in a page description language such as PCL XL, PCL 5e, PCL 5c, PostScript.

  Next, the control unit 70 transmits the print data generated in S102 to the MFP 20 (S103), and ends the processing shown in FIG.

  Upon receiving print data from the PC 50, the control unit 40 of the MFP 20 generates an image based on the print data and prints this image on a recording medium. Here, when the print data includes characters, the control unit 40 draws the characters when generating the image.

  FIG. 8 is a flowchart of the operation of the MFP 20 when drawing a character.

  As shown in FIG. 8, the control unit 40 of the MFP 20 targets the first character among the characters included in the print data (S131).

  Next, the cache management unit 40b of the control unit 40 determines whether or not the font cache 43a for the currently targeted character (hereinafter referred to as “target character”) exists in the RAM 43, and the font and font of the character. A determination is made based on the size and resolution (S132).

  When the cache management unit 40b determines in S132 that the font cache 43a for the target character does not exist on the RAM 43, the expansion unit, which is a unit for expanding the font cache 43a, is set to the font size and resolution corresponding to the font cache 43a. It is determined according to the number of character types (S133). Note that the cache management unit 40b determines the number of character types corresponding to the font cache 43a based on the information on the number of character types included in the print data.

  Here, since the data size of the character bitmap image is larger as the font size of the character is larger, the cache management unit 40b preferably increases the expansion unit as the font size of the character is larger. Further, since the data size of the character bitmap image is larger as the character resolution is higher, it is preferable that the cache management unit 40b increases the expansion unit as the character resolution is higher. Further, the larger the number of character types included in the print data, the larger the required capacity in the corresponding font cache 43a. Therefore, the cache management unit 40b increases the expansion unit as the number of character types included in the print data increases. It is preferable to enlarge it.

  FIG. 9 is a diagram showing an example of an expansion unit table determined by the cache management unit 40b.

  In the process of S133, the cache management unit 40b determines an expansion unit using, for example, a table as shown in FIG.

  As shown in FIG. 8, the cache management unit 40b of the control unit 40 of the MFP 20 secures the font cache 43a for the extended unit determined in S133 on the RAM 43 for the target character after the process of S133 (S134). .

  Next, the character drawing unit 40a of the control unit 40 draws a bitmap image of the target character (S135).

  Next, the character drawing unit 40a stores the bitmap image of the target character in the font cache 43a for the target character (S136).

  Next, the character drawing unit 40a acquires a bitmap image of the target character from the font cache 43a on the RAM 43 (S137).

  Next, the control unit 40 determines whether or not all characters included in the print data are targeted (S138).

  If the control unit 40 determines in S138 that all characters included in the print data have been processed, the process illustrated in FIG. 8 ends.

  On the other hand, when the control unit 40 determines in S138 that any character included in the print data is not the target, the control unit 40 targets the next character after the target character among the characters included in the print data. (S139), the process returns to S132 again.

  When determining in S132 that the target character font cache 43a exists on the RAM 43, the cache management unit 40b determines whether or not the target character bitmap cache 43a is stored in the target character font cache 43a. (S140).

  When it is determined in S140 that the bitmap image of the target character is stored in the font cache 43a for the target character, the character drawing unit 40a executes the process of S137.

  If it is determined in S140 that the bitmap image of the target character is not stored in the font cache 43a for the target character, the character drawing unit 40a draws the bitmap image of the target character (S141).

  Next, the cache management unit 40b determines whether or not the capacity for storing the bitmap image drawn in S141 remains in the unused portion of the font cache 43a for the target character (S142).

  If it is determined in S142 that the capacity for storing the bitmap image of the target character remains in the unused portion of the font cache 43a for the target character, the character drawing unit 40a executes the process of S136.

  When the cache management unit 40b determines in S142 that the capacity for storing the bitmap image of the target character does not remain in the unused portion of the font cache 43a for the target character, the cache management unit 40b sets the font cache 43a for the target character in S133. Expansion is performed in the determined expansion unit (S143).

  The cache management unit 40b releases the unused portion of the font cache 43a before expansion in S143 for the font cache 43a for the target character (S144). That is, the cache management unit 40b optimizes the font cache 43a for the target character.

  The control unit 40 executes the process of S136 after the process of S144.

  FIG. 10 is a diagram illustrating an example of print data printed on the recording medium by the MFP 20.

  All the characters included in the print data shown in FIG. 10 have a typeface of Arial, a font size of 12 points, and a resolution of 1200 dpi. In the print data shown in FIG. 10, the number of character types is 26 when the typeface is Arial, the font size is 12 points, and the resolution is 1200 dpi.

