JPH0528392B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a display device that automatically displays a straight line between two specified points by specifying two points on a display using an external input device such as a light pen. Concerning straight line drawing method.

[Prior art and its problems] Conventionally, as a method for displaying a specific straight line on a display, two lines on the display are displayed using an external input device such as a light pen or a touch panel.
A method called linear interpolation, in which points are specified and a line segment having both ends at these two points is displayed, has been widely used.

However, in such linear interpolation,
Particularly, when it is desired to display a straight line horizontally or vertically to the display, an external input device such as a light pen requires manual operation, so accurate position specification cannot be performed and the desired straight line cannot be accurately obtained. For example, when performing horizontal linear interpolation, the coordinate positions of two points on the display are x ₁ , y ₁ ,
If x ₂ , y ₂ , the position must be specified so that y ₁ = y ₂ , but considering the precision of the operation of the light pen etc. and the size of the display pixel on the display, as shown above, y It is difficult to set ₁ = y ₂ , so in the past linear interpolation was often performed using a slightly slanted straight line.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and when linear interpolation is performed using two points specified on the display by an external input device, by specifying horizontal linear interpolation or vertical linear interpolation in advance, It is an object of the present invention to provide a straight line drawing method that can display an accurate straight line by automatically correcting the coordinates of two points.

[Summary of the Invention] The present invention detects x-coordinate data and y-coordinate data of a starting point and an ending point specified with a light pen or the like in a display device, and converts either of these data into a horizontal linear interpolation key or a vertical linear interpolation key. Depending on the key input, one point x
The coordinate data and y-coordinate data are corrected in the same manner, and linear interpolation is performed at the corrected coordinate position.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the circuit configuration of the linear drawing method of the present invention, and 11 is a key input section. This key input section 11 includes a start key (indicated as "START" in the figure) 1 for starting the execution of linear interpolation.
11. Simple linear interpolation key to specify linear interpolation without correction (represented as "simple" in the figure) 11
2. A horizontal linear interpolation key (represented as "horizontal" in the figure) 113, a vertical interpolation key (represented as "vertical" in the figure) 114, and a touch panel 115 are provided for performing correction. And this key input section 1
The input data from 1 is input to the CPU 12.
The CPU 12 performs the control operation of this linear drawing method, and the input data from the touch panel 115 is sent to the input control unit 13 by the CPU 12.
sent to. A light pen 14 is connected to this input control section 13.
Data input from the touch panel 115 via the CPU 12 is decoded into starting point data x ₁ , y ₁ and ending point data x ₂ , y ₂ . The x coordinate data x ₁ of this starting point data is input to the x ₁ register 151, the y coordinate data y ₁ is input to the y ₁ register 152, and
Also, the x coordinate data x ₂ of the end point data is x ₂ register 1
At 61, the y-coordinate data y ₂ is input to the y ₂ register 162, respectively. The contents of the x ₁ register 151 are input to the x ₁ register 181 via the gate circuit G ₁ of the gate circuit section 17, and to the x ₂ register 191 via the gate circuit G ₄ . The contents of the y ₁ register 152 are similarly input to the Y ₁ register 182 via the gate circuit G ₂ and to the Y ₂ register 192 via the gate circuit G ₂ . moreover,
The contents of the _x2 register 161 are transferred to the _x2 register 191 via the gate circuit _G6 , and to the _y2 register 162.
The contents of _Y2 register 19 via gate circuit _G5
2 is input. The gate circuits G ₁ to _{G 6} of the gate circuit section 17 are brought into an open state by a gate signal input from the CPU 12 . Also, X ₁
Register 181, Y ₁ register 182 and X ₂ register 191, Y ₂ register 192 respectively contain corrected start point data X ₁ , Y ₁ and end point data X ₂ , Y _{2 .}
is temporarily stored, and the stored data is input to the line drawing circuit 20. This line drawing circuit 20
The linear data is formed by the input start point data and end point data, and the linear data is written into the video RAM 21. and,
This video RAM 21 uses the written linear data and follows the control signal from the CPU 12.
This allows straight lines to be displayed on the CRT 22.

