Question

我正在使用Java中的Swing开发一个简单的object drawing程序。我的程序应该在单击时根据按钮绘制形状，并使用鼠标移动任何形状。我有四个按钮，在屏幕上绘制矩形，圆形和方形。到目前为止，当我点击按钮时，我确实设法绘制了形状。但是我想在屏幕上移动它没有用完的形状。

问题在于：当我点击圆圈形状用鼠标拖动它时，它会清除所有屏幕，并在屏幕上显示。

并且，当我点击清除按钮时，有没有办法清理所有屏幕？

谢谢？

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


public class PaintProject extends JComponent implements ActionListener, 
    MouseMotionListener {

    private  int CircleX=0;
    private  int CircleY=0;
    private  int RectX=100;
    private  int RectY=100;
    private  int SquareX=300;
    private  int SquareY=200;


    public static void main(String[] args) {
        JFrame frame = new JFrame("NEW PAINT PROGRAME!");

        JButton CircleButton = new JButton("Circle");
        CircleButton.setActionCommand("Circle");

        JButton RectangleButton = new JButton("Rectangle");
        RectangleButton.setActionCommand("Rectangle");

        JButton SquareButton = new JButton("Square");
        SquareButton.setActionCommand("Square");

        PaintProject paint = new PaintProject();

        CircleButton.addActionListener(paint);
        RectangleButton.addActionListener(paint);
        SquareButton.addActionListener(paint);


        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setLayout(new FlowLayout());
        frame.add(paint);
        frame.add(CircleButton);
        frame.add(RectangleButton);
        frame.add(SquareButton);


        frame.addMouseMotionListener(paint);

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

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(500, 500);

    }

    private void drawCircle() {
        Graphics g = this.getGraphics();
        g.setColor(Color.red);
        g.fillOval(CircleX, CircleY, 100, 100);
    }

    private void drawRectangle() {
        Graphics g = this.getGraphics();
        g.setColor(Color.green);
        g.fillRect(RectX, RectY, 100, 300);
    }
    private void drawSquare() {
        Graphics g = this.getGraphics();
        g.setColor(Color.blue);
        g.fillRect(SquareX, SquareY, 100, 100);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String command = e.getActionCommand();
        if (command.equals("Circle")) {
        drawCircle();
    }
    else if (command.equals("Rectangle")) {
        drawRectangle();
    }
    else if (command.equals("Square")) {
        drawSquare();
    }

    }

    @Override
    public void mouseDragged(MouseEvent e) {
        CircleX=e.getX();
        CircleY=e.getY();
        repaint();
    }

}

Answer 1

如上所述here和here，getGraphics()不是如何在Swing中执行custom painting的。相反，覆盖paintComponent()以呈现所需内容。看起来您想使用鼠标拖动形状。显示移动所选对象的基本方法here;将fillXxx()调用替换为此处显示的drawString()。对于多种形状，请使用List<Shape>; clear命令变为简单List::clear。引用了一个完整的例子here;它具有通过边缘连接的可移动，可选择，可调整大小的彩色节点。

Java Swing用鼠标移动形状

1 个答案: