pyqt5 tab area not filling the whole available space

Question

I am experimenting with a GUI - I'd like to have scrollbars and tabs. I've tinkered with the scroll bars as the "outer most" widget, with a QTabWidget inside, and also the other way around: The QTabWidget has a QWidget tab, and the QScrollArea's parent is the tab. Succinctly, I can't get the scroll area to expand to fill the available space. There are some comments below that illustrate everything I've tried. No adjustment of sizePolicies seems to help. I've looked at similar issues that other people have posted, notably Issue with scrollarea in pyqt?

# -*- coding: utf-8 -*-
"""
Created on Fri Nov 17 07:07:08 2017

@author: Erik
"""

import sys
from PyQt5.QtWidgets import QLayout, QVBoxLayout ,QTabWidget, QMainWindow,QApplication, QWidget, QSizePolicy, QScrollArea
from PyQt5.QtGui import QColor, QPalette
from PyQt5.QtCore import QSize
class Color2(QWidget):

    def __init__(self, color, *args, **kwargs):
        super(Color2, self).__init__(*args, **kwargs)
        self.setAutoFillBackground(True)
        palette = self.palette()
        palette.setColor(QPalette.Window, QColor(color))
        self.setPalette(palette)
        self.setSizePolicy(QSizePolicy(QSizePolicy.Maximum, QSizePolicy.Maximum))

    def sizeHint(self):
        return QSize(250,150)

class MyTableWidget(QWidget):
    def __init__(self, parent):   
        super(QWidget, self).__init__(parent)
        self.layout = QVBoxLayout(self)
        # Initialize tab screen
        self.tabs = QTabWidget(self)      
        self.layout.addWidget(self.tabs)
        #self.setSizePolicy(QSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored))
        #self.tabs.setSizePolicy(QSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored))

    def addTab(self, widget, text):
        self.tabs.addTab(widget, text)
        widget.setAutoFillBackground(True)
        my_yellow = QColor.fromHsl(35, 255, 153, 128 )
        dark_blue = QColor.fromHsl(211, 196, 38, 255)
        widget.palette().setColor(QPalette.Window, dark_blue)
        widget.palette().setColor(QPalette.WindowText, my_yellow)

class Example(QMainWindow):

    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):               

        self.statusBar().showMessage('Ready')
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Statusbar')
        self.table_widget = MyTableWidget(self)
        self.tab1 = QWidget()        
        self.tab2 = QWidget()
        #self.tab1.setSizePolicy(QSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding))
        self.table_widget.addTab(self.tab1, "Tab1")
        self.table_widget.addTab(self.tab2, "Tab2")

        self.scrollArea = QScrollArea(self.tab1)
        #self.scrollArea = QScrollArea(self)
        self.scrollArea.setWidgetResizable(True)
        self.scrollAreaWidgetContents = QWidget(self.scrollArea)
        #self.scrollAreaWidgetContents.setGeometry(QtCore.QRect(0, 0, 380, 247))
        self.scrollAreaWidgetContents.setMinimumSize(QSize(1100, 1300))
        #self.scrollAreaWidgetContents.setSizePolicy(QSizePolicy(QSizePolicy.Ignored, QSizePolicy.Ignored))
        #self.scrollAreaWidgetContents.setWidgetResizable(True)
        #self.scrollArea.setWidget(self.scrollAreaWidgetContents)

        self.verticalLayout = QVBoxLayout(self.scrollAreaWidgetContents)
        #self.verticalLayout.addWidget(self.scrollArea)
        self.verticalLayout.addWidget(Color2('blue'))
        self.verticalLayout.addWidget(Color2('red'))
        self.verticalLayout.insertStretch(-1)
        #self.verticalLayout.setSizeConstraint(1)#QLayout.SizeConstraint.setNoConstraint)
        self.verticallayout2 = QVBoxLayout(self.tab2)
        self.verticallayout2.addWidget(Color2('green'))

