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Custom Layout Manager: PyramidLayout(�?

Sha Jiang — Sun, 15 Jul 2012 14:14:00 GMT

Custom Layout Manager: PyramidLayout

    已有太多关于自定义部局��理器的文章了。本文仅是一��学习笔讎ͼ�描述了如何实��C��U�像堆金字塔似的部局��理器，很简单，也有点儿意思，可能你也会感兴趣的�?2012.07.17最后更�?

    I have developed Swing application for several years, although I'm not professional GUI developer, I'm shamed of never creating any custom layout manager. Maybe the existing Swing layout managers are too powerful to create new ones. At least, GridBagLayout is powerful enough for my real works. And we have much more flexible GroupLayout and SpringLayout, of course, both of them are too complex, in fact I never use them directly. However I indirectly take advantage of GroupLayout due to using NetBeans' GUI designer Matisse.

1. Layout Manager basics
    Let's start with some layout manager foundation. Before this time I learn to customize layout, I always think layout manager is very mysterious. Layout is like a magic player that put a variety of components to right positions in containers. I haven't browsed any code of any layout, event the simplest one. That's why I think layout is mystery. But it's simple for me now.
    Generally, all of layout implements one or both of LayoutManager and LayoutManager2 interfaces. LayoutManager2 is LayoutManager's sub-interface, then if someone implements LayoutManager2 that means it really implements LayoutManager. Mostly all modern layouts implements LayoutManager2.
    Interface LayoutManager defines the basic methods must be implemented by every layout, all of them are intuitional: add new component--addLayoutComponent(); remove component--removeLayoutComponent(); calculate preferred size--preferredLayoutSize(); calculate minimum size--minimumLayoutSize(); how to layout the components--layoutContainer(). Absolutely, the layoutContainer() method is essential, you must instruct the parent container how to allocate space(bounds) for every component.
    The extension interface LayoutManager2 introduces more methods that if you have to: support constraints--addLayoutComponent(Component, Object); specify maximum size--maximumLayoutSize(); specify alignment--getLayoutAlignmentX() and getLayoutAlignmentY(); destroy specific caches or reset some variables when invaliding container--invalidateLayout().

2. PyramidLayout
    Now let's feature a simple and funny layout manager--PyramidLayout. The layout allows container to add components like building a Pyramid, as shown as the image below,

    As the above, PyramidLayout puts the first component on the bottom, then puts the second on top of the first, but its bounds is smaller, ... It looks like a Pyramid, doesn't it? Here is the full codes,

public class PyramidLayout implements LayoutManager2 {

    private List<Component> comps = new LinkedList<Component>();

    public void addLayoutComponent(final Component comp,
            final Object constraints) {
        synchronized (comp.getTreeLock()) {
            comps.add(comp);
        }
    }

    public void addLayoutComponent(final String name, final Component comp) {
        addLayoutComponent(comp, null);
    }

    public void removeLayoutComponent(final Component comp) {
        synchronized (comp.getTreeLock()) {
            comps.remove(comp);
        }
    }

    public float getLayoutAlignmentX(final Container target) {
        return 0.5F;
    }

    public float getLayoutAlignmentY(final Container target) {
        return 0.5F;
    }

    public void invalidateLayout(final Container target) {
        System.out.println();
    }

    public Dimension preferredLayoutSize(final Container parent) {
        synchronized (parent.getTreeLock()) {
            Insets insets = parent.getInsets();
            int width = insets.left + insets.right;
            int height = insets.top + insets.bottom;
            if (comps.size() == 0) {
                return new Dimension(width, height);
            }

            Dimension size = comps.get(0).getPreferredSize();
            width += size.width;
            height += size.height;

            return new Dimension(width, height);
        }
    }

    public Dimension minimumLayoutSize(final Container parent) {
        synchronized (parent.getTreeLock()) {
            Insets insets = parent.getInsets();
            int width = insets.left + insets.right;
            int height = insets.top + insets.bottom;
            if (comps.size() == 0) {
                return new Dimension(width, height);
            }

            Dimension size = comps.get(0).getMinimumSize();
            width += size.width;
            height += size.height;

            return new Dimension(width, height);
        }
    }

    public Dimension maximumLayoutSize(final Container target) {
        return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE);
    }

    public void layoutContainer(final Container parent) {
        synchronized (parent.getTreeLock()) {
            Dimension parentSize = parent.getSize();
            int compsCount = comps.size();
            Dimension step = new Dimension(parentSize.width / (2 * compsCount),
                    parentSize.height / (2 * compsCount));

            for (int i = 0; i < compsCount; i++) {
                Component comp = comps.get(i);
                comp.setBounds(calcBounds(parentSize, step, i));
                parent.setComponentZOrder(comp, compsCount - i - 1);
            }
        }
    }

    private Rectangle calcBounds(Dimension parentSize, Dimension step, int index) {
        int x = step.width * index;
        int y = step.height * index;
        int width = parentSize.width - step.width * 2 * index;
        int height = parentSize.height - step.height * 2 * index;
        return new Rectangle(x, y, width, height);
    }
}

