將背景圖像添加到帶有圓角的JPanel

Question

我剛剛將JPanel擴展用於我們希望看起來更“3D”的項目中。 這是我的老板要求在組件上留下陰影和圓角的方式。 這已經完成，如許多在線示例所示。 我是這樣做的：

public class RoundedPanel extends JPanel
{
    protected int _strokeSize = 1;
    protected Color _shadowColor = Color.BLACK;
    protected boolean _shadowed = true;
    protected boolean _highQuality = true;
    protected Dimension _arcs = new Dimension(30, 30);
    protected int _shadowGap = 5;
    protected int _shadowOffset = 4;
    protected int _shadowAlpha = 150;

    protected Color _backgroundColor = Color.LIGHT_GRAY;

    public RoundedPanel()
    {
        super();
        setOpaque(false);
    }

    @Override
    public void setBackground(Color c)
    {
        _backgroundColor = c;
    }

    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);

        int width = getWidth();
        int height = getHeight();
        int shadowGap = this._shadowGap;
        Color shadowColorA = new Color(_shadowColor.getRed(), _shadowColor.getGreen(), _shadowColor.getBlue(), _shadowAlpha);
        Graphics2D graphics = (Graphics2D) g;

        if(_highQuality)
        {
            graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        }

        if(_shadowed)
        {
            graphics.setColor(shadowColorA);
            graphics.fillRoundRect(_shadowOffset, _shadowOffset, width - _strokeSize - _shadowOffset,
                    height - _strokeSize - _shadowOffset, _arcs.width, _arcs.height);
        }
        else
        {
            _shadowGap = 1;
        }

        graphics.setColor(_backgroundColor);
        graphics.fillRoundRect(0,  0, width - shadowGap, height - shadowGap, _arcs.width, _arcs.height);
        graphics.setStroke(new BasicStroke(_strokeSize));
        graphics.setColor(getForeground());
        graphics.drawRoundRect(0,  0, width - shadowGap, height - shadowGap, _arcs.width, _arcs.height);
        graphics.setStroke(new BasicStroke());
    }
}

我正在使用以下代碼創建一個測試框架：

public class UITest
{
    private static JFrame mainFrame;
    private static ImagePanel mainPanel;

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                mainFrame = new JFrame();
                mainFrame.setVisible(true);

                try
                {
                    mainPanel = new ImagePanel(ImageIO.read(this.getClass().getResource("/content/diamondPlate_Light.jpg")));
                    //mainPanel.setBounds(0, 0, 800, 600);
                }
                catch(IOException e)
                {

                }
                mainPanel.setLayout(null);

                RoundedPanel rPanel = new RoundedPanel();
                rPanel.setBounds(10, 10, 200, 200);
                rPanel.setBackground(new Color(168, 181, 224));

                mainPanel.add(rPanel);

                rPanel = new RoundedPanel();
                rPanel.setBounds(220, 10, 560, 200);
                rPanel.setBackground(new Color(168, 224, 168));

                mainPanel.add(rPanel);

                rPanel = new RoundedPanel();
                rPanel.setBounds(10, 220, 770, 300);
                rPanel.setBackground(new Color(224, 168, 168));

                mainPanel.add(rPanel);

                mainFrame.setSize(800, 600);
                mainFrame.getContentPane().add(mainPanel);
            }
        });
    }
}

它導致了這個（沒有JFrame的contentPane的背景圖片：

我真正想做的是生成帶有圓角的紅色，綠色和藍色面板，但是用不同的圖像而不是Color填充。 我仍然想要正確的圓角，但我不確定如何做到這一點。

如果我有一個大的紋理，我可以簡單地“剪切”它的一部分在RoundedPanel的大小和形狀？ 我需要對此進行評估，因為它只是在我輸入時發生的，但是如果我可以像在graphics.fillRoundRect(...)使用的那樣創建一個幾何體，然后剪切圖像，這可能會起作用。

