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How do I programatically determine the byte length of a windows BITMAP?

Posted on 2015-01-10
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Last Modified: 2015-01-10
Hi:

I'm building a windows utility application that works with bitmaps.

If I have an HBITMAP or LPBITMAP, how do I determine the byte count of the actual image?

Is it inferred from bmBitsPixel * bmWidth * bmHeight?

Thanks,
JohnB
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Question by:jxbma
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jkr earned 500 total points
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>> Is it inferred from bmBitsPixel * bmWidth * bmHeight?

In short: Yes, that is exactly it. Or, almost, since you have to round up 'bmBitsPerPixel' to the next byte boundary and divide it by 8 to get the actual number of bytes the color information is taking up. Then you multiply that value with the dimensions (or width and height),.
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by:jkr
ID: 40542581
Um, it's actually a bit simpler than 'rounding up':

DWORD dwBmpSize = ((bm.bmBitsPixe / 8) + 1) * bm.bmWidth * bm.bmHeight;

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by:jxbma
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Once again. Cool. Thx
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