[英]how to add Mouselistener to line in graphics java
public Line2D line2d;
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(40, 0, 400, 400);
g2.draw(line2d);
}
@Override
public void mouseClicked(MouseEvent e) {
if(line2d.contains(e.getX(), e.getY())) {
System.out.println("Line clicked");
}
}
此变体无法正常工作。 还有其他方法可以将MouseListener添加到该行吗?
我找到了解决方案。 我认为最好在其中添加不可见的多边形。 并捕获其Mouseevents。 因为线没有与多边形不同的可点击区域。请参见以下代码:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Line2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MyPanel extends JPanel implements MouseListener {
public Line2D line2d;
public Polygon pol;
public int x1 = 40;
public int y1 = 0;
public int x2 = 400;
public int y2 = 400;
public int margin = 3;
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setPreferredSize(new Dimension(500, 500));
frame.getContentPane().add(new MyPanel());
frame.pack();
frame.setVisible(true);
}
public MyPanel(){
setBackground(Color.WHITE);
addMouseListener(this);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(x1, y1, x2, y2);
g2.draw(line2d);
int xPoints[] = { x1 - margin, x1 + margin, x2 + margin, x2 - margin };
int yPoints[] = { y1 + margin, y1 - margin, y2 - margin, y2 + margin };
pol = new Polygon(xPoints, yPoints, yPoints.length);
}
@Override
public void mouseClicked(MouseEvent e) {
if (pol.contains(e.getX(), e.getY())) {
System.out.println("Line clicked");
}
}
@Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
}
可以将MouseListener添加到Component中,例如:JPanel,JTextfield等,或带有扩展Component的自定义类。 请参见以下示例。
public class T extends JComponent {
public T(){
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
// TODO: do your business.
}
});
}
public Line2D line2d;
Graphics2D g2;
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g2 = (Graphics2D) g;
g2.setColor(Color.BLACK);
g2.setStroke(new BasicStroke(2.0F));
line2d = new Line2D.Double(40, 0, 400, 400);
g2.draw(line2d);
}
}
您可以使用bessenheim(不知道如何正确发音)algorith来创建线...
那么您只需检查是否单击该行...
public class Line {
public static ArrayList<Point> getLine(Point start, Point target) {
ArrayList<Point> ret = new ArrayList<Point>();
int x0 = start.x;
int y0 = start.y;
int x1 = target.x;
int y1 = target.y;
int sx = 0;
int sy = 0;
int dx = Math.abs(x1-x0);
sx = x0<x1 ? 1 : -1;
int dy = -1*Math.abs(y1-y0);
sy = y0<y1 ? 1 : -1;
int err = dx+dy, e2; /* error value e_xy */
for(;;){ /* loop */
ret.add( new Point(x0,y0) );
if (x0==x1 && y0==y1) break;
e2 = 2*err;
if (e2 >= dy) { err += dy; x0 += sx; } /* e_xy+e_x > 0 */
if (e2 <= dx) { err += dx; y0 += sy; } /* e_xy+e_y < 0 */
}
return ret;
}
}
注意-这个算法不是我的主意,它是由一个名叫“ bessenheim”的人开发的。 ^^呵呵,太好玩了^^
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