bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/SimpleStyledCellLabelProvider.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2007, 2008 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
  *     Michael Krkoska - initial API and implementation (bug 188333)
  *******************************************************************************/
 package org.eclipse.jface.viewers;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.jface.window.Window;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.StyleRange;
 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.Rectangle;
 import org.eclipse.swt.graphics.TextLayout;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Item;
 import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.swt.widgets.TreeItem;

 /**
  * A {@link SimpleStyledCellLabelProvider} supports styled labels by using owner
  * draw by preserving native viewer behavior:
  * <ul>
  * <li>similar image and label positioning</li>
  * <li>native drawing of focus and selection</li>
  * </ul>
  *
  *
  * <p>
  * For providing the label's styles, create a subclass and overwrite
  * {@link SimpleStyledCellLabelProvider#getLabelPresentationInfo(Object)} to
  * return all information needed to render a element.
  * </p>
  * <p>
  * The {@link SimpleStyledCellLabelProvider} will ignore all font settings on
  * {@link StyleRange}. Different fonts would make labels wider, and the native
  * selection drawing could not be reused.
  * </p>
  *
  * <p><strong>NOTE:</strong> This API is experimental and may be deleted or
  * changed before 3.4 is released.</p>
  *
  *
  * @deprecated Will be removed before 3.4 M6. Use {@link StyledCellLabelProvider} instead.
  *
  * @since 3.4
  */
 public abstract class SimpleStyledCellLabelProvider extends
 		OwnerDrawLabelProvider {

 	/**
 	 * Holds all information used to render a styled element.
 	 */
 	public static class LabelPresentationInfo {

 		private final String text;
 		private final Image image;
 		private final StyleRange[] ranges;

 		private final Font defaultFont;
 		private final Color defaultForegroundColor;
 		private final Color defaultBackgroundColor;

 		/**
 		 * Creates a {@link SimpleStyledCellLabelProvider.LabelPresentationInfo}.
 		 *
 		 * @param text
 		 *            the text of the current element
 		 * @param ranges
 		 *            the styled ranges for the element
 		 * @param image
 		 *            the image for the element or <code>null</code>
 		 * @param defaultFont
 		 *            the default font for the element or <code>null</code>
 		 * @param defaultForegroundColor
 		 *            the default foreground color for the element or
 		 *            <code>null</code>
 		 * @param defaultBackgroundColor
 		 *            the default background color for the element or
 		 *            <code>null</code>
 		 */
 		public LabelPresentationInfo(String text, StyleRange[] ranges,
 				Image image, Font defaultFont, Color defaultForegroundColor,
 				Color defaultBackgroundColor) {
 			Assert.isNotNull(text);
 			Assert.isNotNull(ranges);
 			this.text = text;
 			this.ranges = ranges;
 			this.image = image;
 			this.defaultFont = defaultFont;
 			this.defaultForegroundColor = defaultForegroundColor;
 			this.defaultBackgroundColor = defaultBackgroundColor;
 		}

 		/**
 		 * Provides the text of the current element.
 		 *
 		 * @return returns the text.
 		 */
 		public String getText() {
 			return this.text;
 		}

 		/**
 		 * Provides the styled ranges that can be applied to the text provided
 		 * by {@link #getText()}. The {@link SimpleStyledCellLabelProvider}
 		 * will ignore all font settings.
 		 *
 		 * @return the styled ranges for the element
 		 */
 		public StyleRange[] getStyleRanges() {
 			return this.ranges;
 		}

 		/**
 		 * Provides the image of the current element.
 		 *
 		 * @return returns the image.
 		 */
 		public Image getImage() {
 			return this.image;
 		}

 		/**
 		 * Provides a default background color of the current element, which is
 		 * used for the part of the label where no background color is specified
 		 * in the StyleRanges provided by {@link #getStyleRanges}.
 		 *
 		 * @return the background color for the element, or <code>null</code>
 		 *         to use the default background color
 		 */
 		public Color getDefaultBackground() {
 			return this.defaultBackgroundColor;
 		}

 		/**
 		 * Provides a default font of the current element.
 		 *
 		 * @return the font for the element, or <code>null</code> to use the
 		 *         default font
 		 */
 		public Font getDefaultFont() {
 			return this.defaultFont;
 		}

 		/**
 		 * Provides a default foreground color of the current element, which is
 		 * used for the part of the label where no foreground color is specified
 		 * in the StyleRanges provided by {@link #getStyleRanges}.
 		 *
 		 * @return the foreground color for the element, or <code>null</code>
 		 *         to use the default foreground color
 		 */
 		public Color getDefaultForeground() {
 			return this.defaultForegroundColor;
 		}

