pyside - how to delete widgets from gridLayout

Question

I built a ui in QT Designer and then used pyside-uic turned it into a python file and have then written some code to edit it programmatically. In otherwords I have a pushbutton Add Row that when clicked will rename itself to Remove1 and create another pusbutton name it Add Row and add it to the layout.

Code when clicking Add Row, changes the name and the signals/slots:

self.pb_Row[-1].setText('Remove'+str(self.nRows))
self.pb_Row[-1].clicked.disconnect( self.addRow )
self.pb_Row[-1].clicked.connect( self.removeRow )

Code when clicking Remove, removes selected button:

iRow = int(self.sender().objectName().split('_')[-1])-1
ind = self.PropertyLayout.indexOf(self.pb_Row[iRow])
t = self.PropertyLayout.takeAt(ind)
t.widget().deleteLater()
# self.pb_Row[iRow].hide()
# self.pb_Row[iRow].deleteLater()
self.pb_Row.pop(iRow)

This works just fine until you add at least one and then remove it, the next time round it messes up. Basically, it misbehaves when I have two buttons and remove one and then try to add one. By misbehaves I mean that the new button ends up on top of the old, sometimes it appears below instead of above.

Also, with the lines as they currently are it doesn't really reorganise things in the gridlayout, if I use the .hide() function it does. I'm not quite sure which I should be using.

Thanks!

Here is a sequence that produces undesirable results:

Fresh start

After Clicking Add

After clicking remove (all fine so far), then click Add (no visible difference)

After clicking Add a second time

After clicking Remove2, Remove1 appears from under it

"Working" example of code

import numpy as np
import sys
from PySide import QtCore, QtGui
import matplotlib.pyplot as plt

from ModesInFiber import Ui_fiberModesMainWindow

class Ui_fiberModesMainWindow(object):
    def setupUi(self, fiberModesMainWindow):
        fiberModesMainWindow.setObjectName("fiberModesMainWindow")
        fiberModesMainWindow.resize(653, 597)
        self.centralwidget = QtGui.QWidget(fiberModesMainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.horizontalLayout_2 = QtGui.QHBoxLayout(self.centralwidget)
        self.horizontalLayout_2.setObjectName("horizontalLayout_2")
        self.MainLayout = QtGui.QGridLayout()
        self.MainLayout.setObjectName("MainLayout")
        self.PropertyLayout = QtGui.QGridLayout()
        self.PropertyLayout.setObjectName("PropertyLayout")
        self.lbl_Name = QtGui.QLabel(self.centralwidget)
        self.lbl_Name.setObjectName("lbl_Name")
        self.PropertyLayout.addWidget(self.lbl_Name, 0, 1, 1, 1)
        self.pb_addRow_1 = QtGui.QPushButton(self.centralwidget)
        self.pb_addRow_1.setObjectName("pb_addRow_1")
        self.PropertyLayout.addWidget(self.pb_addRow_1, 1, 5, 1, 1)
        self.ledit_Name_1 = QtGui.QLineEdit(self.centralwidget)
        self.ledit_Name_1.setObjectName("ledit_Name_1")
        self.PropertyLayout.addWidget(self.ledit_Name_1, 1, 1, 1, 1)
        self.MainLayout.addLayout(self.PropertyLayout, 0, 0, 1, 1)
        spacerItem2 = QtGui.QSpacerItem(20, 40, QtGui.QSizePolicy.Minimum, QtGui.QSizePolicy.Expanding)
        self.MainLayout.addItem(spacerItem2, 1, 0, 1, 1)
        self.horizontalLayout_2.addLayout(self.MainLayout)
        fiberModesMainWindow.setCentralWidget(self.centralwidget)

        self.retranslateUi(fiberModesMainWindow)
        QtCore.QMetaObject.connectSlotsByName(fiberModesMainWindow)
#         fiberModesMainWindow.setTabOrder(self.ledit_Name_1, self.ledit_Width_1)
#         fiberModesMainWindow.setTabOrder(self.ledit_Width_1, self.cmb_RIType_1)
#         fiberModesMainWindow.setTabOrder(self.cmb_RIType_1, self.ledit_RIParam_1)
#         fiberModesMainWindow.setTabOrder(self.ledit_RIParam_1, self.pb_addRow_1)

    def retranslateUi(self, fiberModesMainWindow):
        fiberModesMainWindow.setWindowTitle(QtGui.QApplication.translate("fiberModesMainWindow", "MainWindow", None, QtGui.QApplication.UnicodeUTF8))
        self.lbl_Name.setText(QtGui.QApplication.translate("fiberModesMainWindow", "Name", None, QtGui.QApplication.UnicodeUTF8))
        self.pb_addRow_1.setText(QtGui.QApplication.translate("fiberModesMainWindow", "Add Row", None, QtGui.QApplication.UnicodeUTF8))


class DesignerMainWindow(QtGui.QMainWindow, Ui_fiberModesMainWindow):

    def __init__(self, parent = None):
        super(DesignerMainWindow, self).__init__(parent)
        self.setupUi(self)
        self.pb_addRow_1.clicked.connect( self.addRow )

        self.ledit_Name     = [ self.ledit_Name_1 ]
        self.pb_Row      = [ self.pb_addRow_1 ]

