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Creating and Printing a Bitmap from a Dialog

I was handed down a CDialog based program. This program does all sorts of graphing, and just doodles all over the dialog area (using SetPixelV, LineTo, etc). What I want to do is know the most efficient code for extracting a rectangular region of pixels from the dialog area, and spooling them out to the printer so that it fills exactly the entire page no matter what printer I am on.

Example to make myself more clear:
There is a dialog box. There are no controls or buttons or anything on it whatsoever. Some stuff was doodled onto it.
The dialog boxes coordinates are (0,0 to 400,400)
I want to extract a (50,50 to 200,200) rect from the dialog box and send it to the printer in such a way that it always fills one full piece of paper.

How do I accomplish this the best possible way?
Thanks in advance.
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lesinsm
Asked:
lesinsm
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1 Solution
 
galkinCommented:
The easieast way is to stretch dialog area giving dialog window HDC directly to printer DC with StrechBlt. The problem can be if dialog area contains color graphics. In this case you should copy dialog area into compatible bitmap selected into memory DC, then convert this memory DDB into 24 bit DIB and only then send this DIB to printer with StretchDIBits. In this case printer will perform the best dithering.
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lesinsmAuthor Commented:
How do you convert the memory from DDB into 24-bit DIB?
Thanks, Galkin!
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galkinCommented:
It is not trivial task. You cannot use any of syetm DIB API since they are dealing with HDC but you cannot use printer DC as b/w printer contains only two colows. so if you try to convert other then two colow bitmap any function will fail. you will have to allocate memory block 3 * height * width bytes in heap with GlobalAlloc, Then lock it with GlobalLock. Then directly set RGB value for each bits in this memory block. handle to this memory is your DIB handle. you can use StretchDIBits to send this DIB to the printer.
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