How to prevent parent scroll view from scrolling from gesture capturing child - xamarin

Question

I'm creating a custom control (custom skia canvas) which I would like to embed within a scroll view, at the moment, because the custom control (child element) is capturing gesture input, this means that the parent scroll view will sometimes scroll and sometimes will not on iOS.
So far we've created a custom renderer for the scroll view which we can enable/disable a property on called 'ScrollEnabled', this works perfectly fine on Android and allows us to interact with the child element when we tap and hold on the child, however this solution is not satisfactory for iOS as we aren't getting a cancel trigger from the child element to tell the ScrollEnabled on the parent to be set back to True (therefore allowing the scrollview to scroll again).
ChartView:
public static readonly BindableProperty AllowStackScrollProperty = BindableProperty.Create(nameof(AllowStackScroll), typeof(bool), typeof(TPChartView), false);
public bool AllowStackScroll
{
get { return (bool)GetValue(AllowStackScrollProperty); }
set { SetValue(AllowStackScrollProperty, value); }
}
{
_currentTouchAction = e.ActionType;
if (e.ActionType == SKTouchAction.Cancelled) return;
((MasterDetailPage)Application.Current.MainPage).IsGestureEnabled = false;
if (e.ActionType == SKTouchAction.Released || e.ActionType == SKTouchAction.Exited)
{
AllowStackScroll = true;
this.Chart.OnTouchEnd();
this.InvalidateSurface();
e.Handled = true;
((MasterDetailPage)Application.Current.MainPage).IsGestureEnabled = true; //Enable the menu gestures again
return;
}
TPVector point = new TPVector(e.Location.X, e.Location.Y);
this.Chart.OnTouchBegan(point);
this.InvalidateSurface();
e.Handled = true;
}
ScrollView renderer (iOS)
public class TPScrollViewIOSRenderer : ScrollViewRenderer
{
public new static void Init()
{
}
public bool ScrollDisabled { get; set; } = false;
private string _currentTouchAction { get; set; }
public TPScrollViewIOSRenderer()
{
if (((TPScrollView)Element) == null) return;
((TPScrollView)Element).PropertyChanged += Element_PropertyChanged;
ScrollEnabled = ((TPScrollView)Element).ScrollingEnabled;
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
}
public override void TouchesBegan(Foundation.NSSet touches, UIEvent evt)
{
if (((TPScrollView)Element) == null) return;
UITouch touch = touches.AnyObject as UITouch;
_currentTouchAction = "press";
LongPress(50, resp =>
{
if (resp)
{
Device.BeginInvokeOnMainThread(() =>
{
ScrollEnabled = false;
});
}
else
{
Device.BeginInvokeOnMainThread(() =>
{
ScrollEnabled = true;
});
}
});
base.TouchesBegan(touches, evt);
}
public override void TouchesMoved(Foundation.NSSet touches, UIKit.UIEvent evt)
{
if (((TPScrollView)Element) == null) return;
_currentTouchAction = "move";
base.TouchesMoved(touches, evt);
}
public override void TouchesEnded(Foundation.NSSet touches, UIKit.UIEvent evt)
{
if (((TPScrollView)Element) == null) return;
_currentTouchAction = "end";
Device.BeginInvokeOnMainThread(() =>
{
ScrollEnabled = true;
});
base.TouchesEnded(touches, evt);
}
public override void TouchesCancelled(Foundation.NSSet touches, UIEvent evt)
{
if (((TPScrollView)Element) == null) return;
_currentTouchAction = "canceled";
Device.BeginInvokeOnMainThread(() =>
{
ScrollEnabled = true;
});
base.TouchesCancelled(touches, evt);
}
public void LongPress(int ExecutionTime, Action<bool> OnComplete)
{
var timer = new System.Threading.Timer(
e =>
{
if (_currentTouchAction == "press" || _currentTouchAction == "move")
{
OnComplete.Invoke(true);
return;
}
OnComplete.Invoke(false);
},
null,
TimeSpan.FromMilliseconds(ExecutionTime),
TimeSpan.FromMilliseconds(-1));
}
protected override void OnElementChanged(VisualElementChangedEventArgs e)
{
base.OnElementChanged(e);
if (e.OldElement != null) Dispose();
ScrollEnabled = ((TPScrollView)Element).ScrollingEnabled;
}
private void Element_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
if (e.PropertyName == "ScrollingEnabled");
{ }
}
}
We just want behaviour on iOS where the internal element only captures gesture on tap and hold and when released, the parent ScrollView takes precedence again and allows scrolling.