org.eclipse.jface.text/projection/org/eclipse/jface/text/source/projection/ProjectionSupport.java - platform/eclipse.platform.text - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2015 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
  *******************************************************************************/
 package org.eclipse.jface.text.source.projection;

 import java.util.ArrayList;
 import java.util.List;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.custom.StyledTextContent;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.graphics.FontMetrics;
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.RGB;
 import org.eclipse.swt.widgets.Display;

 import org.eclipse.jface.text.IInformationControlCreator;
 import org.eclipse.jface.text.source.Annotation;
 import org.eclipse.jface.text.source.AnnotationPainter;
 import org.eclipse.jface.text.source.IAnnotationAccess;
 import org.eclipse.jface.text.source.IAnnotationHover;
 import org.eclipse.jface.text.source.IAnnotationModel;
 import org.eclipse.jface.text.source.ISharedTextColors;
 import org.eclipse.jface.text.source.ISourceViewer;

 /**
  * Supports the configuration of projection capabilities a {@link org.eclipse.jface.text.source.projection.ProjectionViewer}.
  * <p>
  * This class is not intended to be subclassed. Clients are supposed to configure and use it as is.</p>
  *
  * @since 3.0
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class ProjectionSupport {

 	/**
 	 * Key of the projection annotation model inside the visual annotation
 	 * model. Also internally used as key for the projection drawing strategy.
 	 */
 	public final static Object PROJECTION= new Object();

 	private static class ProjectionAnnotationsPainter extends AnnotationPainter {

 		/**
 		 * Creates a new painter indicating the location of collapsed regions.
 		 *
 		 * @param sourceViewer the source viewer for the painter
 		 * @param access the annotation access
 		 */
 		public ProjectionAnnotationsPainter(ISourceViewer sourceViewer, IAnnotationAccess access) {
 			super(sourceViewer, access);
 		}

 		@Override
 		protected IAnnotationModel findAnnotationModel(ISourceViewer sourceViewer) {
 			if (sourceViewer instanceof ProjectionViewer) {
 				ProjectionViewer projectionViewer= (ProjectionViewer) sourceViewer;
 				return projectionViewer.getProjectionAnnotationModel();
 			}
 			return null;
 		}

 		@Override
 		protected boolean skip(Annotation annotation) {
 			if (annotation instanceof ProjectionAnnotation)
 				return !((ProjectionAnnotation) annotation).isCollapsed();

 			return super.skip(annotation);
 		}
 	}

 	private static class ProjectionDrawingStrategy implements AnnotationPainter.IDrawingStrategy {
 		@Override
 		public void draw(Annotation annotation, GC gc, StyledText textWidget, int offset, int length, Color color) {
 			if (annotation instanceof ProjectionAnnotation) {
 				ProjectionAnnotation projectionAnnotation= (ProjectionAnnotation) annotation;
 				if (projectionAnnotation.isCollapsed()) {

 					if (gc != null) {

 						StyledTextContent content= textWidget.getContent();
 						int line= content.getLineAtOffset(offset);
 						int lineStart= content.getOffsetAtLine(line);
 						String text= content.getLine(line);
 						int lineLength= text == null ? 0 : text.length();
 						int lineEnd= lineStart + lineLength;
 						Point p= textWidget.getLocationAtOffset(lineEnd);

 						Color c= gc.getForeground();
 						gc.setForeground(color);

 						FontMetrics metrics= gc.getFontMetrics();

 						// baseline: where the dots are drawn
 						int baseline= textWidget.getBaseline(offset);
 						// descent: number of pixels that the box extends over baseline
 						int descent= Math.min(2, textWidget.getLineHeight(offset) - baseline);
 						// ascent: so much does the box stand up from baseline
 						int ascent= metrics.getAscent();
 						// leading: free space from line top to box upper line
 						int leading= baseline - ascent;
 						// height: height of the box
 						int height= ascent + descent;

 						int width= metrics.getAverageCharWidth();
 						gc.drawRectangle(p.x, p.y + leading, width, height);
 						int third= width/3;
 						int dotsVertical= p.y + baseline - 1;
 						gc.drawPoint(p.x + third, dotsVertical);
 						gc.drawPoint(p.x + width - third, dotsVertical);

 						gc.setForeground(c);

 					} else {
 						textWidget.redrawRange(offset, length, true);
 					}
 				}
 			}
 		}
 	}

 	private class ProjectionListener implements IProjectionListener {

 		@Override
 		public void projectionEnabled() {
 			doEnableProjection();
 		}

 		@Override
 		public void projectionDisabled() {
 			doDisableProjection();
 		}
 	}

 	private ProjectionViewer fViewer;
 	private IAnnotationAccess fAnnotationAccess;
 	private ISharedTextColors fSharedTextColors;
 	private List<String> fSummarizableTypes;
 	private IInformationControlCreator fInformationControlCreator;
 	private IInformationControlCreator fInformationPresenterControlCreator;
 	private ProjectionListener fProjectionListener;
 	private ProjectionAnnotationsPainter fPainter;
 	private ProjectionRulerColumn fColumn;
 	/**
 	 * @since 3.1
 	 */
 	private AnnotationPainter.IDrawingStrategy fDrawingStrategy;

 	/**
 	 * Creates new projection support for the given projection viewer. Initially,
 	 * no annotation types are summarized. A default hover control creator and a
 	 * default drawing strategy are used.
 	 *
 	 * @param viewer the projection viewer
 	 * @param annotationAccess the annotation access
 	 * @param sharedTextColors the shared text colors to use
 	 */
 	public ProjectionSupport(ProjectionViewer viewer, IAnnotationAccess annotationAccess, ISharedTextColors sharedTextColors) {
 		fViewer= viewer;
 		fAnnotationAccess= annotationAccess;
 		fSharedTextColors= sharedTextColors;
 	}

 	/**
 	 * Marks the given annotation type to be considered when creating summaries for
 	 * collapsed regions of the projection viewer.
 	 * <p>
 	 * A summary is an annotation that gets created out of all annotations with a
 	 * type that has been registered through this method and that are inside the
 	 * folded region.
 	 * </p>
 	 *
 	 * @param annotationType the annotation type to consider
 	 */
 	public void addSummarizableAnnotationType(String annotationType) {
 		if (fSummarizableTypes == null) {
 			fSummarizableTypes= new ArrayList<>();
 			fSummarizableTypes.add(annotationType);
 		} else if (!fSummarizableTypes.contains(annotationType))
 			fSummarizableTypes.add(annotationType);
 	}

 	/**
 	 * Marks the given annotation type to be ignored when creating summaries for
 	 * collapsed regions of the projection viewer. This method has only an effect
 	 * when <code>addSummarizableAnnotationType</code> has been called before for
 	 * the give annotation type.
 	 * <p>
 	 * A summary is an annotation that gets created out of all annotations with a
 	 * type that has been registered through this method and that are inside the
 	 * folded region.
 	 * </p>
 	 *
 	 * @param annotationType the annotation type to remove
 	 */
 	public void removeSummarizableAnnotationType(String annotationType) {
 		if (fSummarizableTypes != null) {
 			fSummarizableTypes.remove(annotationType);
 			if (fSummarizableTypes.size() == 0)
 				fSummarizableTypes= null;
 		}
 	}

 	/**
 	 * Sets the hover control creator that is used for the annotation hovers
 	 * that are shown in the projection viewer's projection ruler column.
 	 *
 	 * @param creator the hover control creator
 	 */
 	public void setHoverControlCreator(IInformationControlCreator creator) {
 		fInformationControlCreator= creator;
 	}

 	/**
 	 * Sets the information presenter control creator that is used for the annotation
 	 * hovers that are shown in the projection viewer's projection ruler column.
 	 *
 	 * @param creator the information presenter control creator
 	 * @since 3.3
 	 */
 	public void setInformationPresenterControlCreator(IInformationControlCreator creator) {
 		fInformationPresenterControlCreator= creator;
 	}

 	/**
 	 * Sets the drawing strategy that the projection support's annotation
 	 * painter uses to draw the indication of collapsed regions onto the
 	 * projection viewer's text widget. When <code>null</code> is passed in,
 	 * the drawing strategy is reset to the default. In order to avoid any
 	 * representation use {@link org.eclipse.jface.text.source.AnnotationPainter.NullStrategy}.
 	 *
 	 * @param strategy the drawing strategy or <code>null</code> to reset the
 	 *            strategy to the default
 	 * @since 3.1
 	 */
 	public void setAnnotationPainterDrawingStrategy(AnnotationPainter.IDrawingStrategy strategy) {
 		fDrawingStrategy= strategy;
 	}

 	/**
 	 * Returns the drawing strategy to be used by the support's annotation painter.
 	 *
 	 * @return the drawing strategy to be used by the support's annotation painter
 	 * @since 3.1
 	 */
 	private AnnotationPainter.IDrawingStrategy getDrawingStrategy() {
 		if (fDrawingStrategy == null)
 			fDrawingStrategy= new ProjectionDrawingStrategy();
 		return fDrawingStrategy;
 	}

 	/**
 	 * Installs this projection support on its viewer.
 	 */
 	public void install() {
 		fViewer.setProjectionSummary(createProjectionSummary());

 		fProjectionListener= new ProjectionListener();
 		fViewer.addProjectionListener(fProjectionListener);
 	}

 	/**
 	 * Disposes this projection support.
 	 */
 	public void dispose() {
 		if (fProjectionListener != null) {
 			fViewer.removeProjectionListener(fProjectionListener);
 			fProjectionListener= null;
 		}
 	}

 	/**
 	 * Enables projection mode. If not yet done, installs the projection ruler
 	 * column in the viewer's vertical ruler and installs a painter that
 	 * indicate the locations of collapsed regions.
 	 *
 	 */
 	protected void doEnableProjection() {

 		if (fPainter == null) {
 			fPainter= new ProjectionAnnotationsPainter(fViewer, fAnnotationAccess);
 			fPainter.addDrawingStrategy(PROJECTION, getDrawingStrategy());
 			fPainter.addAnnotationType(ProjectionAnnotation.TYPE, PROJECTION);
 			fPainter.setAnnotationTypeColor(ProjectionAnnotation.TYPE, fSharedTextColors.getColor(getColor()));
 			fViewer.addPainter(fPainter);
 		}

 		if (fColumn == null) {
 			fColumn= new ProjectionRulerColumn(9, fAnnotationAccess);
 			fColumn.addAnnotationType(ProjectionAnnotation.TYPE);
 			fColumn.setHover(createProjectionAnnotationHover());
 			fViewer.addVerticalRulerColumn(fColumn);
 		}

 		fColumn.setModel(fViewer.getVisualAnnotationModel());
 	}

 	/**
 	 * Removes the projection ruler column and the painter from the projection
 	 * viewer.
 	 */
 	protected void doDisableProjection() {
 		if (fPainter != null) {
 			fViewer.removePainter(fPainter);
 			fPainter.dispose();
 			fPainter= null;
 		}

 		if (fColumn != null) {
 			fViewer.removeVerticalRulerColumn(fColumn);
 			fColumn= null;
 		}
 	}

 	private ProjectionSummary createProjectionSummary() {
 		ProjectionSummary summary= new ProjectionSummary(fViewer, fAnnotationAccess);
 		if (fSummarizableTypes != null) {
 			int size= fSummarizableTypes.size();
 			for (int i= 0; i < size; i++)
 				summary.addAnnotationType(fSummarizableTypes.get(i));
 		}
 		return summary;
 	}

 	private IAnnotationHover createProjectionAnnotationHover() {
 		ProjectionAnnotationHover hover= new ProjectionAnnotationHover();
 		hover.setHoverControlCreator(fInformationControlCreator);
 		hover.setInformationPresenterControlCreator(fInformationPresenterControlCreator);
 		return hover;
 	}

 	/**
 	 * Implements the contract of {@link org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class)}
 	 * by forwarding the adapter requests to the given viewer.
 	 *
 	 * @param viewer the viewer
 	 * @param required the required class of the adapter
 	 * @return the adapter or <code>null</code>
 	 *
 	 */
 	@SuppressWarnings("unchecked")
 	public <T> T getAdapter(ISourceViewer viewer, Class<T> required) {
 		if (ProjectionAnnotationModel.class.equals(required)) {
 			if (viewer instanceof ProjectionViewer) {
 				ProjectionViewer projectionViewer= (ProjectionViewer) viewer;
 				return (T) projectionViewer.getProjectionAnnotationModel();
 			}
 		}
 		return null;
 	}

