自定义Java Swing组件模型，UIDelegate，组件格式

Question

我被赋予创建自定义Swing组件的任务。在测试应用程序中，我的组件可以正常运行，并包括JSlider以缩放图像。然而，我需要在Model、UIDelegate和Component类格式中展示我的自定义组件，但我完全不知道如何转换我的代码以符合这个格式。下面是我的测试应用程序代码：

package test;

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.event.*;

import java.io.File;
import java.net.URL;

import javax.imageio.ImageIO;

public class ZoomDemo extends JComponent implements ChangeListener {

JPanel gui;
/**
 * Displays the image.
 */
JLabel imageCanvas;
Dimension size;
double scale = 1.0;
private BufferedImage image;

public ZoomDemo() {
    size = new Dimension(10, 10);
    setBackground(Color.black);
    try {
         image = ImageIO.read(new File("car.jpg"));
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

public void setImage(Image image) {
    imageCanvas.setIcon(new ImageIcon(image));
}

public void initComponents() {
    if (gui == null) {
        gui = new JPanel(new BorderLayout());
        gui.setBorder(new EmptyBorder(5, 5, 5, 5));
        imageCanvas = new JLabel();
        JPanel imageCenter = new JPanel(new GridBagLayout());
        imageCenter.add(imageCanvas);
        JScrollPane imageScroll = new JScrollPane(imageCenter);
        imageScroll.setPreferredSize(new Dimension(300, 100));
        gui.add(imageScroll, BorderLayout.CENTER);
    }
}

public Container getGui() {
    initComponents();
    return gui;
}

public void stateChanged(ChangeEvent e) {
    int value = ((JSlider) e.getSource()).getValue();
    scale = value / 100.0;
    paintImage();
}

protected void paintImage() {

    int imageWidth = image.getWidth();
    int imageHeight = image.getHeight();
    BufferedImage bi = new BufferedImage(
            (int)(imageWidth*scale), 
            (int)(imageHeight*scale), 
            image.getType());
    Graphics2D g2 = bi.createGraphics();
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
    AffineTransform at = AffineTransform.getTranslateInstance(0, 0);
    at.scale(scale, scale);
    g2.drawRenderedImage(image, at);
    setImage(bi);
}

public Dimension getPreferredSize() {
    int w = (int) (scale * size.width);
    int h = (int) (scale * size.height);
    return new Dimension(w, h);
}

private JSlider getControl() {
    JSlider slider = new JSlider(JSlider.HORIZONTAL, 1, 500, 50);
    slider.setMajorTickSpacing(50);
    slider.setMinorTickSpacing(25);
    slider.setPaintTicks(true);
    slider.setPaintLabels(true);
    slider.addChangeListener(this);
    return slider;
}

public static void main(String[] args) {
    ZoomDemo app = new ZoomDemo();
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(app.getGui());
    app.setImage(app.image);

    // frame.getContentPane().add(new JScrollPane(app));  
    frame.getContentPane().add(app.getControl(), "Last");
    frame.setSize(700, 500);
    frame.setLocation(200, 200);
    frame.setVisible(true);
}
}

以下是我需要遵循的类格式代码

组件类

package component;

import javax.swing.JComponent;

import javax.swing.JSlider;
import javax.swing.plaf.ComponentUI;

public class ProgressBar extends JComponent {

public static ComponentUI createUI(JComponent c) {
    return new ZoomUI();
}

public void installUI(JComponent c){



}

public void uninstallUI (JComponent c){

}
}

模型类

public class ZoomModel extends JSLider  {



}

UIDelegate Class

public class ZoomUI extends ComponentUI implements ChangeListener{

}

任何有关如何以这种格式实现我的自定义组件的帮助都将不胜感激。我对Swing非常陌生，我找到的有关自定义组件的文档非常令人困惑且帮助很少。

测试应用程序

package test;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
import javax.swing.event.*;

import java.io.File;
import java.net.URL;

import javax.imageio.ImageIO;

import component.ZoomComponent;

public class ZoomDemo  extends JPanel implements PropertyChangeListener, ActionListener {

ZoomComponent zoomer;
JPanel board;
private BufferedImage image;

public ZoomDemo( ) {
    super(true);  
    setLayout(new BorderLayout( )); 
    board = new JPanel(true); 
    board.setPreferredSize(new Dimension(300, 300)); 
    board.setBorder(new LineBorder(Color.black, 5));

    zoomer = new ZoomComponent();
    add(board, BorderLayout.NORTH);
    add(zoomer, BorderLayout.SOUTH);



