Question

I have little experience in GUI programming but I’m writing a GUI application with PyQt. With this application, user can open a binary file and do some editing with it.

When the file is opened, I do some processing that takes a while (~15s). So when the user pick the file and press the “Open” button in the file open dialog, the GUI is frozen. What’s the best way to achieve a better user experience?

Thanks

Answer 1

Load in the background showing the progress via a Gauge in the statusbar.

To to this, you can initiate the loading using QThread. Your thread class can look as follows (assuming parent will have an attribute progress):

QtFileLoader(QtCore.QThread):
    def __init__(self,parent=None, filepath=None):
        QtCore.QThread.__init__(self,parent)
        self.data = None
        self.filepath = filepath

    def run(self):
        """ load data in parts and update the progess par """
        chunksize = 1000
        filesize = ... # TODO: get length of file
        n_parts = int(filesize/chunksize) + 1
        with open(self.filepath, 'rb') as f:
            for i in range(n_parts):
                self.data += f.read(chunksize)
                self.parent.progress = i 

The question whether to use QThread or trheading.Thread is discussed here

edit (according to hint of @Nathan):
On the parent, a timerfunction should check, say each 100ms, the value of self.parent.progress and set the progressbar accordingly. This way, the progressbar is set from within the main thread of the GUI.