 	}

 	private static final String KEY_TEXT_LAYOUT = "styled_label_key_"; //$NON-NLS-1$

 	/**
 	 * Style constant for indicating that the styled colors are to be applied
 	 * even it the viewer's item is selected. Default is not to apply colors.
 	 */
 	public static final int COLORS_ON_SELECTION = 1 << 0;

 	/**
 	 * Style constant for indicating to draw the focus if requested by the owner
 	 * draw event. Default is to draw the focus.
 	 */
 	public static final int NO_FOCUS = 1 << 1;

 	/**
 	 * Private constant to indicate if owner draw is enabled for the
 	 * label provider's column.
 	 */
 	private static final int OWNER_DRAW_ENABLED = 1 << 4;

 	private int style;

 	private TextLayout cachedTextLayout; // reused text layout for
 											// 'cachedLabelInfo'
 	private LabelPresentationInfo cachedLabelInfo;
 	private boolean cachedWasWithColors;

 	private ColumnViewer viewer;
 	private ViewerColumn column;

 	/**
 	 * Creates a new StyledCellLabelProvider. By default, owner draw is enabled, focus is drawn and no
 	 * colors are painted on selected elements.
 	 */
 	public SimpleStyledCellLabelProvider() {
 		this(0);
 	}

 	/**
 	 * Creates a new StyledCellLabelProvider. By default, owner draw is enabled.
 	 *
 	 * @param style
 	 *            the style bits
 	 * @see SimpleStyledCellLabelProvider#COLORS_ON_SELECTION
 	 * @see SimpleStyledCellLabelProvider#NO_FOCUS
 	 */
 	public SimpleStyledCellLabelProvider(int style) {
 		this.style = style & (COLORS_ON_SELECTION | NO_FOCUS)
 							| OWNER_DRAW_ENABLED;
 	}

 	/**
 	 * Returns <code>true</code> is the owner draw rendering is enabled for this label provider.
 	 * By default owner draw rendering is enabled. If owner draw rendering is disabled, rending is
 	 * done by the viewer and no styled ranges (see {@link LabelPresentationInfo#getStyleRanges()})
 	 * are drawn.
 	 *
 	 * @return <code>true</code> is the rendering of styles is enabled.
 	 */
 	public boolean isOwnerDrawEnabled() {
 		return (this.style & OWNER_DRAW_ENABLED) != 0;
 	}

 	/**
 	 * Specifies whether owner draw rendering is enabled for this label
 	 * provider. By default owner draw rendering is enabled. If owner draw
 	 * rendering is disabled, rendering is done by the viewer and no styled
 	 * ranges (see {@link LabelPresentationInfo#getStyleRanges()}) are drawn.
 	 * It is the caller's responsibility to also call
 	 * {@link StructuredViewer#refresh()} or similar methods to update the
 	 * underlying widget.
 	 *
 	 * @param enabled
 	 *            specifies if owner draw rendering is enabled
 	 */
 	public void setOwnerDrawEnabled(boolean enabled) {
 		boolean isEnabled= isOwnerDrawEnabled();
 		if (isEnabled != enabled) {
 			if (enabled) {
 				this.style |= OWNER_DRAW_ENABLED;
 			} else {
 				this.style &= ~OWNER_DRAW_ENABLED;
 			}
 			if (this.viewer != null) {
 				setOwnerDrawEnabled(this.viewer, this.column, enabled);
 			}
 		}
 	}

 	/**
 	 * Returns the viewer on which this label provider is installed on or <code>null</code> if the
 	 * label provider is not installed.
 	 *
 	 * @return the viewer on which this label provider is installed on or <code>null</code> if the
 	 * label provider is not installed.
 	 */
 	protected final ColumnViewer getViewer() {
 		return this.viewer;
 	}

 	/**
 	 * Returns the column on which this label provider is installed on or <code>null</code> if the
 	 * label provider is not installed.
 	 *
 	 * @return the column on which this label provider is installed on or <code>null</code> if the
 	 * label provider is not installed.
 	 */
 	protected final ViewerColumn getColumn() {
 		return this.column;
 	}


 	/**
 	 * Returns a {@link LabelPresentationInfo} instance containing the text,
 	 * image and style information to use for displaying element.
 	 *
 	 * @param element
 	 *            the element to create a presentation info for
 	 * @return the presentation info
 	 */
 	protected abstract LabelPresentationInfo getLabelPresentationInfo(
 			Object element);


