// If no current snap action, set it to the action.
// Otherwise, if set, we're possibly undoing the last snap action (these are always opposite attach/detach actions),
// if re-attaching or re-detaching from the connection point.
// Lastly, if attaching to a different connection point, buffer the last snap action (which would always be a detach)
// and set the current snap action to what will always be the attach to another connection point.
protected void SetCurrentAction(SnapAction action)
{
if (currentSnapAction == null)
{
currentSnapAction = action;
}
else
{
// Connecting to a different shape?
if (action.TargetShape != currentSnapAction.TargetShape
// connecting to a different endpoint on the connector?
|| action.GripType != currentSnapAction.GripType
// connecting to a different connection point on the shape?
|| action.ShapeConnectionPoint != currentSnapAction.ShapeConnectionPoint)
{
snapActions.Add(currentSnapAction);
currentSnapAction = action;
}
else
{
// User is undoing the last action by re-connecting or disconnecting from the shape to which we just connected / disconnected.
currentSnapAction = null;
}
}
}
public void Reset()
{
snapActions.Clear();
nearElements.Clear();
currentlyNear.Clear();
runningDelta = new Point();
currentSnapAction = null;
}
public bool SnapCheck(GripType gripType, Point delta, Action <Point> update, bool isByKeyPress = false)
{
SnapAction action = Snap(gripType, delta, isByKeyPress);
if (action != null)
{
if (action.SnapType == SnapAction.Action.Attach)
{
runningDelta = action.Delta;
update(action.Delta);
// Controller.DragSelectedElements(action.Delta);
// Don't attach at this point, as this will be handled by the mouse-up action.
SetCurrentAction(action);
}
else if (action.SnapType == SnapAction.Action.Detach)
{
runningDelta = action.Delta;
update(action.Delta);
// Controller.DragSelectedElements(action.Delta);
// Don't detach at this point, as this will be handled by the mouse-up action.
SetCurrentAction(action);
}
else // Attached
{
// The mouse move had no affect in detaching because it didn't have sufficient velocity.
// The problem here is that the mouse moves, affecting the total delta, but the shape doesn't move.
// This affects the computation in the MouseUp handler:
// Point delta = CurrentMousePosition.Delta(startedDraggingShapesAt);
// ===================
// We could set the mouse cursor position, which isn't a bad idea, as it keeps the mouse with the shape:
//Controller.Canvas.MouseMove -= HandleMouseMoveEvent;
//Cursor.Position = Controller.Canvas.PointToScreen(LastMousePosition);
//Application.DoEvents(); // sigh - we need the event to trigger, even though it's unwired.
//Controller.Canvas.MouseMove += HandleMouseMoveEvent;
// The above really doesn't work well because I think we can get multiple move events, and this only handles the first event.
// ===================
// ===================
// Or we could add a "compensation" accumulator for dealing with the deltas that don't move the shape.
// This works better, except the attached compensation has to be stored for each detach.
// attachedCompensation = attachedCompensation.Add(delta);
// That doesn't work either, as the attachedCompensation is treated as a move even though there is no actual movement of the connector!
// ===================
// Final implementation is to use the runningDelta instead of the CurrentMouseMosition - startDraggingShapesAt difference.
// startedDraggingShapesAt = CurrentMousePosition;
}
}
return(action != null);
}
public SnapAction Clone()
{
SnapAction ret = new SnapAction();
ret.SnapType = SnapType;
ret.connector = connector;
ret.gripType = gripType;
ret.targetShape = targetShape;
ret.lineConnectionPoint = lineConnectionPoint;
ret.shapeConnectionPoint = shapeConnectionPoint;
ret.Delta = Delta;
return(ret);
}
protected void DoUndoSnapAction(UndoStack undoStack, SnapAction action)
{
SnapAction closureAction = action.Clone();
// Do/undo/redo as part of of the move group.
if (closureAction.SnapType == SnapAction.Action.Attach)
{
undoStack.UndoRedo("Attach",
() => closureAction.Attach(),
() => closureAction.Detach(),
false);
}
else
{
undoStack.UndoRedo("Detach",
() => closureAction.Detach(),
() => closureAction.Attach(),
false);
}
}