5

我在 JScrollpane 中有一个 JPanel。我在显示在 JPanel 上的 BufferedImage 上绘图。在 JScrollpane 的左上角，我想要一张图片，当我向下滚动查看我的 JPanel 的其余部分时，它总是停留在那个角落。这里是 Jpanel 的 paintComponent 方法：

@Override
public void paintComponent(Graphics g){
    super.paintComponent(g);
    if (bufferedImage != null){
        g.drawImage(bufferedImage, 0, 0, this);
        Point p = parent.getViewPosition();
        System.out.println("paintComponent(): "+ p.x + "," + p.y);
        g.setColor(Color.RED);
        g.fillRect(p.x + 20, p.y + 20, 200, 200);
    }
}

parent.getViewPosition() 在哪里给我 scrollPane.getViewport().getViewPosition()。当我启动时，我可以看到左上角带有红色矩形的缓冲图像。当我向下滚动时，我可以看到缓冲图像的其余部分，但是红色矩形向上移动然后消失，并且当我向上滚动时不再出现。在控制台中，我可以看到滚动时点 p 发生了变化：

paintComponent(): 0,0
paintComponent(): 0,10
paintComponent(): 0,20
paintComponent(): 0,30
paintComponent(): 0,40
paintComponent(): 0,50

谁能帮我解决这个问题？

4

5 回答 5

4

您可以为此使用玻璃窗格并告诉它在取决于视口位置的位置绘制图像。例如：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;

import javax.swing.*;

@SuppressWarnings("serial")
public class ScrollImgGlass extends JPanel {
   private static final int BI_W = 40;
   private static final int BI_H = BI_W;
   private static final String[] DATA = { "One", "Two", "Three", "Four",
         "Five", "Six", "Seven", "Eight", "Nine", "Zero", "One", "Two",
         "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine", "Zero",
         "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight",
         "Nine", "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven",
         "Eight", "Nine", "Zero" };
   private BufferedImage img = null;
   private JViewport viewport;

   public ScrollImgGlass(JViewport viewport) {
      setOpaque(false);
      this.viewport = viewport;
      img = new BufferedImage(BI_W, BI_H, BufferedImage.TYPE_INT_ARGB);
      Graphics2D g2 = img.createGraphics();
      g2.setColor(Color.red);
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
      g2.fillOval(0, 0, BI_W, BI_H);
      g2.dispose();
   }

   @Override
   protected void paintComponent(Graphics g) {
      Point vpLocation = viewport.getLocationOnScreen();
      Point gpLocation = getLocationOnScreen();

      int x = vpLocation.x - gpLocation.x;
      int y = vpLocation.y - gpLocation.y;

      super.paintComponent(g);
      if (img != null) {
         g.drawImage(img, x, y, this);
      }
   }

   private static void createAndShowGui() {
      JList<String> jList = new JList<String>(DATA);
      jList.setOpaque(false);

      JViewport viewport = new JViewport();
      JScrollPane scrollpane = new JScrollPane();
      scrollpane.setViewport(viewport);
      viewport.setView(jList);

      ScrollImgGlass glass = new ScrollImgGlass(viewport);

      JFrame frame = new JFrame("ScrollImg");
      frame.setGlassPane(glass);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(scrollpane, BorderLayout.CENTER);

      // just to show that this works if the viewport is shifted over
      frame.getContentPane().add(Box.createRigidArea(new Dimension(20, 20)), BorderLayout.NORTH);
      frame.getContentPane().add(Box.createRigidArea(new Dimension(20, 20)), BorderLayout.WEST);

      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);

      glass.setVisible(true);
   }

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

会显示如下：

在此处输入图像描述

于 2013-03-18T00:08:41.550 回答
4

正如 MadProgrammer 所建议的，JLayer 确实有效：

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

public class FixedImageLayerUI extends LayerUI<JComponent>
{
    @Override
    public void paint(Graphics g, JComponent c)
    {
        super.paint(g, c);

        Graphics2D g2 = (Graphics2D) g.create();

        g2.setColor( Color.RED );
        g2.fillOval(0, 0, 10, 10);

        g2.dispose();
    }

    private static void createAndShowUI()
    {
        String[] data =
        {
            "a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
            "k", "l", "m", "n", "o", "p", "q", "r", "s", "t",
            "u", "v", "w", "x", "y", "z"
        };

        JList<String> list = new JList<String>( data );
        JScrollPane scrollPane = new JScrollPane( list );

        LayerUI<JComponent> layerUI = new FixedImageLayerUI();
        JLayer<JComponent> layer = new JLayer<JComponent>(scrollPane, layerUI);

        JFrame frame = new JFrame("FixedImage");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( layer );
        frame.pack();
        frame.setLocationByPlatform( true );
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

此外，正如 MadProgrammer 所指出的，覆盖 JScrollPane 的绘制方法不起作用。但是，如果您使 JList 不透明，它确实可以工作：

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

public class FixedImageScrollPane
{

    private static void createAndShowUI()
    {
        String[] data =
        {
            "a", "b", "c", "d", "e", "f", "g", "h", "i", "j",
            "k", "l", "m", "n", "o", "p", "q", "r", "s", "t",
            "u", "v", "w", "x", "y", "z"
        };