 	/* (non-Javadoc)
 	 * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#initialize(org.eclipse.jface.viewers.ColumnViewer, org.eclipse.jface.viewers.ViewerColumn)
 	 */
 	public void initialize(ColumnViewer viewer, ViewerColumn column) {
 		Assert.isTrue(this.viewer == null && this.column == null, "Label provider instance already in use"); //$NON-NLS-1$

 		this.viewer= viewer;
 		this.column= column;
 		super.initialize(viewer, column, isOwnerDrawEnabled());
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.viewers.BaseLabelProvider#dispose()
 	 */
 	public void dispose() {
 		if (this.cachedTextLayout != null) {
 			cachedTextLayout.dispose();
 			cachedTextLayout = null;
 		}
 		cachedLabelInfo = null;

 		this.viewer= null;
 		this.column= null;

 		super.dispose();
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#update(org.eclipse.jface.viewers.ViewerCell)
 	 */
 	public void update(ViewerCell cell) {
 		LabelPresentationInfo info = getLabelPresentationInfo(cell.getElement());

 		cell.setImage(info.getImage());
 		cell.setText(info.getText());
 		cell.setFont(info.getDefaultFont());
 		cell.setBackground(info.getDefaultBackground());
 		cell.setForeground(info.getDefaultForeground());

 		if (isOwnerDrawEnabled()) {
 			// store info in the item to avoid recomputation
 			cell.getItem().setData(KEY_TEXT_LAYOUT + cell.getColumnIndex(), info);
 		} else {
 			// make sure the info is cleared to avoid leaks
 			cell.getItem().setData(KEY_TEXT_LAYOUT + cell.getColumnIndex(), null);
 		}
 		super.update(cell); // calls 'repaint' to trigger the paint listener
 	}

 	private TextLayout getSharedTextLayout(Display display) {
 		if (cachedTextLayout == null) {
 			cachedTextLayout = new TextLayout(display);
 			cachedTextLayout.setOrientation(Window.getDefaultOrientation());
 		}
 		return cachedTextLayout;
 	}

 	private boolean useColors(Event event) {
 		return (event.detail & SWT.SELECTED) == 0
 				|| (this.style & COLORS_ON_SELECTION) != 0;
 	}

 	private boolean drawFocus(Event event) {
 		return (event.detail & SWT.FOCUSED) != 0
 				&& (this.style & NO_FOCUS) == 0;
 	}

 	private LabelPresentationInfo getInfo(Event event) {
 		return (LabelPresentationInfo) event.item.getData(KEY_TEXT_LAYOUT + event.index);
 	}

 	/**
 	 * Returns a {@link TextLayout} instance for the given
 	 * {@link LabelPresentationInfo}. The text layout instance is managed by
 	 * the label provider. Caller of the method must not dispose the text
 	 * layout.
 	 *
 	 * @param diplay
 	 *            the current display
 	 * @param labelPresentation
 	 *            the viewerLabel the label info
 	 *
 	 * @param applyColors
 	 *            if set, create colors in the result
 	 * @param element
 	 *            the model element
 	 * @param item
 	 *            the item
 	 * @param index
 	 *            the index
 	 * @return a TextLayout instance
 	 */
 	private TextLayout getTextLayoutForInfo(Display display,
 			LabelPresentationInfo labelPresentation, boolean applyColors, Item item, int index) {
 		// can use cache?
 		if (cachedLabelInfo == labelPresentation
 				&& applyColors == cachedWasWithColors) {
 			return cachedTextLayout; // use cached layout
 		}

 		TextLayout sharedLayout = getSharedTextLayout(display);
 		applyInfoToLayout(sharedLayout, labelPresentation, applyColors, item, index);

 		cachedLabelInfo = labelPresentation;
 		cachedWasWithColors = applyColors;

 		return sharedLayout;
 	}

 	/**
 	 * Fills the given text layout with the styles, text and font of the label
 	 * info.
 	 *
 	 * @param layout
 	 *            the text layout to fill
 	 * @param labelInfo
 	 *            the viewer label
 	 * @param applyColors
 	 *            if set, colors will be used
 	 * @param item
 	 *            the item
 	 * @param index
 	 *            the index
 	 */
 	private void applyInfoToLayout(TextLayout layout,
 			LabelPresentationInfo labelInfo, boolean applyColors, Item item, int index) {
 		layout.setText(""); // make sure no previous ranges are kept //$NON-NLS-1$
 		layout.setText(labelInfo.getText());
 		Font font = labelInfo.getDefaultFont();
 		if (font == null) {
 			if (item instanceof TableItem) {
 				font = ((TableItem)item).getFont(index);
 			} else if (item instanceof TreeItem) {
 				font = ((TreeItem)item).getFont(index);
 			}
 		}
 		layout.setFont(font); // set also if null to clear previous usages

