JPH0553557A - Character data generation device - Google Patents

Abstract

PURPOSE:To hold more character shape data within the same capacity and to generate characters of an outline font which can be processed at a high speed. CONSTITUTION:A character generating means 2 reads necessary data regarding corresponding characters out of outline font data 3 according to the specification of character codes and performs arithmetic processing to generate a group of picture elements. Picture element data generated by the character shape generating means 2 are outputted to an output device 1 and written in a storage device 4. At this time, if the storage device 4 has no free area, picture element data on characters which are low in frequency of use among picture element data in the storage device 4 are taken out and picture element data on a character which is outputted last are recorded in the storage device 4 instead. The taken-out picture element data are compressed by a compressing means 5 and recorded in another storage device 7. At a request for character output to an output device 1, data are read out of a compressive storage area when the character code matches a character whose data are recorded in the compressive storage area; and the data are expanded into the original shape, outputted to the output device 1, and written in a noncompressive storage area again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a character data generating device on a printing device and a display device, and more particularly to an outline font generating means.

[0002]

2. Description of the Related Art A character whose outer shape is described by using a straight line or a curved line, and which forms a character shape by pixels included in an area closed by the outer shape curve or a broken line is called an outline font. Outline font is
The generation method does not depend on the pixel resolution of the output device,
It is also easy to perform processing such as deformation and rotation. Therefore, in recent years, it has been widely used in printing devices for personal word processors and personal computers.

FIG. 7 shows an example of a device configuration used in a conventional outline font generating means. In this example, the display device 1 is used as a character output device.
As the outline font data 3, data such as the coefficient term of the equation of the external curve and the type of curve to be used is stored in the semiconductor R.
It is stored in a storage device such as OM. Using this data, the character generation means 2 generates a pixel group forming a character shape. The generated pixel group is sent to the display device 1 for display, but after the display, the unnecessary pixel data is not immediately discarded but is temporarily recorded in the storage device 4. As the storage device 4, a device such as a semiconductor RAM capable of reading at a relatively high speed is used. In such a configuration, if the character requested to be displayed next to the display device is a character that has already been displayed, pixel data may remain in the storage device 4. If pixel data remains in the storage device 4, it is possible to display characters without using the character shape generating means 2. Conventionally, the storage device 4 is configured to have a capacity capable of holding pixel data corresponding to a few hundreds to a thousand characters. In addition, when new pixel data is written, if the upper limit of the capacity is already reached, the data of the less frequently used character is discarded instead.

[0004]

In general, the character shape generating means 2 often requires a long processing time. Therefore, it is necessary to reuse the character pixel data generated in the past as much as possible. In the case of Japanese processing, it is necessary to handle about 7,000 Kanji and Kana characters, but the number of frequently used characters is limited. Therefore, in the conventional example shown in FIG. 7, the more character data that can be stored in the storage device 4, the more advantageous the processing speed. However, the pixel data temporarily stored by using the storage device 4 has already been converted into pixels in conformity with the resolution of the output device (display device 1 in the example of FIG. 7). For this reason, a large character consumes more memory.
Also, as the resolution of the output device increases, more memory is consumed with a smaller number of characters. For example, when outputting a character having a size of 0.2 inch to an output device having 75 pixels per inch, about 1 is stored in a memory having a capacity of 32 kbytes.
Pixels corresponding to 090 characters can be recorded. However, if a display device with 300 pixels per inch is used, even if the same 0.2-inch size character is used, 32 kbyte
The memory of the capacity of e can record pixels of about 70 characters. As described above, in order to improve the processing speed, it is advisable to store the data regarding as many characters as possible in the storage device 4. Therefore, in a high-density output device, it is desired that the capacity of the storage device 4 be as large as possible.

Further, in a device configuration using a microprocessor capable of high-speed processing, a high-speed storage element such as a static RAM is often used in order to configure the storage device 4. However, since static RAM is generally more expensive than dynamic RAM, it is disadvantageous in terms of cost to construct a large-capacity storage area.

From the above, when the high speed and high density are advanced, there is a problem that in the conventional configuration, it is necessary to sacrifice either the cost or the processing speed.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an outline curve or a polygonal line of a character is generated from a data string describing an equation of a curve or a straight line, and a pixel in a portion surrounded by the curve or the polygonal line is filled in to form the character. A means for forming a shape, a means for accumulating a pixel group representing a character shape in a memory for a character used frequently, a means for compressing a pixel group representing a character shape in a memory for an infrequently used character, and accumulating in a memory; It is characterized in that it is constituted by means for restoring a character shape by expansion from a compressed pixel group.

