GEF中用鼠标移动画布

第一步 增加Palette项：

		moveTool = new PanningSelectionTool() {
			private Point viewLocation;

			protected Cursor getDefaultCursor() {
				return new Cursor(PlatformUI.createDisplay(), Activator
						.getImage("icons/pan.gif").getImageData(), 0, 0);
			}

			public boolean handleButtonDown(int which) {
				if (which == 1
						&& getCurrentViewer().getControl() instanceof FigureCanvas) {
					viewLocation = ((FigureCanvas) getCurrentViewer()
							.getControl()).getViewport().getViewLocation();
					return true;
				}
				return super.handleButtonDown(which);
			}

			protected boolean handleDrag() {
				if (getCurrentViewer().getControl() instanceof FigureCanvas) {
					FigureCanvas canvas = (FigureCanvas) getCurrentViewer()
							.getControl();
					canvas.scrollTo(viewLocation.x - getDragMoveDelta().width,
							viewLocation.y - getDragMoveDelta().height);
					return true;
				} else {
					return super.handleDragInProgress();
				}
			}
		};
		ToolEntry moveToolEntry = new ToolEntry("Panning", "Drag", Activator
				.getImageDescriptor("icons/pan.gif"), Activator
				.getImageDescriptor("icons/pan.gif")) {
			public Tool createTool() {
				return moveTool;
			}
		};

 

 第二步 增加监听：

	private void initListeners() {
		getGraphicalControl().addMouseListener(new MouseListener() {

			public void mouseDoubleClick(MouseEvent me) {
			}

			public void mouseDown(MouseEvent me) {
				EditPart editPart = getGraphicalViewer().findObjectAt(
						new Point(me.x, me.y));
				if (editPart instanceof JavaProjectEditPart) {
					isMouseDown = true;
					updateActiveTool(me);
				}
			}

			public void mouseUp(MouseEvent me) {
				isMouseDown = false;
				isMouseMoved = false;
				if (isHandled) {
					getEditDomain().setActiveTool(
							getEditDomain().getDefaultTool());
				}
				isHandled = false;
			}
		});
		getGraphicalControl().addMouseMoveListener(new MouseMoveListener() {

			public void mouseMove(MouseEvent me) {
				if (isMouseDown) {
					isMouseMoved = true;
				}
			}
		});
	}

	private boolean isMouseDown = false;
	private boolean isMouseMoved = false;
	private boolean isHandled = false;

	protected void updateActiveTool(final MouseEvent me) {
		new Thread() {
			public void run() {
				try {
					sleep(200);
				} catch (InterruptedException e) {
				}

				if (isMouseDown && !isMouseMoved) {
					isHandled = true;
					Display.getDefault().asyncExec(new Runnable() {
						public void run() {
							moveTool.mouseDown(me, getGraphicalViewer());
							getEditDomain().setActiveTool(moveTool);
							moveTool.setViewer(null);
						};
					});
				}
			}
		}.start();
	}