java - 显示概览的滚动窗格/视口摆动组件

Question

我正在寻找一个 Swing 组件，它是滚动窗格/视口的扩展，允许打开并导航到当前显示的内容的概述中。我敢肯定，在过去的几个月（几年？）中，我看到过一些博客文章显示了这样的组件，但再也找不到该组件了。

这是我正在寻找的图片：

带有概览的滚动面板

如果您记得这样的帖子，或者您的书签中有一些链接，我会感谢您分享这些信息。

谢谢你的帮助。

score 2 · Accepted Answer

这是一个工作示例，但您将需要java-image-scaling库（其 LGPL） - 它用于平滑缩放预览图像，否则您会完全破坏图像：

public static void main ( String[] args )
{
    final JFrame mainFrame = new JFrame ();

    JPanel content = new JPanel ( new GridLayout ( 20, 20 ) );
    for ( int i = 0; i < 20; i++ )
    {
        for ( int j = 0; j < 20; j++ )
        {
            content.add ( new JLabel ( "Test " + i + ":" + j )
            {
                {
                    setBorder ( BorderFactory.createEmptyBorder ( 20, 20, 20, 20 ) );
                }
            } );
        }
    }

    final JScrollPane pane = new JScrollPane ( content );
    pane.setCorner ( JScrollPane.LOWER_TRAILING_CORNER, new JButton ()
    {
        {
            final JButton button = this;
            addActionListener ( new ActionListener ()
            {
                public void actionPerformed ( ActionEvent e )
                {
                    JComponent comp = ( JComponent ) pane.getViewport ().getView ();
                    Dimension size = comp.getSize ();
                    Rectangle viewRect = comp.getVisibleRect ();

                    // Drawing preview
                    BufferedImage image = new BufferedImage ( size.width, size.height,
                            BufferedImage.TYPE_INT_RGB );
                    Graphics2D g2d = image.createGraphics ();
                    comp.print ( g2d );
                    g2d.dispose ();

                    // Rescaling preview
                    int width = 200;
                    int height = comp.getHeight () * width / comp.getHeight ();
                    BufferedImage rescaled =
                            new ResampleOp ( width, height ).filter ( image, null );

                    // Drawing view rect
                    float diff = (float)width / size.width;
                    g2d = rescaled.createGraphics ();
                    g2d.setPaint ( Color.RED );
                    g2d.drawRect ( Math.round ( viewRect.x * diff ),
                            Math.round ( viewRect.y * diff ),
                            Math.round ( viewRect.width * diff ),
                            Math.round ( viewRect.height * diff ) );
                    g2d.dispose ();

                    // Displaying preview
                    final JDialog preview = new JDialog ( mainFrame );
                    preview.setUndecorated ( true );
                    preview.add ( new JLabel ( new ImageIcon ( rescaled ) )
                    {
                        {
                            setBorder ( BorderFactory.createLineBorder ( Color.BLACK ) );
                            setFocusable ( true );
                        }
                    } );
                    Point los = button.getLocationOnScreen ();
                    preview.setSize ( width + 2, height + 2 );
                    preview.setLocation ( los.x - width - 2, los.y - height - 2 );
                    preview.setVisible ( true );

                    preview.requestFocus ();
                    preview.addFocusListener ( new FocusAdapter ()
                    {
                        public void focusLost ( FocusEvent e )
                        {
                            preview.dispose ();
                        }
                    } );
                }
            } );
        }
    } );
    mainFrame.add ( pane );

    mainFrame.setSize ( 600, 600 );
    mainFrame.setLocationRelativeTo ( null );
    mainFrame.setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE );
    mainFrame.setVisible ( true );
}

所以基本上我创建了面板的快照，重新调整它并放入在按钮附近打开并在焦点丢失时关闭的小对话框中。虽然创建快照可能会浪费时间，但我不知道有什么更好的方法来创建整个滚动窗格容器的渲染预览 - 你必须将它绘制到某些东西上才能显示预览，这意味着它将花费相同的时间。

您还可以轻松修改预览组件，以便您可以通过在预览对话框上拖动红色矩形来移动可见矩形：)