(C++) SetGreyness

The greyness of a pixels is the averaged red, green and blue value of it. You can set a single pixel's greyness, a horizontal line or a square of pixels.

To get pixels' their greynesses, use GetGreyness.

 ``` //Set a pixel's greyness //From http://www.richelbilderbeek.nl void SetGreyness(   TImage * const image,   const int x,   const int y,   const unsigned char grey) {   assert(image!=0 && "Image is NULL");   assert(image->Picture->Bitmap!=0 && "Bitmap is NULL");   assert(image->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");   assert( x >= 0 && "x coordinat is below zero");   assert( y >= 0 && "y coordinat is below zero");   assert( x < image->Picture->Bitmap->Width  && "x coordinat is beyond image width");   assert( y < image->Picture->Bitmap->Height && "y coordinat is beyond image height");   unsigned char * const myLine     = static_cast(image->Picture->Bitmap->ScanLine[y]);   myLine[x*3+2] = grey;   myLine[x*3+1] = grey;   myLine[x*3+0] = grey; } //Set a line of pixel's greyness //From http://www.richelbilderbeek.nl void SetGreyness(   TImage * const image,   const int x1,   const int x2,   const int y,   const unsigned char grey) {   assert(image!=0 && "Image is NULL");   assert(image->Picture->Bitmap!=0 && "Bitmap is NULL");   assert(image->Picture->Bitmap->PixelFormat == pf24bit && "Bitmap must be 24 bit");   assert( x1 >= 0 && "x1 coordinat is below zero");   assert( x2 >= 0 && "x2 coordinat is below zero");   assert( y >= 0 && "y coordinat is below zero");   assert( x1 < image->Picture->Bitmap->Width  && "x1 coordinat is beyond image width");   assert( x2 <= image->Picture->Bitmap->Width  && "x2 coordinat is beyond image width");   assert( y < image->Picture->Bitmap->Height && "y coordinat is beyond image height");   unsigned char * const myLine     = static_cast(image->Picture->Bitmap->ScanLine[y]);   for (int x=x1; x!=x2; ++x)   {     myLine[x*3+2] = grey;     myLine[x*3+1] = grey;     myLine[x*3+0] = grey;   } } //Set a square of pixels' greyness //From http://www.richelbilderbeek.nl void SetGreyness(   TImage * const image,   const int x1,   const int y1,   const int x2,   const int y2,   const unsigned char grey) {   for (int y=y1; y!=y2; ++y)   {     SetGreyness(image,x1,x2,y,grey);   } } ```