JPH0594526A - Font compression processor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a font compression processing device capable of efficiently compressing outline font data to save memory and reduce system cost. A means for data compression is provided by setting the coordinates of the next control point in the vector font data to a position that can be predicted from the coordinates of the current control point and the coordinates of the control point before this current control point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a vector font
The present invention relates to a font compression processing device capable of compressing data and reducing the memory device.

[0002]

2. Description of the Related Art In recent years, with the development of desktop publishing (DTP), vector fonts capable of arbitrarily enlarging, reducing and rotating characters, especially natural characters without jaggedness when characters are enlarged Outline fonts that can be provided have become indispensable.

On the other hand, the outline font requires more vector position information as the character shape becomes more complicated, and thus requires a memory device having a larger memory capacity to store the position information. Was taken. Therefore, the position information is compressed to reduce the data amount and then stored in the memory to reduce the memory capacity. Regarding this data compression, AD
There are CT system and Huffman coding. Also,
As a method of compressing the existing outline font data, a method of taking the difference between the previous control points and making the data a relative value is also proposed.

However, since the outline font needs to have a larger memory capacity as the character shape becomes more complicated, conventionally, it cannot be said that the memory capacity reduction by the data compression is sufficient. ..

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to efficiently describe outline font data, thereby compressing the data to save memory and reduce system cost. To do.

[0006]

To achieve the above object, the first invention of the present application is such that the coordinates of the next control point in the vector font data are calculated from the coordinates of the current control point and the coordinates of the control point before this current control point. The feature is that data is compressed by setting the position to be predictable.

According to the second invention of the present application, the coordinates of the next control point are set in accordance with the operator's information contained in the vector font data, and the distance and angle between the current control point and the control point preceding this current control point. And a character forming means for forming a character from control points sequentially calculated by the calculating means.

The font compression processing apparatus according to the first aspect of the present invention sets the coordinates of the current control point and the control point before the current control point when setting the coordinates of the next control point by the vector font data. Data compression is performed by setting the position that can be predicted from the coordinate as the coordinate of the next control point.

The font compression processing apparatus according to the second aspect of the present invention generates vector font data corresponding to the input character code and forms a character in accordance with the operator information in the vector font data. The coordinate of the next control point is calculated by sequentially calculating the next control point from the distance and angle between the current control point and the control point before this current control point, and the target control is used as the coordinate data of the control point. Only the difference between the point and the predicted control point is enough. Further, a character is formed from the calculated control points.

That is, the more curves in the character, the more effective the compression is, and in fact, the number of bytes could be halved in the coordinate portion of the font data. This also allows font data to be compressed, saving memory.

The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. The operating method of the present invention is shown in FIG. First, the character code input by the character input means 1 such as a keyboard is read, and then the font generation means 3 forms this character code by using a font dictionary. Further, the character is output to a printer, a CRT or the like by the character output means 5.

Next, the operation of the font generating means 3 will be described with reference to the flow chart shown in FIG. First, in step S1, a character code is read, and based on the read character code, font data is read from the font dictionary in step S5 to generate a font (step S7). Further, the process returns to step S1, the characters are read, and when the reading is completed (step S
3) The font generation routine ends.

Next, the font generation in step S7 will be described in more detail with reference to the flowchart shown in FIG. First, in step S11, the font data of each character code read from the font dictionary is read. Then, steps S15 to S1
At 9, the operator information in the font data is checked, and the control point prediction operation is sequentially performed based on the information of each operator.

That is, in step S15, the operator sets a reference point for drawing a Beze curve (hereinafter, simply C
(Also referred to as TRL), the process proceeds to step S21, and it is confirmed whether or not the distance and the angle to the previous control point are stored in the buffer. Here, if it is not stored, the process proceeds to step S41, and if it is stored, the process proceeds to step S23 to check whether or not the immediately preceding operator is CTRL.

In step S23, the immediately preceding operator is C
If it is not TRL, the process proceeds to step S25, and it is checked whether or not the operator draws a Beze curve (hereinafter, also referred to as CURVETO). The operator is C
When it is not URVETO, the process proceeds to step S27,
After performing Prediction 4 described below, the process proceeds to step S39. When the operator is CURVETO, the process proceeds to step S29. After Prediction 3 described below is performed, the process proceeds to step S39.

On the other hand, when the previous operator is CTRL in step S23, the process proceeds to step S31, and after performing prediction 2 described later, the process proceeds to step S39. Further, in step S15, the operator makes a CTR.
If it is not L, the process proceeds to step S17, and it is checked whether the operator is CURVETO. When the operator is CURVETO, step S33
Then, the distance and angle with respect to the previous control point are calculated, the calculated values are stored in the buffer (step S35), the prediction 1 described later is performed, and then the process proceeds to step S39.

In this step S39, font data correction data is added to the control points predicted in prediction 1 (step S37), prediction 2 (step S31), prediction 3 (step S29) and prediction 4 (step S27). It proceeds to step S41.

Further, in step S17, this step S
When the operator in 17 is not CURVETO, the process proceeds to step S19, and it is checked whether or not the operator in step S19 is MOVETO. If the operator is not MOVETO, the process proceeds to step S41, and if it is MOVETO, the process proceeds to step S43, and after clearing the buffer, step S41 is performed.
Proceed to.

In step S41, the outline of the font is formed by connecting the control points created as described above, and then the process returns to step S11 to read the font data (step S1).
This routine ends in 3).

The operator (the operation method for connecting the control points) for drawing the font used in the above flow chart is shown below. The Beze curve is shown in FIG.

MOVETO: movement of depiction point LINETO: draw a straight line CTRL: reference point for drawing a Beze curve CURVETO: draw a Beze curve Next, a method of predicting a control point in each operator in the flowchart shown in FIG. Prediction 1 (step S37), prediction 2 (step S31), prediction 3 (step S29), and prediction 4 (step S27) will be described in this order.

First, CURVETO prediction 1 shown in step S37 will be described with reference to FIG. The operator at the previous two points (C2, C3) is the distance L2 between the control points of CTRL.
Then, the angle .theta.1 obtained by connecting these control points (C1-C2-C3) is calculated. At that time, the distance L2 between the control points and the angle θ1 are stored in the buffer. The position (distance L3, angle θ2) of the predicted control point is calculated as the calculated distance L2.
And the angle is θ1 (L3 = L2
, Θ2 = θ1).

Next, CTRL-CTRL prediction 2 shown in step S31 will be described with reference to FIG. The previous operator is CURVETO and the previous operator is C
When it is TRL, the angle L1 between the control points is obtained using the angle (angle stored in the buffer) θ1 obtained by the previous operator CURVETO, and the position of the predicted control point (distance L4
, And the angle θ3) is determined so that the obtained angle θ1 is equal to the distance L3 (θ3 = θ1, L4 = L3).

Next, the CURVETO-CT shown in step S29
RL prediction 3 will be described with reference to FIG. When the previous operator is CURVETO (CURVETO -CTR
L), the distance L1 to the previous control point is obtained, and the predicted control point (distance L3) is positioned so that it is on the extension of the previous control point and at the obtained distance (L3 = L2).

Next, LINETO-CTRL shown in step S27
Prediction 4 will be described with reference to FIG. When the previous operator is LINETO, the predicted control point (distance L4) is positioned on the extension of the previous control point, and is positioned so as to be the distance L1 between the previous operator CURVETO and CTRL (L4 = L2).

In the case of the operator MOVETO, no prediction is made, and the angle θ1 and distance L stored in the buffer are not predicted.
1 is cleared (step S43), and operator LI
In the case of NETO, do not predict.

Next, an example of font depiction will be described with reference to FIG. FIG. 6 shows a method of predicting points B to E when drawing from point A to point E.

First, at the point B, A-B is set to H on the extension of G-A.
The length is the same as between -G. Then, point C is A
-B-C has the same length as J-I-H, and B-C has the same length as A-B. Also, at the point D, BCD is A-
Similar to BC, CD has the same length as BC. In addition, E point is C-D extension of D-E
It has the same length as D.

As described above, the present embodiment is a method of predicting the next control point from the previously pointed control point and adding the correction amount. By predicting this control point, the font data of the font data is The coordinate data need only be the difference between the target control point and the predicted control point. Therefore, the size of the font data to be stored can be reduced and the data can be compressed.

[0030]

As described above, according to the present invention, the next control point is predicted from the previous control point. Therefore, outline font data can be efficiently compressed to save the memory. The effect of.

[Brief description of drawings]

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

FIG. 2 is a flow chart showing details of a font generating means shown in FIG.

FIG. 3 is a flowchart showing details of the font generation shown in FIG.

FIG. 4 is a diagram illustrating a Beze curve.

5A to 5D are diagrams for explaining the prediction method shown in FIG.

6 (a) and 6 (b) are font depictions to which the present invention is applied.

[Explanation of symbols]

 1 character input means 3 font generation means 5 character output means

Claims (2)

[Claims] 1. In vector font data,
A font compression processing device having means for compressing data by setting the coordinates of the next control point to a position that can be predicted from the coordinates of the current control point and the coordinates of the control point before this current control point. 2. A computing means for computing the coordinates of the next control point from the distance and angle between the current control point and the control point preceding this current control point according to the operator's information in the vector font data. A font compression processing device comprising: a character forming unit that forms a character from control points sequentially calculated by the calculating unit.