I'm writing a paint app.
When drawing a line in CGContext, the background with the size of the bounding box of the line is always got erased - the underlying lines in that box will be cleared.
How to avoid the background erasing?
I'm writing a paint app.
When drawing a line in CGContext, the background with the size of the bounding box of the line is always got erased - the underlying lines in that box will be cleared.
How to avoid the background erasing?