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QListWidget item editing

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  • VRoninV Offline
    VRoninV Offline
    VRonin
    wrote on last edited by VRonin
    #2

    That's because it's handled by the delegate.
    Subclass QStyledItemDelegate

    class SignalItemDelegate : public QStyledItemDelegate{
    Q_OBJECT
    Q_DISABLE_COPY(SignalItemDelegate)
    public:
    explicit SignalItemDelegate(QObject* parent = Q_NULLPTR):QStyledItemDelegate(parent){
    QObject::connect(this,&SignalItemDelegate::closeEditor,this,&SignalItemDelegate::editFinished);
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE{
    editStarted();
    return QStyledItemDelegate::setEditorData(editor,index);
    }
    Q_SIGNALS:
    void editStarted();
    void editFinished();
    };
    

    And then call something like:

    SignalItemDelegate* delegate = new SignalItemDelegate(listWidget);
    QObject::connect(delegate,&SignalItemDelegate::editStarted,[](){qDebug("edit started")});
    QObject::connect(delegate,&SignalItemDelegate::editFinished,[](){qDebug("edit finished")});
    listWidget->setItemDelegate(delegate);
    

    "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
    ~Napoleon Bonaparte

    On a crusade to banish setIndexWidget() from the holy land of Qt

    JonBJ 2 Replies Last reply
    5
    • VRoninV VRonin

      That's because it's handled by the delegate.
      Subclass QStyledItemDelegate

      class SignalItemDelegate : public QStyledItemDelegate{
      Q_OBJECT
      Q_DISABLE_COPY(SignalItemDelegate)
      public:
      explicit SignalItemDelegate(QObject* parent = Q_NULLPTR):QStyledItemDelegate(parent){
      QObject::connect(this,&SignalItemDelegate::closeEditor,this,&SignalItemDelegate::editFinished);
      }
      void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE{
      editStarted();
      return QStyledItemDelegate::setEditorData(editor,index);
      }
      Q_SIGNALS:
      void editStarted();
      void editFinished();
      };
      

      And then call something like:

      SignalItemDelegate* delegate = new SignalItemDelegate(listWidget);
      QObject::connect(delegate,&SignalItemDelegate::editStarted,[](){qDebug("edit started")});
      QObject::connect(delegate,&SignalItemDelegate::editFinished,[](){qDebug("edit finished")});
      listWidget->setItemDelegate(delegate);
      
      JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by
      #3

      @VRonin
      Ah ha! Your famous QStyledItemDelegate, which I have steadfastly not got into so far! OK, let me go set this up and see where I get. I may have further questions for what I'm trying to actually achieve fully (the above is just one part), I'll come back to your expertise on that if I may....

      1 Reply Last reply
      0
      • dheerendraD Offline
        dheerendraD Offline
        dheerendra
        Qt Champions 2022
        wrote on last edited by
        #4

        Did you get a chance to look other set of signals like.

        currentItemChanged(..)
        clicked(..)
        entered(..)
        pressed(..)
        

        Dheerendra
        @Community Service
        Certified Qt Specialist
        http://www.pthinks.com

        JonBJ 1 Reply Last reply
        1
        • dheerendraD dheerendra

          Did you get a chance to look other set of signals like.

          currentItemChanged(..)
          clicked(..)
          entered(..)
          pressed(..)
          
          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by
          #5

          @dheerendra
          Yep, I looked through all those. None of them pick up, e.g., terminating editing, at least, so no good....

          1 Reply Last reply
          0
          • dheerendraD Offline
            dheerendraD Offline
            dheerendra
            Qt Champions 2022
            wrote on last edited by
            #6

            terminatingEditing has to be custom. You have no choice other the your own delegate :)

            Dheerendra
            @Community Service
            Certified Qt Specialist
            http://www.pthinks.com

            JonBJ 1 Reply Last reply
            0
            • dheerendraD dheerendra

              terminatingEditing has to be custom. You have no choice other the your own delegate :)

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by
              #7

              @dheerendra
              Yep, that's fine, as I wrote to @VRonin above, I am presently having a go at his code (converted to Python/PyQt!) to get me going....

