How to show a moving progress bar in QGIS

Question

I want to sum values and during do it, a window shows progress percentage. I write below code but when I run it in qgis python console, qgis crashes. what is error in this code?

from qgis.PyQt.QtGui import *
from qgis.PyQt.QtWidgets import *

def progdialog(progress):
    dialog = QProgressDialog()
    dialog.setWindowTitle("Progress")
    dialog.setLabelText("text")

    bar = QProgressBar(dialog)
    bar.setTextVisible(True)
    bar.setValue(progress)
    dialog.setBar(bar)
    dialog.setMinimumWidth(300)
    dialog.show()

def calc(x, y):
    sum = 0
    progress = 0
    for i in range(x):
        for j in range(y):
            k = i + j
            sum =+ k
            progress =+1
            progdialog(progress)
    print sum

calc(10000, 2000)

Answer 1

I think there's a few minor issues:

• You're using =+ which means you're setting it to equal a positive value. I think you meant to use += which adds and sets the new value to the variable.

• Within your two for loops, you are calling the progdialog() function x*y times. Each time it is recreating the progress dialog and bar instead of updating it. I'm guessing this cause QGIS to crash.

• As @gisnside mentioned, you need to set the progress values accordingly.

---

You could try using the following which calls the progdialog function once and returns the reference to the progress dialog and bar:

from PyQt4.QtGui import QProgressDialog, QProgressBar

def progdialog(progress):
    dialog = QProgressDialog()
    dialog.setWindowTitle("Progress")
    dialog.setLabelText("text")
    bar = QProgressBar(dialog)
    bar.setTextVisible(True)
    bar.setValue(progress)
    dialog.setBar(bar)
    dialog.setMinimumWidth(300)
    dialog.show()
    return dialog, bar

def calc(x, y):
    dialog, bar = progdialog(0)
    bar.setValue(0)
    bar.setMaximum(100)
    sum = 0
    progress = 0
    for i in range(x):
        for j in range(y):
            k = i + j
            sum += k
        i += 1
        progress = (float(i) / float(x)) * 100
        bar.setValue(progress)
    print sum

calc(10000, 2000)