最近时而忙一阵,也在看些书,几篇文章都没写完.一晃8月最后一天,昝发篇简洁的,努力写些文章.

 

*概述

---这篇文章说明了如下问题:

如何把gef的内容导出为图片,本质是如何把figure绘制到需要的地方,而不是默认的FigureCanvas.

---实现代码

实现分成了2部分

1)导出的action,即代码主体

2)提炼的工具方法

 

*工具方法ImageUtil

ImageUtil源码/******************************************************************************* * Copyright(C) 2011 Arzan Corporation. All rights reserved. * * Contributors: *     Arzan Corporation - initial API and implementation *******************************************************************************/package galaxy.gef.extension.utils;import org.eclipse.draw2d.Graphics;import org.eclipse.draw2d.IFigure;import org.eclipse.draw2d.SWTGraphics;import org.eclipse.swt.graphics.GC;import org.eclipse.swt.graphics.Image;import org.eclipse.swt.graphics.ImageData;import org.eclipse.swt.graphics.ImageLoader;import org.eclipse.swt.widgets.Display;/** * @author dzh * @date 2011-8-31 上午10:11:31 */public class ImageUtil {		/**	 * 返回figure的图片	 * @param figure	 * @param width	 * @param height	 * @return	 */	public static final Image getFigureImage(IFigure figure, int width, int height) {		Image rootImage = new Image(Display.getDefault(), width, height);		GC gc = new GC(rootImage);		Graphics graphics = new SWTGraphics(gc);		figure.paint(graphics);  //通过过给figure传入自定义GC,这个GC将figure绘制到rootImage		gc.dispose();		return rootImage;	}		/**	 * 保存ImageData到指定的文件中	 * @param image	 * @param savePath	 * @param format IMAGE_PNG,IMAGE_BMP and so on.	 */	public static final void saveImage(Image image,String savePath,int format){		ImageLoader loader = new ImageLoader();		ImageData data = image.getImageData();		loader.data = new ImageData[] {data};				loader.save(savePath, format); 	}	}

注意IMAGE_GIF由于色深8位,高位到低位的保存会失败.如何保存为GIF格式,可以研究下.

 

*导出action

Action源码/******************************************************************************* * Copyright(C) 2011 Arzan Corporation. All rights reserved. * * Contributors: *     Arzan Corporation - initial API and implementation *******************************************************************************/package galaxy.gef.extension.action;import galaxy.gef.extension.utils.ImageUtil;import org.eclipse.draw2d.IFigure;import org.eclipse.gef.GraphicalViewer;import org.eclipse.gef.LayerConstants;import org.eclipse.gef.editparts.LayerManager;import org.eclipse.gef.ui.actions.SelectionAction;import org.eclipse.gef.ui.parts.GraphicalEditor;import org.eclipse.jface.dialogs.MessageDialog;import org.eclipse.swt.SWT;import org.eclipse.swt.graphics.Image;import org.eclipse.swt.widgets.FileDialog;import org.eclipse.ui.IWorkbenchPart;/** * @author dzh * @date 2011-8-31 上午10:06:44 */public class ExportImageAction extends SelectionAction {	public static final String ID = "galaxy.mars.ide.flow.node.action.ExportImageAction";	private static final String[] EXTENSIONS = new String[] { "*.bmp", "*.jpg",			"*.png" };	private static final int[] TYPES = new int[] { SWT.IMAGE_BMP,			SWT.IMAGE_JPEG, SWT.IMAGE_PNG };	public ExportImageAction(IWorkbenchPart part) {		super(part);	}	/*	 * (non-Javadoc)	 * 	 * @see org.eclipse.gef.ui.actions.WorkbenchPartAction#calculateEnabled()	 */	@Override	protected boolean calculateEnabled() {		if (getWorkbenchPart() instanceof GraphicalEditor) {			return true;		}		return false;	}	protected void init() {		super.init();		setText("导出为图片");		setId(ID);	}	public void run() {		FileDialog dialog = new FileDialog(getWorkbenchPart().getSite()				.getShell(), SWT.SAVE);		dialog.setFilterExtensions(EXTENSIONS);		dialog.setText(getText());		dialog.setOverwrite(true);		String savePath = null;		try {			savePath = dialog.open(); //获取保存路径		} catch (Exception e) {			MessageDialog.openError(getWorkbenchPart().getSite().getShell(),					getText(), "图片保存失败!");			return;		}		if (savePath != null) {			int type = dialog.getFilterIndex();			GraphicalViewer viewer = (GraphicalViewer) getWorkbenchPart()					.getAdapter(GraphicalViewer.class);			LayerManager lm = (LayerManager) viewer.getEditPartRegistry().get(					LayerManager.ID); //获取继承LayerManager的RootEditPart,当然也有不继承LayerManager的,故需要判断一下			if (lm == null)				return;			IFigure f = lm.getLayer(LayerConstants.PRINTABLE_LAYERS);　//获取需要导出为图片的figure,这里获取RootEditPart的内容层figure			if (f == null)				return;			Image rootImage = ImageUtil.getFigureImage(f, f.getBounds().width,					f.getBounds().height);			ImageUtil.saveImage(rootImage, savePath, TYPES[type]); //调用ImageUtil			rootImage.dispose(); //释放资源		}	}}

说明,

1)很多RootEditPart,如FreeformGraphicalRootEditPart,在注册时使用LayerManager.ID为key.

2)GEF中Figure分层的原理,简单说,就是把不同的图形如连线,移动时的阴影图形等等放在不同的层上,这些层也是Figure,注册在RootEditPart中.

所以看看RootEditPart的几个实现类源码,就会明白了.

 

*总结

---把GraphicalViewer编辑器导出到图片的原理,就是定义一个Image的GC,并传给Figure的paint()方法.

---上面例子还需要优化,如导出图片时把图片内容绘制在合适的大小,就是说可能编辑器的边界会大于图形的边界

---org.eclipse.gef.ui.actions.PrintAction,对于绘制可以参考下它的实现.