我的程序涉及绘制三角形,我点击它们。
有两个类,Ecad和Line类。 Ecad是主框架,Line类用于绘制线条。
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class Ecad extends JFrame implements MouseListener{
ArrayList<Line2> lines=new ArrayList();
public Ecad(){
this.setVisible(true);
this.setSize(600,400);
this.addMouseListener(this);
}
public void mouseReleased(MouseEvent me){
Point p1,p2,p3;
int X=me.getX();
int Y=me.getY();
p1=new Point(X,Y);
p2=new Point((int)(p1.getX()-100),(int)(p1.getY()+(1.732/2*200)));
p3=new Point((int)(p1.getX()+100),(int)(p1.getY()+(1.732/2*200)));
Line2 l1=new Line2(p2,p1);
Line2 l2=new Line2(p1,p3);
Line2 l3=new Line2(p2,p3);
lines.add(l1);
lines.add(l2);
lines.add(l3);
this.repaint();
}
public void mouseClicked(MouseEvent me){
}
public void mouseExited(MouseEvent me){
}
public void mouseEntered(MouseEvent me){
}
public void mousePressed(MouseEvent me){
}
public void mouseMoved(MouseEvent me){
}
public static void main(String args[]){
new Ecad();
}
public void paint(Graphics g){
Graphics2D g2=(Graphics2D)g;
super.paintComponents(g2);
//g2.scale(0.5, 0.5);
for(final Line2 r:lines){
r.paint((Graphics2D)g2);
}
}
}
这是Line类
import java.awt.*;
public class Line2 {
Point start,end;
public Line2(Point a,Point b){
start=a;
end=b;
}
public void paint(Graphics2D g){
g.drawLine((int)start.getX(),(int)start.getY(),(int)end.getX(),(int)end.getY());
}
}
在Ecad类的paint()方法中,如果我使用缩放选项放大或缩小,鼠标坐标不会被转换。因此,在缩放之后,如果我在一个点上单击,则将三角形放置在其他点上。当我缩放Graphics组件时,有没有办法转换鼠标坐标?
答案 0 :(得分:2)
同样,您应该使用比例和固定点来转换您正在绘制的形状(再次在这里看起来每个形状的固定点将是三角形的顶点,但它可能是您的中心,如果你所以决定。翻译是基于简单的几何原理,并且是fixedPoint.x *(1 - scale)/ scale,y翻译也是如此。
例如(并且这个使用JPanel作为上面的例子):
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import java.util.List;
class EcadB extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = 600;
private List<MyShape> myShapes = new ArrayList<MyShape>();
private double scale = 1.0;
private JSlider slider = new JSlider(0, 200, 100);
public EcadB() {
addMouseListener(new MyMouseAdapter());
setLayout(new BorderLayout());
slider.setOpaque(false);
slider.setMajorTickSpacing(20);
slider.setMinorTickSpacing(10);
slider.setPaintLabels(true);
slider.setPaintTicks(true);
slider.addChangeListener(new SliderChangeListener());
add(slider, BorderLayout.SOUTH);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
Graphics2D g2b = (Graphics2D)g2.create();
g2b.scale(scale, scale);
for (MyShape myShape : myShapes) {
myShape.draw(g2b, scale);
}
g2b.dispose();
}
public void setScale(double scale) {
this.scale = scale;
repaint();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private class MyMouseAdapter extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
Point2D p1 = e.getPoint();
Point2D p2 = new Point((int) (p1.getX() - 100),
(int) (p1.getY() + (1.732 / 2 * 200)));
Point2D p3 = new Point((int) (p1.getX() + 100),
(int) (p1.getY() + (1.732 / 2 * 200)));
Path2D path = new Path2D.Double();
path.moveTo(p1.getX(), p1.getY());
path.lineTo(p2.getX(), p2.getY());
path.lineTo(p3.getX(), p3.getY());
path.lineTo(p1.getX(), p1.getY());
myShapes.add(new MyShape(path, p1));
repaint();
}
}
private class SliderChangeListener implements ChangeListener {
@Override
public void stateChanged(ChangeEvent arg0) {
double value = slider.getValue() / 100.0;
setScale(value);
}
}
public static void main(String args[]) {
// new Ecad();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
EcadB ecadB = new EcadB();
JFrame frame = new JFrame("Scale");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(ecadB);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
class MyShape {
Shape shape;
Point2D fixedPoint;
public MyShape(Shape shape, Point2D fixedPoint) {
this.shape = shape;
this.fixedPoint = fixedPoint;
}
public void draw(Graphics2D g2, double scale) {
Graphics2D g2b = (Graphics2D) g2.create();
double tx = fixedPoint.getX() * (1.0 - scale) / scale;
double ty = fixedPoint.getY() * (1.0 - scale) / scale;
g2b.translate(tx, ty);
g2b.draw(shape);
g2b.dispose();
}
}
请注意,我会在转换图形对象之前复制它,以便不会对图形对象可能绘制的其他对象产生转换效果。例如,如果你摆脱了我在JPanel的paintComponent(...)
方法中使用的Graphics2D副本,你会发现JSlider与其他所有东西一起缩放。