JPH0627923A - Outline font conversion processing method - Google Patents

Abstract

PURPOSE:To increase the probability of a cache hit to reduce a rasterizing process, and to improve the processing speed by utilizing bit map data stored in a cache memory for mutually symmetrical characters. CONSTITUTION:When bit map data 16-1 on an outline font 15-1 which is already converted in past are stored in the cache memory 9, no converting processing is not performed for an outline font 15-2 which is currently requested to be printed and the symmetry conversion of symmetrical bit map data 16-1 read out of the cache memory 9 is performed to obtain new bit map data 16-2. Consequently, a cache hit is made even when symmetrical characters are used in addition to a case wherein the same character is used frequently, and the printing speed can be made fast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outline font conversion processing method for obtaining bitmap data when a character or a graphic is displayed on a printer or a display using an outline font.

[0002]

2. Description of the Related Art When displaying characters or graphics on a printer or a display, an outline font is used for high-quality printing. FIG. 2 shows an explanatory diagram of a general outline font conversion process. The outline font is composed of data representing a figure corresponding to the outline of a character by its vertices and line segments connecting the vertices. When an actual print request is made, the original outline font data 1 shown in this figure is subjected to reduced coordinate conversion and converted into a new outline font 2 having the size of the character to be printed. After that, the portion surrounded by the contour line is painted out to obtain the bitmap data 3. The bitmap data 3 is supplied to the print head for printing, or is supplied to the display for displaying characters.

FIG. 3 shows a block diagram of a conventional general printing apparatus. When the outline font as described above is used, the printing apparatus has such a block structure. This apparatus is composed of a print data buffer 6, an outline font memory 7, an arithmetic processing unit 8, a cache memory 9, a print data buffer 10 and a printer 11, which are connected to a bus line 5, for example. Print data buffer 6
Is a memory for storing a character code, a control code, and the like transferred from the host device. The outline font memory 7 is a memory for storing the outline fonts of all characters required for printing. Arithmetic processing unit 8
Is composed of an arithmetic circuit that obtains bitmap data from outline font data by performing the arithmetic processing shown in FIG. The cache memory 9 stores the most recently converted bitmap data,
This is a memory for increasing the printing speed of characters by omitting the conversion processing for characters that are frequently required to be converted. The print data buffer 10 is a memory for temporarily storing the converted bitmap data for transfer to the printer 11. The printer 11 is composed of a device which sequentially reads bitmap data from the print data buffer 10 and prints on the paper.

FIG. 4 shows a conventional outline font conversion processing flowchart. The apparatus as described above converts the outline font into bitmap data according to the following procedure. In step S1, when there is a first outline font conversion request, it is first determined whether or not any bit map data is already stored in the cache memory 9. For example, immediately after the start of printing, no data is stored in the cache memory 9. In such a case, the process proceeds to step S3. Also,
If the printing operation is already in progress, some bitmap data is stored in the cache memory 9. At this time, in step S2, it is determined whether or not the outline font to be arithmetically processed is already stored in the cache memory 9 as bitmap data. If the font is an outline font that is converted for the first time, the process proceeds to step S3.

Then, in step S3, the outline font data is read out, and in step S4, rasterization processing for converting this into bitmap data is performed. Then, the bitmap data is written to the cache memory 9 (step S
5). On the other hand, if it is determined in step S2 that the bitmap data has already been stored in the cache memory 9, the process proceeds to step S6, and the corresponding bitmap data is read from the cache memory 9. Then, the bitmap data obtained in step S6 or step S5 is used for character output in step S7.

[0006]

By the way, the conversion processing for obtaining the bitmap data from the outline font as described above requires a corresponding processing time. Therefore, store the recently used bitmap data in the cache memory, and if there is a so-called cache hit, skip the outline font conversion process and immediately obtain the bitmap data to speed up the process. I have to. However, there is a limit to the amount of bitmap data that can be stored in the cache memory as described above. Further, when the same character is not repeatedly printed, the effect of providing the cache memory is reduced. Therefore, when there are few cache hits, it takes a long time to print characters, which affects the throughput of the entire apparatus.

