Read Parameters Like Eta From Youtube-dl

Hi I would like to read the output from youtube dl on cmd and put in my wxpython program. This is the function I used. def execute(self,command,textctrl):

Solution 1:

As long as you are blocked in this function and are not letting control return to the event loop, then there can be no events dispatched to handlers. With no events being sent and processed, there can be no repainting of the contents of the widgets, no interaction with with the mouse and keyboard, nothing. Basically the application is frozen because your execute function is not letting its heart beat and the brain is cut off from the rest of the body.

When programming GUIs or other implementations of event driven programming the key is to never do anything in an event handler or callback that would take more than a noticeable (by a human) amount of time before it returns to the event loop. If you have something that will take longer than that time, then you need to redesign it so the long running task is managed a different way.

One way would be to set things up in the event handler (such as starting the process) and then return from the event handler. Part of that setup would be to start a timer that comes back periodically and checks if there is output available. If so then read it (without blocking) and process it, and then return to the event loop again. Continue until the process is done and then stop the timer after the last chunk of data is processed.

Another approach is to use a thread to run the long running task. This is a common approach but you need to be careful to not manipulate any UI objects from the worker thread. So in your example the text you read from the process will need to be sent back to the GUI thread in order to have it appended to the text control. wx.CallAfter is an easy way to do that.

See https://wiki.wxpython.org/LongRunningTasks for more details and some examples.