        # number of rows
        self.nRows = 1


    def addRow( self ):

        self.ledit_Name[-1].setEnabled(False)
        self.pb_Row[-1].setText('Remove'+str(self.nRows))
        self.pb_Row[-1].clicked.disconnect( self.addRow )
        self.pb_Row[-1].clicked.connect( self.removeRow )

        self.nRows += 1

        self.ledit_Name.append( QtGui.QLineEdit(self.centralwidget) )
        self.ledit_Name[-1].setObjectName('ledit_Name_'+str(self.nRows))
        self.PropertyLayout.addWidget( self.ledit_Name[-1], self.nRows, 1, 1, 1)

        self.pb_Row.append( QtGui.QPushButton(self.centralwidget) )
        self.pb_Row[-1].setObjectName( 'pb_addRow_'+str(self.nRows) )
        self.pb_Row[-1].setText('Add Row')
        self.pb_Row[-1].clicked.connect( self.addRow )
        self.PropertyLayout.addWidget( self.pb_Row[-1], self.nRows, 5, 1, 1)


    def removeRow( self ):

        iRow = int(self.sender().objectName().split('_')[-1])-1
        self.nRows -= 1

        ind = self.PropertyLayout.indexOf(self.ledit_Name[iRow])
        t = self.PropertyLayout.takeAt(ind)
        t.widget().setParent(None)
#             t.widget().deleteLater()
#             self.ledit_Name[iRow].hide()
#             self.ledit_Name[iRow].deleteLater()
#             self.ledit_Name[iRow].setParent(None)
        self.ledit_Name.pop(iRow)

        ind = self.PropertyLayout.indexOf(self.pb_Row[iRow])
        t = self.PropertyLayout.takeAt(ind)
        t.widget().setParent(None)
#             t.widget().deleteLater()
#             self.pb_Row[iRow].hide()
#             self.pb_Row[iRow].deleteLater()
#             self.pb_Row[iRow].setParent(None)
        self.pb_Row.pop(iRow)

        for iAfterRow in range(iRow, self.nRows):
            self.ledit_Name[iAfterRow].setObjectName( 'ledit_Name_' + str(iAfterRow+1) )
            self.pb_Row[iAfterRow].setObjectName( 'ledit_Name_' + str(iAfterRow+1) )

        print 'Remove row', iRow

if __name__ == '__main__':
    app = QtGui.QApplication( sys.argv )
    dmw = DesignerMainWindow()
    dmw.show()
    sys.exit( app.exec_() )

Answer 1

The problem here is caused by an implementation detail of QGridLayout.

Whenever items are deleted from a QGridLayout, the number of logical rows and columns will never decrease, even though the number of visual rows or colums may do. Because of this, you should always work directly with the items in the QGridLayout using methods such as getItemPosition and itemAtPosition.

Below is a re-write of the DesignerMainWindow class from the example using this approach. Obviously, it may need tweaking somewhat to work with your real application.

class DesignerMainWindow(QtGui.QMainWindow, Ui_fiberModesMainWindow):
    def __init__(self, parent = None):
        super(DesignerMainWindow, self).__init__(parent)
        self.setupUi(self)
        self.pb_addRow_1.clicked.connect( self.addRow )

    def addRow( self ):
        rows = self.PropertyLayout.rowCount()
        columns = self.PropertyLayout.columnCount()
        for column in range(columns):
            layout = self.PropertyLayout.itemAtPosition(rows - 1, column)
            if layout is not None:
                widget = layout.widget()
                if isinstance(widget, QtGui.QPushButton):
                    widget.setText('Remove %d' % (rows - 1))
                    widget.clicked.disconnect(self.addRow)
                    widget.clicked.connect(self.removeRow)
                else:
                    widget.setEnabled(False)
        widget = QtGui.QLineEdit(self.centralwidget)
        self.PropertyLayout.addWidget(widget, rows, 1, 1, 1)
        widget = QtGui.QPushButton(self.centralwidget)
        widget.setText('Add Row')
        widget.clicked.connect(self.addRow)
        self.PropertyLayout.addWidget(widget, rows, columns - 1, 1, 1)

    def removeRow(self):
        index = self.PropertyLayout.indexOf(self.sender())
        row = self.PropertyLayout.getItemPosition(index)[0]
        for column in range(self.PropertyLayout.columnCount()):
            layout = self.PropertyLayout.itemAtPosition(row, column)
            if layout is not None:
                layout.widget().deleteLater()
                self.PropertyLayout.removeItem(layout)

Answer 2

It looks like you didn't call QGridLayout::removeWidget() for all cells in row that you would like to remove. Then due to PySide the layout will keep referencing to the widgets and they are not really removed/deleted when you call setParent(None).

Also when you try deleteLater() of widget in the cell without QLayout::removeWidget(), then the cell will be not removed but stay alive (there is QLayoutItem will be left in the cell)

Answer 3

EDIT: This doesn't solve the problem, also I found the source of my knowledge: Is there any way to remove a QWidget in a QGridLayout?

-- For some reason, removing widgets from layouts is hard. I spent a long time searching for the answer once, and no longer remember where I found it, but I digress...

What you need to do is the following. First find the item you want to remove. You can use layout.itemAt() or layout.itemAtPosition to get a reference to it.

Now, to remove the item from the layout, simply call item.widget().setParent(None). This will have the effect of removing the item from the layout!

Note: If you already have a reference to the widget, you can probably just call setParent on it without having to find it from the layout. I haven't tried that though (but don't see why it wouldn't work).