How to use multiple windows in Python Plugin

Question

I wrote a plugin in PyQGIS, which contains several Ui's (using QT Designer). When I run the code in the QGIS Python console, it works wonderfully. Now I would like to make it available internally for the company as a classic QGIS plugin (start in menu bar). It always worked well with previous plugins, but there was always only one Ui.

At its core there are three important files. 1. __ init __.py, 2. geowerkzeug.py, which is responsible for starting from the menu, and 3. functionality.py, which contains all my functions.

##__init__.py   
 from Plugin.geowerkzeug import GeoWerkzeug
    
    def classFactory(iface):
        plugin = GeoWerkzeug(iface)
        return plugin

Now the geowerkzeug.py:

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from plugin.functionality import *
from qgis.utils import iface
import os

class GeoWerkzeug:

    def __init__ (self, iface):
        self.iface = iface

    def initGui (self):
        self.startButton = QAction("Plugin starten", self.iface.mainWindow())    
        self.iface.addPluginToMenu('Plugin', self.startButton)
        self.startButton.triggered.connect(self.maskeAufrufen)

    def unload (self):
        self.iface.removePluginMenu('Plugin', self.startButton)

    def maskeAufrufen (self):
        self.gui = MainWindow(self)
        dock_widget = QDockWidget("Plugin", self.iface.mainWindow())
        dock_widget.setWidget(self.gui)
        self.iface.addDockWidget(QtCore.Qt.RightDockWidgetArea, dock_widget)
        dock_widget.setAllowedAreas(QtCore.Qt.RightDockWidgetArea) 
        self.gui.show()

Up to here it works. MainWindow is the first class on functionality.py. The window will appear. But if I click on a button to switch to the next Ui (class), the Ui does not change. I have a total of 17 Ui's in my plugin. Here I only show two classes as an example.

Now the functionality.py:

from PyQt5.uic import loadUi
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import *
from PyQt5 import *
from qgis.core import *
from qgis.utils import iface
from qgis.gui import *
import processing
from PyQt5 import uic
import os

pluginPath = os.path.dirname(__file__)
uiPath = os.path.join(pluginPath, 'mainwindow.ui')
uiPath_second_window = os.path.join(pluginPath, 'window2.ui')

WIDGET, BASE = uic.loadUiType(uiPath)

widget = QDockWidget()

class MainWindow(BASE, WIDGET):
def __init__(self, parent=None):
        super(MainWindow, self).__init__()
        self.gui = loadUi(uiPath, self)
        self.window_second.clicked.connect(self.next_window)

    def next_window(self):
        window_the_second=Second_window()
        widget.setWidget(window_the_second)

class Second_window(BASE, WIDGET):
    def __init__(self):
        super(Second_window, self).__init__()
        self.gui = loadUi(uiPath_second_window , self)

My biggest problem with understanding is how to correctly link my code from functionality.py (which runs in the console) with the other two files. The next problem is that I don't even get an error message that I could build on. The plugin is in the menu bar and it can be started, but after that I can't get any further. I hope my explanations are understandable.

score 2 · Accepted Answer · answered Aug 21 '21 at 19:08

The main issue which causes the second window not to appear, is that you never show the QDockWidget. With widget.setWidget(window_the_second) you set the content, but it doesn't make the window appear.

In your method that shows the first window, add the dockwidget with self.iface.addDockWidget(QtCore.Qt.RightDockWidgetArea, widget)

then set your first window as content of that dockwidget (widget.setWidget(self.gui)).

In general, you got some things a bit mixed up, so I'll try to clarify two points.

The contents of a window are set by subclassing the results of uic.loadUiType. In order to have a second window display your second ui, you can't sublass the same BASE and WIDGET. Call uic.loadUiType for each of your UI-Files instead.
You are missing a call to setupUi() to initialize the UI. Then you can also get rid of any loadUi.

Implementing my advices then results in the following:

WIDGET, BASE = uic.loadUiType('1.ui')
WIDGET2, BASE2 = uic.loadUiType('2.ui')

widget = QDockWidget()

class GeoWerkzeug:

    def __init__ (self, iface):
        self.iface = iface

    def initGui (self):
        self.startButton = QAction("Plugin starten", self.iface.mainWindow())    
        self.iface.addPluginToMenu('Plugin', self.startButton)
        self.startButton.triggered.connect(self.maskeAufrufen)

    def unload (self):
        self.iface.removePluginMenu('Plugin', self.startButton)

    def maskeAufrufen (self):
        # add DockWidget to GUI
        self.iface.addDockWidget(QtCore.Qt.RightDockWidgetArea, widget)
        widget.setAllowedAreas(QtCore.Qt.RightDockWidgetArea) 
        # set first window as content of the DockWidget 
        self.gui = MainWindow(self)
        widget.setWidget(self.gui)

class MainWindow(BASE, WIDGET):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__()
        self.setupUi(self)
        self.window_second.clicked.connect(self.next_window)

    def next_window(self):   
        # set second window as content of the DockWidget  
        window_the_second=Second_window()
        widget.setWidget(window_the_second)

class Second_window(BASE2, WIDGET2):
    def __init__(self):
        super(Second_window, self).__init__()
        self.setupUi(self)

How to use multiple windows in Python Plugin

1 Answers1