问题
Is it possible to edit a layer's image? I mean, having a TImgView with multiple selectable layers, I would like to know if it is possible to select one layer (rubber-band and all), and for example click a button in the menu, and the mouse would turn into a rubber eraser that can delete contents under the mouse, on click. Just like the eraser in Paint.net or Photoshop.
Is it possible to achieve this? And if so, then how? I could not find a way of doing that so far. In regular TImage (TPaintBox) the solution would be to draw with white on top of the background, but that is not a solution when working with transparent layers/images. So what to do?
Any help (code) would be appreciated.
Thank you
来源：https://stackoverflow.com/questions/28279408/delphi-graphics32-edit-layer-erase-parts-of-tbitmap32-layer