JPH0573689A - Line segment plotting device - Google Patents

Abstract

PURPOSE:To automatically plot a line segment keeping fixed interval to a plotted line segment. CONSTITUTION:At the time of newly plotting the curved line parallel with the curved line which is already plotted on a CRT display device 14, when the interval between the plotted line segment and the line segment to newly plot is specified from a key input part 12, a distance calculating circuit 18 determines the distance between them. A plotting picture element calculating circuit 20 determines a picture element to newly plotted based on the distance obtained by the distance calculating circuit 18 and the analyzing result of a line segment analyzing circuit 19. A plotting circuit 21 successively combines the plotting picture elements and plots the new line segment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line segment drawing apparatus for drawing a curve or the like in graphic processing of a personal computer, a word processor or the like.

[0002]

2. Description of the Related Art Conventionally, in a graphic processing of a word processor or the like, an arbitrary curve pattern is drawn according to a freehand method by using an input means such as a cursor key. For example, as shown in FIG. Even when a curved line RS parallel to the existing curved line PQ is maintained at a constant interval a, a new curved line RS is drawn in accordance with the freehand method using a cursor key or the like.

[0003]

By the way, the parallel 2
When drawing a straight line of a book, if one line segment is drawn according to the freehand method and then this line segment is copied to draw the other line segment, two parallel straight lines, etc. However, the method of drawing two parallel line segments by copying is limited to a relatively simple line segment such as a straight line. For this reason, as shown in FIG. 6, when the curved line RS parallel to the curved line PQ having a complicated shape at a constant interval a is drawn, the freehand method is used. It has been extremely difficult to draw a line segment according to the freehand method. An object of the present invention is to make it possible to automatically draw a line segment that maintains a constant interval with respect to a line segment that has already been drawn.

[0004]

The means of the present invention are as follows. The interval designating means 1 (see the functional block diagram of FIG. 1, the same applies hereinafter) is already drawn when newly drawing a second line segment parallel to the already drawn first line segment. The interval between the first line segment that is present and the second line segment that is newly drawn is specified. In this case, the start point position of a line segment to be newly drawn may be designated by a cursor key or the like. The line segment analysis means 2 is the first one already drawn
Analyze the shape of the line segment of. The drawing means 3 is the line segment analysis means 2
The second line segment is drawn while keeping a constant interval with respect to the first line segment based on the analysis result and the interval designated by the interval designating means 1.

[0005]

The operation of the means of the present invention is as follows. Now, in the state where the first line segment (curve) has already been drawn according to the freehand method, when the second line segment parallel to the first line segment is drawn, the interval designating means 1
Specifies the interval between the first line segment and the second line segment.
Then, the line segment analysis means 2 analyzes the shape of the first line segment. Based on the analysis result and the interval designated by the interval designating means 1, the drawing means 3 draws the second line segment while keeping a constant interval with respect to the first line segment. Therefore, it is possible to automatically draw a line segment that maintains a constant interval with respect to a line segment that has already been drawn.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to FIGS. FIG. 2 is a block diagram showing the configuration of the line segment drawing device. The CPU 11 controls the entire operation of this line segment drawing apparatus according to various programs.
Document data and graphic data input from 2 are video RA
It is displayed and output from the CRT display device 14 via the M (VRAM) 13, or written in the input buffer 15 and then stored in the text memory 16. Here, the contents of the text memory 16 are registered and stored in the external storage device 17 when a registration key (not shown) on the key input unit 12 is operated.

In particular, in this embodiment, the CPU 11 is connected to the distance calculating circuit 18, the line segment analyzing circuit 19, the drawing pixel calculating circuit 20, and the drawing circuit 21. Distance calculation circuit 1
A circuit 8 obtains the distance between the starting point of the already drawn line segment and the starting point of the newly drawn line segment when drawing a new line segment parallel to the already drawn line segment. The line segment analysis circuit 19 analyzes a shape (pixel) of the already drawn line segment, and the drawing pixel calculation circuit 20 creates a new line segment from the contents calculated by the distance calculation circuit 18 and the line segment analysis circuit 19. A circuit for obtaining a pixel for drawing, the drawing circuit 21 draws the pixel obtained by the drawing pixel calculation circuit 20 as a drawing point, and also draws a line segment connecting the previously drawn drawing point and the currently drawn drawing point. It is a circuit to do.

