[vb6] Class to make Image Controls Support PNG, TIF, GIF Animation

[LaVolpe]

Yes, you can load an image via GDI+ and render it to a 32bpp DIB to use AlphaBlend to render that to a DC. Couple things:

1) If using GDI+ to load the image and using stdPicture to just cache the image, not sure of the benefits? Why not just use GDI+ to render, you would have the option of rendering at different scales using different interpolation/quality. Once the DIB is created, AlphaBlend's scaling is just as bad as VB. In the class I wrote (post #1), AlphaBlend is used in the assembly thunk. To use GDI+ for scaling would require re-writing that thunk.

2) You really do not need a loop to transfer the LockBits to DIB. One call is all that's needed
MemCopy ByVal pDst, ByVal BMSrc.scan0, Rct.Height * Rct.Width * 4

Caution: LockBits can't be used with metafiles. Crash will result. So, maybe a more generic approach is to render the GDI+ image to the 32bpp DIB instead of transferring the bits. Just a thought.

Edited & FYI: GDI+ rendering to a DIB where all bits are set to zero is identical to creating a premultiplied bitmap.