 		StyleRange[] styleRanges = labelInfo.getStyleRanges();

 		for (int i = 0; i < styleRanges.length; i++) {
 			StyleRange curr = styleRanges[i];

 			// if no colors apply or font is set, create a clone and clear the
 			// colors and font
 			if (curr.font != null || !applyColors
 					&& (curr.foreground != null || curr.background != null)) {
 				curr = (StyleRange) curr.clone();
 				curr.font = null; // ignore font settings until bug 168807 is resolved
 				if (!applyColors) {
 					curr.foreground = null;
 					curr.background = null;
 				}
 			}
 			layout.setStyle(curr, curr.start, curr.start + curr.length - 1);
 		}
 	}

 	/**
 	 * Handle the erase event. The default implementation does nothing to ensure
 	 * keep native selection highlighting working.
 	 *
 	 * @param event
 	 *            the erase event
 	 * @param element
 	 *            the model object
 	 * @see SWT#EraseItem
 	 */
 	protected void erase(Event event, Object element) {
 		// use native erase

 		LabelPresentationInfo labelInfo = getInfo(event);
 		if (labelInfo != null) {
 			// info has been set by 'update': announce that we paint ourselves
 			event.detail &= ~SWT.FOREGROUND;
 		}
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#measure(org.eclipse.swt.widgets.Event,
 	 *      java.lang.Object)
 	 */
 	protected void measure(Event event, Object element) {
 		// use native measuring
 	}

 	/*
 	 * (non-Javadoc)
 	 *
 	 * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#paint(org.eclipse.swt.widgets.Event,
 	 *      java.lang.Object)
 	 */
 	protected void paint(Event event, Object element) {
 		LabelPresentationInfo labelInfo = getInfo(event);
 		if (labelInfo == null) {
 			return; // no info cached: skip this entry, use native painting
 		}

 		boolean applyColors = useColors(event);
 		GC gc = event.gc;
 		Color oldForeground = gc.getForeground(); // remember colors to
 													// restore the GC later
 		Color oldBackground = gc.getBackground();

 		if (applyColors) {
 			Color foreground = labelInfo.getDefaultForeground();
 			if (foreground != null) {
 				gc.setForeground(foreground);
 			}
 			Color background = labelInfo.getDefaultBackground();
 			if (background != null) {
 				gc.setBackground(background);
 			}
 		}

 		Image image = labelInfo.getImage();
 		if (image != null) {
 			Rectangle imageBounds = getImageBounds(event);
 			Rectangle bounds = image.getBounds();

 			// center the image in the given space
 			int x = imageBounds.x
 					+ Math.max(0, (imageBounds.width - bounds.width) / 2);
 			int y = imageBounds.y
 					+ Math.max(0, (imageBounds.height - bounds.height) / 2);
 			gc.drawImage(image, x, y);
 		}

 		TextLayout textLayout = getTextLayoutForInfo(event.display, labelInfo,
 				applyColors, (Item)event.item, event.index);

 		Rectangle layoutBounds = textLayout.getBounds();
 		Rectangle textBounds = getTextBounds(event);

 		int x = textBounds.x;
 		int y = textBounds.y
 				+ Math.max(0, (textBounds.height - layoutBounds.height) / 2);

 		textLayout.draw(gc, x, y);

 		if (drawFocus(event)) {
 			Rectangle focusBounds = getBounds(event);
 			gc.drawFocus(focusBounds.x, focusBounds.y, focusBounds.width,
 					focusBounds.height);
 		}

 		gc.setForeground(oldForeground);
 		gc.setBackground(oldBackground);
 	}

 	private Rectangle getBounds(Event event) {
 		Item item = (Item) event.item;
 		if (item instanceof TreeItem) {
 			return ((TreeItem) item).getBounds();
 		} else if (item instanceof TableItem) {
 			return ((TableItem) item).getBounds();
 		}
 		return null;
 	}

 	private Rectangle getImageBounds(Event event) {
 		Item item = (Item) event.item;
 		if (item instanceof TreeItem) {
 			return ((TreeItem) item).getImageBounds(event.index);
 		} else if (item instanceof TableItem) {
 			return ((TableItem) item).getImageBounds(event.index);
 		}
 		return null;
 	}

 	private Rectangle getTextBounds(Event event) {
 		Item item = (Item) event.item;
 		if (item instanceof TreeItem) {
 			return ((TreeItem) item).getTextBounds(event.index);
 		} else if (item instanceof TableItem) {
 			return ((TableItem) item).getTextBounds(event.index);
 		}
 		return null;
 	}