    Collection instance "comps" manages all of components, in this case, I take a LinkedList object to add and remove UI components. The layout doesn't concern any constraint, so the two addLayoutComponent() methods have the same actions. Please see the codes for details.
    As aforementioned, layoutContainer() method really takes charge of layouting the components. The key work is allocating space for each component, namely, specifying the bounds. Calculating bounds values just applies the simplest arithmetic operations.
    According to the intention, the bottom component fills the whole parent container, so it determines the preferred and the minimum sizes. For details, please take a look at methods preferredLayoutSize() and minimumLayoutSize(). Since the layout manager doesn't take care of the maximum size, the maximumLayoutSize() method simply returns a constant value.

Sha Jiang 2012-07-15 22:14 发表评论

构徏不规则窗�?�?

Sha Jiang — Tue, 31 May 2011 12:46:00 GMT

构徏不规则窗�?/span>

在开发一个新��微博Swing客户端的�q�程中希望能展现不规则的�H�体界面�Q�原�?a >JDK 6 update 10提供了创建指定�Ş状窗体的�Ҏ��，��单易用，��C��此处�?2010.05.31最后更�?

Java�?a >JDK 6 update 10开始将内徏支持构徏指定形状的窗体，�c�com.sun.awt.AWTUtilities中的�Ҏ��setWindowShape会根据不同的Shape实现��L��造相应�Ş状的�H�体。AWTUtilities�c�L��攑֜�SUN的包中，在��用该�Ҏ��时应该通过反射去进行调用，如下代码所�C�，

Class clazz = Class.forName("com.sun.awt.AWTUtilities");
Method method = clazz.getMethod("setWindowShape", Window.class, Shape.class);

1. 创徏正常�H�体
先创��Z��个简单的界面�Q�它使用BorderLayout�Q�在其中安放5个JButton�Q�如下代码所�C�，

public class ShapedFrame extends JFrame {

    private static final long serialVersionUID = -2291343874280454383L;

    private JButton centerButton = new JButton("Center");

    public ShapedFrame() {
        super("Shaped Frame");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        initUI();
    }

    private void initUI() {
        Container container = getContentPane();
        container.setLayout(new BorderLayout());

        container.add(new JButton("TOP"), BorderLayout.PAGE_START);
        container.add(new JButton("RIGHT"), BorderLayout.LINE_END);
        container.add(new JButton("BOTTOM"), BorderLayout.PAGE_END);
        container.add(new JButton("LEFT"), BorderLayout.LINE_START);
        container.add(centerButton, BorderLayout.CENTER);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                ShapedFrame frame = new ShapedFrame();
                frame.setSize(new Dimension(400, 300));
                frame.setUndecorated(true);
                setAtCenter(frame);
                frame.setVisible(true);
            }
        });
    }

    // ��Window�|�于屏幕正中
    private static void setAtCenter(Window window) {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        window.setLocation((screenSize.width - window.getWidth()) / 2,
                (screenSize.height - window.getHeight()) / 2);
    }
}

执行上述�E�序的效果如下图所�C�，

2. 创徏不规则窗�?
��Z��上述�E�序创徏不规则窗体，使整个窗体正好缺失掉RIGHT JButton所在的区域�Q�如下代码所�C�，

public class ShapedFrame extends JFrame {

    private static final long serialVersionUID = -2291343874280454383L;

    private static Method method = null;

    static {
        try {
            Class clazz = Class.forName("com.sun.awt.AWTUtilities");
            method = clazz.getMethod("setWindowShape", Window.class, Shape.class);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private JButton centerButton = new JButton("Center");

    public ShapedFrame() {
        super("Shaped Frame");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        initUI();
        addComponentListener(componentListener);
    }

    private void initUI() {
        Container container = getContentPane();
        container.setLayout(new BorderLayout());

        container.add(new JButton("TOP"), BorderLayout.PAGE_START);
        container.add(new JButton("RIGHT"), BorderLayout.LINE_END);
        container.add(new JButton("BOTTOM"), BorderLayout.PAGE_END);
        container.add(new JButton("LEFT"), BorderLayout.LINE_START);
        container.add(centerButton, BorderLayout.CENTER);
    }

    private ComponentListener componentListener = new ComponentAdapter() {

        @Override
        public void componentResized(ComponentEvent evt) { // 当UI�l��g(JFrame)的尺寸发生改变时�Q�调用该�Ҏ��
            Rectangle frameRect = getBounds();
            Rectangle spaceRect = centerButton.getBounds();

