Java 为文件导出调整JComponent的大小

我有一个JPanel，在它的基础上，我使用通常的“paintComponent（Graphics g）”方法绘制了许多自定义编写的JComponent。我使用JLayeredPane控制自定义组件的显示顺序，如下所示：

public Class MyPanel extends JPanel {
    private JLayeredPane layeredPane = new JLayeredPane();
    private JComponent component1;
    private JComponent component2;

    public MyPanel() {
        super();
        setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));

        component1 = new CustomComponent1();
        layeredPane.add (component1, new Integer(0));

        component2 = new CustomComponent2();
        layeredPane.add (component2, new Integer(1));

        add (layeredPane);
    }

    public void resizePanel(Graphics g, int newWidth, int newHeight) {
        component1.setBounds (f(x), f(y), f(newWidth), f(newHeight));
        component2.setBounds (f(x), f(y), f(newWidth), f(newHeight));
    }

    public void paintComponent(Graphics g) {
        if ((getWidth() != oldWidth) || (getHeight() != oldHeight)) {
            oldWidth = getWidth();
            oldHeight = getHeight();
            resizePanel (g, getWidth(), getHeight());
        }
        super.paintComponent(g);
    }

现在，我想将此面板导出为JPEG文件，但大小不同。当我使用以下代码时，它成功地创建/导出了所需大小的JPEG文件，但它也将面板的屏幕图像版本更新为新的大小！哎呀

public void export(File file, int width, int height)
    throws IOException
{
    BufferedImage scaledImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = scaledImage.createGraphics();
    resizePanel (g2, width, height);
    super.paintComponent (g2);

    try {
        OutputStream out = new FileOutputStream(file);
        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        encoder.encode(scaledImage);
        out.close();
    } catch (FileNotFoundException e) {
        throw new IOException ("Unable to export chart to ("
                  + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } finally {
        g2.dispose();
    }
}

如何“绘制”适合导出的图像，但不实际显示此新图像

谢谢

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嗯，我又回到这个问题上来了

我正在绘制的场景包含一些文本，现在最终用户希望以“纵向”纵横比导出图形。因为我不是在新的维度中重新绘制场景，而是缩放图像，这会导致文本被严重水平挤压

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不管怎么说

根本不调整面板的大小；只需创建一个面板的当前大小，并绘制它。获得快照后，立即使用或将其缩放到所需的尺寸

附录：的一个优点是控制旋转、插值、比例和纵横比：

BufferedImage image = ...
int w = image.getWidth();
int h = image.getHeight();
AffineTransform scaleTransform = new AffineTransform();
// last-in-first-applied: rotate, scale
scaleTransform.scale(scaleX, scaleY);
scaleTransform.rotate(Math.PI / 2, w / 2, h / 2);
AffineTransformOp scaleOp = new AffineTransformOp(
        scaleTransform, AffineTransformOp.TYPE_BILINEAR);
BufferedImage new = scaleOp.filter(image, null);

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看起来是第二个很好的解决方案。我的最终解决方案如下所示：

public void export(File file, int width, int height)
throws IOException
{
    BufferedImage scaledImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = scaledImage.createGraphics();
    g2.scale(((double) width)/((double)getWidth()), ((double) height)/((double)getHeight()));
    paintComponents(g2);
    try {
        ImageIO.write(scaledImage, "jpg", file);            
    } catch (FileNotFoundException e) {
        throw new IOException ("Unable to export chart to ("
         + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } finally {
        g2.dispose();
    }
}

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好的，我能让一切看起来正常的唯一方法（例如，光栅化后的文本没有缩放）是使用新的大小在新的图形上下文上绘制图像。这是我的新“export（）”方法

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上面调用的“draw（）”方法在我的所有子组件上调用“setbounds（）”方法，将它们绘制到新的缓冲图像上。需要做一点工作，但结果正是我所需要的。

Cross-posted:这正确地建议使用javax.imageio:嗯，这种方法看起来比“g2.scale（）”n重画组件稍微好一点，但文本仍然有点水平扭曲。我现在就用这个方法。再次感谢。R

    public void export(File file, final int width, final int height)
    throws IOException
{

    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    final Graphics2D g2 = image.createGraphics();

    //  Must wait for the bloody image to be drawn as Swing 'paint()' methods
    //  merely schedule painting events.  The 'draw()' below may not complete
    //  the painting process before the 'write()' of the image is performed.

    //  thus, we wait....

    try {
        SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
                draw (g2, new Rectangle (0, 0, width, height));
            }
        });
        ImageIO.write(image, "png", file);
    } catch (Exception e) {
        throw new IOException ("Unable to export chart to ("
                + file.getAbsolutePath() + "): " + e.getLocalizedMessage());
    } finally {
        g2.dispose();
    }
}