 	private RGB getColor() {
 		// TODO read out preference settings
 		Color c= Display.getDefault().getSystemColor(SWT.COLOR_DARK_GRAY);
 		return c.getRGB();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2015 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
	*******************************************************************************/
	package org.eclipse.jface.text.source.projection;

	import java.util.ArrayList;
	import java.util.List;

	import org.eclipse.swt.SWT;
	import org.eclipse.swt.custom.StyledText;
	import org.eclipse.swt.custom.StyledTextContent;
	import org.eclipse.swt.graphics.Color;
	import org.eclipse.swt.graphics.FontMetrics;
	import org.eclipse.swt.graphics.GC;
	import org.eclipse.swt.graphics.Point;
	import org.eclipse.swt.graphics.RGB;
	import org.eclipse.swt.widgets.Display;

	import org.eclipse.jface.text.IInformationControlCreator;
	import org.eclipse.jface.text.source.Annotation;
	import org.eclipse.jface.text.source.AnnotationPainter;
	import org.eclipse.jface.text.source.IAnnotationAccess;
	import org.eclipse.jface.text.source.IAnnotationHover;
	import org.eclipse.jface.text.source.IAnnotationModel;
	import org.eclipse.jface.text.source.ISharedTextColors;
	import org.eclipse.jface.text.source.ISourceViewer;

	/**
	* Supports the configuration of projection capabilities a {@link org.eclipse.jface.text.source.projection.ProjectionViewer}.
	* <p>
	* This class is not intended to be subclassed. Clients are supposed to configure and use it as is.</p>
	*
	* @since 3.0
	* @noextend This class is not intended to be subclassed by clients.
	*/
	public class ProjectionSupport {

	/**
	* Key of the projection annotation model inside the visual annotation
	* model. Also internally used as key for the projection drawing strategy.
	*/
	public final static Object PROJECTION= new Object();

	private static class ProjectionAnnotationsPainter extends AnnotationPainter {

	/**
	* Creates a new painter indicating the location of collapsed regions.
	*
	* @param sourceViewer the source viewer for the painter
	* @param access the annotation access
	*/
	public ProjectionAnnotationsPainter(ISourceViewer sourceViewer, IAnnotationAccess access) {
	super(sourceViewer, access);
	}

	@Override
	protected IAnnotationModel findAnnotationModel(ISourceViewer sourceViewer) {
	if (sourceViewer instanceof ProjectionViewer) {
	ProjectionViewer projectionViewer= (ProjectionViewer) sourceViewer;
	return projectionViewer.getProjectionAnnotationModel();
	}
	return null;
	}

	@Override
	protected boolean skip(Annotation annotation) {
	if (annotation instanceof ProjectionAnnotation)
	return !((ProjectionAnnotation) annotation).isCollapsed();

	return super.skip(annotation);
	}
	}

	private static class ProjectionDrawingStrategy implements AnnotationPainter.IDrawingStrategy {
	@Override
	public void draw(Annotation annotation, GC gc, StyledText textWidget, int offset, int length, Color color) {
	if (annotation instanceof ProjectionAnnotation) {
	ProjectionAnnotation projectionAnnotation= (ProjectionAnnotation) annotation;
	if (projectionAnnotation.isCollapsed()) {

	if (gc != null) {

	StyledTextContent content= textWidget.getContent();
	int line= content.getLineAtOffset(offset);
	int lineStart= content.getOffsetAtLine(line);
	String text= content.getLine(line);
	int lineLength= text == null ? 0 : text.length();
	int lineEnd= lineStart + lineLength;
	Point p= textWidget.getLocationAtOffset(lineEnd);

	Color c= gc.getForeground();
	gc.setForeground(color);

	FontMetrics metrics= gc.getFontMetrics();

	// baseline: where the dots are drawn
	int baseline= textWidget.getBaseline(offset);
	// descent: number of pixels that the box extends over baseline
	int descent= Math.min(2, textWidget.getLineHeight(offset) - baseline);
	// ascent: so much does the box stand up from baseline
	int ascent= metrics.getAscent();
	// leading: free space from line top to box upper line
	int leading= baseline - ascent;
	// height: height of the box
	int height= ascent + descent;

	int width= metrics.getAverageCharWidth();
	gc.drawRectangle(p.x, p.y + leading, width, height);
	int third= width/3;
	int dotsVertical= p.y + baseline - 1;
	gc.drawPoint(p.x + third, dotsVertical);
	gc.drawPoint(p.x + width - third, dotsVertical);

	gc.setForeground(c);

	} else {
	textWidget.redrawRange(offset, length, true);
	}
	}
	}
	}
	}

	private class ProjectionListener implements IProjectionListener {

	@Override
	public void projectionEnabled() {
	doEnableProjection();
	}

	@Override
	public void projectionDisabled() {
	doDisableProjection();
	}
	}

	private ProjectionViewer fViewer;
	private IAnnotationAccess fAnnotationAccess;
	private ISharedTextColors fSharedTextColors;
	private List<String> fSummarizableTypes;
	private IInformationControlCreator fInformationControlCreator;
	private IInformationControlCreator fInformationPresenterControlCreator;
	private ProjectionListener fProjectionListener;
	private ProjectionAnnotationsPainter fPainter;
	private ProjectionRulerColumn fColumn;
	/**
	* @since 3.1
	*/
	private AnnotationPainter.IDrawingStrategy fDrawingStrategy;

	/**
	* Creates new projection support for the given projection viewer. Initially,
	* no annotation types are summarized. A default hover control creator and a
	* default drawing strategy are used.
	*
	* @param viewer the projection viewer
	* @param annotationAccess the annotation access
	* @param sharedTextColors the shared text colors to use
	*/
	public ProjectionSupport(ProjectionViewer viewer, IAnnotationAccess annotationAccess, ISharedTextColors sharedTextColors) {
	fViewer= viewer;
	fAnnotationAccess= annotationAccess;
	fSharedTextColors= sharedTextColors;
	}

	/**
	* Marks the given annotation type to be considered when creating summaries for
	* collapsed regions of the projection viewer.
	* <p>
	* A summary is an annotation that gets created out of all annotations with a
	* type that has been registered through this method and that are inside the
	* folded region.
	* </p>
	*
	* @param annotationType the annotation type to consider
	*/
	public void addSummarizableAnnotationType(String annotationType) {
	if (fSummarizableTypes == null) {
	fSummarizableTypes= new ArrayList<>();
	fSummarizableTypes.add(annotationType);
	} else if (!fSummarizableTypes.contains(annotationType))
	fSummarizableTypes.add(annotationType);
	}

	/**
	* Marks the given annotation type to be ignored when creating summaries for
	* collapsed regions of the projection viewer. This method has only an effect
	* when <code>addSummarizableAnnotationType</code> has been called before for
	* the give annotation type.
	* <p>
	* A summary is an annotation that gets created out of all annotations with a
	* type that has been registered through this method and that are inside the
	* folded region.
	* </p>
	*
	* @param annotationType the annotation type to remove
	*/
	public void removeSummarizableAnnotationType(String annotationType) {
	if (fSummarizableTypes != null) {
	fSummarizableTypes.remove(annotationType);
	if (fSummarizableTypes.size() == 0)
	fSummarizableTypes= null;
	}
	}

	/**
	* Sets the hover control creator that is used for the annotation hovers
	* that are shown in the projection viewer's projection ruler column.
	*
	* @param creator the hover control creator
	*/
	public void setHoverControlCreator(IInformationControlCreator creator) {
	fInformationControlCreator= creator;
	}

	/**
	* Sets the information presenter control creator that is used for the annotation
	* hovers that are shown in the projection viewer's projection ruler column.
	*
	* @param creator the information presenter control creator
	* @since 3.3
	*/
	public void setInformationPresenterControlCreator(IInformationControlCreator creator) {
	fInformationPresenterControlCreator= creator;
	}

	/**
	* Sets the drawing strategy that the projection support's annotation
	* painter uses to draw the indication of collapsed regions onto the
	* projection viewer's text widget. When <code>null</code> is passed in,
	* the drawing strategy is reset to the default. In order to avoid any
	* representation use {@link org.eclipse.jface.text.source.AnnotationPainter.NullStrategy}.
	*
	* @param strategy the drawing strategy or <code>null</code> to reset the
	* strategy to the default
	* @since 3.1
	*/
	public void setAnnotationPainterDrawingStrategy(AnnotationPainter.IDrawingStrategy strategy) {
	fDrawingStrategy= strategy;
	}

