Bitmap problem

Have you checked both the picture''s and primary/back- buffers lPitch ??

Sometimes the pitch are not the same as the width.

/maq

The picture''s pitch could be different from the width?? I don''t know if that would make any difference anyway, though. As it happens, I''m always drawing from a RECT in the source picture.

And as far as I know, the picture''s width is always the picture''s width. It''s also stored in a single dimensional array..

But yes I check the backbuffer. When one of the picture''s is the wrong size, and is drawn skewed, the others still draw correctly, so it''s something that only effects certain widths of bitmaps.

Do you take care of the extra bytes after each line in the bmp file? After each horizontal line bmp puts in a couple of empty bytes to make it dividable by four... I know most numbers are dividable by four but I hope you see what I mean...


Edited by - Geradian on 5/1/00 3:52:47 AM

I was unaware that the format put extra bytes at the end.. I think this could describe the problem, but where can I find more info on this?

We saw the same thing here by looking at the data through a hex editor.

"... you act as if stupidity were a virtue."
-- Flight of the Phoenix

Here is a part of my reading routine. It supposes that the file has already been read into
memory. I am currently only supporting 1 bit and 24 bit modes. Mainly because I can''t manage
to create a bmp file in 32 bit and 16 bit . Why I don''t have 8 bit is because I am lazy!

HRESULT clsSurface::ReadBMPFromMemory(char *Offset)
{
HRESULT hr;
LPBITMAPFILEHEADER BMPFileHeader;
LPBITMAPINFOHEADER BMPInfoHeader;
clsColor Color;
clsColor Palette[255]; //Used when reading in palette. Max is 256 entries.
int X,
Y,
Mod,
Mod2; //Sometime I need two mods...
unsigned char Counter;

//Get the file header.
BMPFileHeader = (LPBITMAPFILEHEADER) Offset;

//Check so this is a window bitmap.
if(BMPFileHeader->bfType != 19778)
return -1;

//Get the info header.
BMPInfoHeader = (LPBITMAPINFOHEADER) (Offset + 14);

//Make sure this size is a windows bitmap.
if(BMPInfoHeader->biSize != 40)
return -1;

//Make sure it ain''t compressed.
if(BMPInfoHeader->biCompression != 0)
return -1;

//Create the surface.
hr = Create(BMPInfoHeader->biWidth, BMPInfoHeader->biHeight);
if FAILED(hr)
return hr;

//Check the bit depth.
switch(BMPInfoHeader->biBitCount)
{
case 1:
//Read in the palette.
for(Counter = 0; Counter < BMPInfoHeader->biClrUsed; Counter++)
{
Palette[Counter].Blue = (int) *(Offset + 54 + (Counter * 4) );
Palette[Counter].Green = (int) *(Offset + 54 + (Counter * 4) + 1);
Palette[Counter].Red = (int) *(Offset + 54 + (Counter * 4) + 2);
}

//Run through all pixels.
Offset += BMPFileHeader->bfOffBits;
Mod = Width % 8;
Mod2 = ((Mod + Width) / 8) % 4;
for(Y = Height - 1; Y >= 0; Y--)
{
for(X = 0; X < Width
{
Counter = 128;
//Run through each byte in this line
do
{
if( (* (Offset + X/8) ) & Counter )
Color.Color = 1;
else
Color.Color = 0;

Color.Red = Palette[ Color.Color ].Red;
Color.Green = Palette[ Color.Color ].Green;
Color.Blue = Palette[ Color.Color ].Blue;
DrawPixel(X, Y, Color);
X++;

if(Counter == 1)
Counter = 0;
else
Counter -= (Counter/2);
} while(Counter > 0);
}
Offset += ((Width + Mod)/8) + Mod2;
}

break;
case 16:
break;
case 24:
Mod = Width % 4;
Offset += BMPFileHeader->bfOffBits ;

//Run through all the pixels.
for(Y = Height - 1; Y >= 0; Y--)
{
for(X = 0; X < Width; X++)
{
//Extract the red, green and blue component.
Color.Red = (char) *Offset;
Color.Green = (char) *(Offset + 1);
Color.Blue = (char) *(Offset + 2);

hr = DrawPixel(X, Y, Color);
if FAILED(hr)
return hr;

Offset += 3;
}
Offset += Mod;
}

break;
case 32:
break;
}

return 0;
}