scaleSimple 
  Create a new pixbuf containing a copy of src scaled to dest_width x dest_height.
This function leaves src unaffected.
The interp_type should be GDK_INTERP_NEAREST if you want maximum speed (but when scaling down GDK_INTERP_NEAREST is usually unusably ugly). The default interp_type should be GDK_INTERP_BILINEAR which offers reasonable quality and speed.
You can scale a sub-portion of src by creating a sub-pixbuf pointing into src; see method@GdkPixbuf.Pixbuf.new_subpixbuf.
If dest_width and dest_height are equal to the width and height of src, this function will return an unscaled copy of src.
For more complicated scaling/alpha blending see method@GdkPixbuf.Pixbuf.scale and method@GdkPixbuf.Pixbuf.composite.
Return
the new pixbuf
Parameters
the width of destination image
the height of destination image
the interpolation type for the transformation.