First, the size of the image should have the size the tree would have without scrolls, and not the current size. For that you should use computeSize(SWT.DEFAULT, SWT.DEFAULT, true)
. Then you should resize the tree that size, print, and then resize it back. Since you don't want users to notice that, during this operation you should disabled draws with setRedraw(false)
.
Here is a full snippet that does all this:
public static void main(String[] args) {
final Display display = new Display();
final Shell shell = new Shell(display);
shell.setLayout(new FillLayout());
Composite composite = new Composite(shell, SWT.NONE);
composite.setLayout(new FillLayout());
final Tree tree = new Tree(composite, SWT.NONE);
for (int i = 0; i < 100; i++) {
final TreeItem treeItem = new TreeItem(tree, SWT.NONE);
treeItem.setText(String.format("item %d long name", i));
}
tree.addListener(SWT.DefaultSelection, new Listener() {
@Override
public void handleEvent(Event event) {
tree.getParent().setRedraw(false);
final Point originalSize = tree.getSize();
final Point size = tree.computeSize(SWT.DEFAULT, SWT.DEFAULT, true);
final Image image = new Image(display, size.x, size.y);
final GC gc = new GC(image);
tree.setSize(size);
tree.print(gc);
tree.setSize(originalSize);
final ImageLoader loader = new ImageLoader();
loader.data = new ImageData[]{image.getImageData()};
final String pathToSave = "out.png";
System.out.println(new File(pathToSave).getAbsolutePath());
loader.save(pathToSave, SWT.IMAGE_PNG);
gc.dispose();
image.dispose();
tree.getParent().setRedraw(true);
}
});
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
Press enter to save the file.