 }
	/*******************************************************************************
	* Copyright (c) 2007, 2008 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
	* Michael Krkoska - initial API and implementation (bug 188333)
	*******************************************************************************/
	package org.eclipse.jface.viewers;

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.jface.window.Window;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.StyleRange;
	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.Rectangle;
	import org.eclipse.swt.graphics.TextLayout;
	import org.eclipse.swt.widgets.Display;
	import org.eclipse.swt.widgets.Event;
	import org.eclipse.swt.widgets.Item;
	import org.eclipse.swt.widgets.TableItem;
	import org.eclipse.swt.widgets.TreeItem;

	/**
	* A {@link SimpleStyledCellLabelProvider} supports styled labels by using owner
	* draw by preserving native viewer behavior:
	* <ul>
	* <li>similar image and label positioning</li>
	* <li>native drawing of focus and selection</li>
	* </ul>
	*
	*
	* <p>
	* For providing the label's styles, create a subclass and overwrite
	* {@link SimpleStyledCellLabelProvider#getLabelPresentationInfo(Object)} to
	* return all information needed to render a element.
	* </p>
	* <p>
	* The {@link SimpleStyledCellLabelProvider} will ignore all font settings on
	* {@link StyleRange}. Different fonts would make labels wider, and the native
	* selection drawing could not be reused.
	* </p>
	*
	* <p><strong>NOTE:</strong> This API is experimental and may be deleted or
	* changed before 3.4 is released.</p>
	*
	*
	* @deprecated Will be removed before 3.4 M6. Use {@link StyledCellLabelProvider} instead.
	*
	* @since 3.4
	*/
	public abstract class SimpleStyledCellLabelProvider extends
	OwnerDrawLabelProvider {

	/**
	* Holds all information used to render a styled element.
	*/
	public static class LabelPresentationInfo {

	private final String text;
	private final Image image;
	private final StyleRange[] ranges;

	private final Font defaultFont;
	private final Color defaultForegroundColor;
	private final Color defaultBackgroundColor;

	/**
	* Creates a {@link SimpleStyledCellLabelProvider.LabelPresentationInfo}.
	*
	* @param text
	* the text of the current element
	* @param ranges
	* the styled ranges for the element
	* @param image
	* the image for the element or <code>null</code>
	* @param defaultFont
	* the default font for the element or <code>null</code>
	* @param defaultForegroundColor
	* the default foreground color for the element or
	* <code>null</code>
	* @param defaultBackgroundColor
	* the default background color for the element or
	* <code>null</code>
	*/
	public LabelPresentationInfo(String text, StyleRange[] ranges,
	Image image, Font defaultFont, Color defaultForegroundColor,
	Color defaultBackgroundColor) {
	Assert.isNotNull(text);
	Assert.isNotNull(ranges);
	this.text = text;
	this.ranges = ranges;
	this.image = image;
	this.defaultFont = defaultFont;
	this.defaultForegroundColor = defaultForegroundColor;
	this.defaultBackgroundColor = defaultBackgroundColor;
	}

	/**
	* Provides the text of the current element.
	*
	* @return returns the text.
	*/
	public String getText() {
	return this.text;
	}

	/**
	* Provides the styled ranges that can be applied to the text provided
	* by {@link #getText()}. The {@link SimpleStyledCellLabelProvider}
	* will ignore all font settings.
	*
	* @return the styled ranges for the element
	*/
	public StyleRange[] getStyleRanges() {
	return this.ranges;
	}

	/**
	* Provides the image of the current element.
	*
	* @return returns the image.
	*/
	public Image getImage() {
	return this.image;
	}

	/**
	* Provides a default background color of the current element, which is
	* used for the part of the label where no background color is specified
	* in the StyleRanges provided by {@link #getStyleRanges}.
	*
	* @return the background color for the element, or <code>null</code>
	* to use the default background color
	*/
	public Color getDefaultBackground() {
	return this.defaultBackgroundColor;
	}