        JList<String> list = new JList<String>( data );
        list.setOpaque( false );

        JScrollPane scrollPane = new JScrollPane( list )
        {
            @Override
            public void paint(Graphics g)
            {
                super.paint(g);
                g.setColor( Color.RED );
                g.fillOval(0, 0, 10, 10);
            }
        };

        JFrame frame = new JFrame("FixedImage");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( scrollPane );
        frame.pack();
        frame.setLocationByPlatform( true );
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}
于 2013-03-18T02:36:29.060 回答
1

不要将图片放在滚动的面板中。将其放在不同的面板中，并使用布局管理器排列两个面板。

我建议看一下 BorderLayout；它在 n、s、e 和 w 处有区域，并且在中心有一个区域，但您不必使用所有这些区域（很少使用所有这些区域）。您可以创建一个 JPanel，将其布局管理器设置为 BorderLayout，将包含您的图像的面板放在该面板的 NORTH 部分，然后将您的滚动面板放在 CENTER 中。作为免费的奖励，当/如果调整窗口大小时，位于中心的 JPanel 将在两个维度上拉伸，因为这就是 BorderLayout 的工作方式。

于 2013-03-17T23:42:38.717 回答
1

在您的代码中的某处，您创建了一个 JScrollPane。

改变

    final JScrollPane scrollpane = new JScrollPane();

到：

    final JScrollPane scrollpane = new JScrollPane() {
        @Override
        public void paint(final Graphics g) {
            super.paint(g);
            // Put you drawing here...example, draw a geen dot...
            g.setColor(Color.GREEN);
            g.fillOval(0, 0, 30, 30);
        }
    };

编辑：根据评论，需要对放置在 JScrollPane 中的对象执行 setOpaque(false)。

例子：

    list.setOpaque(false);
    scrollpane.setViewportView(list);
于 2013-03-18T01:17:14.853 回答
0

好的，以下代码适用于 JTabbedPane。我必须在选项卡式窗格中的面板中添加一个 componentListener，因为当窗格不在屏幕上时，方法“getLocationOnScreen()”出现异常。

public class GlassFrame {
    private JPanel panel;
    private JScrollPane scrollPane;
    private BufferesImage img;

    public GlassFrame() {
        panel = new JPanel(){
            @Override
            public void paintComponent(Graphics g){
                super.paintComponent(g);
                img = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB);
                Graphics2D g2 = img.createGraphics();
                g2.setPaint(Color.WHITE);
                   Rectangle2D rect = new Rectangle2D.Float(0, 0, 420, 420);
                   g2.fill(rect);
                   g2.setPaint(Color.BLACK);
                   for (int i = 0; i <= 10; i++) {
                       g2.draw(new Line2D.Float(10 + i * 40,10,10 + i * 40,410));
                       g2.draw(new Line2D.Float(10,10 + i * 40,410,10 + i * 40));
                   }
                g2.dispose();
                g.drawImage(img, 0, 0, this);
            }
        };
        panel.setPreferredSize(new Dimension(420, 420));
        panel.setOpaque(false);

        scrollPane = new JScrollPane(panel, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS,
                ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
        scrollPane.getVerticalScrollBar().setUnitIncrement(10);

        JFrame frame = new JFrame("ScrollPane and GlassPane");
        final GlassPane glass = new GlassPane(scrollPane.getViewport());
        frame.setGlassPane(glass);

        JTabbedPane tab = new JTabbedPane();
        JPanel panelInTab = new JPanel();
        panelInTab.setLayout(new BorderLayout());
        tab.add("first tab", panelInTab);
        tab.add("second tab", new JPanel());
        panelInTab.add(scrollPane, BorderLayout.CENTER);
        panelInTab.add(new JButton("testbutton"), BorderLayout.NORTH);
        panelInTab.addComponentListener(new ComponentAdapter() {
            @Override
            public void componentShown(ComponentEvent arg0) {
                glass.setVisible(true);
            }
            @Override
            public void componentHidden(ComponentEvent arg0) {
                glass.setVisible(false);
            }
        });

        frame.getContentPane().add(tab);    
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setPreferredSize(new Dimension(300, 400));
        frame.pack();
        frame.setLocation(200, 200);
        frame.setVisible(true);
        glass.setVisible(true);
    }

    class GlassPane extends JPanel{
        private JViewport viewport;
        private BufferedImage image = null;

        public GlassPane(JViewport viewport){
            setOpaque(false);
            this.viewport = viewport;
            image = new BufferedImage(58, 58, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2 = image.createGraphics();
            g2.setColor(Color.red);
            g2.setStroke(new BasicStroke(3.0f));
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);
            g2.drawOval(5, 5, 50, 50);
            g2.dispose();
        }

        @Override
        protected void paintComponent(Graphics g) {
            Point vpLocation = viewport.getLocationOnScreen();
            Point gpLocation = getLocationOnScreen();

            int x = vpLocation.x - gpLocation.x;
            int y = vpLocation.y - gpLocation.y;

            super.paintComponent(g);
            if (image != null) {
                g.drawImage(image, x, y, this);
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                GlassFrame frame = new GlassFrame();
            }
        });
    }
}
于 2013-03-25T18:41:33.390 回答