Hello Kxfeash,
Filled Path and Stroked Path views are working implicitly with alphablending. Since Rotary Knob uses these views to display the track, disabling alphablending in such case is also not available. Disabling alphablending would result in the entire shape of the Filled Path overwriting the background contents. This is probably not what you expect.
What you try to achieve is unfortunately not possible. I suppose you want to implement a kind of mask operation with the mask changing dynamically at the runtime. Even if you would disable the alphablending, the pixel resulting from the path will overwrite the pixel in the background. In other words the Filled Path will replace the alpha AND the color information resulting from the bitmap.
I don't know your exact application case. However, if the affected bitmap is displayed directly in the background of the application and the remaining background is filled with solid color you can do following:
1. Display the bitmap.
2. In front of the Bitmap display a Filled Path view.
3. The content shown in the Filled Path view has to be an inverse of what you want to see of the bitmap.
4. The color of the Filled Path ha to correspond to the color of the background.
With this trick you overwrite the parts of the bitmap which should become invisible. This however will not do what you probably expect to do with the Rotary Knob. To achieve this, we would need to extend the Graphics Engine by bitmap operations with an additional source bitmap as mask.
I hope you can workaround your GUI design to avoid the usage of masked bitmaps.
Best regards
Paul Banach