The present invention has been made by paying attention to the above points, and makes it possible to use the bitmap data stored in the cache memory for mutually symmetrical characters, thereby increasing the probability of a cache hit. It is an object of the present invention to provide an outline font conversion processing method that reduces rasterizing processing and improves processing speed.

[0008]

According to the outline font conversion processing method of the present invention, when the bitmap data obtained by converting the outline font is used, the bitmap data of a predetermined amount of character used immediately before is used. Is temporarily stored in the cache memory, and when a new outline font conversion processing request is made for the character corresponding to the bitmap data stored in the cache memory, the conversion processing is omitted and the cache memory The outline font of the characters other than the bitmap data stored in the cache memory is read and used from the corresponding bitmap data from
When a new outline font conversion processing request is made, it is judged whether the bitmap data of the character symmetrical to the character is stored in the cache memory, and the bitmap data of the symmetrical character is stored. If so, the bitmap data is read from the cache memory, the read bitmap data is symmetrically converted, and new bitmap data is obtained and used.

[0009]

With this method, if the bitmap data of the outline font that has already been converted in the past is stored in the cache memory, the conversion process is not performed for the outline font requested to be printed this time. Symmetric conversion is performed on the symmetrical bitmap data read from the cache memory to obtain new bitmap data. This causes a cache hit not only when the same character is frequently used but also when a symmetrical character is used, which reduces the rasterizing process and increases the printing speed.

[0010]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is an explanatory diagram showing an embodiment of an outline font conversion processing method of the present invention. The present invention is generally carried out as follows. First, the outline font 15-1 is converted to obtain bitmap data 16-1. The bitmap data 16-1 is used for printing and is stored in the cache memory 9 in preparation for repeated use of the same character. Such storage in the cache memory 9 is repeated until the capacity of the cache memory 9 is full, and the oldest ones are expelled.

Here, when the conversion processing is requested for the new outline font 15-2 this time, it is first determined whether or not the bitmap data for the same outline font is stored in the cache memory 9. If it is not stored, it is next determined whether or not symmetrical bitmap data is stored. If symmetrical bitmap data is stored, it is read out and subjected to symmetry conversion processing. As a result, new bitmap data 16-2 is obtained. That is, in this case, the conversion process is omitted for the outline font 15-2 of this time, and the new bitmap data 16-2 is generated.
Is used for printing.

FIG. 5 shows an example of mutually symmetrical characters suitable for carrying out the method of the present invention. (A) is a list of symmetrical characters, and (b) is a list of vertically symmetrical characters. That is, for example, “(” and “)” are often used in combination in general. At this time, only the bitmap data of "(" is stored in the cache memory, and the bitmap data of ")" is immediately necessary without using the original outline font by the symmetric conversion described later. To get Characters of this nature are usually used in relatively large numbers, and a list of them is created in advance to carry out the method of the present invention.

FIG. 6 shows an example of a table referred to when carrying out the method of the present invention. (A) is a symmetric character code conversion table. Further, (b) is an explanatory diagram of a cache table. As shown in (a) of the figure, this table is composed of an original character code 21, a symmetrical character code 22 and a symmetrical direction 23. In the example shown in Fig. 5, for example, ")" is the character code of the original character code 21 and "(" is the character code of the symmetrical character code 22, and the symmetry direction 23 includes data that means left-right symmetry. The easy symmetric data is vertically symmetric or horizontally symmetric as shown in Fig. 5. Therefore, the data corresponding to the symmetry direction 23 is, for example, "1" for left-right symmetry and "0" for up-down symmetry. 1-bit data is acceptable.

In the cache table shown in (b),
The character code 24 of the bitmap data stored in the cache memory is stored. That is, by referring to these tables, it is possible to immediately determine whether or not the outline font for which the conversion process is requested is already stored in the cache memory with the symmetrical bitmap data. .

The method of the present invention is carried out after preparing the table data as described above. FIG. 7 shows a flowchart for determining whether or not the conversion process is necessary when starting the method of the present invention. In addition,
The device for carrying out the method of the present invention may have the same structure as the conventional device as already shown in FIG. Then, the operation program has contents as shown in FIGS. 7 and 8. In FIG. 7, first, it is determined whether the read print data corresponds to character data, that is, a character code or other control code (step S1). Here, if it is not the character code but the control code or the like, the process proceeds to step S2, and a predetermined command process is executed. This process corresponds to, for example, a page break or line feed process. On the other hand, when the processing target is a character code, the rasterizing process of step S3 to be described below is started.

