JPH05290139A - Graphic drawing system - Google Patents

Abstract

PURPOSE:To increase the drawing speed without spoiling the operability at the time of overdrawing as to the graphic drawing system which overdraws a figure such as a straight line, a circle, and a rectangle on a figure, etc., drawn on a graphic display device, etc. CONSTITUTION:This graphic drawing system draws the figure whose position shape is determined by a start point S and an end point E inputted from an input device on the existent figure, etc., on the graphic device; and a specific drawing area A including the start point S and a 1st saving area B including the drawing area A are determined according to the inputted start point S, and the existent figure, etc., in the coordinates of the 1st saving area B is saved and restored to overdraw the part of the figure to be drawn within the coordinates of the drawing area A according to the movement of the end point E. After the end point E is determined, a 2nd saving area C including the figure determined by those start point S and end point E is determined and the existent figure, etc., in the coordinates of the 2nd saving area is saved and restored to overdraw a new figure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic drawing method for overwriting a graphic such as a line, a circle or a rectangle on a graphic drawn by a graphic display device or the like.

In an image communication terminal such as telewriting or a graphic terminal, when a graphic, a picture, a character, etc. (hereinafter abbreviated as a graphic) is drawn by using a graphic, the graphic is drawn on the graphic already drawn. In addition, new graphics may be overwritten. In this case, in order to prevent the already drawn figures and the like from being erased when overwriting, prepare several graphic surfaces (that is, a graphic memory: VRAM) and newly superimpose them on the drawing or the like. There is a method of drawing figures to be written on different surfaces, or saving figures already drawn in a save memory once and performing overwriting and then restoring. The former method is effective when there are multiple graphic surfaces, but when there is only one graphic surface due to cost constraints, etc., the latter method is generally repeated to save and restore. It is used.

However, this latter method requires a long drawing time because the processing time required for saving / restoring is long. Therefore, it is necessary to shorten the drawing time as much as possible to improve the drawing speed. At the same time, it is required to improve the operability without damaging the man-machine interface which is important for data input by graphics.

[0004]

2. Description of the Related Art FIG. 5 shows a structural example of a graphic display device. In the figure, 1 is a CPU, 4 is an image part, and a graphic control part 2 and a graphic memory (V
RAM: Video Random Access Memory (3), 5 is a graphic save memory which is VRAM or RAM, 6 is a CRT display unit, and 7 is an input device such as a mouse.

In this graphic display device, the image drawn and input by the input device 7 is once written in the graphic memory 3 and displayed on the display unit 6. Thus, in the case of performing overwriting drawing using a graphic memory limited to only one surface, the process that takes the longest time is the process of saving / restoring the original figure etc. at the time of overwriting. This save / restore processing is performed by the following method.

Here, it is assumed that the input device 7 such as a mouse is used to input a figure of a predetermined pattern such as a straight line, a rectangle, and a circle, and to overwrite the figure already drawn. ..

FIG. 6 shows a procedure for saving / restoring when a straight line is input as a figure. When inputting a straight line, a method is used in which the start point S and the end point E are determined by pointing the screen coordinate position using the input device 7, and the two points are connected by a line. When a line that determines these two points is drawn, in order to make it easier to draw a vertical line or a parallel line, first, as shown in FIG. Even before the position is finally determined while moving, a straight line connecting the starting point S and the end point E is continuously drawn, thereby making it easy to determine the final end point E. Therefore, the straight line in the middle of drawing has its angle and length variable about the starting point S. By using such a man-machine interface, operability in drawing is improved.

When the above-mentioned straight line is overwritten on the figure or the like already drawn on the display device, the figure or the like on the trajectory of the straight line shown in FIG. 6 is saved in the save memory. However, it is difficult to evacuate only the figure and the like directly below the straight line. That is, since the graphic is saved in dot units, it is difficult to save unless the area to be saved in the screen is rectangular. Therefore, as shown in FIG. 6, a rectangle (hatched portion) is created by the coordinates surrounded by the start point S and the end point E, and the evacuation is performed in that unit. Overwriting is achieved by taking the logical sum of and and restoring it on the screen.

[0009]

The rectangular portion to be saved always changes every time the end point is moved in order to change the length and inclination of the straight line to be drawn. And because I rewrite the line many times on the screen until the final end point is decided,
It is necessary to repeatedly save and restore the above rectangular part. The same applies when drawing circles, rectangles, etc. in addition to straight lines.

