lwcanvas.java

Zaval Light-Weight Visual Components Library (LwVCL) is a pure Java alternative to humble AWT-based

/**
 *     Caption: Zaval Light-Weight Visual Components Library
 *     $Revision: 2.79 $
 *     $Date: 2003/08/22 11:24:16 $
 *
 *     @author:     Andrei Vishnevsky
 *     @version:    3.50
 *
 * Zaval Light-Weight Visual Components Library (LwVCL) is a pure Java
 * alternative to humble AWT-based and SWING-based GUI interfaces for
 * wide ranges of platforms, including J2SE, PersonalJava and J2ME.
 *
 * Designed as light-weight but, alternatively to Swing, built separately
 * from AWT (not on top of the java.awt library like Swing), the LwVCL is
 * the good alternative to highly performant, memory-efficient, flexible
 * GUI solution for embedded, stand-alone and applet applications.
 *
 * For more info on this product read Zaval Light-Weight Visual Components Library Tutorial
 * (It comes within this package).
 * The latest product version is always available from the product's homepage:
 * http://www.zaval.org/products/lwvcl/
 * and from the SourceForge:
 * http://sourceforge.net/projects/zaval0003/
 *
 * Contacts:
 *   Support : [e-mail]
 *   Change Requests : [e-mail]
 *   Feedback : [e-mail]
 *   Other : [e-mail]
 *
 * Copyright (C) 2001-2003  Zaval Creative Engineering Group (http://www.zaval.org)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * (version 2) as published by the Free Software Foundation.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */
package org.zaval.lw;

import java.awt.*;
import org.zaval.lw.event.*;
import org.zaval.util.*;

/**
 * This is basic implemenation of the light weight component interface that should be used
 * to develop own light weight component. As rule when you develop a lightweight components
 * it is necessary to pass through following steps:
 * <ul>
 *   <li>

 *     Inherit the class for your lightweight component.
 *   </li>
 *   <li>
 *     Implement necessary events listeners interfaces, to have ability handling
 *     required lightweight events.
 *   </li>
 *   <li>
 *     Override (if it is necessary) <code>paint</code> method to define the component face.
 *   </li>
 *   <li>
 *     Override (if it is necessary) <code>update</code> method to define the component
 *     background.
 *   </li>
 *   <li>
 *     Override (if it is necessary) <code>recalc</code> method to calculate the component
 *     metrics. For example, you can calculate "pure" preferred size inside the method or
 *     some metrical characteristics that are used to calculate the preferred size.
 *   </li>
 *   <li>
 *     Override (if it is necessary) <code>calcPreferredSize</code> method to define "pure"
 *     preferred size of the component face.
 *   </li>
 * </ul>
 */
public class LwCanvas
extends org.zaval.util.ValidationObject
implements LwComponent
{
   private Color back;
   protected long insets;
   protected short bits = DEFAULT_BITS;

   protected int x, y, width, height, psWidth = -1, psHeight = -1;

  /**
   * The component parent.
   */
   protected LwComponent parent;

  /**
   * The component view manager.
   */
   protected LwViewMan skins;

  /**
   * Calculates and returns the insets of this component. Take care that insets for lightweight
   * components differ from Java AWT components. The lightweight insets
   * defines indents from "left", "top", "right" and "bottom" of the component view.
   * Don't override the method. If you want to define insets use <code>setInsets</code>
   * method.
   * @return the insets of this component.
   */
   public /*C#virtual*/ Insets getInsets()  {
     return getInsets(this);
   }

   public int getX() {
     return x;
   }

   public int getY() {
     return y;
   }

   public int getWidth() {
     return width;
   }

   public int getHeight() {
     return height;
   }

  /**
   * Sets the specified insets for the component.
   * @param <code>top</code> the top indent.
   * @param <code>left</code> the left indent.
   * @param <code>bottom</code> the bottom indent.
   * @param <code>right</code> the right indent.
   */
   public void setInsets (int top, int left, int bottom, int right)
   {
     Insets i1 = getInsets();
     if (!(new Insets (top, left, bottom, right)).equals(i1))
     {
       insets = (top & 0xFFFF) + ((left & 0xFFFF) << 16);
       long l = (bottom & 0xFFFF) + ((right & 0xFFFF) << 16);
       insets += (l << 32);
       vrp();
     }
   }

  /**
   * Returns a size of this component. The size is reperesented with
   * <code>java.awt.Dimension</code> class.
   * @return a <code>Dimension</code> object that indicates the
   * size of this component.
   */
   public Dimension getSize() {
     return new Dimension(width, height);
   }

