// Touch down event handler.
/// <summary>
/// 输入一个点，判定是否为手势，是则不需要在继续判断，手指离开时，将手势标识设置为false
/// 如果不是则继续判断是否为手势.
/// </summary>
/// <param name="drawingCanvas"></param>
/// <param name="e"></param>
public void TouchDownHandler(DrawingCanvas drawingCanvas, TouchEventArgs e)
{
GestureData.Fingers++;//记录手指数
GraphicsPolyLine polyLine;
TouchPoint touchPoint = e.GetTouchPoint(drawingCanvas);
Point p = touchPoint.Position;
if (GestureData.Fingers == 1)//记录第一个手指的基本信息，后后续手势判断使用
{
if (!GestureData.IsSignFoFingerOne)
{
GestureData.IsTouch = true;
GestureData.FirstDeviceId = e.TouchDevice.Id;
GestureData.FirstFingerBeginPoint = p;
GestureData.FirstFingerCurPoint = p;
GestureData.IsSignFoFingerOne = true;
}
}
HelperFunctions.IsGesture(drawingCanvas, e);//判断是否为手势
//如果是手势，则将第一个手指画的几何型的Candraw属性置为false,使得后续不在画出来
if (GestureData.IsGesture && GestureData.Fingers == 2 && _activeStrokes.TryGetValue(GestureData.FirstDeviceId, out polyLine))
{
polyLine.CanDraw = false;
}
if (_activeStrokes.TryGetValue(e.TouchDevice.Id, out polyLine))
{
FinishStroke(polyLine);
return;
}
//当手指的个数大于2时，将第一个手指与第二个手指的canDraw属性置回true
if (!GestureData.IsGesture && GestureData.Fingers > 2)
{
if (_activeStrokes.TryGetValue(GestureData.FirstDeviceId, out polyLine))
{
polyLine.CanDraw = true;
}
if (_activeStrokes.TryGetValue(GestureData.SecondDeviceId, out polyLine))
{
polyLine.CanDraw = true;
}
}
// Create new stroke, add point and assign a color to it.
GraphicsPolyLine newPolyLine = new GraphicsPolyLine(
new Point[]
{
p,
new Point(p.X + 1, p.Y + 1)
},
drawingCanvas.LineWidth,
drawingCanvas.ObjectColor,
drawingCanvas.ActualScale);
newPolyLine.DeviceID = e.TouchDevice.Id;
//是手势并且是第二个手指，将其画的几何的CanDraw置为false，不用画
if (GestureData.IsGesture && GestureData.Fingers == 2)
{
if (!GestureData.IsSignForFingerTwo)
{
GestureData.SecondDeviceId = e.TouchDevice.Id;
GestureData.SecFingerBeginPoint = p;
GestureData.StartDistInTwoFingers = HelperFunctions.CalcDistanceSquare(GestureData.FirstFingerBeginPoint, GestureData.SecFingerBeginPoint);
GestureData.StartCenterPointInTwoFingers = HelperFunctions.getCenterPoint(GestureData.FirstFingerBeginPoint, GestureData.SecFingerBeginPoint);
GestureData.SecFingerCurPoint = p;
newPolyLine.CanDraw = false;
GestureData.IsSignForFingerTwo = true;
if (GestureData.FirstFingerBeginPoint.X < GestureData.SecFingerBeginPoint.X)
{
GestureData.MaxPositionX = true;
}
}
}
//防止已经是手势了，但因为用户不小心使得其他手指不小心碰到了触控，需要使得该误碰的手写内容不画出来
if (GestureData.IsGesture && GestureData.Fingers > 2)
{
newPolyLine.CanDraw = false;
}
AddNewObject(drawingCanvas, newPolyLine);
// Add new stroke to the collection of strokes in drawing.
_activeStrokes[newPolyLine.DeviceID] = newPolyLine;
System.Diagnostics.Debug.WriteLine("Touchdown:{0}", GestureData.IsGesture);
}