[BUG] SKGLView don't redraw after return from other page on Android In Maui

[xtuzy]

Description
I use SKGLView in Maui, when it run Android, it will don't redraw after return from other page, see video:

sharex-20230419174159.mp4

I copy your GLTextureView and SKGLTextureView to my project, and create handler for it, Maui view name SKGpuView, when run, the log will show this line:

SkiaSharp/source/SkiaSharp.Views/SkiaSharp.Views.Android/GLTextureView.cs

Line 959 in b8efe44

LogDebug($"[GLThread {Id}] Waiting mHaveEglContext={haveEglContext} mHaveEglSurface={haveEglSurface} mFinishedCreatingEglSurface={finishedCreatingEglSurface} paused={paused} hasSurface={hasSurface} surfaceIsBad={surfaceIsBad} mWaitingForSurface={waitingForSurface} mWidth={width} mHeight={height} mRequestRender={requestRender} mRenderMode={renderMode}");

I find log show width and height is 0 after return from other page.

I read source code of GLTextureView , search where set width and height:

1. when go to other page, surface will destory, when return from other page, will load GLTextureView.OnAttachedToWindow, then create new GLThread, and set width and height equal to 0.
2. when GLTextureView.OnLayoutChange, then load GLTextureView.OnSurfaceTextureSizeChanged to set GLThread.OnWindowResize, and then set width and height .

when return from other page, GLTextureView.OnLayoutChange don't be invoked. so width and height is 0

I try use width and height as params of OnSurfaceCreated and set width and height of GLThread, my SKGpuView work.

SkiaSharp/source/SkiaSharp.Views/SkiaSharp.Views.Android/GLTextureView.cs

Line 165 in b8efe44

glThread.OnSurfaceCreated();

Code

Expected Behavior

Actual Behavior

Basic Information

• Version with issue: 2.88.2
• Last known good version:
• IDE: Visual Studio
• Platform Target Frameworks:
  • Android: 12 Api31
  • iOS:
  • Linux:
  • macOS:
  • Tizen:
  • tvOS:
  • UWP:
  • watchOS:
  • Windows Classic:
• Target Devices:
  • Android Emulator

Detailed IDE/OS information (click to expand)

PASTE ANY DETAILED VERSION INFO HERE

Screenshots

Reproduction Link

[NatWobble]

I have the same issue using a subclass of SKCanvasView as a control and a handler using SKGLTextureView. I had to create an OnResume() Method and set the size again (when returning to the page) as xtuzy suggested:

public partial class SKCanvasViewGPUHandler : ViewHandler<ISKCanvasView, SKGLTextureView>
{
 private SKSizeI lastCanvasSize;
...

 private void OnPaintSurface(object? sender, SkiaSharp.Views.Android.SKPaintGLSurfaceEventArgs e)
    {
        var newCanvasSize = e.Info.Size;
        if (lastCanvasSize != newCanvasSize)
        {
            lastCanvasSize = newCanvasSize;
            VirtualView?.OnCanvasSizeChanged(newCanvasSize);
        }
        VirtualView?.OnPaintSurface(new SkiaSharp.Views.Maui.SKPaintSurfaceEventArgs(e.Surface, e.Info, e.RawInfo));
    }


   public void OnResume()
   {
        if (this.PlatformView != null)
        {
            //  this.PlatformView?.OnResume(); // Seems to do nothing
            if (lastCanvasSize != null)
            {
                this.PlatformView.SetMinimumWidth(lastCanvasSize.Width);
                this.PlatformView.SetMinimumHeight(lastCanvasSize.Height);
            }
            
        }     
    }
}

Without resetting the size, the OnPaintSurface method isn't called after returning to the page ( await Navigation.PopAsync()) . But strangely, it sometimes restarts after 10 to 30 seconds (on my Android simulator) or never at all.

I am using the Navigation class (not Shell) for navigation.

[taublast]

That looks like the GRContext changed and the VirtualView Handler is still trying to use the old one. Could anyone provide a small repro project so I try to make it work as intended? Thanks.

[mattleibow]

Wow, I never even saw this issue.

I will add it to the backlog and try see if there are some fixes.