gef中打印功能的原理和实现
在gef中关于打印的功能，采用PrintGraphicalViewerOperation实现打印Ifile的功能。如果非特性的打印动作，可以采用gef中相关的PrintActioni类实现打印的工作。
相关的PrintAction类源代码在org.eclipse.gef.ui.actions.PrintAction;
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在源代码：public class PrintFigureOperation extends PrintOperation ；
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实现打印实质是一种的绘制页面的过程。代码如下：其他忽略；
/**
?* Prints the pages based on the current print mode.
?* @see org.eclipse.draw2d.PrintOperation#printPages()
?*/
protected void printPages() {
?Graphics graphics = getFreshPrinterGraphics();
?IFigure figure = getPrintSource();
?setupPrinterGraphicsFor(graphics, figure);
?Rectangle bounds = figure.getBounds();
?int x = bounds.x, y = bounds.y;
?Rectangle clipRect = new Rectangle();
?while (y < bounds.y + bounds.height) {
??while (x < bounds.x + bounds.width) {
???graphics.pushState();
???getPrinter().startPage();
???graphics.translate(-x, -y);
???graphics.getClip(clipRect);
???clipRect.setLocation(x, y);
???graphics.clipRect(clipRect);
???figure.paint(graphics);
???getPrinter().endPage();
???graphics.popState();
???x += clipRect.width;
??}
??x = bounds.x;
??y += clipRect.height;
?}
}
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在打印时必须注意的重点代码如下：
??? public void run(IAction action) {
?????? int style = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell().getStyle();
?????? Shell shell = new Shell((style & SWT.MIRRORED) != 0 ? SWT.RIGHT_TO_LEFT : SWT.NONE);
?????? //构建当前的视图编辑器对象
?????? GraphicalViewer viewer = new ScrollingGraphicalViewer();
?????? viewer.createControl(shell);
?????? viewer.setEditDomain(new DefaultEditDomain(null));
?????? viewer.setRootEditPart(new ScalableFreeformRootEditPart());
?????? viewer.setEditPartFactory(new GraphicalPartFactory());
?????? //设置编辑的内容
?????? viewer.setContents(getContents());
?????? viewer.flush();
?????? //设置打印的模式
?????? int printMode =PrintFigureOperation.FIT_PAGE;
?????? //调用自定义的代码对话框
?????? if (printMode == -1)
?????????? return;
?????? //开始执行打印操作
?????? PrintDialog dialog = new PrintDialog(shell, SWT.NULL);
?????? PrinterData data = dialog.open();
?????? if (data != null) {
?????????? //gef中打印的操作
????????? PrintGraphicalViewerOperation op =new PrintGraphicalViewerOperation(new Printer(data), viewer);
?????????? //设置答应的模式
?????????? op.setPrintMode(printMode);
?????????? //运行打印的文件
?????????? op.run(selectedFile.getName());
?????? }
??? }
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