Question

我有一个应用程序，它将使用JLabel和图标大小为32x32的ImageIcon。

我现在想使用64x64图像，如果DPI较低，则将其加载并调整为32x32，否则将其用作高DPI图像。

调整大小很容易，此技巧例如适用于

ImageIcon icon = ...
Image lowRes = icon.getImage().getScaledInstance(32, 32, Image.SCALE_SMOOTH);
return new ImageIcon(lowRes);

但是，我无法找到一种方法来将ImageIcon设置为高DPI图像。

我尝试使用MultiResolutionImage，但没有成功。

编辑：尝试以天真的方式使用MultiResolutionImage：

private ImageIcon loadIcon(String iconName)
{
  ImageIcon icon = new ImageIcon(getClass().getClassLoader()
                       .getResource("res/icons/toolbar/" + iconName));
  BaseMultiResolutionImage baseMultiResolutionImage = new BaseMultiResolutionImage(
    icon.getImage().getScaledInstance(32, 32, Image.SCALE_SMOOTH),
    icon.getImage()
  );
  return new ImageIcon(baseMultiResolutionImage);
}

Stacktrace：

2019-06-11 14:00:45,962 ERROR [AWT-EventQueue-0] Catch.all - Uncaught exception on [AWT-EventQueue-0]: Invalid Image variant
java.lang.IllegalArgumentException: Invalid Image variant
    at java.desktop/sun.awt.image.SurfaceManager.getManager(SurfaceManager.java:82)
    at java.desktop/sun.java2d.SurfaceData.getSourceSurfaceData(SurfaceData.java:218)
    at java.desktop/sun.java2d.pipe.DrawImage.renderImageCopy(DrawImage.java:572)
    at java.desktop/sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:67)
    at java.desktop/sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:1027)
    at java.desktop/sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:3415)
    at java.desktop/sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:3391)
    at java.desktop/javax.swing.ImageIcon.paintIcon(ImageIcon.java:425)
    at java.desktop/com.apple.laf.AquaButtonUI.paintIcon(AquaButtonUI.java:395)
    at java.desktop/com.apple.laf.AquaButtonUI.paint(AquaButtonUI.java:304)
    at java.desktop/javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
    at java.desktop/javax.swing.JComponent.paintComponent(JComponent.java:797)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1074)
    at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:907)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1083)
    at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:907)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1083)
    at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:907)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1083)
    at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:907)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1083)
    at java.desktop/javax.swing.JLayeredPane.paint(JLayeredPane.java:590)
    at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:907)
    at java.desktop/javax.swing.JComponent.paintToOffscreen(JComponent.java:5262)
    at java.desktop/javax.swing.RepaintManager$PaintManager.paintDoubleBufferedImpl(RepaintManager.java:1643)
    at java.desktop/javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1618)
    at java.desktop/javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1556)
    at java.desktop/javax.swing.RepaintManager.paint(RepaintManager.java:1323)
    at java.desktop/javax.swing.JComponent.paint(JComponent.java:1060)
    at java.desktop/java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:39)
    at java.desktop/sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:78)
    at java.desktop/sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:115)
    at java.desktop/java.awt.Container.paint(Container.java:2002)
    at java.desktop/java.awt.Window.paint(Window.java:3926)
    at java.desktop/javax.swing.RepaintManager$4.run(RepaintManager.java:876)
    at java.desktop/javax.swing.RepaintManager$4.run(RepaintManager.java:848)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
    at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
    at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:848)
    at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:823)
    at java.desktop/javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:772)
    at java.desktop/javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1884)

Answer 1

这是一个使用SVG图标并创建多分辨率图像以支持hidpi屏幕的示例，如上一条注释中所述：

  // Create a multi-resolution image with all 0.25 scaling steps up to 3x
  final int size = ...; // base size = 16, 24, 32 etc.

  // Create all resolution variants that Windows 10 offers by default
  // Could probably drop some, e.g. 1.25 = 2.50 / 2 (Swing should handle that...)
  final List< Integer > sizes = ImmutableList.of(
      (int) ( size * 1.00 ), // Base image
      (int) ( size * 1.25 ),
      (int) ( size * 1.50 ),
      (int) ( size * 1.75 ),
      (int) ( size * 2.00 ),
      (int) ( size * 2.25 ),
      (int) ( size * 2.50 ),
      (int) ( size * 2.75 ),
      (int) ( size * 3.00 ) );

  final byte[] rawSvgBytes = ...; // Read bytes from SVG file

  Image[] images = new Image[ sizes.size() ];
  for ( int isize = 0; isize < sizes.size(); isize++ )
  {
    // Create a PNG transcoder
    PNGTranscoder t = new PNGTranscoder();

    // Set the transcoding hints
    t.addTranscodingHint( SVGAbstractTranscoder.KEY_WIDTH, Float.valueOf( sizes.get( isize ) ) );
    t.addTranscodingHint( SVGAbstractTranscoder.KEY_HEIGHT, Float.valueOf( sizes.get( isize ) ) );

    // Create the transcoder input
    TranscoderInput input = new TranscoderInput();
    input.setInputStream( new ByteArrayInputStream( rawSvgBytes ) );
    // Create the transcoder output
    ByteArrayOutputStream ostream = new ByteArrayOutputStream();
    TranscoderOutput output = new TranscoderOutput( ostream );

    // Transcode the image
    t.transcode( input, output );

    // Create an image and ensure its size is initialised
    Image image = Toolkit.getDefaultToolkit().createImage( ostream.toByteArray() );
    while ( image.getWidth( null ) == -1 )
    {
      // HACK! Wait for the image to be loaded, else icons may not render at the correct
      // location as the width and height returned to Swing are -1
    }
    images[ isize ] = image;
  }
  return new ImageIcon( new BaseMultiResolutionImage( images ) ); // First image always the base image

Answer 2

好，所以问题如下：

由ImageIcon（和getScaledInstance上的ImageIcon）创建的图像的类型为ToolkitImage。这些不是Swing期望的BufferedImage。

一种可行的解决方案是拍摄图像，然后将它们转换为两个BufferedImage实例。这是破解以上代码的丑陋解决方案：

  ImageIcon icon = new ImageIcon(getClass().getClassLoader().getResource("res/icons/toolbar/" + iconName));

  BufferedImage ax = new BufferedImage(32, 32, BufferedImage.TYPE_INT_ARGB);
  BufferedImage bx = new BufferedImage(64, 64, BufferedImage.TYPE_INT_ARGB);

  Graphics g = ax.createGraphics();
  new ImageIcon(icon.getImage().getScaledInstance(32, 32, Image.SCALE_SMOOTH)).paintIcon(null, g, 0, 0);
  g.dispose();

  g = bx.createGraphics();
  icon.paintIcon(null, g, 0, 0);
  g.dispose();

  BaseMultiResolutionImage baseMultiResolutionImage = new BaseMultiResolutionImage(ax, bx);
  return new ImageIcon(baseMultiResolutionImage);

从Java Swing中的原始文件生成HiDPI ImageIcon

2 个答案: