How to proportionally adjust column widths in a QTableView?

Question

I want to proportionally change the column width of all columns in a QTableView widget, so that each column has the same width regardless of the data. For example, if a table has three columns, each column should always have a width of one third of the available horizontal space - and the width should be automatically updated whenever the dialog is resized by the user.

So far I've only managed to resize columns to their contents, which is not what I want. Here's the code I've got so far:

main.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Dialog</class>
 <widget class="QDialog" name="Dialog">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>624</width>
    <height>329</height>
   </rect>
  </property>
  <property name="sizePolicy">
   <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
    <horstretch>0</horstretch>
    <verstretch>0</verstretch>
   </sizepolicy>
  </property>
  <property name="windowTitle">
   <string>Dialog</string>
  </property>
  <layout class="QVBoxLayout" name="verticalLayout">
   <item>
    <layout class="QHBoxLayout" name="horizontalLayout">
     <item>
      <widget class="QTableView" name="tableView">
       <property name="alternatingRowColors">
        <bool>true</bool>
       </property>
       <property name="selectionBehavior">
        <enum>QAbstractItemView::SelectRows</enum>
       </property>
      </widget>
     </item>
     <item>
      <layout class="QVBoxLayout" name="verticalLayout_2">
       <item>
        <widget class="QPushButton" name="btnPopulate">
         <property name="text">
          <string>Populate</string>
         </property>
        </widget>
       </item>
      </layout>
     </item>
    </layout>
   </item>
  </layout>
 </widget>
 <tabstops>
  <tabstop>btnPopulate</tabstop>
 </tabstops>
 <resources/>
 <connections/>
</ui>

test.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import sys, os
from PyQt5 import uic
from PyQt5.QtGui import QStandardItemModel
from PyQt5.QtWidgets import QDialog, QApplication, QHeaderView

class GUI(QDialog):

    def __init__(self):
        super(GUI, self).__init__()
        dirname = os.path.dirname(os.path.abspath(__file__))
        uic.loadUi(os.path.join(dirname,'main.ui'), self)
        # button
        self.btnPopulate.clicked.connect(self.populate)
        # table model
        self.header = ['col1', 'col2', 'col3']
        self.QSModel = QStandardItemModel()
        self.QSModel.setColumnCount(3)
        self.QSModel.setHorizontalHeaderLabels(self.header)
        # table view
        self.tableView.setModel(self.QSModel)
        self.tableView.setWordWrap(True)
        self.tableView.horizontalHeader().setStretchLastSection(False)

    def populate(self):
        self.longtext = '''Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla ac tellus nunc. Phasellus imperdiet leo metus, et gravida lacus. Donec metus ligula, elementum at pellentesque pellentesque, suscipit ac nunc.'''
        row = self.QSModel.rowCount()
        for x in range(7):
            self.QSModel.insertRow(row)
            self.QSModel.setData(self.QSModel.index(row, 0), 'Lorem ipsum')
            self.QSModel.setData(self.QSModel.index(row, 1), self.longtext)
            self.QSModel.setData(self.QSModel.index(row, 2), 'Lorem ipsum')
        self.tableView.resizeColumnsToContents()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = GUI()
    window.show()
    sys.exit(app.exec_())

I've got the following questions:

1. How do I change the code to proportionally adjust the column widths?
2. Why doesn't setWordWrap(True) wrap the text?

Answer 1

This can be achieved by setting the section resize mode. To get equal column widths:

self.tableView.horizontalHeader().setSectionResizeMode(QHeaderView.Stretch)

To wrap the contents vertically:

self.tableView.verticalHeader().setSectionResizeMode(QHeaderView.ResizeToContents)

There is no need to call resizeToContents, setWordWrap or setStretchLastSection. Calling setWordWrap(False) will switch to eliding the text on the right, rather than wrapping.

Note that since the row/column resizing is done automatically, the sizes can no longer be changed by the user or programmatically.