单击后防止JButton repaint() [英] Prevent JButton repaint() after click

问题描述

我有一个按钮.我要在单击后更改背景.我的问题在这里是按钮自动调用paintComponent().如何预防呢?我希望在单击按钮后，该按钮将为蓝色，但仍将为红色.

I have a button. I want to change the background after I click on it. My problem here is the button auto call paintComponent(). How can prevent this? I expect after clicking the button the button will be blue, but it will still be red.

package test;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ButtonDemo extends JButton implements ActionListener{

    public ButtonDemo() {
        this.setText("BUTTON TEXT");
        this.addActionListener(this);
    }
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        setBackground(Color.RED);
    }
    public static void main(String[] args){
        JFrame frame = new JFrame();
        JPanel contentPane = new JPanel();
        frame.setContentPane(contentPane);
        contentPane.add(new ButtonDemo());
        frame.setSize(500, 500);

        frame.setVisible(true);

    }
    @Override
    public void actionPerformed(ActionEvent e) {
        this.setBackground(Color.BLUE);
    }  
}

推荐答案

我个人的直觉是JButton可能不适合您的理想目标.

My personal gut feeling is that JButton is probably not suited to your desired goal.

基本上，您想控制何时以及如何更改作品的选定"状态.

Essentially, you want to control when and how the "selected" state of the piece is changed.

就个人而言，我将拥有某种以某种方式监视鼠标事件的控制器(可能使部件组件将事件委托给控制器)​​和某种模型来控制何时选择部件，然后它将通知状态更改的控制器，它将对UI进行适当的更新.

Personally, I would have some kind of controller which monitored the mouse events in some way (probably having the piece component delegate the event back to the controller) and some kind of model which control when pieces become selected, this would then notify the controller of the state change and it would make appropriate updates to the UI.

但这是一个漫长的设置过程.取而代之的是，我展示了一个简单的概念，其中可以使用鼠标选择组件，但是只有控制器可以取消选择.在此示例中，这将仅允许选择单个作品

But that's a long process to setup. Instead, I'm demonstrating a simple concept where a component can be selected with the mouse, but only the controller can de-select. In this example, this will allow only a single piece to be selected

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Main {

    public static void main(String[] args) {
        new Main();
    }

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        public TestPane() {
            setLayout(new GridLayout(5, 5));

            ChangeListener listener = new ChangeListener() {
                private PiecePane selectedPiece;

                @Override
                public void stateChanged(ChangeEvent e) {
                    if (!(e.getSource() instanceof PiecePane)) { return; }

                    PiecePane piece = (PiecePane) e.getSource();

                    // Want to ignore events from the selected piece, as this
                    // might interfer with the changing of the pieces
                    if (selectedPiece == piece) { return; }

                    if (selectedPiece != null) {
                        selectedPiece.setSelecetd(false);
                        selectedPiece = null;
                    }

                    selectedPiece = piece;
                }
            };

            for (int index = 0; index < 5 * 5; index++) {
                PiecePane pane = new PiecePane();
                pane.addChangeListener(listener);
                add(pane);
            }
        }

    }

    public class PiecePane extends JPanel {

        private boolean selecetd;
        private Color selectedBackground;
        private Color normalBackground;

        private MouseListener mouseListener;

        public PiecePane() {
            setBorder(new LineBorder(Color.DARK_GRAY));
            mouseListener = new MouseAdapter() {
                @Override
                public void mouseClicked(MouseEvent e) {
                    setSelecetd(true);
                }
            };

            setNormalBackground(Color.BLUE);
            setSelectedBackground(Color.RED);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(50, 50);
        }

        @Override
        public void addNotify() {
            super.addNotify(); 
            addMouseListener(mouseListener);
        }

        @Override
        public void removeNotify() {
            super.removeNotify(); 
            removeMouseListener(mouseListener);
        }

        public void addChangeListener(ChangeListener listener) {
            listenerList.add(ChangeListener.class, listener);
        }

        public void removeChangeListener(ChangeListener listener) {
            listenerList.remove(ChangeListener.class, listener);
        }

        protected void fireSelectionChanged() {
            ChangeListener[] listeners = listenerList.getListeners(ChangeListener.class);
            if (listeners.length == 0) {
                return;
            }
            ChangeEvent evt = new ChangeEvent(this);
            for (int index = listeners.length - 1; index >= 0; index--) {
                listeners[index].stateChanged(evt);
            }
        }

        public boolean isSelected() {
            return selecetd;
        }

        public void setSelecetd(boolean selecetd) {
            if (selecetd == this.selecetd) { return; }
            this.selecetd = selecetd;
            updateSelectedState();
            fireSelectionChanged();
        }

        public Color getSelectedBackground() {
            return selectedBackground;
        }

        public void setSelectedBackground(Color selectedBackground) {
            this.selectedBackground = selectedBackground;
            updateSelectedState();
        }

        public Color getNormalBackground() {
            return normalBackground;
        }

        public void setNormalBackground(Color normalBackground) {
            this.normalBackground = normalBackground;
            updateSelectedState();
        }

        protected void updateSelectedState() {
            if (isSelected()) {
                setBackground(getSelectedBackground());
            } else {
                setBackground(getNormalBackground());
            }
        }
    }
}

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