gef事件机制--拖曳类Tool(2)

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改变对象大小事件的DragTracer--ResizeTracker:

         当单击节点EditPart的拖动区域时：因为正好在Viewer的热点：

故会返回ResizeTracker。

protected boolean handleButtonDown(int button) {

    if (!stateTransition(STATE_INITIAL, STATE_DRAG)) {

       resetHover();

       return true;

    }

    resetHover();

    EditPartViewer viewer = getCurrentViewer();

    Point p = getLocation();

 

    if (getDragTracker() != null)

       getDragTracker().deactivate();

 

    if (viewer instanceof GraphicalViewer) {

       Handle handle = ((GraphicalViewer) viewer).findHandleAt(p);

       if (handle != null) {

           setDragTracker(handle.getDragTracker());

           return true;

       }

    }

//跟MOVE时不一样，在上面就setDragTracker ResizeTracer，而MOVE是通过下面的

//   setDragTracker(editpart.getDragTracker(getTargetRequest()))设置的

 

    updateTargetRequest();

    ((SelectionRequest)getTargetRequest()).setLastButtonPressed(button);

    updateTargetUnderMouse();

    EditPart editpart = getTargetEditPart();

    if (editpart != null) {

       setDragTracker(editpart.getDragTracker(getTargetRequest()));

       lockTargetEditPart(editpart);

       return true;

    }

    return false;

}

ResizeTracer和DrageEditPartTracker的处理差别很大，首先是REQ的type.

protected String getCommandName() {

    return REQ_RESIZE;

}

不一样，导致request type是REQ_RESIZE而以，且request都是changeBoundrequest，

 

同时处理过程也不一样，主要体现在handleDragInProgress中.

protected boolean handleDragInProgress() {

    if (isInDragInProgress()) {

       updateSourceRequest();

//这个是Source，前面的MOVE是target

       showSourceFeedback();

       showTargetFeedback();

       setCurrentCommand(getCommand());

    }

    return true;

}

 

更主要的区别体现在如下3点：

feedback调用不同

protected void showSourceFeedback() {

    List editParts = getOperationSet();

    for (int i = 0; i < editParts.size(); i++) {

       EditPart editPart = (EditPart) editParts.get(i);

       editPart.showSourceFeedback(getSourceRequest());

  //这个是用getSourceRequest

    }

    setFlag(FLAG_SOURCE_FEEDBACK, true);

}

protected void showTargetFeedback() {

    setFlag(FLAG_TARGET_FEEDBACK, true);

    if (getTargetEditPart() != null)

       getTargetEditPart().showTargetFeedback(getSourceRequest());

}

同时showTargetFeedback也用的是getSourceRequest().

Request更新不同

updateSourceRequest的函数更复杂，其由8中情况的变化操作，SOUTH_EAST, NORTH_WEST, NORTH_EAST , SOUTH_WEST，SOUTH,EAST，NORTH，WEST：

protected void updateSourceRequest() {

    ChangeBoundsRequest request = (ChangeBoundsRequest) getSourceRequest();

    Dimension d = getDragMoveDelta();

 

    Point location = new Point(getLocation());

    Point moveDelta = new Point(0, 0);

    Dimension resizeDelta = new Dimension(0, 0); 

 

    if (getCurrentInput().isShiftKeyDown() && owner != null) {

       request.setConstrainedResize(true);

      

       int origHeight = owner.getFigure().getBounds().height;

       int origWidth = owner.getFigure().getBounds().width;

       float ratio = 1;

      

       if (origWidth != 0 && origHeight != 0)

           ratio = ((float)origHeight / (float)origWidth);

       //东南边方向改变

       if (getResizeDirection() == PositionConstants.SOUTH_EAST) {

           if (d.height > (d.width * ratio))

              d.width = (int)(d.height / ratio);

           else

              d.height = (int)(d.width * ratio);

//西北边方向改变

       } else if (getResizeDirection() == PositionConstants.NORTH_WEST) {

           if (d.height < (d.width * ratio))

              d.width = (int)(d.height / ratio);

           else

              d.height = (int)(d.width * ratio);

       } else if (getResizeDirection() == PositionConstants.NORTH_EAST) {

           if (-(d.height) > (d.width * ratio))

              d.width = -(int)(d.height / ratio);

           else

              d.height = -(int)(d.width * ratio);

       } else if (getResizeDirection() == PositionConstants.SOUTH_WEST) {

           if (-(d.height) < (d.width * ratio))

              d.width = -(int)(d.height / ratio);

           else

              d.height = -(int)(d.width * ratio);

       }

    } else

       request.setConstrainedResize(false);

   

    request.setCenteredResize(getCurrentInput().isModKeyDown(SWT.MOD1));

   

   

    if ((getResizeDirection() & PositionConstants.NORTH) != 0) {

       if (getCurrentInput().isControlKeyDown()) {

           resizeDelta.height -= d.height;

       }

       moveDelta.y += d.height;

       resizeDelta.height -= d.height;

    }

    if ((getResizeDirection() & PositionConstants.SOUTH) != 0) {

       if (getCurrentInput().isControlKeyDown()) {

           moveDelta.y -= d.height;

           resizeDelta.height += d.height;

       }

       resizeDelta.height += d.height;

    }

    if ((getResizeDirection() & PositionConstants.WEST) != 0) {

       if (getCurrentInput().isControlKeyDown()) {

           resizeDelta.width -= d.width;

       }

       moveDelta.x += d.width;

       resizeDelta.width -= d.width;