	/**
	* Provides a default font of the current element.
	*
	* @return the font for the element, or <code>null</code> to use the
	* default font
	*/
	public Font getDefaultFont() {
	return this.defaultFont;
	}

	/**
	* Provides a default foreground color of the current element, which is
	* used for the part of the label where no foreground color is specified
	* in the StyleRanges provided by {@link #getStyleRanges}.
	*
	* @return the foreground color for the element, or <code>null</code>
	* to use the default foreground color
	*/
	public Color getDefaultForeground() {
	return this.defaultForegroundColor;
	}

	}

	private static final String KEY_TEXT_LAYOUT = "styled_label_key_"; //$NON-NLS-1$

	/**
	* Style constant for indicating that the styled colors are to be applied
	* even it the viewer's item is selected. Default is not to apply colors.
	*/
	public static final int COLORS_ON_SELECTION = 1 << 0;

	/**
	* Style constant for indicating to draw the focus if requested by the owner
	* draw event. Default is to draw the focus.
	*/
	public static final int NO_FOCUS = 1 << 1;

	/**
	* Private constant to indicate if owner draw is enabled for the
	* label provider's column.
	*/
	private static final int OWNER_DRAW_ENABLED = 1 << 4;

	private int style;

	private TextLayout cachedTextLayout; // reused text layout for
	// 'cachedLabelInfo'
	private LabelPresentationInfo cachedLabelInfo;
	private boolean cachedWasWithColors;

	private ColumnViewer viewer;
	private ViewerColumn column;

	/**
	* Creates a new StyledCellLabelProvider. By default, owner draw is enabled, focus is drawn and no
	* colors are painted on selected elements.
	*/
	public SimpleStyledCellLabelProvider() {
	this(0);
	}

	/**
	* Creates a new StyledCellLabelProvider. By default, owner draw is enabled.
	*
	* @param style
	* the style bits
	* @see SimpleStyledCellLabelProvider#COLORS_ON_SELECTION
	* @see SimpleStyledCellLabelProvider#NO_FOCUS
	*/
	public SimpleStyledCellLabelProvider(int style) {
	this.style = style & (COLORS_ON_SELECTION \| NO_FOCUS)
	\| OWNER_DRAW_ENABLED;
	}

	/**
	* Returns <code>true</code> is the owner draw rendering is enabled for this label provider.
	* By default owner draw rendering is enabled. If owner draw rendering is disabled, rending is
	* done by the viewer and no styled ranges (see {@link LabelPresentationInfo#getStyleRanges()})
	* are drawn.
	*
	* @return <code>true</code> is the rendering of styles is enabled.
	*/
	public boolean isOwnerDrawEnabled() {
	return (this.style & OWNER_DRAW_ENABLED) != 0;
	}

	/**
	* Specifies whether owner draw rendering is enabled for this label
	* provider. By default owner draw rendering is enabled. If owner draw
	* rendering is disabled, rendering is done by the viewer and no styled
	* ranges (see {@link LabelPresentationInfo#getStyleRanges()}) are drawn.
	* It is the caller's responsibility to also call
	* {@link StructuredViewer#refresh()} or similar methods to update the
	* underlying widget.
	*
	* @param enabled
	* specifies if owner draw rendering is enabled
	*/
	public void setOwnerDrawEnabled(boolean enabled) {
	boolean isEnabled= isOwnerDrawEnabled();
	if (isEnabled != enabled) {
	if (enabled) {
	this.style \|= OWNER_DRAW_ENABLED;
	} else {
	this.style &= ~OWNER_DRAW_ENABLED;
	}
	if (this.viewer != null) {
	setOwnerDrawEnabled(this.viewer, this.column, enabled);
	}
	}
	}

	/**
	* Returns the viewer on which this label provider is installed on or <code>null</code> if the
	* label provider is not installed.
	*
	* @return the viewer on which this label provider is installed on or <code>null</code> if the
	* label provider is not installed.
	*/
	protected final ColumnViewer getViewer() {
	return this.viewer;
	}

	/**
	* Returns the column on which this label provider is installed on or <code>null</code> if the
	* label provider is not installed.
	*
	* @return the column on which this label provider is installed on or <code>null</code> if the
	* label provider is not installed.
	*/
	protected final ViewerColumn getColumn() {
	return this.column;
	}


