/*******************************************************************************
 * Copyright (c) 2007 Actuate Corporation.
 * 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:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.report.designer.internal.ui.swt.custom;

import org.eclipse.core.commands.common.EventManager;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.swt.SWT;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.ColorDialog;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

/**
 * The <code>ColorSelector</code> is a wrapper for a button that displays a
 * selected <code>Color</code> and allows the user to change the selection.
 * 
 * Note: this is a patched version from jface ColorSelector since 3.3 to fix
 * bugzilla#139368, once jface has fixed that, we should switch back.
 */
public class ColorSelector extends EventManager
{

	/**
	 * Property name that signifies the selected color of this
	 * <code>ColorSelector</code> has changed.
	 * 
	 * @since 3.0
	 */
	public static final String PROP_COLORCHANGE = "colorValue"; //$NON-NLS-1$

	private Button fButton;

	private Color fColor;

	private RGB fColorValue;

	private Point fExtent;

	private Image fImage;

	/**
	 * Create a new instance of the reciever and the button that it wrappers in
	 * the supplied parent <code>Composite</code>.
	 * 
	 * @param parent
	 *            The parent of the button.
	 */
	public ColorSelector( Composite parent )
	{
		fButton = new Button( parent, SWT.PUSH );
		fExtent = computeImageSize( parent );
		fImage = new Image( parent.getDisplay( ), fExtent.x, fExtent.y );
		GC gc = new GC( fImage );
		gc.setBackground( fButton.getBackground( ) );
		gc.fillRectangle( 0, 0, fExtent.x, fExtent.y );
		gc.dispose( );
		fButton.setImage( fImage );
		fButton.addSelectionListener( new SelectionAdapter( ) {

			public void widgetSelected( SelectionEvent event )
			{
				open( );
			}
		} );
		fButton.addDisposeListener( new DisposeListener( ) {

			public void widgetDisposed( DisposeEvent event )
			{
				if ( fImage != null )
				{
					fImage.dispose( );
					fImage = null;
				}
				if ( fColor != null )
				{
					fColor.dispose( );
					fColor = null;
				}
			}
		} );
		fButton.getAccessible( )
				.addAccessibleListener( new AccessibleAdapter( ) {

					/*
					 * (non-Javadoc)
					 * 
					 * @see org.eclipse.swt.accessibility.AccessibleAdapter#getName(org.eclipse.swt.accessibility.AccessibleEvent)
					 */
					public void getName( AccessibleEvent e )
					{
						e.result = JFaceResources.getString( "ColorSelector.Name" ); //$NON-NLS-1$
					}
				} );
	}

	/**
	 * Adds a property change listener to this <code>ColorSelector</code>.
	 * Events are fired when the color in the control changes via the user
	 * clicking an selecting a new one in the color dialog. No event is fired in
	 * the case where <code>setColorValue(RGB)</code> is invoked.
	 * 
	 * @param listener
	 *            a property change listener
	 * @since 3.0
	 */
	public void addListener( IPropertyChangeListener listener )
	{
		addListenerObject( listener );
	}

	/**
	 * Compute the size of the image to be displayed.
	 * 
	 * @param window -
	 *            the window used to calculate
	 * @return <code>Point</code>
	 */
	private Point computeImageSize( Control window )
	{
		GC gc = new GC( window );
		Font f = JFaceResources.getFontRegistry( )
				.get( JFaceResources.DIALOG_FONT );
		gc.setFont( f );
		int height = gc.getFontMetrics( ).getHeight( );
		gc.dispose( );
		Point p = new Point( height * 3 - 6, height );
		return p;
	}

	/**
	 * Get the button control being wrappered by the selector.
	 * 
	 * @return <code>Button</code>
	 */
	public Button getButton( )
	{
		return fButton;
	}

	/**
	 * Return the currently displayed color.
	 * 
	 * @return <code>RGB</code>
	 */
	public RGB getColorValue( )
	{
		return fColorValue;
	}

	/**
	 * Removes the given listener from this <code>ColorSelector</code>. Has
	 * no affect if the listener is not registered.
	 * 
	 * @param listener
	 *            a property change listener
	 * @since 3.0
	 */
	public void removeListener( IPropertyChangeListener listener )
	{
		removeListenerObject( listener );
	}

	/**
	 * Set the current color value and update the control.
	 * 
	 * @param rgb
	 *            The new color.
	 */
	public void setColorValue( RGB rgb )
	{
		fColorValue = rgb;
		updateColorImage( );
	}

	/**
	 * Set whether or not the button is enabled.
	 * 
	 * @param state
	 *            the enabled state.
	 */
	public void setEnabled( boolean state )
	{
		getButton( ).setEnabled( state );
	}

	/**
	 * Update the image being displayed on the button using the current color
	 * setting.
	 */
	protected void updateColorImage( )
	{
		Display display = fButton.getDisplay( );
		GC gc = new GC( fImage );

		if ( fColor != null )
		{
			fColor.dispose( );
		}

		if ( fColorValue == null )
		{
			gc.setBackground( fButton.getBackground( ) );
			gc.fillRectangle( 0, 0, fExtent.x, fExtent.y );
		}
		else
		{
			gc.setForeground( display.getSystemColor( SWT.COLOR_BLACK ) );
			gc.drawRectangle( 0, 2, fExtent.x - 1, fExtent.y - 4 );
			fColor = new Color( display, fColorValue );
			gc.setBackground( fColor );
			gc.fillRectangle( 1, 3, fExtent.x - 2, fExtent.y - 5 );
		}
		gc.dispose( );
		fButton.setImage( fImage );
	}

	/**
	 * Activate the editor for this selector. This causes the color selection
	 * dialog to appear and wait for user input.
	 * 
	 * @since 3.2
	 */
	public void open( )
	{
		Shell shell = new Shell( Display.getCurrent( ), SWT.SHELL_TRIM );
		shell.setLocation( fButton.toDisplay( 0, 0 ).x
				+ fButton.getBounds( ).width, fButton.toDisplay( 0, 0 ).y
				- fButton.getBounds( ).height );
		ColorDialog colorDialog = new ColorDialog( shell, SWT.APPLICATION_MODAL );
		colorDialog.setRGB( fColorValue );
		RGB newColor = colorDialog.open( );
		if ( newColor != null )
		{
			RGB oldValue = fColorValue;
			fColorValue = newColor;
			final Object[] finalListeners = getListeners( );
			if ( finalListeners.length > 0 )
			{
				PropertyChangeEvent pEvent = new PropertyChangeEvent( this,
						PROP_COLORCHANGE,
						oldValue,
						newColor );
				for ( int i = 0; i < finalListeners.length; ++i )
				{
					IPropertyChangeListener listener = (IPropertyChangeListener) finalListeners[i];
					listener.propertyChange( pEvent );
				}
			}
			updateColorImage( );
		}
		shell.dispose( );
	}
}
