How to maintan aspect ratio with bitblt?
Author
Any ideas (theory) on how to maintan an aspect ratio using bitblt?
MSVC++ 6, GDI
I have a source bitmap of x size (arbatrary size)
I have a destination rect of set size (96x96)
Currently I just StretchBlt.
I would like to maintan the aspect ratio with a black backgound.
Any ideas? (theroy, steps, process not just cut/paste code)
Thanks up front,
Aman
Well.. it''s actually pretty simple... you could trying something like this..
Basically what this does is checks which ratio is going to be larger (X or Y ratio). If the x is larger, then the bitmap will be completely across, and leave gaps at the top/bottom (to keep aspect ratio). If the y is larger, then the opposite happens. It''s really simple actually.
Billy - BillyB@mrsnj.com
Disclaimer: This was written in this text box, and is subject to mispellings, and non-compiling problems without warning... so use at your own risk :o)
void BlitImage(long DestHdc, long SrcHdc, BitmapSizeX, BitmapSizeY) { float Ratio, size; if (BitmapSizeX>BitmapSizeY) //X > Y! { Ratio = 96.0/BitmapSizeX; size = Ratio*BitmapSizeY; //Size Y in new ratio!//48.0-size/2.0 centers the bitmap! StretchBlt(DestHdc,0,48.0- size/2.0,96.0,size,SrcHdc,0,0,BitmapSizeX,BitmapSizeY,SRCCOPY); } else //Y > X! { Ratio = 96.0/BitmapSizeY; size = Ratio*BitmapSizeX; //Size X in new ratio!//48.0-size/2.0 centers the bitmap! StretchBlt(DestHdc,48.0-size/2.0,0,size,96.0,SrcHdc,0,0,BitmapSizeX,BitmapSizeY,SRCCOPY); }} Basically what this does is checks which ratio is going to be larger (X or Y ratio). If the x is larger, then the bitmap will be completely across, and leave gaps at the top/bottom (to keep aspect ratio). If the y is larger, then the opposite happens. It''s really simple actually.
Billy - BillyB@mrsnj.com
Disclaimer: This was written in this text box, and is subject to mispellings, and non-compiling problems without warning... so use at your own risk :o)
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