PixbufSaveFunc

Save functions used by method@GdkPixbuf.Pixbuf.save_to_callback.

This function is called once for each block of bytes that is "written" by gdk_pixbuf_save_to_callback().

If successful it should return TRUE; if an error occurs it should set error and return FALSE, in which case gdk_pixbuf_save_to_callback() will fail with the same error.

• param count number of bytes in @buf.

• return TRUE if successful, FALSE otherwise