System.NotSupportedException: Unable to activate instance of type Xamarin.Forms.PancakeView.Droid.PancakeDrawable from native handle

[domenk]

When using GradientStopCollection together with Background setter, in certain scenarios Android throws mentioned exception.

I was not able to trim down code for sharing, because it's called after a series of callbacks and skipping some of them makes issue go away.

Exception:

System.NotSupportedException: Unable to activate instance of type Xamarin.Forms.PancakeView.Droid.PancakeDrawable from native handle 0xbfb0fafc (key_handle 0x2f236dc9).
---> System.MissingMethodException: No constructor found for Xamarin.Forms.PancakeView.Droid.PancakeDrawable::.ctor(System.IntPtr, Android.Runtime.JniHandleOwnership)
---> Java.Interop.JavaLocationException: Exception of type 'Java.Interop.JavaLocationException' was thrown.

Unable to activate instance of type Xamarin.Forms.PancakeView.Droid.PancakeDrawable from native handle 0xbfb0fb1c (key_handle 0xf639376).
  at Java.Interop.TypeManager.CreateInstance (System.IntPtr handle, Android.Runtime.JniHandleOwnership transfer, System.Type targetType) [0x0017e] in <123>:0 
  at Java.Lang.Object.GetObject (System.IntPtr handle, Android.Runtime.JniHandleOwnership transfer, System.Type type) [0x00023] in <123>:0 
  at Java.Lang.Object._GetObject[T] (System.IntPtr handle, Android.Runtime.JniHandleOwnership transfer) [0x00017] in <123>:0 
  at Java.Lang.Object.GetObject[T] (System.IntPtr handle, Android.Runtime.JniHandleOwnership transfer) [0x00000] in <123>:0 
  at Java.Lang.Object.GetObject[T] (System.IntPtr jnienv, System.IntPtr handle, Android.Runtime.JniHandleOwnership transfer) [0x00006] in <123>:0 
  at Android.Graphics.Drawables.Drawable.n_GetOpacity (System.IntPtr jnienv, System.IntPtr native__this) [0x00000] in <123>:0 
  at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.74(intptr,intptr)

(Visual Studio stops at base.OnElementPropertyChanged(sender, e); line in Droid.PancakeViewRenderer.OnElementPropertyChanged.)

Style that causes exception:

<Style x:Key="styleName" TargetType="pancake:PancakeView">
  <Setter Property="Background" Value="red" />
  <Setter Property="BackgroundGradientStartPoint" Value="0,0" />
  <Setter Property="BackgroundGradientEndPoint" Value="0,1" />
  <Setter Property="BackgroundGradientStops">
    <pancake:GradientStopCollection>
      <pancake:GradientStop Color="green" Offset="0" />
      <pancake:GradientStop Color="blue" Offset="1" />
    </pancake:GradientStopCollection>
  </Setter>
</Style>

Commenting out Background or BackgroundGradientStops setter resolves the issue.

Occurs on Xamarin.Forms 5.0.0.1874.

Maybe related: #113. Adding constructor public PancakeDrawable(IntPtr handle, global::Android.Runtime.JniHandleOwnership transfer) { } and null-check for _pancake in Dispose method seems to resolve the issue.

[justintoth]

For me I ran into the same exception with PancakeView when dynamically setting the background color.

<cake:PancakeView.Triggers>
                <DataTrigger
                    Binding="{Binding IsPartialReceipt}"
                    TargetType="cake:PancakeView"
                    Value="True">
                    <Setter Property="BackgroundColor" Value="#FBF8ED" />
                </DataTrigger>
                <DataTrigger
                    Binding="{Binding IsPartialReceipt}"
                    TargetType="cake:PancakeView"
                    Value="False">
                    <Setter Property="BackgroundColor" Value="White" />
                </DataTrigger>
            </cake:PancakeView.Triggers>