line.java

java编写的最好的画图板程序

/*
 * Line.java
 *
 * Created on April 29, 2005, 5:30 PM
 */

package hysun.draw;

import java.awt.*;
import java.awt.event.MouseEvent;

/**
 *
 * @author hysun
 */
public class Line extends RectBoundedShape {
    
    public Line(Color c, Stroke s, int x, int y) {
        super(c, s, x, y);
    }
    
    /**
     * Line object doesn't follow the cursor event processing specifed by its
     * superclass GeometryShape.
     * The difference lies in the processing when shift mask is present.
     * Line will not always regulate its bounding rectangle to a square.
     * There will be three cases: the bounding rectangle is either square,
     * a horizontal line or a vertical line, depending the slope of the line.
     * 
     * tan(30) = 0.577;
     * tan(60) = 1.155;
     */
    public void processCursorEvent(MouseEvent e, int t) {
        if (t != IShape.CURSOR_DRAGGED)
            return;
        int x = e.getX();
        int y = e.getY();
        if (e.isShiftDown()) {
            if (x - startX == 0) {  //vertical
                endX = startX;
                endY = y;
            } else {
                float slope = Math.abs(((float) (y - startY)) / (x - startX));
                if (slope < 0.577) { //horizontal
                    endX = x;
                    endY = startY;
                } else if (slope < 1.155) { //deg45
                    regulateShape(x, y);
                } else { //vertical
                    endX = startX;
                    endY = y;
                }
            }
        } else {
            endX = x;
            endY = y;
        }
    }
    
    public void draw(Graphics2D g) {
        g.setColor(color);
        g.setStroke(stroke);
        g.drawLine(startX, startY, endX, endY);
    }
    
}