DIBs and BMP's

Tommy2k

In my project, i just PNG's for the GUI's graphics. I can paint them on the canvas using StretchDIBits. Problem is that my project has some dialogs too, in which i use Static controls to hold a BMP image. Is there a way to convert a DIB image to a BMP handle that i can use in such a dialog other than writing the Dib as a BMP to the harddisk and loading it again?

Gary R Wheeler

The following steps should do it:

Create a bitmap compatible with the screen device context.
Create a memory device context compatible with the screen.
Select the bitmap created in step 1 into the DC created in step 2. Be sure to save the return value, so you can restore the original bitmap.
Draw the PNG into the memory device context using StretchDIBits, or whatever's appropriate.
Restore the original bitmap into the memory device context. This 'detaches' the bitmap created in step 1 from the memory device context.

The bitmap created in step 1 now contains the image from the PNG, rendered in a fashion that's compatible with the screen. You can then use SetBitmap to display the image in the static controls in your dialog.

Software Zen: delete this;

Ryan Binns

If you've got a HBITMAP handle for your DIB, then the static control will display it directly. To create an HBITMAP from DIB data, use CreateDIBitmap(). Hope this helps Ryan Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Gary R Wheeler

Nice answer. I had a feeling mine was too complicated :-O.

Software Zen: delete this;

Ryan Binns

:-O Thanks. I got a bit confused when he started out talking about PNGs, but then he said his question was how to convert a DIB to a HBITMAP, so that bit was easy :). I just assumed the PNG to be a typo or unnecessary information. Ryan Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Tommy2k

well i did it this way: HDC hDC = GetDC(); HDC memDC = CreateCompatibleDC ( hDC ); HBITMAP memBM = CreateCompatibleBitmap (hDC,dib->biWidth,dib->biHeight); HBITMAP memBM2 = CreateCompatibleBitmap (hDC,dib->biWidth,dib->biHeight); memBM2 = (HBITMAP)SelectObject ( memDC, memBM ); StretchDIBits(memDC,0,0,dib->biWidth,dib->biHeight,0,0,dib->biWidth,dib->biHeight,lpbits,(LPBITMAPINFO)&dib,DIB_RGB_COLORS,SRCCOPY); memBM = (HBITMAP)SelectObject(memDC,memBM2); ReleaseDC(memDC); CStatic temp = GetDlgItem (IDC_LOGO); temp.SetBitmap((HBITMAP)memBM); and it only draws a black square...size is ok though...

Tommy2k

I dont think i can use this sollution because i only have these things handy: BITMAPINFOHEADER dib; int dib_size, dib_bits_offs; char * lpbits; So i don't see how i can work with that functions...

Ryan Binns

That's all you need. The BITMAPINFO structure is simply a BITMAPINFOHEADER followed by a colour table, which I assume you've got. If your image is 16-bit or above, no colour table is needed, so you don't have to worry about it. For a 16, 24, or 32-bit image, just do this:

BITMAPINFO bi = { dib, 0 };
HBITMAP hbm = CreateDIBitmap(hDC, &dib, CBM_INIT, lpbits, &bi, DIB_RGB_COLORS);

For a 256 or less colour image, you'll need to include the colour table in the BITMAPINFO structure. Ryan Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Ryan Binns

You don't need to create the second bitmap, as it is returned by SelectObject(). Also, you're overwriting memBM with the second SelectObject(). Try this:

HDC hDC = GetDC();
HDC memDC = CreateCompatibleDC ( hDC );
HBITMAP memBM = CreateCompatibleBitmap (hDC,dib->biWidth,dib->biHeight);
HBITMAP memBM2;
memBM2 = (HBITMAP)SelectObject ( memDC, memBM );

StretchDIBits(memDC,0,0,dib->biWidth,dib->biHeight,0,0,dib->biWidth,dib->biHeight,lpbits,
(LPBITMAPINFO)&dib,DIB_RGB_COLORS,SRCCOPY);

SelectObject(memDC,memBM2);
ReleaseDC(memDC);

CStatic *temp = (CStatic*)GetDlgItem (IDC_LOGO);
temp->SetBitmap((HBITMAP)memBM);

Also make sure that your BITMAPINFOHEADER is setup correctly. I assume it is because you mentioned you can draw it elsewhere. If the image is 256 colours or less, the BITMAPINFOHEADER structure is NOT equivalent to a BITMAPINFO structure. The BITMAPINFO structure contains a BITMAPINFOHEADER plus the colour table. If the image has more than 256 colours, the colour table is not used and not required. For less than 256 colours it is. Ryan Being little and getting pushed around by big guys all my life I guess I compensate by pushing electrons and holes around. What a bully I am, but I do enjoy making subatomic particles hop at my bidding - Roger Wright (2nd April 2003, The Lounge)
Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late - John Nichol "Point Of Impact"

Tommy2k

Great :-D, it works! Thank you all :-)