the width of destination image
the height of destination image
the interpolation type for the transformation.
overall alpha for source image (0..255)
the size of checks in the checkboard (must be a power of two)
the color of check at upper left
the color of the other check
the new #GdkPixbuf, or %NULL if not enough memory could be allocated for it.
Creates a new #GdkPixbuf by scaling @src to @dest_width x @dest_height and alpha blending the result with a checkboard of colors @color1 and @color2.