Month: September 2020

# from PySide import QtGui
from PyQt4 import QtGui

class CustomTextBrowser(QtGui.QTextBrowser):
    '''Reimplment show event to append text'''

    def showEvent(self, event):
        # do stuff here 
        #self.append('This random text string ')
        event.accept()

References
https://stackoverflow.com/questions/36975782/how-to-connect-signal-after-the-display-of-a-page-in-pyqt-wizard

import PyQt5.QtWidgets
print(PyQt5.QtWidgets.QStyleFactory.keys())
['Breeze', 'Oxygen', 'QtCurve', 'Windows', 'Fusion']

app = QApplication([])
app.setStyle('Windows')

References
https://pythonbasics.org/pyqt-style/

class Form(QMainWindow):
    finished = pyqtSignal()
    updateProgress = pyqtSignal(int) # use Slot in PySide2

    def __init__(self, parent=None):
        super(Form, self).__init__(parent)
        ...
        self.updateProgress.connect(self.ui.progressBar.setValue)

    def run_test(self):
        for i in range(100):
            per = i + 1
            self.updateProgress.emit(per)
            ...

References
https://stackoverflow.com/questions/42682544/pyqt5-listwidget-add-list-items

from PySide2.QtGui import *
from PySide2.QtWidgets import *
from PySide2.QtCore import *

import time
import traceback, sys


class WorkerSignals(QObject):
    '''
    Defines the signals available from a running worker thread.

    Supported signals are:

    finished
        No data
    
    error
        `tuple` (exctype, value, traceback.format_exc() )
    
    result
        `object` data returned from processing, anything

    progress
        `int` indicating % progress 

    '''
    finished = Signal()
    error = Signal(tuple)
    result = Signal(object)
    progress = Signal(int)




class Worker(QRunnable):
    '''
    Worker thread

    Inherits from QRunnable to handler worker thread setup, signals and wrap-up.

    :param callback: The function callback to run on this worker thread. Supplied args and 
                     kwargs will be passed through to the runner.
    :type callback: function
    :param args: Arguments to pass to the callback function
    :param kwargs: Keywords to pass to the callback function

    '''

    def __init__(self, fn, *args, **kwargs):
        super(Worker, self).__init__()

        # Store constructor arguments (re-used for processing)
        self.fn = fn
        self.args = args
        self.kwargs = kwargs
        self.signals = WorkerSignals()    

        # Add the callback to our kwargs
        self.kwargs['progress_callback'] = self.signals.progress        

    @Slot()
    def run(self):
        '''
        Initialise the runner function with passed args, kwargs.
        '''
        
        # Retrieve args/kwargs here; and fire processing using them
        try:
            result = self.fn(*self.args, **self.kwargs)
        except:
            traceback.print_exc()
            exctype, value = sys.exc_info()[:2]
            self.signals.error.emit((exctype, value, traceback.format_exc()))
        else:
            self.signals.result.emit(result)  # Return the result of the processing
        finally:
            self.signals.finished.emit()  # Done



class MainWindow(QMainWindow):


    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
    
        self.counter = 0
    
        layout = QVBoxLayout()
        
        self.l = QLabel("Start")
        b = QPushButton("DANGER!")
        b.pressed.connect(self.oh_no)
    
        layout.addWidget(self.l)
        layout.addWidget(b)
    
        w = QWidget()
        w.setLayout(layout)
    
        self.setCentralWidget(w)
    
        self.show()

        self.threadpool = QThreadPool()
        print("Multithreading with maximum %d threads" % self.threadpool.maxThreadCount())

        self.timer = QTimer()
        self.timer.setInterval(1000)
        self.timer.timeout.connect(self.recurring_timer)
        self.timer.start()
    
    def progress_fn(self, n):
        print("%d%% done" % n)

    def execute_this_fn(self, progress_callback):
        for n in range(0, 5):
            time.sleep(1)
            progress_callback.emit(n*100/4)
            
        return "Done."
 
    def print_output(self, s):
        print(s)
        
    def thread_complete(self):
        print("THREAD COMPLETE!")
 
    def oh_no(self):
        # Pass the function to execute
        worker = Worker(self.execute_this_fn) # Any other args, kwargs are passed to the run function
        worker.signals.result.connect(self.print_output)
        worker.signals.finished.connect(self.thread_complete)
        worker.signals.progress.connect(self.progress_fn)
        
        # Execute
        self.threadpool.start(worker) 

        
    def recurring_timer(self):
        self.counter +=1
        self.l.setText("Counter: %d" % self.counter)
    
    
app = QApplication([])
window = MainWindow()
app.exec_()

References
https://www.learnpyqt.com/courses/concurrent-execution/multithreading-pyqt-applications-qthreadpool/