Next, the operation of this embodiment will be described. Now
It is assumed that a curve PQ as shown in FIG. 4 is drawn on the CRT display device 14. Here, when drawing a new curve parallel to the curve PQ, a parallel drawing key (not shown) on the key input unit 12 is operated. Then, parallel drawing processing according to the flowchart of FIG. 3 is executed. First, when the start point R of the newly drawn curve is designated by the cursor key or the like (step S1), the distance calculation circuit 18 sets the start point P of the already drawn curve PQ and the start point R of the newly drawn curve. And obtain the distance A of
Distance (drawing distance) a from the distance A to the normal line passing through the point P
Is calculated (step S2).

Next, assuming that the main points (pixels) from the start point to the end point of the line segment analysis circuit 19 on the already drawn curve PQ are P ₀ , P ₁ , P _2, ... Two matching points P _n and P _{n + 1} (n = 0, 1, 2 ...) Are obtained (step S3). Initially, P ₀ and P ₁ are obtained as two points (see FIG. 5). Then, the line segment analysis circuit 19 obtains a straight line (tangent line) f ₁ passing through these two points P ₀ and P ₁ (step S4), and is orthogonal to this tangent line f ₁ and has two points P ₀ and P 1.
_A normal line g ₁ passing through the center of ₁ is obtained (step S5).

On the normal line g ₁ thus obtained, the drawing pixel calculation circuit 20 finds a position coordinate at a drawing distance a from the center of the points P ₀ and P ₁ (step S6), and this is newly drawn. This is the first pixel R ₀ to be processed. Next, the drawing circuit 21 connects the pixel R _n thus obtained and the previously obtained pixel R _n-1 by a straight line (step S7), but when the first pixel R ₀ is obtained, the step S7 is The process is skipped, the process proceeds to step S8, and it is checked whether or not all the new line segments have been drawn to the end point. If not completed, the process returns to step S3.

As a result, this time, the tangent line f passing through the points P ₁ and P ₂
Perpendicular to _2, normal g ₂ a determined (step S5) passing through the center of the points P _1, P _2, obtains the pixel R ₁ with a distance a on the normal line g ₂ (step S6). Next, the pixel R ₁ obtained this time and the pixel R ₀ obtained last time are connected by a straight line (step S7).

[0012] Hereinafter, the point P _n by repeating the same operation as described above, and perpendicular to the normal line f _n through P n _{+ 1,} the point P _n, P
_The pixels R _n and R _n-1 are combined while obtaining the pixel R _n separated by the distance a on the normal line g _n passing through the center of _{n + 1} . As a result, a curve separated by a distance a from the already drawn curve PQ is newly drawn, and a curve parallel to the curve PQ is automatically drawn.

The type of the already drawn curve (solid line, broken line, thick line, thin line, etc.) is discriminated, and a line type similar to that of the curve is automatically selected to draw a new curve. You may do it.

[0014]

According to the present invention, it is possible to automatically draw a line segment having a constant interval with respect to a line segment that has already been drawn. Therefore, the line segment has a complicated shape. However, it is possible to accurately draw parallel line segments. In particular, when many roads are drawn on a map, a large number of curved curves having a constant width can be efficiently drawn, which is extremely effective in creating a map.

[Brief description of drawings]

FIG. 1 is a functional block diagram of the present invention.

FIG. 2 is a block diagram of a line segment drawing apparatus showing an embodiment.

FIG. 3 is a flowchart for explaining the operation of this embodiment.

FIG. 4 is a diagram showing a drawing distance a calculated by designating a start point R of a new line segment when drawing a new line segment parallel to the already drawn line segment.

FIG. 5 is a diagram showing how a new line segment is drawn by analyzing a line segment that has already been drawn.

FIG. 6 is a diagram for explaining a conventional example and is a diagram showing parallel curves.

[Explanation of symbols]

 11 CPU 12 Key Input Section 13 VRAM 14 CRT Display Device 18 Distance Calculation Circuit 19 Line Segment Analysis Circuit 20 Drawing Pixel Calculation Circuit 21 Drawing Circuit

Claims (1)

[Claims] 1. When a second line segment parallel to the already drawn first line segment is newly drawn, the first line segment already drawn and the second line segment newly drawn Based on an interval designating means for designating an interval with the line segment, a line segment analyzing means for analyzing the shape of the first line segment, an analysis result of the line segment analyzing means and an interval designated by the interval designating means. And a drawing means for drawing the second line segment while keeping a constant interval with respect to the first line segment.