        #self.scrollArea.setSizePolicy(QSizePolicy(QSizePolicy.Ignored, QSizePolicy.Expanding))
        self.scrollArea.setWidget(self.scrollAreaWidgetContents)

        self.setCentralWidget(self.table_widget)
        self.show()
        print(self.table_widget.minimumSizeHint())

if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

I've learned the basics from http://zetcode.com/gui/pyqt5/ . Also, one clue in the behavior of the above code is that the area the QScrollArea is actually using is somehow related to the sizeHint of the Color2 class. I have an example of scroll bars working on their own just fine... it is just their behavior of having them in the tab of a QTabWidget that I don't understand. Any tips? Thanks very much.

eyllanesc eyllanesc · Accepted Answer · 2018-04-30T00:47:12

The problem is that you do not use a layout to set the QScrollArea inside a tab. When you establish that one widget is the parent of another, you are only indicating that the child's coordinate system is relative to the parent, but not that it will take the size of the parent, for this you must use a layout since it handles the size.

# -*- coding: utf-8 -*-
"""
Created on Fri Nov 17 07:07:08 2017

@author: Erik
"""

import sys
from PyQt5.QtWidgets import QLayout, QVBoxLayout ,QTabWidget, QMainWindow,QApplication, QWidget, QSizePolicy, QScrollArea
from PyQt5.QtGui import QColor, QPalette
from PyQt5.QtCore import QSize

class Color2(QWidget):
    def __init__(self, color, *args, **kwargs):
        super(Color2, self).__init__(*args, **kwargs)
        self.setAutoFillBackground(True)
        palette = self.palette()
        palette.setColor(QPalette.Window, QColor(color))
        self.setPalette(palette)
        self.setSizePolicy(QSizePolicy(QSizePolicy.Maximum, QSizePolicy.Maximum))

    def minimumSizeHint(self):
        return QSize(250,150)

class MyTableWidget(QWidget):
    def __init__(self, parent):   
        super(QWidget, self).__init__(parent)
        self.layout = QVBoxLayout(self)
        self.tabs = QTabWidget(self)      
        self.layout.addWidget(self.tabs)

    def addTab(self, widget, text):
        self.tabs.addTab(widget, text)
        widget.setAutoFillBackground(True)
        my_yellow = QColor.fromHsl(35, 255, 153, 128 )
        dark_blue = QColor.fromHsl(211, 196, 38, 255)
        widget.palette().setColor(QPalette.Window, dark_blue)
        widget.palette().setColor(QPalette.WindowText, my_yellow)

class Example(QMainWindow):

    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):               

        self.statusBar().showMessage('Ready')
        self.setGeometry(300, 300, 250, 150)
        self.setWindowTitle('Statusbar')
        self.table_widget = MyTableWidget(self)
        self.tab1 = QWidget()        
        self.tab2 = QWidget()
        self.table_widget.addTab(self.tab1, "Tab1")
        self.table_widget.addTab(self.tab2, "Tab2")
        lay = QVBoxLayout(self.tab1)

        self.scrollArea = QScrollArea()
        lay.addWidget(self.scrollArea)
        self.scrollArea.setWidgetResizable(True)
        self.scrollAreaWidgetContents = QWidget()
        self.scrollArea.setWidget(self.scrollAreaWidgetContents)

        self.verticalLayout = QVBoxLayout(self.scrollAreaWidgetContents)
        self.verticalLayout.addWidget(Color2('blue'))
        self.verticalLayout.addWidget(Color2('red'))
        self.verticalLayout.insertStretch(-1)
        self.verticallayout2 = QVBoxLayout(self.tab2)
        self.verticallayout2.addWidget(Color2('green'))

        self.scrollArea.setWidget(self.scrollAreaWidgetContents)

        self.setCentralWidget(self.table_widget)
        self.show()

if __name__ == '__main__':

    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

pyqt5 tab area not filling the whole available space

1 Answers