  When the print data transmitted from the PC 50 to the MFP 20 is, for example, the print data shown in FIG. 10, when there is no font cache 43a for characters having a typeface of Arial, a font size of 12 points, and a resolution of 1200 dpi, In the process shown in FIG. 8, the MFP 20 targets “A”, which is the first character among the characters included in the print data (S131).

  Next, in S132, the MFP 20 determines that the font cache 43a for the target character does not exist in the RAM 43, and determines the expansion unit of the font cache 43a for the target character as 16 KBytes based on the table shown in FIG. (S133).

  Next, as shown in FIG. 11A, the MFP 20 secures a font cache 43a for 16 KBytes as an expansion unit on the RAM 43 for the target character (S134).

  Next, after rendering the bitmap image of “A” as the target character (S135), the MFP 20 stores the bitmap image of the target character in the font cache 43a for the target character as shown in FIG. 11B. (S136).

  Next, after the process of S137, the MFP 20 determines in S138 that any character included in the print data is not the target, and among the characters included in the print data, the next character of the target character is determined. One character “A” is targeted (S139).

  Next, after determining in S132 that the font cache 43a for the target character exists on the RAM 43, the MFP 20 determines in S140 that a bitmap image of the target character is stored in the font cache 43a for the target character. Then, after the process of S137, it is determined in S138 that any character included in the print data is not the target, and one character next to the target character among the characters included in the print data is determined. "B" is targeted (S139).

  Next, after determining in S132 that the font cache 43a for the target character exists in the RAM 43, the MFP 20 determines in S140 that the bitmap image of the target character is not stored in the font cache 43a for the target character. Then, a bitmap image of “B” as the target character is drawn (S141).

  Next, the MFP 20 determines in S142 that the capacity for storing the bitmap image of the target character remains in the unused portion of the font cache 43a for the target character, and as shown in FIG. The bitmap image of the target character is stored in the font cache 43a for the target character (S136).

  Next, after the process of S137, the MFP 20 determines in S138 that any character included in the print data is not the target, and among the characters included in the print data, the next character of the target character is determined. One character “C” is targeted (S139).

  Thereafter, until “E” becomes the target character, it is the same as the case of “B” described above, so the description is omitted. When “E” becomes the target character, the font cache 43a for the target character is as shown in FIG.

  When “E” is set as the target character in S139, the MFP 20 determines in S132 that the font cache 43a for the target character exists in the RAM 43, and then the bitmap image of the target character in the font cache 43a for the target character. Is stored in S140, and a bitmap image of “E” as the target character is drawn (S141).

  Next, the MFP 20 determines in S142 that the capacity for storing the bitmap image of the target character does not remain in the unused portion of the font cache 43a for the target character, and as illustrated in FIG. The font cache 43a for the target character is expanded with 16 Kbytes as an expansion unit (S143).

  Next, as shown in FIG. 12B, the MFP 20 releases the unused portion of the font cache 43a before expansion in S143 for the font cache 43a for the target character (S144).

  Next, as shown in FIG. 12C, the MFP 20 stores the bitmap image of the target character in the font cache 43a for the target character (S136).

  Next, after the process of S137, the MFP 20 determines in S138 that any character included in the print data is not the target, and among the characters included in the print data, the next character of the target character is determined. One character "F" is targeted (S139).

  The subsequent steps are the same as in the case of “B” or “E” described above, and thus description thereof is omitted.

  As described above, when the capacity for storing the bitmap image of the character does not remain in the unused portion of the font cache 43a (NO in S142), the MFP 20 determines the character font size, the character resolution, In addition, since the font cache 43a can be expanded in an appropriate expansion unit corresponding to the number of character types (S143), it is possible to suppress unnecessary expansion of the font cache 43a on the RAM 43. Therefore, the MFP 20 can improve the use efficiency of the RAM 43 with respect to the font cache 43a as compared with the conventional case.

  In addition, since the MFP 20 can expand the font cache 43a by an appropriate expansion unit corresponding to the font size of the character, the character resolution, and the number of character types, compared to a configuration in which the expansion unit is too small, It is difficult for a situation in which the capacity for storing the bitmap image does not remain in the unused portion of the font cache 43a. Therefore, the MFP 20 can reduce the number of executions of the processes of S143 and S144 compared to a configuration in which the expansion unit is too small. Therefore, the MFP 20 can improve the performance of the printing process and reduce the fragmentation of the RAM 43 as compared with the configuration in which the expansion unit is too small.