}


@Override
public void actionPerformed(ActionEvent arg0) {
    // TODO Auto-generated method stub

}

@Override
public void propertyChange(PropertyChangeEvent arg0) {
    // TODO Auto-generated method stub

}

public static void main(String[] args) {

    UIManager.getDefaults().put("ZoomComponentUI", "component.BasicZoomUI");
    ZoomDemo s= new ZoomDemo();
    JFrame frame = new JFrame("Sample Sketch Application"); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    frame.setContentPane(s); 
    frame.pack( ); 
    frame.setVisible(true);
}

}

- Wheels99

---

你的模型类不正确，它应该对数据进行建模，而不是UI，因此可能包含图像和缩放级别等内容。例如。 - MadProgrammer

对于模型，您应该重用或扩展现有的Swing模型。UIdelegate（“用户界面”类）扩展ComponentUI。它负责绘制组件并解释用户的鼠标或键盘操作，因此它应该实现适当的监听器和接口。Component类扩展了JComponent。这些是我收到的说明，但我不知道如何使其工作。 - Wheels99

“你应该重用或者扩展一个已存在的Swing模式。” 比如呢？ - MadProgrammer

我假设这意味着像我的代码中所做的那样扩展现有模型，比如“JSLider”。 - Wheels99

JSlider 不是一个模型，它是一个组件 ;) - MadProgrammer

Answer 1

好的，那么这是一个有趣的冒险，进入了我不常使用的API部分 :), 首先阅读如何编写自定义Swing组件及其相关链接，这将为您提供理解即将发生的事情的基础...

模型

接口

就个人而言，我总是从一个接口开始，接口会让生活更美好，并且给您更多的灵活性。现在，根据您的要求，应该从哪个模型继承呢...？

嗯，我能找到的最好选择是BoundedRangeModel，它也被JSlider使用...这实际上意味着我不仅可以将此模型传递给视图，还可以将其传递给JSlider，并且不需要任何额外工作，就可以改变图像！双赢

import java.awt.Dimension;
import java.awt.Image;
import javax.swing.BoundedRangeModel;

public interface ZoomModel extends BoundedRangeModel {

    public Image getImage();

    public Dimension getScaledSize();

}

摘要

接下来，我喜欢制作一个摘要版本，其中我会放置"通用"功能，这些功能很可能对大多数实现都相同，在这种情况下，可能不是必需的，但我就是这么挑剔...

import java.awt.Dimension;
import java.awt.Image;
import javax.swing.DefaultBoundedRangeModel;

public abstract class AbstractZoomModel extends DefaultBoundedRangeModel implements ZoomModel {

    public AbstractZoomModel() {
        super(100, 0, 0, 200);
    }

    @Override
    public Dimension getScaledSize() {
        Dimension size = new Dimension(0, 0);
        Image image = getImage();
        if (image != null) {
            double scale = getValue() / 100d;
            size.width = (int) Math.round(image.getWidth(null) * scale);
            size.height = (int) Math.round(image.getHeight(null) * scale);

        }
        return size;
    }

}

因此，你可以看到我定义了一些基本属性，起始缩放级别为100，最大级别为200，最小级别为0，并且我实现了getScaledSize，这在使用时非常方便...

默认值...

现在，因为我们喜欢友好，我们提供了模型的“默认”实现。这相当基本，它只需要一个图像的引用...

import java.awt.Image;

public class DefaultZoomModel extends AbstractZoomModel {
    Image image;

    public DefaultZoomModel(Image image) {
        this.image = image;
    }

    @Override
    public Image getImage() {
        return image;
    }

}

您可以创建实现，例如从URL下载图像...

视图

好的，这实际上是组件本身，它被添加到您的UI中。它包含构建和准备UI委托以及管理模型所需的基本功能。这里感兴趣的关键是使用属性更改支持来提供对模型更改的通知，这很重要，因为您将看到...

import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JComponent;
import javax.swing.UIManager;

public class ZoomComponent extends JComponent {

    private static final String uiClassID = "ZoomComponentUI";
    private ZoomModel model;

    public ZoomComponent() {
        setBackground(Color.black);
        setFocusable(true);
        updateUI();
    }

    public void setModel(ZoomModel newModel) {
        if (model != newModel) {
            ZoomModel old = model;
            this.model = newModel;
            firePropertyChange("model", old, newModel);
        }
    }

    public ZoomModel getModel() {
        return model;
    }

    @Override
    public Dimension getPreferredSize() {
        ZoomModel model = getModel();
        Dimension size = new Dimension(100, 100);
        if (model != null) {
            size = model.getScaledSize();
        }
        return size;
    }

    public void setUI(BasicZoomUI ui) {
        super.setUI(ui);
    }

    @Override
    public void updateUI() {
        if (UIManager.get(getUIClassID()) != null) {
            ZoomUI ui = (ZoomUI) UIManager.getUI(this);
            setUI(ui);
        } else {
            setUI(new BasicZoomUI());
        }
    }

    public BasicZoomUI getUI() {
        return (BasicZoomUI) ui;
    }

    @Override
    public String getUIClassID() {
        return uiClassID;
    }
}

UI代理

现在是另一个有趣的部分...如果我们遵循标准惯例，通常会提供一个UI代理的抽象概念，例如...

