Skiasharp - Detected Selected Touch Point

Question

Hi
In this example there are four touch points

TouchPoints[0], touchPoints1, touchPoints[2] and touchPoints[3]

https://github.com/xamarin/xamarin-forms-samples/blob/master/SkiaSharpForms/Demos/Demos/SkiaSharpFormsDemos/Curves/BezierCurvePage.xaml.cs

How can I detected which touch point is being moved

Thank you in advance.

@Matthew Leibowitz

Answer 1

Hello,

Welcome to Microsoft Q&A!

• Define a new public variable ID inside TouchPoint class .
• Assign the value when initializing in BezierCurvePage.cs . for (int i = 0; i < 4; i++)
  {
  TouchPoint touchPoint = new TouchPoint
  {
  Center = new SKPoint(100 + 200 * (i % 2),100 + 200 * i),
  ID = i
  };
  touchPoints[i] = touchPoint
  }
• Detect which point is dragged in method ProcessTouchEvent in TouchPoint class case TouchActionType.Moved:
  if (isBeingDragged && touchId == id)
  {
  Console.WriteLine("ID=" + ID); //here you can get which is dragged

          Center += location - previousPoint;  
          previousPoint = location;  
          centerMoved = true;  
     }  
  

  break;

Thank you.

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Answer 2

there is a toucheffect in xaml file.
in OnTouchEffectAction you can get the points which is moved.

to overview the OnTouchEffectAction you can download the project and press F12 to check the function.