This program will show you how to rotate a bitmap onto another bitmap. The code shows both a simple inefficient procedure for it and optimized versions of the rotation.
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I was wondering how the bitmap rotation code avoids missing pixels in the destination image. You scan through the pixels of the source image and calculate the corresponding position in the destination image so how does it avoid missing pixels in the destination image due to rounding? The way it is normally done is to scan through the pixels of the destination image and calculate the corresponding pixel in the source image. This also avoids repeating pixels. The code is very optimized but I think that with the minor change of back mapping rather than forward mapping it would be better. (If this comment was disrespectful, please report it.)
bone, you could be right about the conventional algorithm being more efficient. I just wanted to keep it quite simple and clear and mapping from an orthogonal rectangle was simplest. Copying to 2 by 2 pixel squares doesn't seem to be a big sacrifice for that simplicity. (If this comment was disrespectful, please report it.)
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10/2/2005 10:58:12 AM: 
