JPS59177593A - Detection of display graphic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of the h method for finding (printing) a part of a figure indicated by a cursor in a device equipped with a CRT and displaying figures on the screen. Specifically, in the above-mentioned apparatus, a figure is usually composed of a plurality of pixels.

Due to a malfunction of the device, there may be cases where it is desired to select a specific pixel within this figure using a cursor. The present invention relates to a method for finding the pixel closest to the cursor position.

The present invention mainly focuses on CAl) (Q computer
Since the present invention is often used in A1ded□es:gn) devices, the present invention will be explained using a CAD device as an example. In a CAD device, various designs are made while displaying figures on a CRI screen and interacting with a combination coater. When performing such a setting 81 operation, O
You may want to point to a part of the figure displayed in R[- with the cursor and specially display or recognize that part. In order to recognize the part of the figure pointed to by the cursor and specially display this part, it is necessary to calculate the distance between the cursor and each pixel and select the pixel with the closest distance. The following methods (a) and (b) are known as methods for finding the pixel closest to this cursor.

(b) A method of calculating the distance to the 7J-vine for all pixels of the figure and detecting the desired pixel as a result.

According to this method, it is not necessary to calculate the distance mt for all pixels. As a result, it takes a long time to extract the pixel closest to the cursor.

(b) A method in which the CRT screen is divided into N equal blocks in the X and Y directions, and the distance from the cursor is calculated only for pixels in the block where the cursor exists.

According to this method, although the total lft is reduced compared to the method (a) above, there are still many a1 holes, and it takes a long time to extract a predetermined pixel. Depending on the position of the cursor, at worst four blocks may have to be searched. Also, where a pixel belongs changes depending on the state of the screen (enlargement, reduction, parallel movement), so RE
There is also the drawback that the BIT indicating whether the rotary movement block 1 cock is present must be updated every time the RAIN downward movement is performed.

The present invention has been made in view of the points explained below. To summarize the present invention, the steps include setting an area that moves as the cursor moves, searching for coordinate data within this area, and when coordinate data is detected in this search, at that point the cursor and and a step of reducing the area based on the distance to the detected coordinates, and by repeating these two steps, the area is reduced one after another, and the remaining pixels in the last reduced area are This method recognizes the pixel closest to the cursor position.

The operation of the present invention will be explained in detail below using the drawings. 1st
The figure shows an example of a display on a CRT screen of a CAD device. In the figure, J5 is a cursor, and the person operating the CAD device uses a joystick (joy 5tick).
), etc., and can be set at any position on the CRT. Δ1 to A6 are pixels. In FIG. 1, each pixel is represented as one independent tc figure (circle or triangle), but it may be divided into finer levels (line segments).

For example, the pixel A5 may be divided into four straight lines.

When selecting, for example, pixel A2 on such a CRT screen and attempting to modify it, it is first necessary to make the computer recognize pixel A2.

To do this, we move cursor 1 to pixel A2.However, it is a nerve-wracking operation to accurately place cursor 1 on the line of pixel Δ2.

Therefore, as described above, the computer searches for the pixel closest to the cursor, and selects the pixel that is found as a result of the search. The present invention was developed because the conventional search method has drawbacks.

All pixels are given names based on input from a CAD device operator, and this information is managed as a two-dimensional database. Also, each pixel has a maximum and minimum (MIN-MΔX) value in the definition space, but each pixel is
When inputting to the device, the maximum and minimum coordinate values are extracted by a computer and managed as a database along with information on the name of each pixel. The concept of this database is shown in Figure 3. For example, in Fig. 1, the maximum and minimum values of pixel △6 are (Xn, Yn) and (Xm
, Ym). Therefore, if the name of this pixel is 86, the maximum and minimum coordinate values are stored as shown in FIG.

Based on the CRT display and database status as described above, the display graphic detection method of the present invention operates as follows.

The operation when selecting, for example, pixel Δ2 in FIG. 1 will be explained. First, the cursor is moved to the vicinity of pixel Δ2 using a joystick or the like.

The operation up to this point is the same as the conventional one. However, the search operation Q described below is different from the conventional one.

In the present invention, an area is set that moves as the cursor moves. This area is, for example, as shown at 81 to B3 in FIG. That is, the largest area is a rectangular area based on the + mark of the cursor. Here, FIG. 2 is an enlarged view of the vicinity of the cursor in FIG. 1.

First, the computer searches within the largest area B1 at the position where the cursor has been moved. What to search for is the maximum and minimum coordinate values of each pixel in the database shown in Figure 3 above area B.
It is whether or not it is included in +.

When the computer sequentially scans the database 17 and detects the maximum or minimum coordinate value belonging to this area B+, the area to be searched is changed at that point. The method of change is to reduce the area based on the distance between the origin O of the cursor and its detected coordinates.

To explain specifically with reference to FIG. 2, it is assumed that a database is searched and the maximum value of pixel A is detected. At that point, the search area is reduced to one area as shown in B2 of FIG.

Then, the computer will search again within this reduced area. As a result, since the combi coater detects the minimum value of pixel A2, the search area becomes B3, which is even smaller.

Next, the computer searches within this area B+, but as a result, it is no longer possible to detect other maximum and minimum coordinates, so it recognizes this pixel A2 as the desired pixel.

The flow of such operations is shown in Figure 4.

As explained above, according to the present invention, the following effects can be obtained.

(a) Since the search range is narrow as described in FIG. 2, the search time is shortened compared to the conventional case.

Although the first search range (B+) is a rectangle matching the size of the cursor in FIG. 2, it is not limited to this. That is, it may be larger or smaller than the thickness of the cursor. Further, the shape may be other than a rectangle.

(b) As a result of the search explained in (a), when the first coordinate value is detected, the search range is immediately reduced at that point, so there is no need to search the remaining part in area B1. Therefore, the search time is further shortened.

<C) Since the maximum and minimum coordinate values of the database are used to determine whether or not a pixel belongs to the search range, it is not affected by the square shape of the pixel and the scanning speed is fast.

Note that if the area of the search range is made infinitely small, it is impossible to predict when the search will end. Therefore, in the present invention, the search range is made smaller. A certain limit is set for I (B3 in FIG. 2), and the search ends within that range.

[Brief explanation of drawings]

Figure 1 shows an example of the display on the CRT screen of a CADI device, Figure 2 is an enlarged view of the cursor area in Figure 1, Figure 3 is a diagram showing the concept of the database, and Figure 4 is the booklet. FIG. 3 is a diagram showing an example of an operation flow of the invention. 1...Cursor, A1-86...Pixel, BI-B3
···area.

Claims (1)

[Scope of Claims] A device for displaying each pixel on a CRT by providing maximum and minimum coordinate data on a display plane for each pixel, which displays a plurality of pixels displayed on the CRT screen. In the method of detecting the pixel closest to the cursor position, the pixel moves as the cursor moves, and the step of searching for the presence or absence of the maximum or minimum coordinate data in the area, If the maximum or minimum coordinate data is detected, at that point, the area is reduced based on the distance between the cursor and the detected coordinate, and these two steps are repeated. In this method, the area is successively reduced to a predetermined size limit, and the remaining pixels in the last area that has been reduced are recognized as the pixels closest to the cursor position.