Strange Delphi Android image assign / image garbled issue

Question

I have some code that works fine in iOs, but which results in completely messed up images when on Android. I have found a partial workaround (not call some code), but it hints something is terrible wrong:

// some bitmap object buffer for mainthread only
R.BitmapRef := FPersistentBitmapBuffer;

// this TImage now contains the original wrongly sized bitmap
ImageBackground.Bitmap.Assign(R.BitmapRef); 

// calculated somewhere
TmpNewWidth := 500; 
TmpNewHeight := 500;

// draw the bitmap resized to wanted size
R.BitmapRef.Width := Round(TmpNewWidth);
R.BitmapRef.Height := Round(TmpNewHeight);
R.BitmapRef.Canvas.BeginScene();
R.BitmapRef.Canvas.DrawBitmap(ImageBackground.Bitmap, RectF(0,0,ImageBackground.Bitmap.Width,ImageBackground.Bitmap.Height), RectF(0,0,TmpNewWidth,TmpNewHeight), 1);
R.BitmapRef.Canvas.EndScene();

// assign it back to the image 
ImageBackground.Bitmap.Assign(R.BitmapRef);

// THIS code causes the image shown in TImageBackground to look completely garbled ... which would indicate something is shareing memory/reference somewhere somehow... There is more odd behavior like debugger unhooking (it seems) if mouse in Delphi debugger hovers over ImageBackground.Bitmap - no error is reported
R.BitmapRef.Clear(TAlphaColorRec.White); 

As can be seen, it the last line that messes it up. In some tests it has seemed to be enough to remove he line, but not in others. This is my best lead/description/example of the problem.

Here is an example of how a garbled image looks like. Since they look garbled the same way each time I run the app, I suspect it must be somehow relate to the image, but there is not any visual similarity.

My question is what could be wrong? I am testing the Delphi XE7 trial, so I can not access the source. It worked flawlessly on iOS using XE4 and XE7, but with Android something is going on. I am thinking it could possibly be some bitmap data that is sharing a reference... Does anyone have any ideas on how to test this theory / possible workarounds?

Answer 1

This looks plainly wrong. I'd suggest that you fill a bugreport at http://quality.embarcadero.com

Try using CopyFromBitmap instead of the "Assign". This will create a unique copy of the image. You'll also get a new unique image if you call MyBitmap.Map(TMapAccess.Write, MyBitmapData); followed by MyBitmap.UnMap(MyBitmapData);.