Next, the operation of the above embodiment will be explained with reference to the flowchart of FIG. First, in order to execute linear interpolation, the start key 111 of the key input unit 11 is operated, and then, as shown in step _S11 , starting point data and ending point data are input using the touch panel 115 or the light pen 14. do. This start point data and end point data are input to the input control section 13, and the input control section 13
As shown in step _S12 , x-coordinate data and y-coordinate data are created for each input data.
In this case, the x coordinate data x ₁ of the start point data is written to the x ₁ register 151, the y coordinate data y ₁ is written to the y ₁ register 152, and the x coordinate data of the end point data
x ₂ is stored in the x ₂ register 161, and y coordinate data y ₂ is stored in the x 2 register 161.
Written to _y2 register 162. After that, in step _S13 , gate circuits G ₁ , G ₂ , G ₅ , G ₆ are
It is opened by the gate signal from the CPU 12, and the contents of the _x1 register 151 are transferred to the _x1 register 18.
1, the contents of y ₁ register 152 are set to y ₁ register 1.
82, the contents of the _x2 register 161 are stored in the _X2 register 191, and the contents of the _y2 register 162 are stored in the Y2 register _191.
Each is written to the register 192. Then, in the next step _S14 , it is determined whether the horizontal line interpolation key 113 has been operated. If the horizontal linear interpolation key 113 is operated, the process advances to step _S15 , and the gate circuits G ₃ and G ₆ are output from the CPU 12.
A gate signal is input to the gate, which opens the gate, and the contents of the _x2 register 161 are transferred to the _x2 register 191.
The contents of the y ₁ register 152 are transferred to the y ₂ register 192,
The y-coordinate data _y2 of the written end point is corrected to the y-coordinate data _y1 of the starting point. Then, in the next step _S16 , when the above-mentioned starting point data and corrected end point data are held in the _X1 register 181, _Y1 register 182, _X2 register 191, and _Y2 register 192, the CPU 12 starts the line drawing circuit. A line drawing command is given to the line drawing circuit 20, straight line data is created in the line drawing circuit 20, and this straight line data is
The data is written to the RAM 21, a straight line is displayed on the CRT 22, and the linear interpolation operation is completed.

Furthermore, if the operating key is not the horizontal linear interpolation key 113 in step _S14 , the process advances to step _S17 , and this time the operating key is the vertical linear interpolation key 114.
It is determined whether Here, if it is the vertical linear interpolation key 114, the step
Proceeding to _S18 , the CPU 12 inputs gate signals to the gate circuits G ₄ and G ₅ to open them, and the x ₁ register 15
The contents of 1 are input to the X ₂ register 191 and the contents of the y ₂ register 162 are input to the Y ₂ register 192. Then, the process shown in step _S16 above is performed, and the vertical linear interpolation operation is completed.

Furthermore, if it is determined in step _S17 that the operation key is not the vertical linear interpolation key 114, then the operation key is the simple linear interpolation key 112, so the corrections as in steps _S15 and _S18 are performed. Without performing any operation, the linear display operation shown in step _S16 is performed using the coordinate data of the start point and end point written in the _X1 register 181, _Y1 register 182, _X2 register 191, and _Y2 register 192 in step _S13 above. It becomes the thing which carries out.

[Example of invention display]

Here, FIGS. 3 and 4 show differences in display depending on whether or not a correction operation is performed when linear interpolation is performed. Figure 3 1 is simple linear interpolation key 1
12 shows horizontal linear interpolation without performing a correction operation. Due to the precision and operation precision of the external input device light pen 14 and touch panel 115, the y-coordinate components of the start point and end point become different, and the row of display pixels that are displayed in a straight line is shifted and becomes two rows. Therefore, the straight line connecting the two points will not be displayed accurately. FIG. 3 shows linear interpolation in which a correction operation is performed by operating the horizontal linear interpolation key 113. Even if the y-coordinate data _y1 of the starting point and the y-coordinate data _y2 of the ending point are different, the y-coordinate data y2 of the ending point is automatically set to the starting point, as shown in step _S15 in Figure ₂ above. Since the y coordinate data of y is corrected to ₁ , a horizontal straight line will always be displayed.