  /**
   * Returns the bounding rectangle of the visible part for the component.
   * @return a visible part bounding rectangle.
   */
   public /*C#virtual*/ Rectangle getVisiblePart()
   {
     if (isVisible())
     {
       //???
       if (parent == null) return new Rectangle (0, 0, width, height);
       Rectangle pr  = parent.getVisiblePart();

       if (pr != null) pr = MathBox.intersection(pr.x, pr.y, pr.width, pr.height,
                                                 x, y, width, height);
       if (pr != null && pr.width > 0 && pr.height > 0)
       {
         pr.x -= x;
         pr.y -= y;
         return pr;
       }
     }
     return null;
   }

  /**
   * Sets the lightweight parent of this component. It is supposed that the parent implements
   * LwContainer interface. The method is provided for lightweight core usage to support components
   * hierarchy, not for applications that base on the library.
   * Don't touch the method.
   * @param <code>o</code> the parent component of this lightweight component.
   */
   public void setLwParent(LwComponent o)
   {
     if (o != parent)
     {
       parent = o;
       invalidate();
     }
   }

  /**
   * Gets the location of this component point specifying the component top-left corner.
   * The location is relative to the parent component coordinate space.
   * @return an instance of <code>Point</code> representing the top-left corner
   * of the component bounds in the coordinate space of the component parent.
   */
   public Point getLocation() {
     return new Point(x, y);
   }

  /**
   * Gets the background color of this lightweight component.
   * @return a componen background color.
   */
   public Color getBackground() {
     return back == null?LwToolkit.BACK_COLOR:back;
   }

  /**
   * Determines if this component is visible. The component is visible
   * if the visibility flag is true.
   * @return <code>true</code> if the component is visible;
   * <code>false</code> otherwise.
   */
   public /*C#virtual*/ boolean isVisible() {
     return MathBox.checkBit(bits, VISIBLE_BIT);
   }

  /**
   * Shows or hides this lightweight component depending on the value of parameter
   * <code>b</code>. The method performs appropriate LwComponentEvent.
   * @param <code>b</code> if it is <code>true</code>, shows this component;
   * otherwise, hides this component.
   */
   public /*C#virtual*/ void setVisible(boolean b)
   {
     if (MathBox.checkBit(bits, VISIBLE_BIT) != b)
     {
       bits = MathBox.getBits(bits, VISIBLE_BIT, b);
       invalidate();
       if (b)
       {
         LwEventManager.manager.perform(new LwComponentEvent(this, LwComponentEvent.COMP_SHOWN));
         repaint();
       }
       else
       {
         LwEventManager.manager.perform(new LwComponentEvent(this, LwComponentEvent.COMP_HIDDEN));
         if (parent != null) parent.repaint(x, y, width, height);
       }
     }
   }

  /**
   * Determines whether this component is enabled. If the method returns
   * <code>true</code> than the component is enabled and can participate in event
   * handling and performing processes. Components are enabled initially by default.
   * A component can be enabled or disabled by calling its <code>setEnabled</code>
   * method.
   * @return <code>true</code> if the component is enabled; <code>false</code> otherwise.
   */
   public /*C#virtual*/ boolean isEnabled() {
     return MathBox.checkBit(bits, ENABLE_BIT) && (parent == null || parent.isEnabled());
   }

  /**
   * Enables or disables this component. An enabled component can participate
   * in events handling and performing processes. Component is enabled initially
   * by default. The method performs appropriate LwComponentEvent.
   * @param  <code>b</code> if <code>true</code>, this component is
   * enabled; otherwise this component is disabled.
   */
   public /*C#virtual*/ void setEnabled(boolean b)
   {
     if (MathBox.checkBit(bits, ENABLE_BIT) != b)
     {
       bits = MathBox.getBits(bits, ENABLE_BIT, b);
       if (b) LwEventManager.manager.perform(new LwComponentEvent(this, LwComponentEvent.COMP_ENABLED ));
       else   LwEventManager.manager.perform(new LwComponentEvent(this, LwComponentEvent.COMP_DISABLED));
       repaint();
     }
   }

  /**
   * Sets the background color of this component. The color is used to fill the component
   * background in case if it is not transparent.
   * @param <code>c</code> the color to become this component background color. Use <code>null</code>
   * as the color value to set the background to the default color value.
   */
   public /*C#virtual*/ void setBackground(Color c)
   {
     if (c != back && (c == null || !c.equals(back)))
     {
       back = c;
       repaint();
     }
   }

  /**
   * Invalidates this component. The parent will be invalidated with this component too.
   */
   public /*C#override*/ void invalidate()  {
     if (parent != null) parent.invalidate();
     super.invalidate();
   }

  /**
   * Validates this component. The method initiates validation process only if it is necessary.
   * It means that you don't need to care about frequency the method executing. The method executes
   * <code>recalc</code> method to calculate the component metrics if it is necessary. So,
   * override the method (<code>recalc</code> method) to calculate some metrical characteristics
   * to minimize the computation time.
   */
   public /*C#override*/ void validate()
   {
     if (isVisible())
     {
       if (skins != null) skins.validate();
       super.validate();
     }
   }