import javax.swing.plaf.ComponentUI;

public abstract class ZoomUI extends ComponentUI {       
}

从此处开始，其他委托将增长...

基本的UI委托

通常惯例建议您提供一种“基本”实现，它可以执行大量的重活，但允许其他实现机会来更改它们可能喜欢的东西。

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.KeyStroke;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ComponentUI;

public class BasicZoomUI extends ZoomUI {

    private ZoomComponent zoomComponent;
    private MouseAdapter mouseHandler;
    private ChangeListener changeHandler;

    private Action zoomIn;
    private Action zoomOut;
    private PropertyChangeListener propertyChangeHandler;

    protected ChangeListener getChangeHandler() {
        if (changeHandler == null) {
            changeHandler = new ChangeHandler();
        }
        return changeHandler;
    }

    protected void installMouseListener() {
        mouseHandler = new MouseAdapter() {

            @Override
            public void mouseClicked(MouseEvent e) {
                zoomComponent.requestFocusInWindow();
            }

            @Override
            public void mouseWheelMoved(MouseWheelEvent e) {
                int amount = e.getWheelRotation();
                ZoomModel model = zoomComponent.getModel();
                if (model != null) {

                    int value = model.getValue();
                    model.setValue(value + amount);

                }
            }

        };
        zoomComponent.addMouseListener(mouseHandler);
        zoomComponent.addMouseWheelListener(mouseHandler);

    }

    protected void installModelPropertyChangeListener() {

        propertyChangeHandler = new PropertyChangeListener() {
            @Override
            public void propertyChange(PropertyChangeEvent evt) {
                ZoomModel old = (ZoomModel) evt.getOldValue();
                if (old != null) {
                    old.removeChangeListener(getChangeHandler());
                }
                ZoomModel newValue = (ZoomModel) evt.getNewValue();
                if (newValue != null) {
                    newValue.addChangeListener(getChangeHandler());
                }
            }
        };

        zoomComponent.addPropertyChangeListener("model", propertyChangeHandler);

    }

    protected void installKeyBindings() {

        zoomIn = new ZoomInAction();
        zoomOut = new ZoomOutAction();

        InputMap inputMap = zoomComponent.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_ADD, 0), "zoomIn");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_SUBTRACT, 0), "zoomOut");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_PLUS, 0), "zoomIn");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_MINUS, 0), "zoomOut");

        ActionMap actionMap = zoomComponent.getActionMap();
        actionMap.put("zoomIn", zoomIn);
        actionMap.put("zoomOut", zoomOut);
    }

    protected void installModelChangeListener() {

        ZoomModel model = getModel();
        if (model != null) {
            model.addChangeListener(getChangeHandler());
        }

    }

    @Override
    public void installUI(JComponent c) {

        zoomComponent = (ZoomComponent) c;

        installMouseListener();
        installModelPropertyChangeListener();
        installKeyBindings();
        installModelChangeListener();

    }

    protected void uninstallModelChangeListener() {

        getModel().removeChangeListener(getChangeHandler());

    }

    protected void uninstallKeyBindings() {

        InputMap inputMap = zoomComponent.getInputMap(JComponent.WHEN_FOCUSED);
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_ADD, 0), "donothing");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_SUBTRACT, 0), "donothing");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_PLUS, 0), "donothing");
        inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_MINUS, 0), "donothing");

        AbstractAction blank = new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
            }
        };

        ActionMap actionMap = zoomComponent.getActionMap();
        actionMap.put("zoomIn", blank);
        actionMap.put("zoomOut", blank);

    }

    protected void uninstallModelPropertyChangeListener() {

        zoomComponent.removePropertyChangeListener(propertyChangeHandler);
        propertyChangeHandler = null;

    }

    protected void uninstallMouseListener() {

        zoomComponent.removeMouseWheelListener(mouseHandler);
        mouseHandler = null;