    }

    if ((getResizeDirection() & PositionConstants.EAST) != 0) {

       if (getCurrentInput().isControlKeyDown()) {

           moveDelta.x -= d.width;

           resizeDelta.width += d.width;

       }

       resizeDelta.width += d.width;

    }

   

    request.setMoveDelta(moveDelta);

    request.setSizeDelta(resizeDelta);

    request.setLocation(location);

    request.setEditParts(getOperationSet());

 

    request.getExtendedData().clear();

   

    if (!getCurrentInput().isAltKeyDown() && snapToHelper != null) {

       PrecisionRectangle rect = sourceRect.getPreciseCopy();

       rect.translate(moveDelta);

       rect.resize(resizeDelta);

       PrecisionRectangle result = new PrecisionRectangle();

      

       snapToHelper.snapRectangle(request, request.getResizeDirection(), rect, result);

       if (request.isCenteredResize()) {

           if (result.preciseX != 0.0)

              result.preciseWidth += -result.preciseX;

           else if (result.preciseWidth != 0.0) {

              result.preciseX = -result.preciseWidth;

              result.preciseWidth *= 2.0;

           }

          

           if (result.preciseY != 0.0)

              result.preciseHeight += -result.preciseY;

           else if (result.preciseHeight != 0.0) {

              result.preciseY = -result.preciseHeight;

              result.preciseHeight *= 2.0;

           }

           result.updateInts();

       }

 

       PrecisionPoint preciseMove = new PrecisionPoint(

              result.x + moveDelta.x,

              result.y + moveDelta.y);

      

       PrecisionDimension preciseResize = new PrecisionDimension(

              result.width + resizeDelta.width,

              result.height + resizeDelta.height);

      

       request.setMoveDelta(preciseMove);

       request.setSizeDelta(preciseResize);

    }

}

 

Command调用不同

ResizeTracer的getCommand是调用节点EditParT的getCommand，然后在间接调用节点EditParT的parent-ContentEditPart的getCommand,同时中间requst类型发生了变化，由REQ_RESIZE变成REQ_RESIZE_CHILDREN，而DragEditPartTracer是直接调用TargetEditPart即ContentEditPart的getCommand。

 

protected Command getCommand() {

    List editparts = getOperationSet();

//被选择的节点。

    EditPart part;

    CompoundCommand command = new CompoundCommand();

    command.setDebugLabel("Resize Handle Tracker");//$NON-NLS-1$

    for (int i = 0; i < editparts.size(); i++) {

       part = (EditPart)editparts.get(i);

       command.add(part.getCommand(getSourceRequest()));

    }

    return command.unwrap();

}

这个是支持拖放的节点的resizablePolicy的函数：

public Command getCommand(Request request) {

    if (REQ_RESIZE.equals(request.getType()))

//注意，这里是REQ_RESIZE

       return getResizeCommand((ChangeBoundsRequest)request);

 

    return super.getCommand(request);

}

 

protected Command getResizeCommand(ChangeBoundsRequest request) {

ChangeBoundsRequest req = new ChangeBoundsRequest(REQ_RESIZE_CHILDREN);

//到这里变成REQ_RESIZE_CHILDREN了，因为要发给节点父节点contentEditpart

    req.setEditParts(getHost());

   

    req.setMoveDelta(request.getMoveDelta());

    req.setSizeDelta(request.getSizeDelta());

    req.setLocation(request.getLocation());

    req.setExtendedData(request.getExtendedData());

    req.setResizeDirection(request.getResizeDirection());

    return getHost().getParent().getCommand(req);

//调用父亲节点处理。

}

在空白处拖曳事件的DragTracer—MarqueeDragTracker

当在空白处点击时：Target是rootEditpart,而rootEditPart的getDragTracer就是MarqueeDragTracker，这样这个事件的DragTracer就是MarqueeDragTracker。

 

Class MarqueeDragTracker

鼠标按下时：

protected boolean handleButtonDown(int button) {

    if (!isGraphicalViewer())

       return true;

    if (button != 1) {

       setState(STATE_INVALID);

       handleInvalidInput();

    }

    if (stateTransition(STATE_INITIAL, STATE_DRAG_IN_PROGRESS)) {

       if (getCurrentInput().isModKeyDown(SWT.MOD1))

           setSelectionMode(TOGGLE_MODE);

//这个是修改选择效果

       else if (getCurrentInput().isShiftKeyDown())

           setSelectionMode(APPEND_MODE);

//这个是加了shift建的选择效果，就是增加选项

       else

           setSelectionMode(DEFAULT_MODE);

    }

    return true;

}

拖曳过程中：

protected boolean handleDragInProgress() {

    if (isInState(STATE_DRAG | STATE_DRAG_IN_PROGRESS)) {

        showMarqueeFeedback();

//显示选择虚线框。

       eraseTargetFeedback();

       calculateNewSelection(selectedEditParts = new ArrayList(), newArrayList());

//重新计算被选择的节点。。

       showTargetFeedback();

    }

    return true;

}

 

 几种和拖曳有关的Tool就讲完了。

 现在还有几个问题？

1.选择，平移，改变大小这些操作的source,target的editpart分别是什么？

2.选择，平移，改变大小操作出来的虚框是怎么出来的，这个是feedback产生的？如果是feedback产生的，由于平移，改变会执行showTargetFeedback和showSourceFeedback，那么这个虚框是Target产生，还是Source产生。

3．当我们拖曳时，尽管鼠标在source editpart上，为什么target editpart始终是content editpart呢？

 这些问题将在下面一章讲解：