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因此，我尝试将paintComponent() 的使用以及MouseListener 和MouseActionListener 的使用结合起来，但是当我运行它时出现很多错误，并且它不起作用，因为我想要它。在这段代码中，我希望程序在你按下、拖动和释放按钮时，获取按下的坐标，然后是释放的坐标，然后测量形状有多大，并绘制指定的形状通过 JComboBox。我还有 JFrame 底部带有按钮的颜色选择器。我想知道如何在不自动运行的情况下运行 paintComponent() 方法，这样我就可以在它绘制之前给它规范，并让它按需绘制。另外，我想知道是否有另一种方法可以做到这一点，我完全错了我如何接近它。我希望解释是' 太混乱了:)。任何帮助都很棒，谢谢！

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

@SuppressWarnings({"unchecked", "rawtypes"})
public class GraphicGUI extends JPanel implements ActionListener  {

    HandlerClass handler = new HandlerClass();

    public int x1, x2, y1, y2, width, height;
    public String event;
    public JButton colorChooserButton;
    public Color color = (Color.WHITE);
    public JComboBox shapeBox;
    public JLabel eventLabel;


    public GraphicGUI(){
        shapeBox = new JComboBox();
        eventLabel = new JLabel();
        colorChooserButton = new JButton("Choose a color");
        colorChooserButton.addActionListener(this);

        shapeBox.addItem("Oval");
        shapeBox.addItem("Rectangle");
        shapeBox.addItem("Line");

        super.addMouseListener(handler);
        super.addMouseMotionListener(handler);
    }

    public void actionPerformed(ActionEvent arg0){
        if(arg0.getSource().equals(colorChooserButton)){
            color = JColorChooser.showDialog(null, "Pick Your Color", color);
            if(color==null){
                color = (Color.BLACK);
            }
        }
    }

    public void paintComponent(Graphics g){
        super.paintComponent(g);
        this.setBackground(Color.white);
        if(shapeBox.getSelectedItem() == "Oval")
            if(event.equals("released")){
                width = x1-x2;
                height = y1-y2;
                g.setColor(color);
                g.fillOval(x1, y1, width, height);
            }
    }

    private class HandlerClass implements MouseListener, MouseMotionListener{

            //Mouse Events
            public void mouseClicked(MouseEvent arg0){
                event = "click";
            }
            public void mousePressed(MouseEvent arg0){
                event = "pressed";
                x1 = arg0.getX();
                y1 = arg0.getY();
                eventLabel.setText(String.format("Mouse pressed at %d, %d", x1, y1));
            }
            public void mouseReleased(MouseEvent arg0){
                event = "released";
                x2 = arg0.getX();
                y2 = arg0.getY();
                eventLabel.setText(String.format("Mouse released at %d, %d", x2, y2));
            }
            public void mouseEntered(MouseEvent arg0){
            }
            public void mouseExited(MouseEvent arg0){
            }

            //Mouse Motion Events
            public void mouseDragged(MouseEvent arg0){
            }
            public void mouseMoved(MouseEvent arg0){
            }

    }
}
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1 回答 1

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您应该开始绘制形状。

public void paintComponent(Graphics g){
    //Draw the oval
    g.setColor(color);
    g.fillOval(x1, y1, width, height);
}

public void mouseReleased(MouseEvent arg0){
    event = "released";
    x2 = arg0.getX();
    y2 = arg0.getY();       
    if( x2 > x1 ) {
        width = x2-x1;
    } else {
        width = x1-x2;
    }       
    if( y2 > y1 ) {
        height = y2-y1;
    } else {
        height = y1-y2;
    }
    eventLabel.setText(String.format("Mouse released at %d, %d", x2, y2));  
}

然后（如果您想添加更多形状）您需要一种添加形状的方法（duh），因此您可以拥有一个形状列表并遍历该列表。

而且您确实应该（必须）初始化所有变量。

询问您是否需要更多详细信息。:)

于 2013-04-23T02:08:47.907 回答