Ticket #967 (new enhancement)
Loading screens are impossible
|Reported by:||bemasc||Owned by:||erikos|
If an activity author knows that read_file is going to take a long time, it would be great to be able to show a specific loading screen, rather than waiting at the pulsing activity icon. Unfortunately, this is impossible (at least in 0.82). The problem is that set_canvas() causes read_file to be invoked, if the activity is being resumed. read_file() is invoked before the screen is drawn, so there is no way to use set_canvas() to show a loading screen.
One reason this might be is: in activity.py, set_canvas() connects 'map' to canvas_map_cb(). canvas_map_cb() then calls read_file if there is a file to read. However, disabling this callback entirely does not solve the problem. There must be something more complicated going on that prevents the activity from showing a GUI until after read_file.