	/**
	* Returns a {@link LabelPresentationInfo} instance containing the text,
	* image and style information to use for displaying element.
	*
	* @param element
	* the element to create a presentation info for
	* @return the presentation info
	*/
	protected abstract LabelPresentationInfo getLabelPresentationInfo(
	Object element);


	/* (non-Javadoc)
	* @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#initialize(org.eclipse.jface.viewers.ColumnViewer, org.eclipse.jface.viewers.ViewerColumn)
	*/
	public void initialize(ColumnViewer viewer, ViewerColumn column) {
	Assert.isTrue(this.viewer == null && this.column == null, "Label provider instance already in use"); //$NON-NLS-1$

	this.viewer= viewer;
	this.column= column;
	super.initialize(viewer, column, isOwnerDrawEnabled());
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.viewers.BaseLabelProvider#dispose()
	*/
	public void dispose() {
	if (this.cachedTextLayout != null) {
	cachedTextLayout.dispose();
	cachedTextLayout = null;
	}
	cachedLabelInfo = null;

	this.viewer= null;
	this.column= null;

	super.dispose();
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#update(org.eclipse.jface.viewers.ViewerCell)
	*/
	public void update(ViewerCell cell) {
	LabelPresentationInfo info = getLabelPresentationInfo(cell.getElement());

	cell.setImage(info.getImage());
	cell.setText(info.getText());
	cell.setFont(info.getDefaultFont());
	cell.setBackground(info.getDefaultBackground());
	cell.setForeground(info.getDefaultForeground());

	if (isOwnerDrawEnabled()) {
	// store info in the item to avoid recomputation
	cell.getItem().setData(KEY_TEXT_LAYOUT + cell.getColumnIndex(), info);
	} else {
	// make sure the info is cleared to avoid leaks
	cell.getItem().setData(KEY_TEXT_LAYOUT + cell.getColumnIndex(), null);
	}
	super.update(cell); // calls 'repaint' to trigger the paint listener
	}

	private TextLayout getSharedTextLayout(Display display) {
	if (cachedTextLayout == null) {
	cachedTextLayout = new TextLayout(display);
	cachedTextLayout.setOrientation(Window.getDefaultOrientation());
	}
	return cachedTextLayout;
	}

	private boolean useColors(Event event) {
	return (event.detail & SWT.SELECTED) == 0
	\|\| (this.style & COLORS_ON_SELECTION) != 0;
	}

	private boolean drawFocus(Event event) {
	return (event.detail & SWT.FOCUSED) != 0
	&& (this.style & NO_FOCUS) == 0;
	}

	private LabelPresentationInfo getInfo(Event event) {
	return (LabelPresentationInfo) event.item.getData(KEY_TEXT_LAYOUT + event.index);
	}

	/**
	* Returns a {@link TextLayout} instance for the given
	* {@link LabelPresentationInfo}. The text layout instance is managed by
	* the label provider. Caller of the method must not dispose the text
	* layout.
	*
	* @param diplay
	* the current display
	* @param labelPresentation
	* the viewerLabel the label info
	*
	* @param applyColors
	* if set, create colors in the result
	* @param element
	* the model element
	* @param item
	* the item
	* @param index
	* the index
	* @return a TextLayout instance
	*/
	private TextLayout getTextLayoutForInfo(Display display,
	LabelPresentationInfo labelPresentation, boolean applyColors, Item item, int index) {
	// can use cache?
	if (cachedLabelInfo == labelPresentation
	&& applyColors == cachedWasWithColors) {
	return cachedTextLayout; // use cached layout
	}

	TextLayout sharedLayout = getSharedTextLayout(display);
	applyInfoToLayout(sharedLayout, labelPresentation, applyColors, item, index);

	cachedLabelInfo = labelPresentation;
	cachedWasWithColors = applyColors;

	return sharedLayout;
	}

	/**
	* Fills the given text layout with the styles, text and font of the label
	* info.
	*
	* @param layout
	* the text layout to fill
	* @param labelInfo
	* the viewer label
	* @param applyColors
	* if set, colors will be used
	* @param item
	* the item
	* @param index
	* the index
	*/
	private void applyInfoToLayout(TextLayout layout,
	LabelPresentationInfo labelInfo, boolean applyColors, Item item, int index) {
	layout.setText(""); // make sure no previous ranges are kept //$NON-NLS-1$
	layout.setText(labelInfo.getText());
	Font font = labelInfo.getDefaultFont();
	if (font == null) {
	if (item instanceof TableItem) {
	font = ((TableItem)item).getFont(index);
	} else if (item instanceof TreeItem) {
	font = ((TreeItem)item).getFont(index);
	}
	}
	layout.setFont(font); // set also if null to clear previous usages

