Java/SWT JFace Eclipse/Canvas

A paint canvas.

   <source lang="java">

/*

* JFreeChart : a free chart library for the Java(tm) platform
* 
*
* (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
*
* Project Info:  http://www.jfree.org/jfreechart/index.html
*
* This library is free software; you can redistribute it and/or modify it 
* under the terms of the GNU Lesser General Public License as published by 
* the Free Software Foundation; either version 2.1 of the License, or 
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but 
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
* USA.  
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
* in the United States and other countries.]
*
* -------------------
* SwtPaintCanvas.java
* -------------------
* (C) Copyright 2000-2007, by Object Refinery Limited.
*
* Original Author:  Henry Proudhon (henry.proudhon AT ensmp.fr);
* Contributor(s):   David Gilbert (for Object Refinery Limited);
*
* Changes
* -------
* 04-Aug-2006 : New class (HP);
* 25-Oct-2007 : Fixed Eclipse warnings (DG);
* 
*/

import org.eclipse.swt.SWT; import org.eclipse.swt.events.PaintEvent; import org.eclipse.swt.events.PaintListener; import org.eclipse.swt.graphics.Color; import org.eclipse.swt.widgets.Canvas; import org.eclipse.swt.widgets.ruposite; /**

* A paint canvas.
*/

public class SWTPaintCanvas extends Canvas {

   private Color myColor;
   
   /**
    * Creates a new instance.
    * 
    * @param parent  the parent.
    * @param style  the style.
    * @param color  the color.
    */
   public SWTPaintCanvas(Composite parent, int style, Color color) {
       this(parent, style);
       setColor(color);
   }
   
   /**
    * Creates a new instance.
    * 
    * @param parent  the parent.
    * @param style  the style.
    */
   public SWTPaintCanvas(Composite parent, int style) {
       super(parent, style);
       addPaintListener(new PaintListener() {
           public void paintControl(PaintEvent e) {
               e.gc.setForeground(e.gc.getDevice().getSystemColor(
                       SWT.COLOR_BLACK));
               e.gc.setBackground(SWTPaintCanvas.this.myColor);
               e.gc.fillRectangle(getClientArea());
               e.gc.drawRectangle(getClientArea().x, getClientArea().y, 
                       getClientArea().width - 1, getClientArea().height - 1);
           }
       });
   }
   
   /**
    * Sets the color.
    * 
    * @param color  the color.
    */
   public void setColor(Color color) {
       if (this.myColor != null) {
           this.myColor.dispose();
       }
       //this.myColor = new Color(getDisplay(), color.getRGB());
       this.myColor = color;
   }
   /**
    * Returns the color.
    * 
    * @return The color.
    */
   public Color getColor() {
       return this.myColor;
   }
   
   /**
    * Overridden to do nothing.
    * 
    * @param c  the color.
    */
   public void setBackground(Color c) {
       return;
   }
   /**
    * Overridden to do nothing.
    * 
    * @param c  the color.
    */
   public void setForeground(Color c) {
       return;
   }
   
   /**
    * Frees resources.
    */
   public void dispose() {
       this.myColor.dispose();
   }

}

 </source>
   
  
 
  

Canvas example snippet: implement tab traversal

   <source lang="java">

/******************************************************************************

* Copyright (c) 1998, 2004 Jackwind Li Guojie
* All right reserved. 
* 
* Created on Jan 24, 2004 3:03:14 PM by JACK
* $Id$
* 
* visit: http://www.asprise.ru/swt
*****************************************************************************/

/*

* Canvas example snippet: implement tab traversal (behave like a tab group)
*
* For a list of all SWT example snippets see
* http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-swt-home/dev.html#snippets
*/

import org.eclipse.swt.SWT; 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 CanvasExample {

 public static void main(String[] args) {
   Display display = new Display();
   
   Image small = new Image(display, 16, 16);
   GC gc = new GC(small);
   gc.setBackground(display.getSystemColor(SWT.COLOR_RED));
   gc.fillArc(0, 0, 16, 16, 45, 270);
   gc.dispose();
   
   Image large = new Image(display, 32, 32);
   gc = new GC(large);
   gc.setBackground(display.getSystemColor(SWT.COLOR_BLUE));
   gc.fillArc(0, 0, 32, 32, 45, 270);
   gc.dispose();
   
   /* Provide different resolutions for icons to get
    * high quality rendering wherever the OS needs 
    * large icons. For example, the ALT+TAB window 
    * on certain systems uses a larger icon.
    */
   Shell shell = new Shell(display);
   shell.setText("Small and Large icons");
   shell.setImages(new Image[] {small, large});
   /* No large icon: the OS will scale up the
    * small icon when it needs a large one.
    */
   Shell shell2 = new Shell(display);
   shell2.setText("Small icon");
   shell2.setImage(small);
   
   shell.open();
   shell2.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch())
       display.sleep();
   }
   display.dispose();
 }

}

 </source>
   
  
 
  

Demonstrates a Canvas

   <source lang="java">

//Send questions, comments, bug reports, etc. to the authors: //Rob Warner (rwarner@interspatial.ru) //Robert Harris (rbrt_harris@yahoo.ru) import org.eclipse.swt.SWT; import org.eclipse.swt.events.*; import org.eclipse.swt.graphics.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*; /**

* This class demonstrates a Canvas
*/

public class SimpleCanvas {

 /**
  * Runs the application
  */
 public void run() {
   Display display = new Display();
   Shell shell = new Shell(display);
   shell.setText("Canvas Example");
   createContents(shell);
   shell.open();
   while (!shell.isDisposed()) {
     if (!display.readAndDispatch()) {
       display.sleep();
     }
   }
   display.dispose();
 }
 /**
  * Creates the main window"s contents
  * 
  * @param shell the main window
  */
 private void createContents(Shell shell) {
   shell.setLayout(new FillLayout());
   // Create a canvas
   Canvas canvas = new Canvas(shell, SWT.NONE);
   // Create a button on the canvas
   Button button = new Button(canvas, SWT.PUSH);
   button.setBounds(10, 10, 300, 40);
   button.setText("You can place widgets on a canvas");
   // Create a paint handler for the canvas
   canvas.addPaintListener(new PaintListener() {
     public void paintControl(PaintEvent e) {
       // Do some drawing
       Rectangle rect = ((Canvas) e.widget).getBounds();
       e.gc.setForeground(e.display.getSystemColor(SWT.COLOR_RED));
       e.gc.drawFocus(5, 5, rect.width - 10, rect.height - 10);
       e.gc.drawText("You can draw text directly on a canvas", 60, 60);
     }
   });
 }
 /**
  * The application entry point
  * 
  * @param args the command line arguments
  */
 public static void main(String[] args) {
   new SimpleCanvas().run();
 }

}

 </source>