Java DrawRect 问题

Question

我正在使用 Java 编写一个文件管理器。我需要将矩形选择添加到我的程序中，就像在 Windows 中一样(以便选择矩形内的多个文件)。我的问题是，每当我向 DrawRect 面板添加布局来放置图标时，我都无法再绘制矩形了!这是我的 DrawRect 代码:

   import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

public class DrawRect extends JPanel {

    int x, y, x2, y2;

//    public static void main(String[] args) {
//        JFrame f = new JFrame("Draw Box Mouse 2");
//        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//        f.setContentPane(new DrawRect());
//        f.setSize(300, 300);
//        f.setVisible(true);
//    }

   public DrawRect() {
        x = y = x2 = y2 = 0; //
        MyMouseListener listener = new MyMouseListener();
        addMouseListener(listener);
        addMouseMotionListener(listener);
    }

    public void setStartPoint(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public void setEndPoint(int x, int y) {
        x2 = (x);
        y2 = (y);
    }

    public void drawPerfectRect(Graphics g, int x, int y, int x2, int y2) {
        int px = Math.min(x,x2);
        int py = Math.min(y,y2);
        int pw=Math.abs(x-x2);
        int ph=Math.abs(y-y2);
        g.drawRect(px, py, pw, ph);
        g.fillRect(px,py,pw,ph);

    }

    class MyMouseListener extends MouseAdapter {

        public void mousePressed(MouseEvent e) {
            setStartPoint(e.getX(), e.getY());
        }

        public void mouseDragged(MouseEvent e) {
            setEndPoint(e.getX(), e.getY());
            repaint();
        }

        public void mouseReleased(MouseEvent e) {
            setEndPoint(e.getX(), e.getY());
            repaint();
        }
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        int alpha = 50; // 50% transparent
        Color myColour = new Color(0, 0, 200,50);
       g.setColor(myColour);
        drawPerfectRect(g, x, y, x2, y2);

    }

}

enter image description here

为了解释更多，在上图中，我有一个 SplitPane，它的右侧部分是一个 ScrollPane，DrawRect 的实例被添加到滚动痛苦中，并且图标也添加到我的 DrawRect 面板中，每个面板中有多行网格布局有一个流程布局。我该怎么做才能绘制矩形？

正如您在下面看到的，如果我不向 DrawRect 面板添加任何布局，它可以正常工作，但仍然会错过图标和布局存在的部分: enter image description here

最后，我有一个问题:解决这个问题后，我可以告诉这个选择矩形内的按钮被选择吗？非常感谢!

================================================== ===========================更新:

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

abstract public class GridIcon extends JButton {
    private Color pressedBackgroundColor = Color.blue;
    private String shortenedName;
    private String path;
    private boolean setSelected = false;


    public GridIcon(String text, Icon icon, String path) {
        this.addActionListener(new ButtonListener());
        this.path = path;

        if (text.length() > 9) {
            shortenedName = text.substring(0, 9);
            shortenedName += "...";
        } else
            shortenedName = text;

        this.setIcon(icon);
        this.setText(shortenedName);
        this.setFocusable(false);


        this.setVerticalTextPosition(SwingConstants.BOTTOM);
        this.setHorizontalTextPosition(SwingConstants.CENTER);
        super.setOpaque(false);
        super.setContentAreaFilled(false);
        super.setBorderPainted(false);
        super.setBorder(null);
        this.setBackground(new Color(0, 0, 0, 0));


        //  super.setPreferredSize(new Dimension(60,60));

    }

    @Override
    protected void paintComponent(Graphics g) {
        if (getModel().isPressed() || setSelected) {
            g.setColor(pressedBackgroundColor);
        } else {
            g.setColor(getBackground());
        }
        g.fillRect(0, 0, getWidth(), getHeight());
        super.paintComponent(g);
    }

    @Override
    public void setContentAreaFilled(boolean b) {
    }


    public String getPath() {
        return path;
    }

    public Color getPressedBackgroundColor() {
        return pressedBackgroundColor;
    }

    public void setPressedBackgroundColor(Color pressedBackgroundColor) {
        this.pressedBackgroundColor = pressedBackgroundColor;
    }

    public void setSetSelected(boolean isSelected) {
        setSelected = isSelected;
    }

    public boolean isSetSelected() {
        return setSelected;
    }

    class ButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            if (setSelected)
                setSelected = false;

            else
                setSelected = true;

        }
    }


}

Answer 1

查看 A Closer Look at the Painting Mechanism 上的 Swing 教程中的部分了解绘画是如何完成的。

所发生的情况是，添加到面板的组件是在绘制选择矩形之后绘制的。

解决方案是使用您的自定义代码覆盖paint(...)。然后选择矩形将绘制在子组件的顶部。