            Point o1 = new Point(0, 0);
            Point o2 = new Point(frameRect.width, 0);
            Point o3 = new Point(frameRect.width, frameRect.height);
            Point o4 = new Point(0, frameRect.height);

            Point i1 = new Point(spaceRect.x + spaceRect.width, spaceRect.y);
            Point i2 = new Point(frameRect.width, spaceRect.y);
            Point i3 = new Point(frameRect.width, spaceRect.y
                    + spaceRect.height);
            Point i4 = new Point(spaceRect.x + spaceRect.width, spaceRect.y + spaceRect.height);

            int[] xpoints = new int[] { o1.x, o2.x, i2.x, i1.x, i4.x, i3.x, o3.x, o4.x };
            int[] ypoints = new int[] { o1.y, o2.y, i2.y, i1.y, i4.y, i3.y, o3.y, o4.y };
            int npoints = 8
            // 构徏一个六边�Ş�Q�将RIGHT JButton所处的位置�I�缺出来
            Shape shape = new Polygon(xpoints, ypoints, npoints);

            setWindowShape(ShapedFrame.this, shape);
        }
    };

    // 讄��Window的�Ş�?/span>
    private static void setWindowShape(Window window, Shape shape) {
        try {
            method.invoke(null, window, shape);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                ShapedFrame frame = new ShapedFrame();
                frame.setSize(new Dimension(400, 300));
                frame.setUndecorated(true);
                setAtCenter(frame);
                frame.setVisible(true);
            }
        });
    }

    // ��Window�|�于屏幕正中
    private static void setAtCenter(Window window) {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        window.setLocation((screenSize.width - window.getWidth()) / 2,
                (screenSize.height - window.getHeight()) / 2);
    }
}

执行上述�E�序后，会有如下图所�C�的效果�Q?br />

Sha Jiang 2011-05-31 20:46 发表评论

你所不知道的五�g事情--改进Swing(�?

Sha Jiang — Mon, 25 Oct 2010 14:23:00 GMT

摘要: 你所不知道的五�g事情--改进Swing �q�是Ted Neward在IBM developerWorks�? things�p�d��文章中的一��，讲述了关于改�q�Swing应用的一些窍门，值得大家学习�?2010.10.25最后更�? 摘要�Q�Swing已是一个比较老的工具集了�Q�在��观的用��L��面出来之前需要开发很长时间。它�~�少一些你在开发富UI时所需的组件。幸�q�地是，�?Substance�Q�Swi... 阅读全文

Sha Jiang 2010-10-25 22:23 发表评论

数据加蝲模糊�q�度指示面板的实��C��应用(�?

Sha Jiang — Sun, 29 Nov 2009 12:33:00 GMT

数据加蝲模糊�q�度指示面板的实��C��应用

当在加蝲数据(或其它耗时工作)�Ӟ��需要显�C�Z��个进度指�C�面板，本文介绍了一�U�简易的实现方式�?2009.11.30最后更�?

对于许多Swing应用�Q�在与用��L��交互�q�程中可能需要与数据库进行通信(如，加蝲数据)。而这个过�E�往往比较耗时�Q��ؓ了不造成"假死"现象�Q�一般都会显�C�Z��个模�p�进度指�C�器(不一定��?a >JProgressBar�Q�简单地用一个图片代替即�?�Q�当数据加蝲完毕后，该进度指�C�器自动消失�?br /> 一般地�Q�该模糊�q�度指示器不会展�C�在一个弹出的对话框中(因�ؓ�q�样不美�?�Q�而是直接昄��在需要展�C��加蝲数据的面板中�Q��ƈ且对该面板进行模�p�处理。实现这一功能的关键就在于�Q�在屏幕的同一区域内展�C�Z��层面板：一层是展示数据的面板；另一层是展示�q�度指示器的面板。当加蝲数据�Ӟ��昄��q�度指示器面板，�q�模�p�数据面板；当数据加载完毕后�Q�隐藏进度指�C�器面板�Q��ƈ使数据面板清晰显�C�。下面将使用org.jdesktop.swingx.StackLayout方式来实��C��q�功能�?br />
1. LoadingPanel--加蝲指示器面�?/span>
首先创徏一个加载指�C�器面板。如前所�q�ͼ�我们不必使用真正的进度条作�ؓ�q�度指示器，仅需要��用一张动态图片来代替卛_��。LoadingPanel的完整代码如下所�C�，

public class LoadingPanel extends JPanel {

    private static final long serialVersionUID = 1962748329465603630L;

    private String mesg = null;

    public LoadingPanel(String mesg) {
        this.mesg = mesg;
        initUI();
        interceptInput();
        setOpaque(false);
        setVisible(false);
    }

    private void initUI() {
        JLabel label = new JLabel(mesg);
        label.setHorizontalAlignment(JLabel.CENTER);
        label.setIcon(new ImageIcon(getClass().getResource("/path/to/spinner.gif")));

        setLayout(new BorderLayout());
        add(label, BorderLayout.CENTER);
    }

    private void interceptInput() {
        addMouseListener(new MouseAdapter() {});
        addMouseMotionListener(new MouseMotionAdapter() {});
        addKeyListener(new KeyAdapter() {});

        addComponentListener(new ComponentAdapter() {
            @Override
            public void componentShown(ComponentEvent e) {
                requestFocusInWindow();
            }
        });
        setFocusTraversalKeysEnabled(false);
    }
}

上述代码很容易理解，LoadingPanel中仅有一个JLabel�Q�它会展�C�Z��张图�?spinner.gif)及一�D�信息。但有两�D�代码需要特别说明：
[1]构造器中的两行代码

setVisible(false);
setOpaque(false);

LoadingPanel只在加蝲数据时才昄��Q�其它时候是不显�C�的�Q�所以它默认不可见。另外，在显�C�LoadingPanel的同�Ӟ��我们仍然希望能看到数据面板，所以LoadingPanel应该是透明的�?br /> [2]interceptInput�Ҏ��
当LoadingPanel昄��之后�Q�我们不希望用户�q�能够操作数据面板，那么��需要屏蔽掉用户(鼠标�Q�键�?输入�?br />

addMouseListener(new MouseAdapter() {});
addMouseMotionListener(new MouseMotionAdapter() {});
addKeyListener(new KeyAdapter() {});

上述三行代码��׃��得LoadingPanel能捕��h��有的鼠标与键盘事�Ӟ��q�忽略掉它们。但仅仅如此�q�不够，在展�C�LoadingPanel�Ӟ��数据面板中的某个UI�l��g很可能已�l�获得焦点了�Q�那么用户仍然可以通过键盘操控数据面板中的�l��g(因�ؓ�pȝ��会把键盘事�g发送给当前获取焦点的组�?。而且�Q�即使数据面板中没有��M��l��g获得焦点�Q�用户仍然可以通过Tab键把焦点转移到数据面板中的组件上。�ؓ了阻止这一操作�Q�还需要加上如下几行代码，

addComponentListener(new ComponentAdapter() { // 一旦LoadingPanel可见�Q�即获取焦点
    @Override
    public void componentShown(ComponentEvent e) {
        requestFocusInWindow();
    }
});
setFocusTraversalKeysEnabled(false); // ��L��用户转移焦点

2. �C�Z��E�序
在此处的�C�Z��E�序中，数据面板(dataPanel)中仅有一个按钮，当点击该按钮时会昄��loadingPanel�Q�且模糊掉dataPanel�Q��ƈ会启动一个新的线�E�，该线�E�会在睡眠大�U?�U?模拟耗时的数据加载工�?之后隐藏loadingPanel�Q�且使dataPanel重新清晰可见�?br /> 值得注意的是�Q�该�C�Z��E�序使用�?a >SwingX中的两个�l��g�Q?a >JXPanel�?a >StackLayout。JXPanel提供了一个方�?setAlpha)以方便地讄��Panel的透明�?Alpha�?�Q�而StackLayout允许在同一块区域内��d��多层�l��g�Q��ƈ能同时展�C�所有层的组�?而，CardLayout一�ơ只能显�C�某一层的�l��g)。完整的�C�Z��E�序如下所�C�，

public class LoadDataDemo extends JFrame {

    private static final long serialVersionUID = 5927602404779391420L;

    private JXPanel dataPanel = null; // 使用org.jdesktop.swingx.JXPanel�Q�以方便讄��清晰�?/span>

    private LoadingPanel loadingPanel = null;

    public LoadDataDemo() {
        super("LoadData Demo");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        initUI();
    }

    private void initUI() {
        JButton button = new JButton("Load Data");
        button.addActionListener(handler);
        dataPanel = new JXPanel(new FlowLayout(FlowLayout.CENTER));
        dataPanel.add(button);

        loadingPanel = new LoadingPanel("Loading");

        // 使用org.jdesktop.swingx.StackLayout�Q�将loadingPanel�|�于dataPanel的上�?/span>
        JPanel centerPanel = new JXPanel(new StackLayout());
        centerPanel.add(dataPanel, StackLayout.TOP);
        centerPanel.add(loadingPanel, StackLayout.TOP);

        Container container = getContentPane();
        container.setLayout(new BorderLayout());
        container.add(centerPanel, BorderLayout.CENTER);
    }

    transient private ActionListener handler = new ActionListener() {

        public void actionPerformed(ActionEvent e) {
            // ��dataPanel及其子组件的清晰度设�|��ؓ50%�Q��ƈ昄��loadingPanel
            dataPanel.setAlpha(0.5F);
            loadingPanel.setVisible(true);

            Thread thread = new Thread() {
                public void run() {
                    try {
                        Thread.sleep(3000L); // 睡眠�U?�U�钟�Q�以模拟加蝲数据的过�E?/span>
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    // 数据加蝲完毕后，重新隐藏loadingPanel�Q��ƈ使dataPanel及其子组仉��新清晰可�?/span>
                    loadingPanel.setVisible(false);
                    dataPanel.setAlpha(1F);
                };
            };
            thread.start();
        }
    };

    public static void main(String[] args) {
        LoadDataDemo demo = new LoadDataDemo();
        demo.setSize(new Dimension(400, 300));
        demo.setVisible(true);
    }
}

3. 不��用SwingX
SwingX为我们提供了一�p�d��功能强大�Q��用简易的Swing扩展�l��g�Q�我强烈��你去使用它。但若因故，你不准备使用它时�Q�我们仍然有替代的解��x��案，但此处仅��q�C��二�?br /> [1]对于讄��Alpha��|��需要创��Z��个��承自JPanel的DataPanel�c�，覆写paintComponent�Ҏ��Q�在其中使用Alpha合成�Q?br />

Graphics2D.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha));

[2]对于StackLayout�Q�我们可以��用GlassPane(�ȝ��H�格)或LayeredPane(分层�H�格)�q�行替换�Q�将LoadingPanel讄��为GlassPane或LayeredPanel中的一层。由于一个JFrame只有一个GlassPane�Q��ؓ了程序的灉|��性，一般首选��用LayeredPane�?br />

Sha Jiang 2009-11-29 20:33 发表评论

利用SwingX与TimingFramework实现淡入淡出(�?

Sha Jiang — Mon, 28 Sep 2009 01:46:00 GMT

利用SwingX与TimingFramework实现淡入淡出

本文使用SwingX�?a >TimingFramework展示了如何实现��E入��E出效果，�E�序��z�实用，希望对大家能有所助益�?2009.09.28最后更�?

在Swing中��?a >AlphaComposite讄��界面的半透明度，再配�?a >javax.swing.Timer可以比较�Ҏ��地实现��E入��E出效果。但需要我们��承具体的UI�l��g�Q��ƈ重写它的paintComponent�Ҏ��Q�同时还要�ؓTimer提供一个ActionListener的实现。这些对于程序员来说�Q�显得有些乏呟�?br /> �q�运地是�Q�SwingX中的JXPanel(JPanel的子�c?通过setAlpha�Ҏ��来设�|�半透明度，JXPanel中的所有UI�l��g都可随之半透明化。TimingFramework提供的Animator可以帮助我们非线性地讄��JXPanel中的alpha倹{��故�Q�我们在实现淡入淡出�Ӟ��可以使用JXPanel来替代JPanel�Q�用Animator来替代Timer�?br />

下面是一个非常简单的�C�Z��Q�该�C�Z��在一个��用CardLayout的JPanel--cardPanel�Q�中另包含了两个JXPanel--panelA和panelB�Q�这两个子容器中又分别有一个JButton--buttonA和buttonB。当点击buttonA�Ӟ��E入显�C�panelB�Q�当点击buttonB�Ӟ��E入显�C�panelA�?br />