    }

    @Override
    public void uninstallUI(JComponent c) {

        uninstallModelChangeListener();
        uninstallModelPropertyChangeListener();
        uninstallKeyBindings();
        uninstallMouseListener();

        mouseHandler = null;
        zoomComponent = null;

    }

    @Override
    public void paint(Graphics g, JComponent c) {
        super.paint(g, c);
        paintImage(g);
    }

    protected void paintImage(Graphics g) {
        if (zoomComponent != null) {
            ZoomModel model = zoomComponent.getModel();
            Image image = model.getImage();
            Dimension size = model.getScaledSize();
            int x = (zoomComponent.getWidth() - size.width) / 2;
            int y = (zoomComponent.getHeight() - size.height) / 2;
            g.drawImage(image, x, y, size.width, size.height, zoomComponent);
        }
    }

    public static ComponentUI createUI(JComponent c) {
        return new BasicZoomUI();
    }

    protected ZoomModel getModel() {

        return zoomComponent == null ? null : zoomComponent.getModel();

    }

    protected class ChangeHandler implements ChangeListener {

        @Override
        public void stateChanged(ChangeEvent e) {
            zoomComponent.revalidate();
            zoomComponent.repaint();
        }

    }

    protected class ZoomAction extends AbstractAction {

        private int delta;

        public ZoomAction(int delta) {
            this.delta = delta;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            ZoomModel model = getModel();
            if (model != null) {
                model.setValue(model.getValue() + delta);
            }
        }

    }

    protected class ZoomOutAction extends ZoomAction {

        public ZoomOutAction() {
            super(-5);
        }

    }

    protected class ZoomInAction extends ZoomAction {

        public ZoomInAction() {
            super(5);
        }

    }

}

从这里开始，您可以进行特定于平台的实现，但我决定坚持基本的代理模式...

将所有内容整合在一起

如果这还不够，使用任何内容之前，必须安装代理程序...

UIManager.getDefaults().put("ZoomComponentUI", "your.awesome.package.name.BasicZoomUI");

注意: 将 your.awesome.package.name 替换为您实际的包名...

可运行示例

 import java.awt.BorderLayout;
 import java.awt.Dimension;
 import java.awt.EventQueue;
 import java.awt.Graphics;
 import java.awt.Graphics2D;
 import java.io.File;
 import java.io.IOException;
 import javax.imageio.ImageIO;
 import javax.swing.JFrame;
 import javax.swing.JPanel;
 import javax.swing.JScrollPane;
 import javax.swing.JSlider;
 import javax.swing.UIManager;
 import javax.swing.UnsupportedLookAndFeelException;

 public class TestZoom100 {

      public static void main(String[] args) {
           new TestZoom100();
      }

      public TestZoom100() {
           EventQueue.invokeLater(new Runnable() {
                @Override
                public void run() {
                     try {
                          UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                     } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                          ex.printStackTrace();
                     }

                     UIManager.getDefaults().put("ZoomComponentUI", "your.awesome.package.name.BasicZoomUI");

                     try {
                          DefaultZoomModel model = new DefaultZoomModel(ImageIO.read(new File("/your/awesome/image.jpg")));
                          model.setValue(50);
                          ZoomComponent zoomComp = new ZoomComponent();
                          zoomComp.setModel(model);

                          JSlider slider = new JSlider(model);

                          JFrame frame = new JFrame("Testing");
                          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                          frame.add(new JScrollPane(zoomComp));
                          frame.add(slider, BorderLayout.SOUTH);
                          frame.pack();
                          frame.setLocationRelativeTo(null);
                          frame.setVisible(true);
                     } catch (IOException exp) {
                          exp.printStackTrace();
                     }
                }
           });
      }

 }

不要忘记将BasicZoomUI的包名更改为您存储它的包名，并实际指定一个图像文件;)

- MadProgrammer

---

非常感谢！这比我之前阅读的任何文档都更加清晰易懂。非常感激！！ :) - Wheels99

现在你的工作是理解它正在做什么，因为我没有记录大部分的代码 ;) - 想象一下有人现在指着一段代码问：“你为什么这样做？” - MadProgrammer

我已经将我目前拥有的测试应用程序代码添加到我的原始问题中。我不太明白如何设置图像并使组件出现在面板中。 - Wheels99

很抱歉，我仍然不明白如何将所有这些组合在一起，我甚至无法让滑块出现在我的面板中，更别提图片了。 - Wheels99

不要过于担心滑块，模型向代理提供信息，组件充当两者之间的粘合剂。您需要一个控制用户可以缩放的范围、当前缩放值和原始图像的模型... - MadProgrammer