Loading color values from pixel array - c++

Question

I read this tutorial http://tipsandtricks.runicsoft.com/Cpp/BitmapTutorial.html about bitmap and it really helped..I need to read color integer values from elements of pixel array. How to do that?
Ok heres the code for putting data into rgb array
BYTE* ConvertBMPToRGBBuffer ( BYTE* Buffer, int width, int height )
{
if ( ( NULL == Buffer ) || ( width == 0 ) || ( height == 0 ) )
return NULL;
// find the number of padding bytes
int padding = 0;
int scanlinebytes = width * 3;
while ( ( scanlinebytes + padding ) % 4 != 0 ) // DWORD = 4 bytes
padding++;
// get the padded scanline width
int psw = scanlinebytes + padding;
// create new buffer
BYTE* newbuf = new BYTE[width*height*3];
// now we loop trough all bytes of the original buffer,
// swap the R and B bytes and the scanlines
long bufpos = 0;
long newpos = 0;
for ( int y = 0; y < height; y++ )
for ( int x = 0; x < 3 * width; x+=3 )
{
newpos = y * 3 * width + x;
bufpos = ( height - y - 1 ) * psw + x;
newbuf[newpos] = Buffer[bufpos + 2];
newbuf[newpos + 1] = Buffer[bufpos+1];
newbuf[newpos + 2] = Buffer[bufpos];
}
return newbuf;
}

Answer 1

It looks like your image is in RGB interleaved format. To get a pixel at (x,y), simply index the array at that location. It would be easiest if your buffer pointed to a structure type. Something like:
typedef struct RGBPixel {
BYTE red;
BYTE green;
BYTE blue;
} RGBPixel;
Then you could do something like this:
RGBPixel* pixels = (RGBPixel*)newbuf;
To get a pixel at (x,y), you'd do this:
RGBPixel aPixel = pixels [ y * width + x ];