drawLine component with setBounds

Question

I have a problem that I can't seem to fix with my Java code.

I've created a program that shows a map, when u click on the map, u get a edge/node dotted out on the map.. When I connect two nodes with each other, a line is to be shown between the connected dots.

So far so good, or so I thought, but... It's fine when the x1,y1 coordinates have values that are less than x2,y2...

I've figured out that it's the setBounds that been spooking me... But I dont know how to solve my problem, and I can't seem to find any simular problem anywhere around... Has anyone come across this kind of problem, and if so, how did you solve this?

import java.awt.*;
import javax.swing.*;

public class DrawMyLine extends JComponent{
    private int fx, fy, tx, ty;
    private int h,w;
    private int m;
    private double k;
    private Destinations from;
    private Destinations to;

public DrawMyLine(Destinations from, Destinations to){
    this.from=from;
    this.to=to;
    setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));

    fx = from.getX();
    fy = from.getY();
    tx = to.getX();
    ty = to.getY();


    //w = Math.abs(tx - fx);
    //h = Math.abs(ty - fy);
    w = tx - fx;
    h = ty - fy;

    int x,y;

    if(ty>fy){ //This is my, not so great solution so far...
        x = fx;
        y = fy;
    }
    else{
        x = tx;
        y = ty;
    }

    setBounds(x+5,y+5, w, h); //How do I reverse the boundary?
    setPreferredSize(new Dimension(w, h));
    setMinimumSize(new Dimension(w, h));
    setMaximumSize(new Dimension(w, h));
    }

//@Override
protected void paintComponent(Graphics g){
        super.paintComponent(g);
        g.setColor(Color.BLACK);
        g.drawLine(0,0,w,h);
}

//Method to reduce the clickable area to 5 pixels from the line
public boolean contains(int x, int y){

    k = ((ty-fy)/(tx-fx));
    if(k >= 0){
        m = 0;
    }
    else{
        m = ty - fy;
    }
    return Math.abs(y - k * x - m) < 5;
}//contains 

public Destinations getFrom(){
    return from;
}
public Destinations getTo(){
    return to;
}

}

And in the main(when two nodes are connected):

DrawMyLine dml = new DrawMyLine(from,to);
panel.add(dml);
panel.repaint();
dml.addMouseListener(lineListener);

Can anyone help me? Please!

Don't reverse the bounds, reverse the line... – MadProgrammer Apr 12 '13 at 00:23 — MadProgrammer, Apr 12 '13 at 00:23

score 1 · Accepted Answer · answered Apr 12 '13 at 00:48

Don't reverse the bounds, reverse the rendering.

Think about this...

enter image description here

In the images above, the only thing that has changed is the start and end points. The size of the rectangle has not changed.

All bounds must work with positive values. In Swing, there is no such thing as a rectangle that has a negative size.

Now my examples were rendered using a java.awt.Point, but the basic concept remains...

// Find the smallest point between the two
int x = Math.min(p1.x, p2.x);
int y = Math.min(p1.y, p2.y);
// Size is based on the maximum value of the two points differences...
int width = Math.max(p1.x - p2.x, p2.x - p1.x);
int height = Math.max(p1.y - p2.y, p2.y - p1.y);

This now gives you the size of the effect area. Drawing the line is just a matter of drawing a line between the two points (rather then 0, 0, width, height which you have used)

Jorgeuos · Answer 2 · 2013-04-12T17:56:53.977

Ok thx, I think I understand the logic but when I test my program, it seem's like the line get's out of bounds.

import java.awt.*;
import javax.swing.*;

public class DrawMyLine extends JComponent{
    private int fx, fy, tx, ty;
    private int h,w;
    private int m;
    private double k;
    private Destinations from;
    private Destinations to;

    public DrawMyLine(Destinations from, Destinations to){
    this.from=from;
    this.to=to;
    setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));

    fx = from.getX();
    fy = from.getY();
    tx = to.getX();
    ty = to.getY();


    // Find the smallest point between the two
    x1 = Math.min(fx, tx);
    y1 = Math.min(fy, fy);
    // Size is based on the maximum value of the two points differences...
    int w = Math.max(fx - tx, tx - fx);
    int h = Math.max(fy - ty, ty - fy);

    setBounds(x1,y1, w, h);
    setPreferredSize(new Dimension(w, h));
    setMinimumSize(new Dimension(w, h));
    setMaximumSize(new Dimension(w, h));
}

//Method to reduce the clickable area to 5 pixels from the line
public boolean contains(int x, int y){

    k = ((ty-fy)/(tx-fx));
    if(k >= 0){
        m = 0;
    }
    else{
        m = ty - fy;
    }
    return Math.abs(y - k * x - m) < 5;
}//contains 

//@Override
protected void paintComponent(Graphics g){
    super.paintComponent(g);
    g.setColor(Color.BLACK);

    if(fx<tx || fy<ty){ // Something like this?
    g.drawLine(fx,fy,tx,ty);
    }
    else{
    g.drawLine(tx,ty,fx,fy);
    }
}

public Destinations getFrom(){
return from;
}
public Destinations getTo(){
return to;
}

}

Some line's shows just small pieces... See pic...

https://i.stack.imgur.com/U2Fsg.jpg

Why is it so?

drawLine component with setBounds

2 Answers2