[FIXED] QGridLayout does not return all of its child widgets

Issue

I have a QGridLayout and need to remove all of its buttons then re-create them. I've tried looping over the layout using count() followed by takeAt() to delete the returned LayoutItem's widget. For some reason, however, I am only getting half of the widgets: the other LayoutItems don't have widgets. This is very odd, as I can see them.

Here is my current simplified code.

import sys
from PySide.QtGui import *
from PySide.QtCore import *

class GridView(QWidget):

    def __init__(self, parent=None):
        super(GridView, self).__init__(parent)
        self.grid = QGridLayout(self)

    def setButtons(self):

        self.clearPage()
        for i in xrange(10):
            btn = QPushButton(str(i))
            self.grid.addWidget(btn, i / 2, i % 2)

    def clearPage(self):
        for i in xrange(self.grid.count()):
            print i
            layoutItem = self.grid.takeAt(i)
                # the following errors out after the fifth iteration as layoutItem.widget() returns None
            print layoutItem.widget()
            layoutItem.widget().deleteLater()


app = QApplication(sys.argv)
mainWindow = QWidget()
layout = QVBoxLayout()
mainWindow.setLayout(layout)
btn = QPushButton('test')
v = GridView()
btn.clicked.connect(v.setButtons)

layout.addWidget(v)
layout.addWidget(btn)
mainWindow.show()
sys.exit(app.exec_())

Solution

Try using

self.grid.takeAt( 0 ) 

instead of:

self.grid.takeAt(i)

In your code, you takeAt( 0 ) in the first iteration. This internally makes the old #1 being the new #0, the old #2 being the new #1 and so on.

Then in your next iteration you takeAt( 1 ), which in fact is the old #2. That way the old #1 (which is #0 now) will not be deleted.

Answered By - Tim Meyer