import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class GraphicsSnippet {

    public static void main(String[] args) {
        final Display display = new Display();
        final Shell shell = new Shell(display);

        // Create image and GC for drawing
        Image image = new Image(display, 128, 128);
        GC gcImage = new GC(image);

        // Colors
        Color red = new Color(Display.getDefault(), 255, 0, 0);
        Color blue = new Color(Display.getDefault(), 0, 0, 255);

        // Paint shell
        shell.addListener(SWT.Paint, event -> {
            GC gc = event.gc;

            // Draw red background on image
            gcImage.setBackground(red);
            gcImage.fillRectangle(0, 0, 128, 128);
            gc.drawImage(image, 0, 0);

            // Draw blue background on image and move x position
            gcImage.setBackground(blue);
            gcImage.fillRectangle(0, 0, 128, 128);
            gc.drawImage(image, 128, 0);
        });

        shell.setSize(400, 400);
        shell.open();

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

        display.dispose();

        gcImage.dispose();
        image.dispose();

        red.dispose();
        blue.dispose();
    }
}