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Implement a simple scribble program
/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;

public class ScribbleProgram {

  public static void main(String[] args) {
    Display display = new Display();
    final Shell shell = new Shell(display);
    Listener listener = new Listener() {
      int lastX = 0, lastY = 0;

      public void handleEvent(Event event) {
        switch (event.type) {
        case SWT.MouseMove:
          if ((event.stateMask & SWT.BUTTON1) == 0)
            break;
          GC gc = new GC(shell);
          gc.drawLine(lastX, lastY, event.x, event.y);
          gc.dispose();

        case SWT.MouseDown:
          lastX = event.x;
          lastY = event.y;
          break;
        }
      }
    };
    shell.addListener(SWT.MouseDown, listener);
    shell.addListener(SWT.MouseMove, listener);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch())
        display.sleep();
    }
    display.dispose();
  }
}








18.3.SWT Paint
18.3.1.A dynamic gradientA dynamic gradient
18.3.2.Implement a simple scribble programImplement a simple scribble program
18.3.3.Alpha blendingAlpha blending
18.3.4.A paint canvas.