Bitmap format when pasting 32bit DIB from clipboard?

[Anthony Watson]

I'm trying to save a DIB (%CF_DIB) bitmap from the clipboard, which works great for all bit depths except 32 bits per pixel. I can't seem to calculate the proper start of the bitmap data for that depth.

I get the 40 byte header (as read from the header_size) field.

According to the documentation I can find, when the compression field is set to BI_BITFIELDS the header should be followed by three DWORD masks. This should equal 6 bytes, right? Which means the bitmap data should start 6 bytes after the header (there's no color table with a 32 bit depth bitmap, right?)

Unfortunately, the data is not where I'm expecting it to be. What am I missing?

I tried using the %CF_BITMAP method instead, but EVERY image ends up as a 32 bit depth image.

Using the %CF_DIB method I can retain lower bit depth images, but the 32bpp image (such as using the Prnt/Scrn button on the keyboard) comes through invalid.

I'm obviously overlooking something. Any ideas?

Thanks,

Anthony

[José Roca]

[...] three DWORD masks. This should equal 6 bytes, right?

Wrong. 3 * 4 = 12.

[Anthony Watson]

Wrong. 3 * 4 = 12.

Thanks for the correction. You're right, of course, but I still wasn't ending up with a usable DIB. For a 32bit DIB with BI_BITFIELDS compression, I was assuming the packed bitmap should be:

40 Bytes for the BitmapInfoHeader
12 Bytes for the Color Masks
...The start of the bitmap data

In my case, I had no interest in the color masks, and I stumbled across the solution this morning. If I'm no longer using the color masks, I have to change the compression field from BI_BITFIELDS to BI_RGB. Bingo! Works like a charm now.

Thank you for the clarification. I figured it was just something simple I was overlooking.

Anthony