For this reason, there is a problem that the time required for the save / restore processing is long and the drawing speed becomes slow.
In order to prevent this, it is necessary to stop the drawing of the straight line until the final end point is determined so that saving and restoring is not performed, but when such a man-machine interface is used, , It is difficult to draw and the operability is not good.

The present invention has been made in view of such circumstances, and an object thereof is to impair operability in overwriting a figure such as a straight line, a circle or a rectangle on an existing figure or the like. Not to improve its drawing speed.

[0012]

FIG. 1 is an explanatory view of the principle of the present invention. According to the graphic drawing method of the present invention, a graphic (for example, a straight line, a rectangle, a circle, etc.) whose position shape is determined by the start point S and the end point E input by the input device is added to the existing graphic in the graphic display device. A graphic drawing method for overwriting and drawing, and based on an input starting point S, a predetermined drawing area A including the starting point S
And a first save area B including the drawing area A are determined, and existing figures and the like within the coordinates of the first save area B are saved.
By restoring, the part of the figure to be drawn is drawn by overwriting only within the coordinates of the drawing area A according to the movement of the end point E, and after the end point E is determined, the start point S and the end point E are determined. The new figure is overwritten by determining the second save area C including the figure to be saved and saving / restoring the existing figure and the like within the coordinates of the second save area C.

The drawing area A has a circular shape centered on the input starting point, and one or two radial lines are used in this circle to display the state of a newly drawn figure. You can

[0014]

[Operation] The position and shape of the figure to be overwritten is the start point A and the end point B
Determined by For example, by the line connecting these two points,
If the figure is a straight line, its position and length and inclination are determined, if it is a rectangle, the position and size of its diagonal are determined, and if it is a circle, its position and radius are determined.

First, after the start point S is determined, the drawing area A and the first save area B are determined based on the start point S. For example, as shown in FIG. 1, the drawing area A is circular and the first retreat area B is square including this circle. An existing figure or the like within the coordinates of the first save area B is saved, thereby enabling overwriting in the drawing area A.

In determining the shape of the figure, the end point E is moved in order to adjust it to an appropriate size. In this case, for example, if the figure is a straight line, the starting point S is set only in the drawing area A. A fixed-length straight line is drawn on the line connecting the end points E. Further, if the figure is a rectangle, only a part of the two sides sandwiching the start point S of the rectangle is drawn only in the drawing area A. As a result, the operator can generally understand the drawing state of the figure to be drawn, and can maintain good operability.

When the end point E is finally determined, at that time point, a second retreat area including the figure decided by the end point E and the start point S is decided, and the figure and the like within the coordinates of the second retreat area are decided. evacuate. This allows new graphics to be overwritten.

By doing so, it is only necessary to save the existing figure or the like in the narrow first save area during drawing, so that the save / restore processing time can be shortened.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A graphic drawing method as an embodiment of the present invention will be described below with reference to FIG. In the embodiment of FIG. 2, a straight line is overwritten on an existing figure or the like. Here, as the graphic display device that performs this drawing method, the one shown in FIG. 5 is used.

First, as shown in FIG. 2, a starting point S for drawing a straight line is determined. Once the starting point S has been determined, the area A in which a fixed-length straight line is drawn centered on this starting point S
A (circle drawn by a solid line) is determined, and a rectangular area B necessary for saving / restoring an existing figure etc. is included so as to include this drawing area A.
Determine (the area drawn by the dotted line). Here, the fixed-length straight line to be drawn has an n-dot length, and the rectangular area B necessary for saving / restoring existing figure data is a square having a length of 2n-dots in both length and width. Then, the data such as the graphic already drawn in the coordinates of the rectangular area B is temporarily saved in the save memory 5.

Next, as shown in FIG. 2, while operating the input device 7, the end points are set to, for example, E ₁ , E ₂ , E _3.
Adjust the length and inclination of the line you want to draw by moving it as desired. By moving the end point E in this way,
A fixed-length straight line drawn in the drawing area A is rotated about the start point S in accordance with the movement of the end point E, that is, the end point E is on the extension line. Become. In this case, no straight line is drawn outside the drawing area A, but the end point position can be known by a cursor or the like. This makes it easier to determine the end point.

Next, as shown in FIG.
When the position of is finally determined, the evacuation area B that has been evacuated
Restore the data such as the figure. At the same time, a rectangular area C (area surrounded by a chain line) is defined by the start point S and the end point E,
Data such as a figure drawn in the coordinates of the rectangular area C is saved in the save memory 5 again.

After that, as shown in FIG. 2, the saved data such as the figure is read from the save memory 5, and is logically ORed with the straight line connecting the start point S and the end point E to restore it. Then, a straight line is overwritten on the existing figure and displayed on the display unit 6.

