My Windows Graphics Tutorial

[Gunther]

Dave,

the BMP image format includes (contains) a DIB
and - as far as i know, all uncompressed DIB lines are always multiples of 4 bytes
no matter what the bit-depth or image width are

yes. In a certain way, this is a waste of memory space.

Gunther

[jj2007]

if EAX is non-zero, then GetLastError returns undefined
(i.e., GetLastError is only meaningful if EAX tells you to look at it)

I know, but it's still very irritating to see that particular "not enough memory" error in this context. Plain stupid, dear friends in Richmond

and - if you want to calc the size, don't forget that DIB lines are always multiples of 4 bytes

as TWell rightly mentioned, see above; however, it works fine without the size.

Working example (plain Masm32) attached. Something's wrong with RGB - it turns out as BGR...

[TWell]

yes. In a certain way, this is a waste of memory space.

Gunther

Performance/aligning reasons.

the BMP image format includes (contains) a DIB
and - as far as i know, all uncompressed DIB lines are always multiples of 4 bytes
no matter what the bit-depth or image width are

24-bit DIB biSizeImage ?

Code Select Expand

    // Calculate the image size in bytes
    bmpInfoHeader.biSizeImage = lWidth * lHeight * (wBitsPerPixel/8);

[dedndave]

the bytes in a DIB data area, as well as in a palette, are ordered B,G,R,(A)

also, if the biHeight member is positive, the top line of the image is at the higher address
if you assign it as a negative number, the bitmap is "right-side-up"
supposedly, you cannot compress a "right-side-up" image (don't ask me why - lol)

i have been meaning to make some measurements to see if blitting a "right-side-up" image is faster
probably no difference

anyways - all of this was inherited from win1 days (or earlier)
some microsoft guy had his upside-down hat on, that day

[avcaballero]

Hello, I've missed this debate, ... not much time lately... If what you want is an example of mandelbrot in win32 asm, you can get this one that I developped in nasmx

Don't know if you want to do your work by yourself, but why don't use my examples as a starting point ?... Get the code, modify it on your needs, maybe the better way ?...

Regards

PS. If you want, I can look for it and upload it here

[Gunther]

Hi Alfonso,

Hello, I've missed this debate, ... not much time lately... If what you want is an example of mandelbrot in win32 asm, you can get this one that I developped in nasmx

good idea, but the provided link hides your attachment. What about posting it here again?

Gunther

[avcaballero]

Here it goes, Gunther :icon_cool:

By the way, it is no need to create a bmp buffer, you just need a dib section (this source is dated before the dedndave's tip (thank you dave) ;) :

     case WM_PAINT :
          {
              hdc = BeginPaint(hWnd, &ps);
              //PintaObjeto ();
              bResult = BitBlt(hdc, 0, 0, cdXSize, cdYSize, bufDIBDC, 0, 0, SRCCOPY);
              EndPaint(hWnd, &ps);
              return 0 ;
          }

[dedndave]

works under XP SP3, Alfonso   :t

too bad it's Nasm, though - lol

[avcaballero]

Thank you Dave, my idea was to do all the tuto in masm, nasm, fasm and tinyc, but time is short...

[dedndave]

looking at the Nasm code - not too hard to understand   :P

[FORTRANS]

Hi,

   Runs on Windows 2000.  The code looks reasonable.  The decent
amount of comments does help.

Cheers,

Steve N.

[Gunther]

Thank you Alfonso. Works fine under Windows 7.

too bad it's Nasm, though - lol

It's not to hard to translate it into MASM syntax.

Gunther

[jj2007]

Some bits for the graphics tutorial: I've done some testing with the Mandelbrot code. Inter alia, it turns out that BitBlt is about 5% faster than SetDIBitsToDevice:

  CASE WM_PAINT
   invoke BeginPaint, hWnd, addr ps
     NanoTimer() ; MasmBasic macro - any other timer will be fine, too
     if 1      ; 1987 microseconds
      invoke SetDIBitsToDevice, hDC, 0, 0, rc.right, rc.bottom, 0, 0, 0, rc.bottom, ppvBits, offset bmi, DIB_RGB_COLORS
     else      ; 1880 us
      invoke BitBlt, hDC, 0, 0, rc.right, rc.bottom, hDC, 0, 0, SRCCOPY
   endif
   add ntSum, NanoTimer(us)  ; calculate the average
   inc ntCt
   push ntSum
   fild stack
   fidiv ntCt
   deb 4, "Paint", ST(0)  ; show average in microseconds
   fstp st
   invoke EndPaint, hWnd, addr ps

Another observation is that you don't really need a compatible memory DC when working with a DIB:

  CASE WM_SIZE   ; adjust painting rectangle (on resizing problems)
   mov edi, offset rc.right
   movzx eax, word ptr lParam   ; width of client area
   stosd
   push eax
   movzx eax, word ptr lParam+2   ; height
   stosd
   mov edi, offset bmi.bmiHeader.biHeight
   neg eax
   stosd
   pop [edi-8]   ; .biWidth
   mov ecx, oldDib
   jecxz @F
   invoke SelectObject, hDC, ecx   ; de-select,
   ; invoke DeleteDC, hMemDC   ; delete DC,
   invoke DeleteObject, hDib   ; delete old DIB
@@:   ; after a window size change, setup a new bitmap:
   ; mov hMemDC, rv(CreateCompatibleDC, hDC)
   mov hDib, rv(CreateDIBSection, hDC, addr bmi, DIB_RGB_COLORS, addr ppvBits, 0, 0)
   mov oldDib, rv(SelectObject, hDC, eax)

Works fine, but not with BitBlt, only with SetDIBitsToDevice. And it is 5-10% slower than the version with a compatible DC.