如何旋转png图像Delphi？

Question

How can I rotate a png image in Delphi with preserving its transparency? I loaded it via TPNGObject . I'm then using Canvas.StretchDraw(MyRect, the TPNGObject) but I don't know how to rotate it.

Answer 1

The problem is that if you do a rotate using the Canvas, you will lose your transparency, as you noted with TPNGObject.

This is because the Canvas doesn't support transparency at the level required by a PNG image.

Instead, you must use specialized code to rotate the PNG image. Here is a link to a library of code that supports the TPNGObject, including a function to rotate it: http://cc.embarcadero.com/Item/25631