单击绘制的对象

Question

我有一个叫做Shape继承自JPanel的类.

许多子类反过来扩展Shape类,每种类型的形状一个.

每个形状都有自己的覆盖paint()方法,它绘制相应的形状.

我希望能够点击任何形状,我现在正试图实现这个逻辑.请注意,每个形状都已添加到arrayList中.

但是,即使我在形状内部明确单击,contains语句也始终返回false.

有任何想法吗？

Answer 1

永不覆盖paint()在JPanel相当paintComponent(..)

我不太确定我理解但是我做了一个简短的例子,希望能有所帮助.基本上它是一个简单JFrame的DrawingPanel(我自己的类扩展JPanel,形状被绘制).这个面板将创建形状(只有2个用于测试)将它们添加到一个ArrayList并将它们绘制到JPanelvia paintComponent(..)和一个for循环,它还有一个MouseAdapter用来检查用户的mouseClicked(..)evnet JPanel.当点击进行时,我们遍历每Shape一个ArrayList并检查是否Shape包含该点,如果是,则打印其类名并用于instance of检查Shape点击的类型并打印相应的消息:

输出(点击两个形状后):

单击java.awt.geom.Rectangle2D $ Double

单击一个矩形

单击java.awt.geom.Ellipse2D $ Double

点击一个圆圈

ShapeClicker.java:

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class ShapeClicker {

    public ShapeClicker() {
        JFrame frame = new JFrame();
        frame.setTitle("Shape Clicker");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);

        initComponents(frame);

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        //create frame and components on EDT
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new ShapeClicker();
            }
        });
    }

    private void initComponents(JFrame frame) {
        frame.add(new ShapePanel());
    }
}

//custom panel
class ShapePanel extends JPanel {

    private Shape rect = new Rectangle2D.Double(50, 100, 200, 100);
    private Shape cirlce = new Ellipse2D.Double(260, 100, 100, 100);
    private Dimension dim = new Dimension(450, 300);
    private final ArrayList<Shape> shapes;

    public ShapePanel() {
        shapes = new ArrayList<>();
        shapes.add(rect);
        shapes.add(cirlce);
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent me) {
                super.mouseClicked(me);
                for (Shape s : shapes) {

                    if (s.contains(me.getPoint())) {//check if mouse is clicked within shape

                        //we can either just print out the object class name
                        System.out.println("Clicked a "+s.getClass().getName());

                        //or check the shape class we are dealing with using instance of with nested if
                        if (s instanceof Rectangle2D) {
                            System.out.println("Clicked a rectangle");
                        } else if (s instanceof Ellipse2D) {
                            System.out.println("Clicked a circle");
                        }

                    }
                }
            }
        });
    }

    @Override
    protected void paintComponent(Graphics grphcs) {
        super.paintComponent(grphcs);
        Graphics2D g2d = (Graphics2D) grphcs;
        for (Shape s : shapes) {
            g2d.draw(s);
        }
    }

    @Override
    public Dimension getPreferredSize() {
        return dim;
    }
}