Java 将 JPanel 转换为图像
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Convert JPanel to image
提问by Jeff Storey
Is there a way to convert a JPanel (that has not yet been displayed) to a BufferedImage?
有没有办法将 JPanel（尚未显示）转换为 BufferedImage？
thanks,
谢谢，
Jeff
杰夫
采纳答案by Tom
From the BufferedImage you can create a graphics object, which you can use to call paint on the JPanel, something like:
从 BufferedImage 您可以创建一个图形对象，您可以使用它来调用 JPanel 上的绘制，例如：
public BufferedImage createImage(JPanel panel) {
int w = panel.getWidth();
int h = panel.getHeight();
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
panel.paint(g);
g.dispose();
return bi;
}
You may need to make sure you set the size of the panel first.
您可能需要确保首先设置面板的大小。
回答by camickr
Basically I'm building a component that needs to get written to an image but not displayed
基本上我正在构建一个需要写入图像但不显示的组件
ScreenImageexplains how to do what you want.
ScreenImage解释了如何做你想做的事。
Relevant section of ScreenImage.java (slightly edited). layoutComponentforces all buttons appear in the image.
ScreenImage.java 的相关部分（略有编辑）。layoutComponent强制所有按钮出现在图像中。
/**
* @return Renders argument onto a new BufferedImage
*/
public BufferedImage createImage(JPanel panel, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = bi.createGraphics();
panel.setSize(width, height); // or panel.getPreferedSize()
layoutComponent(panel);
panel.print(g);
g.dispose();
return bi;
}
private void layoutComponent(Component component) {
synchronized (component.getTreeLock()) {
component.doLayout();
if (component instanceof Container) {
for (Component child : ((Container) component).getComponents()) {
layoutComponent(child);
}
}
}
}
回答by Rastislav Komara
Take a look at BasicTableUI. The cell renderer is drawn on image without showing and then drawn on visible table component.
看看 BasicTableUI。单元格渲染器在不显示的情况下绘制在图像上，然后绘制在可见的表格组件上。
回答by Pham Trung
The answer from Tom is basically correct, but invoke paint()directly is not recommended, as it is a synchronous call and can interrupt with other operation on the swing thread. Instead of using paint(), we should use print()instead
Tom的回答基本正确，但paint()不建议直接调用，因为它是同步调用，可以中断swing线程上的其他操作。而不是使用的paint()，我们应该用print()代替
public BufferedImage createImage(JPanel panel) {
int w = panel.getWidth();
int h = panel.getHeight();
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
panel.print(g);
g.dispose();
return bi;
}