[0008]

According to the present invention having the above construction, the pixel data generated by the character shape generating means is output to the output device and written in the storage device. At this time, if there is no free area in the storage device, pixel data of a character that is less frequently used is extracted from the pixel data in the storage device, and instead, the pixel data of the character output immediately before is recorded in the storage device. It On the other hand, the pixel data extracted by this processing is compressed by the compression means and recorded in another storage device.

When a character output request is made to the output device, if the character code matches the character recorded in the compressed storage area, the data is read from the compressed storage area. After being decompressed and restored to the original shape, it is output to the output device and written again in the uncompressed storage area.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic diagram of one embodiment of the present invention.

In this embodiment, a display device is illustrated as the output device, but the same effect can be obtained even if the output device is a printing device because of the configuration of the present invention. Below, Figure 1
The function of each part of the embodiment will be described below.

Pixel data representing the shape of a plurality of characters is recorded in the storage device 4. Therefore, a mechanism for managing what character data is currently recorded in the storage device 4 is required. In this embodiment, this management mechanism is performed by the system program generating and referring to a management table as shown in Table 1 as an example.
In the table below, the numbers starting with the symbol "$" represent hexadecimal numbers.

[Table 1] Further, the character record whose head address is shown in Table 1 is a record having the structure illustrated in Table 2.

[Table 2] Table 1 has three fields, and the first item shows the start address of the record storing the information about the character as described above. In the second item, a value indicating the beginning of the address where the pixel data is stored is written. The third item holds a record of when the character indicated by the character record of the first item was last used. To this end, in the operating device of this embodiment,
After the power is turned on, the occurrence of the character output request after the first character output request may be managed by a serial number. That is, the output request is generated for each character, and the output request is issued to the storage area 4
It is necessary to leave the value written in to as the value. Further, when the same character is used repeatedly, this value needs to be updated to the value when it was used recently. This is realized by updating the "last use" item in Table 1 each time a character is used. Naturally, the storage area 4 has a finite size, and the size does not take a large value either. In this embodiment, 64 kbyte
e. Therefore, when the resolution of the output device is 300 pixels per inch and the average size of characters used is 50 pixels in each length and width, the number of characters that can be stored in the storage area 4 is about 180 characters. The value of the item “last use” can be updated by checking the smallest value in Table 1 and subtracting this value from all other data. As an example, when the values in Table 1 are updated, Table 3 is obtained.

[Table 3] This process need only be performed once every several times.

With respect to the storage area 7, it is possible to manage the recorded pixel data by the same processing as that of the storage area 4. The table used for character data management may have the same structure. However, regarding the storage area 7, since the pixels to be stored are compressed, 64 kbytes are stored.
The resolution of the output device for each area is 300 per inch.
When the average size of pixels used is 50 pixels in each of the vertical and horizontal directions, about 300 characters can be stored.

The area 7 can hold about 1.7 times as many characters as the area 4 because the pixel data of each character is compressed to 55 to 60% on average. In this embodiment, hardware is used for the compression device 5 and the decompression device 6, but it goes without saying that the same type of processing can be performed with software.

Next, the compression method used in this embodiment will be described. In this embodiment, a compression method known as the WBS method is used because it is easy to implement hardware. The one-dimensional WBS method divides all data into N-bit partitions,
When all N bits are 0, it is indicated by 0 of 1 bit. In other cases, 1 of 1 bit is added and data is represented by N + 1 bits. For example, when N = 4, the upper data in Table 4 is converted to the lower data in Table 4.

[Table 4] In this method, obviously, the longer the 0 column is, the higher the compression rate is. Therefore, in this embodiment, prior to the actual compression processing,
Pre-processing is performed to increase the compression rate. An explanatory diagram of the pretreatment method is shown in FIGS. In the effective processing range 10,
As shown in FIG. 2A, when there is a pixel representing the shape of the character “A”, the data of the target line and the line immediately below the target line are exclusive ORed in the vertical direction, and the target line is re-selected. When stored in, the pixel group shown in FIG. 2B is obtained. As is clear from FIG. 2B, the white area is enlarged. After that, if the WBS method described above is used, the compression rate can be increased. In the present embodiment, the WBS method of 4-bit length is used for the character data of vertical and horizontal 32 pixels, 56% for the character "A", 50% for the character "A", and 59% for the character "Pan". , I was able to compress each. This processing method can increase the compression rate as the number of pixels forming a character increases, and for a character of 32 to 60 pixels, an average compression of 55 to 60% (depending on the typeface design) can be achieved. did it.

Next, the flow of operation will be described with reference to FIG. In a system including the display device 1, when a request to display a character is generated, the processing of software controlling the system can be roughly divided into three cases.
There are the following three. Process (A) When the pixel data indicating the shape of the character requested to be displayed is not held in the storage device 4 and the storage device 7. Process (B) When the pixel data indicating the shape of the character requested to be displayed is stored in the storage device 4. Process (C) When the pixel data indicating the shape of the character requested to be displayed is stored in the storage device 7.

This will be described with reference to the flowchart of FIG.

When a character output request occurs in the system (20), the system program checks the management table of the storage device 4 to see if the same character as the request has already been converted into pixels (21). At this time, even characters having the same character code are not considered to be the same if any of the character type, the number of vertical pixels, the number of horizontal pixels, and the matrix used for transformation do not match. This can be detected by the character record management table whose example is shown in Table 2. If the corresponding character data cannot be detected in the management table of the storage device 4, then the same investigation is performed using the management table of the storage device 7 (22). When the necessary character data is not stored in the storage device 4 and the storage device 7, character shape data is generated using the character shape generation means 2 (23), and the above-described processing (A) is performed (24). ). If there is character data corresponding to the storage device 4 in the judgment (21), the process (B) is executed. If there is character data corresponding to the storage device 7 in the judgment (22), the process (C) is executed. The information transmitted to the character shape generating means 2 includes the type of character (Mincho, Gothic, etc.), the size of the character,
This is information related to the designation of character codes. When handling Japanese, the JIS code (or similar code) is used as the character code.

Each process will be described in more detail below.

First, the operation of the process (A) will be described.
FIG. 4 is a flow chart showing the flow of the operation of the process (A). Prior to this processing, the character generation means 2 reads necessary data relating to the corresponding character from the outline font data 3 based on the designation of the character code, performs arithmetic processing, and generates a pixel group. As a result, it is possible to know how much free space is needed to store the newly generated character shape data. Based on this numerical value, the system detects a free area in the storage area 4 (30). If there is no free area, the program controlling the system fetches the data regarding the character having the smallest value of the item of the last use (33) and compresses it using the compression device 5 according to the character data management table (34). At this time, the data size after the compression processing is obtained, and the size of the free area of the storage area 7 is checked (35). If there is no free area here (35), then, according to the character data management table for the storage area 7, the data for the character having the smallest value of the item of the last use is discarded (37). If there is still not enough free space, the process is repeated. When the free area is secured, the pixel data compressed by the compression device 5 is transferred to the storage area 7 (36). After this processing, the empty area of the storage device 4 is again detected (3
0), if a vacant area is secured, the pixel group generated by the character shape generating means 2 is immediately recorded in the storage device 4 (31) and further transferred to the display device 1 for display (3).
2). If the size of the free area is insufficient, the process (33) and subsequent steps are repeated. Further, in the process (31), the item of the last use of the management table of the storage device 4 is updated. Similarly, in the processing (36), the item of the last use of the management table of the storage device 7 is updated.

In the case of the process (B), its flow chart is shown in FIG. Since there are character-shaped data pixel groups that can be used for display, display processing can be performed immediately. At this time, the management table of the storage device 4 is updated (42).

In the case of the processing (C), it operates as shown in the flow chart of FIG. That is, the compressed character data is taken out from the storage device 7 (40) and decompressed by the decompression device 6 (41), and then the same operation as the process (A) is executed.

When the above procedure is executed, generally, the data compression / expansion processing can be executed at a higher speed than the outline font generation. With the hardware used in this example, compression / expansion was 300 characters / sec for a character of 60 pixels vertically and horizontally. In contrast, outline font generation was performed by software and was 4 characters / sec. Considering such a processing speed difference, it can be said that holding the shape data of as many characters as possible by using the compression processing means is advantageous for improving the processing speed of the entire system.

Also, in terms of hardware construction, the compression / expansion processing portion is easier than the outline font generation portion.

[0025]

When the present invention having the above-mentioned configuration is used, it is possible to hold more character shape data than in the conventional method, as compared with the case of using the memory having the same capacity. 1 in compression area
In terms of characters, the time consumed until display is slightly slower than the display time of conventional processing. However, since it is possible to store more character shape data in the memory than in the conventional method, it is possible to improve the processing speed of the entire system.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of pre-compression processing.

FIG. 3 is a flowchart of processing in the configuration of FIG.

FIG. 4 is a partial flowchart of the process of FIG.

5 is a partial flowchart of the process of FIG.

FIG. 6 is a partial flowchart of the process of FIG.

FIG. 7 is a configuration diagram showing a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 display device 2 character shape generating means 4 storage device 5 compression device 6 expansion device 7 storage device

Claims (1)

[Claims] 1. A means for forming a character shape by generating an outline curve / broken line of a character from a data string describing a curve / straight line equation and filling pixels in the portion surrounded by the curve / broken line, frequency of use. For high-characters, a means for accumulating a pixel group that represents the character shape on the memory, for a character that is less frequently used, a means for compressing a pixel group that represents the character shape and accumulating it in the memory, a character from the compressed pixel group A character data generating device comprising a means for restoring a shape by expansion.