1 public class FadingCardDemo extends JFrame {
2
3     private static final long serialVersionUID = 8005909309849021746L;
4
5     private String CARD_A = "CARD_A";
6     private String CARD_B = "CARD_B";
7
8     private JPanel cardPanel = null;
9     private JXPanel panelA = null;
10     private JXPanel panelB = null;
11     private JButton buttonA = null;
12     private JButton buttonB = null;
13
14     public FadingCardDemo() {
15         super("FadingButton Demo");
16         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
17         initUI();
18     }
19
20     private void initUI() {
21         cardPanel = new JPanel(new CardLayout());
22
23         buttonA = new JButton("Button A");
24         buttonA.addActionListener(actionHandler);
25         panelA = new JXPanel(new BorderLayout());
26         panelA.add(buttonA, BorderLayout.CENTER);
27         cardPanel.add(panelA, CARD_A);
28
29         buttonB = new JButton("Button B");
30         buttonB.addActionListener(actionHandler);
31         panelB = new JXPanel(new BorderLayout());
32         panelB.add(buttonB, BorderLayout.CENTER);
33         cardPanel.add(panelB, CARD_B);
34
35         Container container = getContentPane();
36         container.setLayout(new BorderLayout());
37         container.add(cardPanel, BorderLayout.CENTER);
38     }
39
40     private ActionListener actionHandler = new ActionListener() {
41
42         private Animator animator = null;
43
44         public void actionPerformed(ActionEvent e) {
45             if (animator == null) {
46                 animator = new Animator(2000);
47                 animator.setDeceleration(0.2F);
48                 animator.setAcceleration(0.4F);
49             } else if (animator.isRunning()) {
50                 animator.stop();
51             }
52
53             JButton button = (JButton) e.getSource();
54             if (button == buttonA) {
55                 animator.addTarget(new PropertySetter(panelB, "alpha", 1.0F));
56                 panelB.setAlpha(0.1F);
57                 ((CardLayout) cardPanel.getLayout()).show(cardPanel, CARD_B);
58             } else if (button == buttonB) {
59                 animator.addTarget(new PropertySetter(panelA, "alpha", 1.0F));
60                 panelA.setAlpha(0.1F);
61                 ((CardLayout) cardPanel.getLayout()).show(cardPanel, CARD_A);
62             }
63             animator.start();
64         }
65     };
66
67     public static void main(String[] args) {
68         SwingUtilities.invokeLater(new Runnable() {
69             public void run() {
70                 FadingCardDemo demo = new FadingCardDemo();
71                 demo.setSize(new Dimension(400, 300));
72                 demo.setVisible(true);
73             }
74         });
75     }
76 }

Sha Jiang 2009-09-28 09:46 发表评论

一个简单的CheckBox Tree实现(�?

Sha Jiang — Wed, 05 Aug 2009 13:10:00 GMT

一个简单的CheckBox Tree实现

CheckBox Tree是一个十分常用的UI�l��g�Q�它能��用户方便地按特定规则��N��树中的节点�?/span>本文实现了一�U�简单的Checking规则�Q�当��N��了某节点后�Q�该节点的所有下�U�节点全部被��N��；当取消勾选某节点后，该节点的所有下�U�节点全部被取消��N��?2009.08.05最后更�?

实现CheckBox Tree的常用方法，��是使用JCheckBox作�ؓJTree的TreeCellRendrer�Q��ƈ且需要实现特定的Checking规则来勾�?取消��N��CheckBox�?br />
1. 树节�?/span>
DefaultMutableTreeNode是最常用的TreeNode实现�Q�此处我们将扩展�q�一实现--CheckBoxTreeNode�Q�增加一个属�?span style="color: #2000ff;">isChecked�Q�用于标识该节点是否要被��N��上。该�cȝ��完整代码如下所�C�：

public class CheckBoxTreeNode extends DefaultMutableTreeNode {

       private static final long serialVersionUID = 3195314943599939279L;

       private boolean isChecked = false;

       public CheckBoxTreeNode(Object userObject) {
               super(userObject);
       }

       public boolean isChecked() {
               return isChecked;
       }

       public void setChecked(boolean isChecked) {
               this.isChecked = isChecked;
       }
}

2. 渲染�?/span>
如本文开头所�q�ͼ�我们��用JCheckBox作�ؓ树节点展现�Ş式的渲染器，同时��定对节点进行勾选或取消��N��的规则。CheckBoxTreeCellRenderer本��n��x��一个JCheckBox�Q�那么在实现getTreeCellRendererComponent�Ҏ��Ӟ��只简单地�q�回它自��q��实例卛_��Q�而对于勾选或取消��N��的条�g�Q�则由CheckBoxTreeNode中的isChecked属性来��定�Q�完整的代码如下所�C�：

public class CheckBoxTreeCellRenderer extends JCheckBox implements TreeCellRenderer {

       private static final long serialVersionUID = -6432020851855339311L;

       public CheckBoxTreeCellRenderer() {
               setOpaque(false);
       }

       public Component getTreeCellRendererComponent(JTree tree, Object value,
                       boolean selected, boolean expanded, boolean leaf, int row,
                       boolean hasFocus) {
               CheckBoxTreeNode node = ((CheckBoxTreeNode) value); // 获取树节点对象�?/span>
               setText(node.toString()); // 讄��CheckBox所展示的文本�?br />
               // 当树节点被设�|��ؓ��N��时�Q�则该节点对应的CheckBox被勾选上�Q�否则，取消��N��?/span>
               if (node.isChecked()) {
                       setSelected(true);
                       setForeground(Color.BLUE);
               } else {
                       setSelected(false);
                       setForeground(tree.getForeground());
               }
               return this;
       }
}

