Hello I changed a bit with your file:
- Set DrawingCanvas size equal your viewport size and move it to position (0,0), I still figuring why it has wrong position of erasing.
- Change Mouse to Touch, I don't know why it doesn't work with mouse.
https://drive.google.com/file/d/1YhIo6ob_x6J9rj8I2L2HwgTOo-MLmxhz/view?usp=sharing
And one non-relative topic question: Are you Vietnamese? :D
Thanks a lot, your adjustments work well, I just need to change some parameters.
However, I found out that it only works if you put everything at the start position of the layout (0,0). This is really problematic as I was trying to put this image revealing section within a larger layout. And it does not work with mouse whatsoever.
I guess I have to make this section its own layout until a fix is found. Oh well.
How do you know that I am Vietnamese? :D