Hello,
Drawing functions in GUIX accept absolute co-ordinates only. This means that if your widget sits at 100,100, you should call gx_canvas_pixelmap_draw(100, 100, p_pixelmap); Moreover, you can use widget properties to get this position automatically: gx_canvas_pixelmap_draw(p_widget->gx_widget_size.gx_rectangle_left, p_widget->gx_widget_size.gx_rectangle_top, p_pixelmap);. In order to center your image, use gx_widget_size members and known screen dimensions to apply necessary offset when calling gx_canvas_pixelmap_draw.
Regards