3. �?/span>
此处对JTree�q�行扩展�Q�创建CheckBoxTree�Q�该�c�d��是�ؓJTree��d��了一个MouseListener�Q�以侦听鼠标选中树节点后�Q�如何设�|�勾选标讎ͼ��q��l�树�?br />

public class CheckBoxTree extends JTree {

       private static final long serialVersionUID = -217950037507321241L;

       public CheckBoxTree(TreeModel newModel) {
               super(newModel);
               addCheckingListener();
       }

       private void addCheckingListener() {
               addMouseListener(new MouseAdapter() {

                       @Override
                       public void mousePressed(MouseEvent e) {
                               int row = getRowForLocation(e.getX(), e.getY());
                               TreePath treePath = getPathForRow(row);
                               if (treePath == null) {
                                       return;
                               }

                               CheckBoxTreeNode node = ((CheckBoxTreeNode) treePath.getLastPathComponent());
                               boolean checking = !node.isChecked(); // 如果该节点已被勾选上�Q�则此次��取消勾选；反之�Q�亦反�?/span>
                               checkNode(node, checking);

                               repaint(); // 重绘整棵树�?/span>
                       }

                       // 递归地勾选或取消��N��指定节点及其所有下�U�节点的CheckBox�?/span>
                       private void checkNode(CheckBoxTreeNode node, boolean checking) {
                               node.setChecked(checking);
                               if (!node.isLeaf()) {
                                       Enumeration<CheckBoxTreeNode> children = node.children();
                                       while (children.hasMoreElements()) {
                                               checkNode(children.nextElement(), checking);
                                       }
                               }
                       }
               });
       }
}

上述�E�序有两个关键点�Q?. 讄��当前节点及其子节点的��N��标�?-checkNode�Q?. 重绘�?-repaint。调用repaint�Ҏ��Ҏ��q�行�l�制�Ӟ��Ҏ��TreeCellRenderer.getTreeCellRendererComponent��׃��被调用，此时�E�序��׃��Ҏ��checkNode�Ҏ��讑֮��?span style="color: #2000ff;">isChecked来勾选或取消��N��对应的树节点CheckBox。简�a�之，��是先设�|�树型数据中的勾选标讎ͼ�然后渲染器再�Ҏ��q�些标记来渲染CheckBox�?br />

Sha Jiang 2009-08-05 21:10 发表评论

判定一个点是否在三角�Ş�?�?

Sha Jiang — Thu, 24 Jul 2008 09:02:00 GMT

判定一个点是否在三角�Ş�?/span>

如何判定一个点P是否存在于指定的三角形ABC内，�q�肯定是一个简单的问题�Q�本文仅用一个图形界面程序展�C�Z��该问题，有兴��的朋友可以看看�?2008.07.24最后更�?

在此处��用一�U�常见且��便的�Ҏ��Q?strong>如果三角形PAB�Q�PAC和PBC的面�U�之和与三角形ABC的面�U�相�{�，卛_��判定点P在三角�ŞABC�?包括在三条边�?�?br /> 可知�Q�该�Ҏ��的关键在于如何计��三角�Ş的面�U�。幸�q�地是，当知道三角�Ş��点(A�Q�B和C)的坐�?(Ax, Ay)�Q?Bx, By)�?Cx, Cy))之后�Q�即可计��出光��U�：

S = |(Ax * By + Bx * Cy + Cx * Zy - Ay * Bx - By * Cx - Cy * Ax) / 2|

关键的代码如下，

// ��q��定的三个��点的坐标，计算三角形面�U��?br /> // Point(java.awt.Point)代表点的坐标�?/span>
private static double triangleArea(Point pos1, Point pos2, Point pos3) {
    double result = Math.abs((pos1.x * pos2.y + pos2.x * pos3.y + pos3.x * pos1.y
            - pos2.x * pos1.y - pos3.x * pos2.y - pos1.x * pos3.y) / 2.0D);
    return result;
}

// 判断点pos是否在指定的三角形内�?/span>
private static boolean inTriangle(Point pos, Point posA, Point posB,
        Point posC) {
    double triangleArea = triangleArea(posA, posB, posC);
    double area = triangleArea(pos, posA, posB);
    area += triangleArea(pos, posA, posC);
    area += triangleArea(pos, posB, posC);
    double epsilon = 0.0001;  // �׃��点数的计算存在着误差�Q�故指定一个��够小的数�Q�用于判定两个面�U�是�?�q�似)相等�?/span>
    if (Math.abs(triangleArea - area) < epsilon) {
        return true;
    }
    return false;
}

