getting workspace with gnome visal effects

I maintain linux-desktop-audit software. My Ubuntu machine recently allowed me to enable 'visual effects' to make nice looking transitions between workspaces.

However, this broke linux-desktop-audit. So, instead of listening to 'active_workspace_changed' the code should be listening to 'viewports_changed'. Once this event fires, to get the current workspace number I use the following code:

def viewport_change (self, screen):
        self.current_workspace = screen.get_active_workspace()
        v_x = self.current_workspace.get_viewport_x()
        v_y = self.current_workspace.get_viewport_y()
        v_w = screen.get_width()
        v_h = screen.get_height()
        v_r = self.current_workspace.get_width()
        v_c = self.current_workspace.get_height()
        total_cols = v_r/v_w
        total_rows = v_c/v_h
        desk_col = v_x/v_w
        desk_row = v_y/v_h
        ws_num = desk_col + (desk_row * total_cols)