在静态图像上设置移动矩形的动画Java SWT

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class RectangleAnimation {
    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new FillLayout());

        Canvas canvas = new Canvas(shell, SWT.NONE);
        canvas.setBackground(new Color(display, 255, 255, 255));

        Rectangle rect = new Rectangle(50, 50, 100, 100);
        int dx = 1;
        int dy = 1;

        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }

            rect.x += dx;
            rect.y += dy;

            if (rect.x <= 0 || rect.x + rect.width >= canvas.getBounds().width) {
                dx = -dx;
            }
            if (rect.y <= 0 || rect.y + rect.height >= canvas.getBounds().height) {
                dy = -dy;
            }

            canvas.redraw();
        }

        display.dispose();
    }
}