FIG. 3 shows another embodiment of the present invention.
In this embodiment, a rectangle is overwritten instead of a straight line. First, as shown in FIG. 3, the starting point S is determined,
The drawing area A and the save area B centered on the starting point S are determined,
Data such as existing figures within the coordinates of the save area B is saved.

Next, the starting point S is set to one corner of a rectangle to be drawn, and the end point E ₁ , which can be arbitrarily moved by the input device 7,
The position and size of the rectangle are arbitrarily determined with E ₂ , E ₃ , E _4, etc. as diagonals of the rectangle. At this time, the two sides sandwiching the start point S of the rectangle are 2 only within the coordinates of the drawing area A.
It is displayed as a straight line with a fixed length in the book. Outside the coordinates of the drawing area A, the end point is displayed with a cursor or the like. This makes it easier to determine the end point.

Next, as shown in FIG. 3, the end point E
When the position of is finally determined, the evacuation area B that has been evacuated
Restore the data such as the figure. At the same time, the rectangular area C is determined by the start point S and the end point E, and the data such as the graphic drawn in the coordinates of the rectangular area C is saved in the save memory 5 again.

After that, as shown in FIG. 3, the saved data such as the figure is read from the save memory 5, and is logically ORed with the rectangle having the start point S and the end point E on the diagonal to restore the data. As a result, the rectangle is overwritten on the existing figure or the like and displayed on the display unit 6.

FIG. 4 shows another embodiment of the present invention in which a figure drawn by overwriting is a circle. In this embodiment, a circle centering on the starting point S is drawn, and a part of the radius of the circle is drawn as a fixed length line in the coordinates of the drawing area A. This is the same as the first embodiment.

That is, as shown in FIG. 4, the start point S is determined, the drawing area A and the save area B centered on the start point S are determined, and the existing figure data within the coordinates of the save area B is saved. ..

Next, the radius of a circle centered on the starting point S is arbitrarily determined by the end points E ₁ , E ₂ , E _3, etc. At that time, the radial direction of the circle is set only within the coordinates of the drawing area A. A fixed length straight line centering on the starting point S is displayed. This drawing area A
Outside the coordinates of, the end point is displayed with a cursor or the like. This makes it easier to determine the end point.

Next, as shown in FIG. 4, the end point E
When the position of is finally determined, the evacuation area B that has been evacuated
Restore the data such as the figure. At the same time, a rectangular area C including a circle whose radius is the start point S and the end point E is determined, and the data such as the figure drawn in the coordinates of the rectangular area C is saved in the save memory 5 again.

Thereafter, as shown in FIG. 4, the saved data such as the figure is read from the save memory 5, and is logically ORed with the circle having the radius of the start point S and the end point E to restore the data. As a result, a circle is overwritten on the existing figure or the like and displayed on the display unit 6.

[0033]

As described above, according to the present invention, a man-machine interface for displaying a part of a figure to be drawn in a predetermined drawing area is provided.
While maintaining good operability for drawing,
By limiting the data such as the figure to be restored only within the fixed drawing area, the processing time required for saving / restoring can be reduced and the drawing speed can be increased.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating an embodiment of a graphic drawing system of the present invention.

FIG. 3 is a diagram for explaining another embodiment of the graphic drawing system of the present invention.

FIG. 4 is a diagram for explaining another embodiment of the graphic drawing system of the present invention.

FIG. 5 is a diagram showing a configuration example of a graphic display device.

FIG. 6 is a diagram illustrating a conventional example.

[Explanation of symbols]

 1 CPU 2 graphic control unit 3 graphic memory 4 image unit 5 save memory 6 CRT display unit 7 input device

Claims (2)

[Claims] 1. A drawing of a graphic in which a graphic whose position shape is determined by a start point (S) and an end point (E) input by an input device is overwritten on an existing graphic in a graphic display device. A predetermined drawing area (A) including the starting point and a first saving area (B) including the drawing area are determined based on the input starting point and are within the coordinates of the first saving area. By saving / restoring an existing figure, etc., the part of the figure to be drawn is drawn by overwriting only within the coordinates of the drawing area according to the movement of the end point, and after the end point is determined, the start point and end point A graphic drawing method in which a new figure is overwritten by deciding a second save area (C) containing the figure determined in step S1, and saving / restoring the existing figure and the like within the coordinates of the second save area. .. 2. The drawing area has a circular shape centered on an input starting point, and one or two radial lines are used within the circle to display the state of a newly drawn figure. The graphic drawing method according to claim 1.