FIG. 8 shows a flowchart of the outline font conversion processing method of the present invention. In the present invention, the rasterizing process is executed according to the procedure shown in this figure. First, steps S1, S2, S3, and S4 are the same contents as steps S1, S3, S4, and S5 described above with reference to FIG. 4, and steps S5 and S6 in FIG. 8 have already been described with reference to FIG. The processing is the same as that of steps S2 and S6. That is, in step S1, it is determined whether or not any bitmap data is stored in the cache memory. If no such bitmap data is stored, the process proceeds to step S2 and outline font data is read. Then, in step S3, the rasterizing process is executed. Further, in step S4, the bitmap data is written in the cache memory. Then step S12
At, printing is performed using the bitmap data.

On the other hand, if it is determined in step S1 that some bit map data is stored in the cache memory, the process proceeds to step S5 and it is determined whether or not bit map data of the corresponding character is stored in the cache memory. To do. This is determined by referring to the cache table as shown in FIG. Here, if there is a so-called cache hit, the process proceeds to step S6, the corresponding bitmap data is read from the cache memory, and the character output in step S12 is performed. On the other hand, if there is no cache hit in step S5, the process proceeds to step S7. The steps from step S7 onward are the characteristic parts of the method of the present invention.

That is, in step S7, the symmetric character code conversion table shown in FIG. 6A is referred to for the character code to be converted. Then, it is determined here whether there is a symmetrical character. When there is no symmetrical character, the process proceeds to step S2, and the rasterizing process similar to the conventional one is performed. On the other hand, if a symmetric character is found by referring to the symmetric character code conversion table, the process proceeds to step S8, and this time, it is determined whether or not the symmetric character is stored in the cache memory.

In this case, a new symmetric character code 22 is called by referring to the symmetric character code conversion table with the character code of the character to be converted as the original character code. The symmetric character code will be used to refer to the cache table. If there is no hit when referring to the cache table again as described above, the process proceeds to step S2. If a hit occurs, the process proceeds to step S9, where the bitmap data stored in the cache memory is left-right or up-down target. Determine if it's the one. This determination is made by the symmetric character code conversion table shown in FIG. That is, by referring to the data in the symmetry direction 23 of the symmetric character code conversion table, it is determined whether the symmetry is vertical or symmetric. Here, in the case of vertical symmetry, the process proceeds to step S10, and the bitmap data is vertically inverted. If left-right symmetrical, step S1
Moving to 1, the horizontal inversion process is performed. As a result, bitmap data corresponding to the relevant outline font is obtained. After that, the process proceeds to step S4, the bitmap data is written in the cache memory, and the character is output in step S12. By performing such processing, not only when the cache hit occurs as the same character code, but also when the symmetrical character is cache hit, the rasterizing process is omitted.

9 and 10 are explanatory views of a method for the inversion process, that is, the symmetric conversion process. First, what is stored in the cache memory is bitmap data 30-1 shown on the left side of FIG. Then, what is required is the bitmap data 30-2 shown on the right side of FIG. Here, it is assumed that one bit map data is composed of a 10 × 10 matrix. In this case, the process is executed line by line from the top. Since this kind of data processing is performed in units of 16 bits, 6 bits of unnecessary bits are present on the right side of the 10-bit data 31-1 of the bitmap data, as shown in the figure. When this is divided into 4 bits and displayed in hexadecimal notation, it becomes "0C00" as shown in the processing of FIG. This is stored in the 16-bit register GR1. This corresponds to Step 1 of the processing of FIG.

Here, in the processing, the data stored in the register GR1 is shifted to the right by an unnecessary bit. As a result, the content of the register GR1 becomes "0".
In the next process of changing to 030 ″, the register GR
The contents of 1 are shifted by 1 bit from Step 1 to Step 6. In Step 1 of the process, 0-bit shift, that is, data that has not been shifted is used. Further, in Step 2 of the processing, the data shifted by 1 bit is used. Therefore, in Step 6 of the process, data shifted by 5 bits is used.

