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using System;
using Android.Runtime;
using Android.Views;
namespace Xamarin.Forms.Platform.Android
{
internal class InnerScaleListener : ScaleGestureDetector.SimpleOnScaleGestureListener
{
Func<float, Point, bool> _pinchDelegate;
Action _pinchEndedDelegate;
Func<Point, bool> _pinchStartedDelegate;
public InnerScaleListener(Func<float, Point, bool> pinchDelegate, Func<Point, bool> pinchStarted, Action pinchEnded)
{
if (pinchDelegate == null)
throw new ArgumentNullException("pinchDelegate");
if (pinchStarted == null)
throw new ArgumentNullException("pinchStarted");
if (pinchEnded == null)
throw new ArgumentNullException("pinchEnded");
_pinchDelegate = pinchDelegate;
_pinchStartedDelegate = pinchStarted;
_pinchEndedDelegate = pinchEnded;
}
// This is needed because GestureRecognizer callbacks can be delayed several hundred milliseconds
// which can result in the need to resurect this object if it has already been disposed. We dispose
// eagerly to allow easier garbage collection of the renderer
internal InnerScaleListener(IntPtr handle, JniHandleOwnership ownership) : base(handle, ownership)
{
}
public override bool OnScale(ScaleGestureDetector detector)
{
float cur = detector.CurrentSpan;
float last = detector.PreviousSpan;
if (Math.Abs(cur - last) < 10)
return false;
return _pinchDelegate(detector.ScaleFactor, new Point(Forms.Context.FromPixels(detector.FocusX), Forms.Context.FromPixels(detector.FocusY)));
}
public override bool OnScaleBegin(ScaleGestureDetector detector)
{
return _pinchStartedDelegate(new Point(Forms.Context.FromPixels(detector.FocusX), Forms.Context.FromPixels(detector.FocusY)));
}
public override void OnScaleEnd(ScaleGestureDetector detector)
{
_pinchEndedDelegate();
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
_pinchDelegate = null;
_pinchStartedDelegate = null;
_pinchEndedDelegate = null;
}
base.Dispose(disposing);
}
}
}
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