执行该应用程序，用鼠标在其中点击三次�Q�即可绘制一个三角�Ş�Q�如下组图所�C�：

然后仅需�U�d��鼠标�Q�就会出��C��个空心圆圈。如果圆圈的中心在三角内(包含在三条边�?�Q�则圆圈昄��为红�Ԍ��否则�Q�显�C�Zؓ蓝色。如下组图所�C�：

完整代码如下�Q?br />

public class CanvasPanel extends JPanel {

    private static final long serialVersionUID = -6665936180725885346L;

    private Point firstPoint = null;

    private Point secondPoint = null;

    private Point thirdPoint = null;

    public CanvasPanel() {
        setBackground(Color.WHITE);
        addMouseListener(mouseAdapter);
        addMouseMotionListener(mouseAdapter);
    }

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

    private void drawTriangel(Graphics g) {
        if (firstPoint != null && secondPoint != null) {
            g.drawLine(firstPoint.x, firstPoint.y, secondPoint.x, secondPoint.y);
            if (thirdPoint != null) {
                g.drawLine(firstPoint.x, firstPoint.y, thirdPoint.x, thirdPoint.y);
                g.drawLine(secondPoint.x, secondPoint.y, thirdPoint.x, thirdPoint.y);
            }
        }
    }

    private static boolean inTriangle(Point pos, Point posA, Point posB,
            Point posC) {
        double triangeArea = triangleArea(posA, posB, posC);
        double area = triangleArea(pos, posA, posB);
        area += triangleArea(pos, posA, posC);
        area += triangleArea(pos, posB, posC);
        double epsilon = 0.0001;
        if (Math.abs(triangeArea - area) < epsilon) {
            return true;
        }
        return false;
    }

    private static double triangleArea(Point pos1, Point pos2, Point pos3) {
        double result = Math.abs((pos1.x * pos2.y + pos2.x * pos3.y + pos3.x * pos1.y
                            - pos2.x * pos1.y - pos3.x * pos2.y - pos1.x * pos3.y) / 2.0D);
        return result;
    }

    private MouseInputAdapter mouseAdapter = new MouseInputAdapter() {

        public void mouseReleased(MouseEvent e) {
            Point pos = e.getPoint();
            if (firstPoint == null) {
                firstPoint = pos;
            } else if (secondPoint == null) {
                secondPoint = pos;
                Graphics g = CanvasPanel.this.getGraphics();
                CanvasPanel.this.paintComponent(g);
                g.drawLine(firstPoint.x, firstPoint.y, secondPoint.x, secondPoint.y);
            } else if (thirdPoint == null) {
                thirdPoint = pos;
                Graphics g = CanvasPanel.this.getGraphics();
                CanvasPanel.this.paintComponent(g);
                g.drawLine(firstPoint.x, firstPoint.y, secondPoint.x, secondPoint.y);
                g.drawLine(firstPoint.x, firstPoint.y, thirdPoint.x, thirdPoint.y);
                g.drawLine(secondPoint.x, secondPoint.y, thirdPoint.x, thirdPoint.y);
            }
        }

        public void mouseMoved(MouseEvent e) {
            Point pos = e.getPoint();
            Graphics2D g2 = (Graphics2D) CanvasPanel.this.getGraphics();
            CanvasPanel.this.paintComponent(g2);
            if (firstPoint != null && secondPoint == null) {
                g2.drawLine(firstPoint.x, firstPoint.y, pos.x, pos.y);
            } else if (firstPoint != null && secondPoint != null && thirdPoint == null) {
                g2.drawLine(firstPoint.x, firstPoint.y, pos.x, pos.y);
                g2.drawLine(secondPoint.x, secondPoint.y, pos.x, pos.y);
            } else if (firstPoint != null && secondPoint != null && thirdPoint != null) {
                if (inTriangle(pos, firstPoint, secondPoint, thirdPoint)) {
                    g2.setColor(Color.RED);
                } else {
                    g2.setColor(Color.BLUE);
                }
                int radius = 4;
                g2.drawOval(pos.x - radius, pos.y - radius, radius * 2, radius * 2);
            }
        }
    };
}

public class Triangle extends JFrame {

    private static final long serialVersionUID = 1L;

    private CanvasPanel mainPanel = null;

    public Triangle() {
        setTitle("Triangle");
        setSize(new Dimension(300, 200));
        setResizable(false);

        init();

        Container container = getContentPane();
        container.add(mainPanel);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    private void init() {
        mainPanel = new CanvasPanel();
    }

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

Sha Jiang 2008-07-24 17:02 发表评论