	/**
	* Returns the drawing strategy to be used by the support's annotation painter.
	*
	* @return the drawing strategy to be used by the support's annotation painter
	* @since 3.1
	*/
	private AnnotationPainter.IDrawingStrategy getDrawingStrategy() {
	if (fDrawingStrategy == null)
	fDrawingStrategy= new ProjectionDrawingStrategy();
	return fDrawingStrategy;
	}

	/**
	* Installs this projection support on its viewer.
	*/
	public void install() {
	fViewer.setProjectionSummary(createProjectionSummary());

	fProjectionListener= new ProjectionListener();
	fViewer.addProjectionListener(fProjectionListener);
	}

	/**
	* Disposes this projection support.
	*/
	public void dispose() {
	if (fProjectionListener != null) {
	fViewer.removeProjectionListener(fProjectionListener);
	fProjectionListener= null;
	}
	}

	/**
	* Enables projection mode. If not yet done, installs the projection ruler
	* column in the viewer's vertical ruler and installs a painter that
	* indicate the locations of collapsed regions.
	*
	*/
	protected void doEnableProjection() {

	if (fPainter == null) {
	fPainter= new ProjectionAnnotationsPainter(fViewer, fAnnotationAccess);
	fPainter.addDrawingStrategy(PROJECTION, getDrawingStrategy());
	fPainter.addAnnotationType(ProjectionAnnotation.TYPE, PROJECTION);
	fPainter.setAnnotationTypeColor(ProjectionAnnotation.TYPE, fSharedTextColors.getColor(getColor()));
	fViewer.addPainter(fPainter);
	}

	if (fColumn == null) {
	fColumn= new ProjectionRulerColumn(9, fAnnotationAccess);
	fColumn.addAnnotationType(ProjectionAnnotation.TYPE);
	fColumn.setHover(createProjectionAnnotationHover());
	fViewer.addVerticalRulerColumn(fColumn);
	}

	fColumn.setModel(fViewer.getVisualAnnotationModel());
	}

	/**
	* Removes the projection ruler column and the painter from the projection
	* viewer.
	*/
	protected void doDisableProjection() {
	if (fPainter != null) {
	fViewer.removePainter(fPainter);
	fPainter.dispose();
	fPainter= null;
	}

	if (fColumn != null) {
	fViewer.removeVerticalRulerColumn(fColumn);
	fColumn= null;
	}
	}

	private ProjectionSummary createProjectionSummary() {
	ProjectionSummary summary= new ProjectionSummary(fViewer, fAnnotationAccess);
	if (fSummarizableTypes != null) {
	int size= fSummarizableTypes.size();
	for (int i= 0; i < size; i++)
	summary.addAnnotationType(fSummarizableTypes.get(i));
	}
	return summary;
	}

	private IAnnotationHover createProjectionAnnotationHover() {
	ProjectionAnnotationHover hover= new ProjectionAnnotationHover();
	hover.setHoverControlCreator(fInformationControlCreator);
	hover.setInformationPresenterControlCreator(fInformationPresenterControlCreator);
	return hover;
	}

	/**
	* Implements the contract of {@link org.eclipse.core.runtime.IAdaptable#getAdapter(java.lang.Class)}
	* by forwarding the adapter requests to the given viewer.
	*
	* @param viewer the viewer
	* @param required the required class of the adapter
	* @return the adapter or <code>null</code>
	*
	*/
	@SuppressWarnings("unchecked")
	public <T> T getAdapter(ISourceViewer viewer, Class<T> required) {
	if (ProjectionAnnotationModel.class.equals(required)) {
	if (viewer instanceof ProjectionViewer) {
	ProjectionViewer projectionViewer= (ProjectionViewer) viewer;
	return (T) projectionViewer.getProjectionAnnotationModel();
	}
	}
	return null;
	}

	private RGB getColor() {
	// TODO read out preference settings
	Color c= Display.getDefault().getSystemColor(SWT.COLOR_DARK_GRAY);
	return c.getRGB();
	}
	}