	StyleRange[] styleRanges = labelInfo.getStyleRanges();

	for (int i = 0; i < styleRanges.length; i++) {
	StyleRange curr = styleRanges[i];

	// if no colors apply or font is set, create a clone and clear the
	// colors and font
	if (curr.font != null \|\| !applyColors
	&& (curr.foreground != null \|\| curr.background != null)) {
	curr = (StyleRange) curr.clone();
	curr.font = null; // ignore font settings until bug 168807 is resolved
	if (!applyColors) {
	curr.foreground = null;
	curr.background = null;
	}
	}
	layout.setStyle(curr, curr.start, curr.start + curr.length - 1);
	}
	}

	/**
	* Handle the erase event. The default implementation does nothing to ensure
	* keep native selection highlighting working.
	*
	* @param event
	* the erase event
	* @param element
	* the model object
	* @see SWT#EraseItem
	*/
	protected void erase(Event event, Object element) {
	// use native erase

	LabelPresentationInfo labelInfo = getInfo(event);
	if (labelInfo != null) {
	// info has been set by 'update': announce that we paint ourselves
	event.detail &= ~SWT.FOREGROUND;
	}
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#measure(org.eclipse.swt.widgets.Event,
	* java.lang.Object)
	*/
	protected void measure(Event event, Object element) {
	// use native measuring
	}

	/*
	* (non-Javadoc)
	*
	* @see org.eclipse.jface.viewers.OwnerDrawLabelProvider#paint(org.eclipse.swt.widgets.Event,
	* java.lang.Object)
	*/
	protected void paint(Event event, Object element) {
	LabelPresentationInfo labelInfo = getInfo(event);
	if (labelInfo == null) {
	return; // no info cached: skip this entry, use native painting
	}

	boolean applyColors = useColors(event);
	GC gc = event.gc;
	Color oldForeground = gc.getForeground(); // remember colors to
	// restore the GC later
	Color oldBackground = gc.getBackground();

	if (applyColors) {
	Color foreground = labelInfo.getDefaultForeground();
	if (foreground != null) {
	gc.setForeground(foreground);
	}
	Color background = labelInfo.getDefaultBackground();
	if (background != null) {
	gc.setBackground(background);
	}
	}

	Image image = labelInfo.getImage();
	if (image != null) {
	Rectangle imageBounds = getImageBounds(event);
	Rectangle bounds = image.getBounds();

	// center the image in the given space
	int x = imageBounds.x
	+ Math.max(0, (imageBounds.width - bounds.width) / 2);
	int y = imageBounds.y
	+ Math.max(0, (imageBounds.height - bounds.height) / 2);
	gc.drawImage(image, x, y);
	}

	TextLayout textLayout = getTextLayoutForInfo(event.display, labelInfo,
	applyColors, (Item)event.item, event.index);

	Rectangle layoutBounds = textLayout.getBounds();
	Rectangle textBounds = getTextBounds(event);

	int x = textBounds.x;
	int y = textBounds.y
	+ Math.max(0, (textBounds.height - layoutBounds.height) / 2);

	textLayout.draw(gc, x, y);

	if (drawFocus(event)) {
	Rectangle focusBounds = getBounds(event);
	gc.drawFocus(focusBounds.x, focusBounds.y, focusBounds.width,
	focusBounds.height);
	}

	gc.setForeground(oldForeground);
	gc.setBackground(oldBackground);
	}

	private Rectangle getBounds(Event event) {
	Item item = (Item) event.item;
	if (item instanceof TreeItem) {
	return ((TreeItem) item).getBounds();
	} else if (item instanceof TableItem) {
	return ((TableItem) item).getBounds();
	}
	return null;
	}

	private Rectangle getImageBounds(Event event) {
	Item item = (Item) event.item;
	if (item instanceof TreeItem) {
	return ((TreeItem) item).getImageBounds(event.index);
	} else if (item instanceof TableItem) {
	return ((TableItem) item).getImageBounds(event.index);
	}
	return null;
	}

	private Rectangle getTextBounds(Event event) {
	Item item = (Item) event.item;
	if (item instanceof TreeItem) {
	return ((TreeItem) item).getTextBounds(event.index);
	} else if (item instanceof TableItem) {
	return ((TableItem) item).getTextBounds(event.index);
	}
	return null;
	}

	}