有沒有其他方法可以做到這一點，我錯過了？ 我很感激您提供的任何反饋。 謝謝。

編輯：

基於以下所選解決方案中的想法，我得到以下結果：

需要將其打造成生產形狀並且背景圖像選擇不當，但作為演示，以下RoundedPanel代碼將我們帶到上面的結果：

public class RoundedPanel extends JPanel
{
    protected int strokeSize = 1;
    protected Color _shadowColor = Color.BLACK;
    protected boolean shadowed = true;
    protected boolean _highQuality = true;
    protected Dimension _arcs = new Dimension(30, 30);
    protected int _shadowGap = 5;
    protected int _shadowOffset = 4;
    protected int _shadowAlpha = 150;

    protected Color _backgroundColor = Color.LIGHT_GRAY;
    protected BufferedImage image = null;

    public RoundedPanel(BufferedImage img)
    {
        super();
        setOpaque(false);

        if(img != null)
        {
            image = img;
        }
    }

    @Override
    public void setBackground(Color c)
    {
        _backgroundColor = c;
    }

    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);

        int width = getWidth();
        int height = getHeight();
        int shadowGap = this._shadowGap;
        Color shadowColorA = new Color(_shadowColor.getRed(), _shadowColor.getGreen(), _shadowColor.getBlue(), _shadowAlpha);
        Graphics2D graphics = (Graphics2D) g;

        if(_highQuality)
        {
            graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        }

        if(shadowed)
        {
            graphics.setColor(shadowColorA);
            graphics.fillRoundRect(_shadowOffset, _shadowOffset, width - strokeSize - _shadowOffset,
                    height - strokeSize - _shadowOffset, _arcs.width, _arcs.height);
        }
        else
        {
            _shadowGap = 1;
        }

        RoundRectangle2D.Float rr = new RoundRectangle2D.Float(0, 0, (width - shadowGap), (height - shadowGap), _arcs.width, _arcs.height);

        Shape clipShape = graphics.getClip();

        if(image == null)
        {
            graphics.setColor(_backgroundColor);
            graphics.fill(rr);
        }
        else
        {
            RoundRectangle2D.Float rr2 =  new RoundRectangle2D.Float(0, 0, (width - strokeSize - shadowGap), (height - strokeSize - shadowGap), _arcs.width, _arcs.height);

            graphics.setClip(rr2);
            graphics.drawImage(this.image, 0, 0, null);
            graphics.setClip(clipShape);
        }

        graphics.setColor(getForeground());
        graphics.setStroke(new BasicStroke(strokeSize));
        graphics.draw(rr);
        graphics.setStroke(new BasicStroke());
    }
}

謝謝您的幫助。

Answer 1

嘗試“剪裁區域”（參見g.setClip()調用）：

public static void main(String[] args) {
    JFrame f = new JFrame();
    f.setSize(new Dimension(600, 400));
    f.getContentPane().setLayout(null);
    RoundPanel rp = new RoundPanel();
    rp.setBounds(100, 50, 400, 300);
    f.getContentPane().add(rp);
    f.setVisible(true);
}

static class RoundPanel extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        // Prepare a red rectangle
        BufferedImage bi = new BufferedImage(400, 300, BufferedImage.TYPE_INT_ARGB);
        Graphics2D gb = bi.createGraphics();
        gb.setPaint(Color.RED);
        gb.fillRect(0, 0, 400, 300);
        gb.dispose();

        // Set a rounded clipping region:
        RoundRectangle2D r = new RoundRectangle2D.Float(0, 0, 400, 300, 20, 20);
        g.setClip(r);

        // Draw the rectangle (and see whether it has round corners)
        g.drawImage(bi, 0, 0, null);
    }
}

請注意Graphics.setClip的API文檔中提到的限制：

將當前剪切區域設置為任意剪輯形狀。 並非所有實現Shape接口的對象都可用於設置剪輯。 唯一可以保證支持的Shape對象是通過getClip方法和Rectangle對象獲得的Shape對象。