In Step 1 of the process, the data of the register GR1 obtained in Step 1 of the process is copied to the register GR2. Further, in the processing, the data stored in the register GR2 and the data “0001” are ANDed. As a result, the LSB, that is, the value of the least significant bit is obtained. Next, in the process, the contents of the register GR2 obtained in the process are shifted to the left by 15 bits. Then, after that, the contents of the register GR2 and the contents of the register GR3 are ORed. This is processing. The contents of the following processes are changed from Step 1 to S while shifting the contents of the register GR1 by 1 bit in the process.
Repeat until step 6. In addition, in the example shown in this figure,
The content of the register GR2 obtained in the processing is Ste
Since all of p1 to Step4 are 0, processing,
Since it does not make sense to perform, the operation is omitted.

Therefore, although only the results of Step 5 and Step 6 are valid, the contents of the register GR3 obtained in Step 5 of the process and the contents of the register GR2 obtained in the process are ORed to perform the process just in Step 6. Data that is symmetrical to the data shown in
C00 ″ is obtained. This is the data 31-2 in FIG. 9. In this way, 1 of the bitmap data is obtained.
Inversion processing is performed on the rows, unnecessary bits are added to the right side, and new bitmap data is generated. This process is executed for 10 lines from top to bottom. The inversion process as described above enables extremely simple high-speed processing. Therefore, the entire printing speed is improved as compared with the case where the bitmap data is obtained from the outline font.

The present invention is not limited to the above embodiments. The configuration of the table that determines the symmetrical character code and the direction of symmetry, or the configuration of the cache table may be changed to various configurations that achieve the same effect. Further, as the symmetrical characters, in addition to left-right symmetry and up-down symmetry, for example, point-symmetrical characters and figures such as Japanese """and""" that are symmetrical with respect to a line at an angle of 45 degrees are also available. In addition, the inversion process may use the well-known digital data conversion process of this type in addition to the method described in FIG.

[0025]

According to the outline font conversion processing method of the present invention described above, the conversion processing from the outline font to the bitmap data is executed before, and the bitmap data once stored in the cache memory is
Not only the same outline font conversion process but also the symmetrical outline font conversion process can be omitted, and the bitmap data can be obtained by a simple calculation process. Therefore, the probability of a so-called cache hit increases, the calculation time for print processing and display processing is shortened, the total processing time can be shortened, and the throughput can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of an outline font conversion processing method of the present invention.

FIG. 2 is an explanatory diagram of general outline font processing.

FIG. 3 is a block diagram of a general printing apparatus.

FIG. 4 is a conventional outline font conversion processing flowchart.

FIG. 5 shows symmetrical characters suitable for the method of the invention,
(A) is an example of left-right symmetrical characters, and (b) is an example of vertically symmetrical characters.

FIG. 6 shows a table used for judgment in carrying out the method of the present invention, (a) is a symmetric character code conversion table,
(B) shows a cache table.

FIG. 7 is a flowchart for determining whether or not a conversion process is necessary when performing the method of the present invention.

FIG. 8 is a flowchart of an outline font conversion processing method embodiment of the present invention.

FIG. 9 is an explanatory diagram (part 1) of the symmetric conversion process by the method of the present invention.

FIG. 10 is an explanatory view (No. 2) of the symmetric conversion processing by the method of the present invention.

[Explanation of symbols]

 15-1 Outline font used last time 15-2 Outline font used this time 16-1 Bit map data 16-2 New bit map data 9 Cache memory

Claims (1)

[Claims] 1. When using bitmap data obtained by converting an outline font, bitmap data of a predetermined amount of character used immediately before is temporarily stored in a cache memory, and the bitmap data is stored in the cache memory. When a new outline font conversion processing request is made for the character corresponding to the stored bitmap data, the conversion processing is omitted and the corresponding bitmap data is read from the cache memory and used. If there is a new outline font conversion request for an outline font of characters other than the bitmap data stored in memory, is the bitmap data of the character symmetrical to that character stored in the cache memory? Judgment is made, and the symmetric character bit When the bitmap data is stored, the bitmap data is read from the cache memory, the read bitmap data is symmetrically converted, and new bitmap data is obtained and used. Outline font conversion processing method.