FIG. 4 shows vertical linear interpolation performed by operating the simple linear interpolation key 112. Similar to FIG. 3 1 above, since no correction operation is performed, 2
Accurate straight lines connecting points are not displayed. FIG. 4 shows linear interpolation performed by operating the vertical linear interpolation key 114. x-coordinate data of starting point
Even if x ₁ and the end point x coordinate data x ₂ are different, as shown in step _S18 in Figure 2 above, the end point x coordinate data x ₂ is automatically changed to the starting point x coordinate data x ₁ . Since the image is corrected vertically, a vertical straight line is always displayed.

Figure 5 is an example of setting a scale on the display. If you want to draw a straight line of how many scales from the starting point x ₁ , y ₁ , after specifying the starting point, set the end point on the scale. If specified, a horizontal straight line of the desired length can be drawn.

In addition, in the above example, the coordinates of the end point were corrected based on the coordinates of the starting point, but this means that, conversely,
The coordinates of the starting point may be corrected using the coordinates of the ending point as a reference, or it is also possible to calculate the average of the coordinates of the starting point and the ending point, and use this to correct both the starting point and the ending point.

Further, in the above embodiment, linear interpolation was performed by inputting the x-coordinate data and y-coordinate data of two points, the starting point and the ending point, using a light pen, etc. However, the x-coordinate data, y-coordinate data of any one point, It is also possible to perform horizontal linear interpolation or vertical linear interpolation by inputting coordinate data and inputting only x-coordinate data or y-coordinate data for the remaining point.

Furthermore, in the above embodiment, the coordinate data is input using an external input device such as a light pen, but the coordinate data may also be input by moving a cursor or the like.

〔Effect of the invention〕

As described above, according to the present invention, accurate horizontal or vertical linear interpolation can always be performed on a CRT display or the like even when using an external input device such as a touch panel or a light pen that does not have high data input accuracy. It is possible to provide a straight line drawing method that allows

[Brief explanation of the drawing]

The drawings show one embodiment of the invention.
The figure is a block diagram showing the circuit configuration, Figure 2 is a flowchart showing the contents of vertical interpolation operation, Figure 3 1 is a diagram showing horizontal linear interpolation without correction, and Figure 3 2 is a diagram showing horizontal linear interpolation with correction. Diagram showing linear interpolation, 4th
Figure 1 is a diagram showing vertical linear interpolation without correction,
FIG. 4 is a diagram showing corrected vertical linear interpolation, and FIG. 5 is a diagram showing another embodiment. 11...Key input section, 111...Start key, 112...Simple linear interpolation key, 113...Horizontal linear interpolation key, 114...Vertical linear interpolation key,
12...CPU, 13...Input control unit, 14...
Light pen, 151...x ₁ register, 152...
y ₁ register, 161... x ₂ register, 162...
y ₂ register, 17...gate circuit, 181...
X ₁ register, 182...Y ₁ register, 191...
...X ₂ registers, 192...Y ₂ registers, 20...
... Line drawing circuit, 21 ... Video RAM, 22 ...
CRT.

Claims (1)

[Claims] 1. In a linear drawing method that automatically interpolates and displays a straight line between two specified points by specifying two points on a display, a coordinate position detection means for detecting the coordinate positions of the two specified points, and this coordinate position detection means a coordinate position data storage means for storing the coordinate position data of the two points detected by the method; a selection means for selecting either horizontal linear interpolation or vertical linear interpolation; The x-coordinate data or y-coordinate data of the coordinate position data is read out from the coordinate position data storage means, and the x-coordinate data or y-coordinate data of one point is corrected to be the same as the x-coordinate data or y-coordinate data of another point. Coordinate position data correction means, one point corrected by this coordinate position data correction means and another point
A straight line drawing characterized by comprising a line drawing means for creating straight line data according to the coordinate position data of a point, and a display control means for displaying the straight line on the display according to the straight line data created by the line drawing means. method.