[ft] Memory Stomp problem in FT_Embolden_Bitmap

[Ted Packard]

The code in FT_Embolden_Bitmap takes a bitmap and produces a bold 
version of it. I want to do this to use as an outline for my glyphs.

The code creates a new bitmap which may have a new pitch and then enters 
a loop to copy the data from the old bitmap to the new bitmap a scan 
line at a time.

However if there was extra padding in the original bitmap it's possible 
for the new bold bitmap to have a smaller pitch than the original 
bitmap. This is often the
case if the original bitmap was produced by the monochrome Freetype 
renderer which pads bitmaps to a 16 bit boundary.

My fix is to compute the number of bytes to copy from the pixel width 
rather than just using the pitch.
>     int nBytesToCopy = ( bitmap->width + ppb - 1 ) / ppb;
>     if ( bitmap->pitch > 0 )
>     {
>       for ( i = 0; i < bitmap->rows; i++ )
>         FT_MEM_COPY( buffer + new_pitch * ( ypixels + i ),
>                      bitmap->buffer + pitch * i, nBytesToCopy );
>     }
>     else
>     {
>       for ( i = 0; i < bitmap->rows; i++ )
>         FT_MEM_COPY( buffer + new_pitch * i,
>                      bitmap->buffer + pitch * i, nBytesToCopy );
>     }
What do you think ?

- Ted Packard