  By executing the printer driver 61, the PC 50 includes the information on the number of character types in the print data transmitted to the MFP 20 (S101, S102), so the font cache is stored in the MFP 20 in an appropriate expansion unit corresponding to the number of character types. 43a can be expanded.

  The MFP 20 determines an expansion unit not only according to the character font size but also according to the character resolution and the number of character types (S133). The unit may be determined, the font size of the character, and the expansion unit according to only the character resolution may be determined, the font size of the character, and the character type The extension unit corresponding to only the number may be determined.

  When the font cache 43a is expanded (S143), the MFP 20 releases the unused portion of the font cache 43a before expansion (S144), so that the usage efficiency of the RAM 43 can be further improved with respect to the font cache 43a.

  Note that the MFP 20 may not execute the process of S144.

  In the process shown in FIG. 8, when the MFP 20 determines in S132 that the font cache 43a for the target character exists in the RAM 43, the MFP 20 does not determine the expansion unit of the font cache 43a (S133). However, the MFP 20 may determine the expansion unit of the font cache 43a for each print data.

  FIG. 13 is a flowchart of the operation of the MFP 20 when determining the expansion unit of the font cache 43a for each print data.

  The process shown in FIG. 13 is the same as the process shown in FIG. 8 except for the processes of S161 and S162.

  As shown in FIG. 13, when the cache management unit 40b of the control unit 40 of the MFP 20 determines in S132 that the font cache 43a for the target character exists in the RAM 43, the font cache for the target character in this print data. It is determined whether or not the expansion unit 43a has been determined (S161).

  If the cache management unit 40b determines in S161 that the expansion unit of the font cache 43a for the target character has not been determined in this print data, the cache management unit 40b determines the expansion unit of the font cache 43a for the target character as in S133 (S162). ).

  In S161, the cache management unit 40b determines that the expansion unit of the font cache 43a for the target character has been determined in the print data, or when the processing of S162 is finished, the bitmap of the target character is stored in the font cache 43a for the target character. It is determined whether an image is stored (S140).

  The computer of the present invention is a PC in this embodiment, but may be a computer other than a PC.

  The image forming apparatus of the present invention is an MFP in the present embodiment, but may be an image forming apparatus other than the MFP, such as a dedicated printer.

20 MFP (image forming apparatus)
31 Character drawing program 40a Character drawing means 40b Cache management means 43 RAM (memory)
43a Font cache 50 PC (computer)
61 Printer Driver

Claims (6)

A memory and a character drawing means for drawing a bitmap image of the character included in the print data;
Cache management means for managing a font cache, which is an area for temporarily storing the bitmap image drawn by the character drawing means,
The cache management means secures the font cache separately on the memory according to at least the typeface and font size of the character,
The character drawing means obtains the bitmap image from the font cache when the bitmap image of the character is stored in the font cache;
The cache management means determines an extension unit, which is a unit for extending the font cache, according to at least the font size;
The cache management means extends the font cache by the extension unit when the capacity for storing the bitmap image drawn by the character drawing means does not remain in an unused part of the font cache. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the cache management unit releases the unused portion of the font cache before expansion when the font cache is expanded. The cache management means secures the font cache separately on the memory according to at least further the resolution of the character,
The image forming apparatus according to claim 1, wherein the cache management unit determines the extension unit at least further according to the resolution.   The cache management unit determines the extension unit at least further according to the number of types of the characters to be stored in the same font cache among the characters included in the print data. The image forming apparatus according to claim 1. A character drawing program executed by an image forming apparatus provided with a memory,
A character drawing step for drawing a bitmap image of characters included in the print data;
Causing the image forming apparatus to execute a cache management step of managing a font cache, which is an area for temporarily storing the bitmap image drawn by the character drawing step,
The cache management step is a step of securing the font cache separately on the memory according to at least the font and font size of the character,
The character drawing step is a step of obtaining the bitmap image from the font cache when the bitmap image of the character is stored in the font cache;
The cache management step is a step of determining an extension unit, which is a unit for extending the font cache, according to at least the font size;
The cache management step is a step of expanding the font cache by the expansion unit when a capacity for storing the bitmap image drawn by the character drawing step does not remain in an unused part of the font cache. A character drawing program characterized by being. A printer driver for generating the print data transmitted to the image forming apparatus according to claim 4,
The character type calculating step for calculating the number of types of the characters to be stored in the same font cache among the characters scheduled to be included in the print data, and the character type calculating step. A printer driver that causes a computer to execute a print data generation step for generating the print data including information on the number of types of the characters.

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