Writing correct bitmap file results - c++

Question

Story:
I have been creating a font renderer for directx9 to draw text, The actual problem got caused by another problem, I was wondering why the texture didnt draw anything (my wrong bitmap), so i tried to copy the bitmap into a file and realized the current problem. yay
Question:
What exactly am i doing wrong? I mean, i just simply copy my CURRENT pixel array in my bitmap wrapper to a file with some other content ( the bitmap infos ), i have seen in an hex editor that there are colors after the bitmap headers.
Pictures:
This is the result of the bitmap which i have written to the filesystem
Code:
CFont::DrawGlyphToBitmap
This code does copy from a bitmap of an freetype glyph ( which have by the way a pixel format of FT_PIXEL_MODE_BGRA ) to the
font bitmap wrapper class instance
void CFont::DrawGlyphToBitmap ( unsigned char * buffer, int rows, int pitch, int destx, int desty, int format )
{
CColor color = CColor ( 0 );
for ( int row = 0; row < rows; row++ )
{
int x = 0;
for ( int left = 0; left < pitch * 3; left += 3,x++ )
{
int y = row;
unsigned char* cursor = &buffer [ ( row*pitch ) + left ];
color.SetAlphab ( 255 );
color.SetBlueb ( cursor [ 0 ] );
color.SetGreenb ( cursor [ 1 ] );
color.SetRedb ( cursor [ 2 ] );
m_pBitmap->SetPixelColor ( color, destx + x, desty + y );
}
}
}
CBitmap::SetPixelColor
This code does set a single "pixel" / color in its local pixel storage.
void CBitmap::SetPixelColor ( const CColor & color, int left, int top )
{
unsigned char* cursor = &m_pBuffer [ ( m_iPitch * top ) + ( left * bytes_per_px ) ];
cursor [ px_red ] = color.GetRedb ( );
cursor [ px_green ] = color.GetGreenb ( );
cursor [ px_blue ] = color.GetBlueb ( );
if ( px_alpha != 0xFFFFFFFF )
cursor [ px_alpha ] = color.GetAlphab ( );
}
CBitmap::Save
Heres a outcut of the function which writes
the bitmap to the file system, it does shows how
i initialize the bitmap info container ( file header & "dib" header )
void CBitmap::Save ( const std::wstring & path )
{
BITMAPFILEHEADER bitmap_header;
BITMAPV5HEADER bitmap_info;
memset ( &bitmap_header, 0, sizeof ( BITMAPFILEHEADER ) );
memset ( &bitmap_info, 0, /**/sizeof ( BITMAPV5HEADER ) );
bitmap_header.bfType = 'B' + ( 'M' << 8 );//0x424D;
bitmap_header.bfSize = bitmap_header.bfOffBits + ( m_iRows * m_iPitch ) * 3;
bitmap_header.bfOffBits = sizeof ( BITMAPFILEHEADER ) + sizeof ( BITMAPV5HEADER );
double _1px_p_m = 0.0002645833333333f;
bitmap_info.bV5Size = sizeof ( BITMAPV5HEADER );
bitmap_info.bV5Width = m_iPitch;
bitmap_info.bV5Height = m_iRows;
bitmap_info.bV5Planes = 1;
bitmap_info.bV5BitCount = bytes_per_px * 8;
bitmap_info.bV5Compression = BI_BITFIELDS;
bitmap_info.bV5SizeImage = ( m_iPitch * m_iRows ) * 3;
bitmap_info.bV5XPelsPerMeter = m_iPitch * _1px_p_m;
bitmap_info.bV5YPelsPerMeter = m_iRows * _1px_p_m;
bitmap_info.bV5ClrUsed = 0;
bitmap_info.bV5ClrImportant = 0;
bitmap_info.bV5RedMask = 0xFF000000;
bitmap_info.bV5GreenMask = 0x00FF0000;
bitmap_info.bV5BlueMask = 0x0000FF00;
bitmap_info.bV5AlphaMask = 0x000000FF;
bitmap_info.bV5CSType = LCS_WINDOWS_COLOR_SPACE;
...
-> the other part does just write those structures & my px array to file
}
CBitmap "useful" macros
i made macros for the pixel array because ive "changed" the
pixel "format" many times -> to make it "easier" i have made those macros which make it easier todo that
#define bytes_per_px 4
#define px_red 0
#define px_green 1
#define px_blue 2
#define px_alpha 3
Notes
My bitmap has a color order of RGBA

Answer 1

This calculation is wrong:
&m_pBuffer [ ( m_iPitch * top ) + ( left * bytes_per_px ) ]
It should be:
&m_pBuffer [ ( ( m_iPitch * top ) + left ) * bytes_per_px ]
Each row is m_iPitch * bytes_per_px bytes wide. If you just multiply by m_iPitch, then your "rows" are overlapping each other.