C# UIEvent.GetCoalescedTouches方法代码示例

		public void DrawTouches (NSSet touches, UIEvent evt)
		{
			var updateRect = CGRectNull ();

			foreach (var touch in touches.Cast<UITouch> ()) {
				Line line;

				// Retrieve a line from activeLines. If no line exists, create one.
				if (!activeLines.TryGetValue (touch, out line))
					line = AddActiveLineForTouch (touch);

				// Remove prior predicted points and update the updateRect based on the removals. The touches
				// used to create these points are predictions provided to offer additional data. They are stale
				// by the time of the next event for this touch.
				updateRect = updateRect.UnionWith (line.RemovePointsWithType (PointType.Predicted));

				// Incorporate coalesced touch data. The data in the last touch in the returned array will match
				// the data of the touch supplied to GetCoalescedTouches
				var coalescedTouches = evt.GetCoalescedTouches (touch) ?? new UITouch[0];
				var coalescedRect = AddPointsOfType (PointType.Coalesced, coalescedTouches, line);
				updateRect = updateRect.UnionWith (coalescedRect);

				// Incorporate predicted touch data. This sample draws predicted touches differently; however, 
				// you may want to use them as inputs to smoothing algorithms rather than directly drawing them. 
				// Points derived from predicted touches should be removed from the line at the next event for this touch.
				if (isPredictionEnabled) {
					var predictedTouches = evt.GetPredictedTouches (touch) ?? new UITouch[0];
					var predictedRect = AddPointsOfType (PointType.Predicted, predictedTouches, line);
					updateRect = updateRect.UnionWith (predictedRect);
				}
			}
			SetNeedsDisplayInRect (updateRect);
		}

		bool Append (HashSet<UITouch> touches, UIEvent uievent)
		{
			var touchToAppend = trackedTouch;
			if (touchToAppend == null)
				return false;

			// Cancel the stroke recognition if we get a second touch during cancellation period.
			foreach (var touch in touches) {
				if (touch != touchToAppend && (touch.Timestamp - initialTimestamp < cancellationTimeInterval)) {
					State = (State == Possible) ? Failed : Cancelled;
					return false;
				}
			}

			// See if those touches contain our tracked touch. If not, ignore gracefully.
			if (!touches.Contains (touchToAppend))
				return false;

			var coalescedTouches = uievent.GetCoalescedTouches (touchToAppend);
			var lastIndex = coalescedTouches.Length - 1;
			for (var index = 0; index <= lastIndex; index++)
				Collect (Stroke, coalescedTouches [index], CoordinateSpaceView, (index != lastIndex), false);

			if (Stroke.State == StrokeState.Active) {
				var predictedTouches = uievent.GetPredictedTouches (touchToAppend);
				foreach (var touch in predictedTouches)
					Collect (Stroke, touch, CoordinateSpaceView, false, true);
			}
			return true;
		}

		public void DrawTouches (NSSet touches, UIEvent evt)
		{
			var updateRect = CGRect.Empty;

			foreach (var touch in touches.Cast<UITouch> ()) {
				Line line;

				// Retrieve a line from `activeLines`. If no line exists, create one.
				if (!activeLines.TryGetValue (touch, out line))
					line = AddActiveLineForTouch (touch);
				updateRect = updateRect.UnionWith (line.RemovePointsWithType (PointType.Predicted));

				var coalescedTouches = evt.GetCoalescedTouches (touch) ?? new UITouch[0];
				var coalescedRect = AddPointsOfType (PointType.Coalesced, coalescedTouches, line, updateRect);
				updateRect = updateRect.UnionWith (coalescedRect);

				if (isPredictionEnabled) {
					var predictedTouches = evt.GetPredictedTouches (touch) ?? new UITouch[0];
					var predictedRect = AddPointsOfType (PointType.Predicted, predictedTouches, line, updateRect);
					updateRect = updateRect.UnionWith (predictedRect);
				}
			}
			SetNeedsDisplay ();
//			SetNeedsDisplayInRect (updateRect);
		}