              1 Reply Last reply
              0
              • D Offline
                D Offline
                DyraSan
                wrote on last edited by DyraSan
                #8

                Hey, I am newbie

                and I want to know how to edit a QListWidget item without removing it to edit and adding back?

                thanks,

                Kissanime

                1 Reply Last reply
                0
                • VRoninV Offline
                  VRoninV Offline
                  VRonin
                  wrote on last edited by
                  #9

                  listWidget->item(i)->setData(role,data);

                  "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                  ~Napoleon Bonaparte

                  On a crusade to banish setIndexWidget() from the holy land of Qt

                  1 Reply Last reply
                  3
                  • VRoninV VRonin

                    That's because it's handled by the delegate.
                    Subclass QStyledItemDelegate

                    class SignalItemDelegate : public QStyledItemDelegate{
                    Q_OBJECT
                    Q_DISABLE_COPY(SignalItemDelegate)
                    public:
                    explicit SignalItemDelegate(QObject* parent = Q_NULLPTR):QStyledItemDelegate(parent){
                    QObject::connect(this,&SignalItemDelegate::closeEditor,this,&SignalItemDelegate::editFinished);
                    }
                    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE{
                    editStarted();
                    return QStyledItemDelegate::setEditorData(editor,index);
                    }
                    Q_SIGNALS:
                    void editStarted();
                    void editFinished();
                    };
                    

                    And then call something like:

                    SignalItemDelegate* delegate = new SignalItemDelegate(listWidget);
                    QObject::connect(delegate,&SignalItemDelegate::editStarted,[](){qDebug("edit started")});
                    QObject::connect(delegate,&SignalItemDelegate::editFinished,[](){qDebug("edit finished")});
                    listWidget->setItemDelegate(delegate);
                    
                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by JonB
                    #10

                    @VRonin
                    OK, I have come up with the basics which I believe emulates/corresponds to your C++ as best I can. I now have a further question about something which you don't do in your example which I would like.

                    First, I'll paste the guts of my Python/PyQt code. You'll see it's rather different in signals/slots/emits. This may help or hinder, I don't know, feel free to ignore if that's best.

                    class JEditableListStyledItemDelegate(QtWidgets.QStyledItemDelegate):
                        # class variable for "editStarted" signal
                        editStarted = QtCore.pyqtSignal(name='editStarted')
                        # class variable for "editFinished" signal
                        editFinished = QtCore.pyqtSignal(name='editFinished')
                    
                        def __init__(self, parent: QtCore.QObject=None):
                            super().__init__(parent)
                    
                            self.closeEditor.connect(self.editFinished)
                    
                        def setEditorData(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                            self.editStarted.emit()
                            return super().setEditorData(editor, index)
                    
                    
                    class JEditableListWidget(QtWidgets.QListWidget):
                        # class variable for "editStarted" signal
                        editStarted = QtCore.pyqtSignal(name='editStarted')
                        # class variable for "editFinished" signal
                        editFinished = QtCore.pyqtSignal(name='editFinished')
                    
                        def __init__(self, parent: QtWidgets.QWidget=None):
                            super().__init__(parent)
                    
                            styledItemDelegate = JEditableListStyledItemDelegate(self)
                            styledItemDelegate.editStarted.connect(self.editStarted)
                            styledItemDelegate.editFinished.connect(self.editFinished)
                            self.setItemDelegate(styledItemDelegate)
                    
                    

                    The above "works". The JEditableListStyledItemDelegate emits its own editStarted/Finished signals. The JEditableListWidget "redirects" those signals to its own editStarted/Finished signals, for the outside world to slot onto. So far so good?

                    Now, if you look at a QListWidget signal for an item like http://doc.qt.io/qt-5/qlistwidget.html#itemChanged, its signature is QListWidget::itemChanged(QListWidgetItem *item). Hence it sends to the outside world a parameter of the QListWidgetItem which has been changed. My editStarted/Finished signals should do the same.

                    Now I get stuck as to how I'm supposed to do that.

                    I start by changing my JEditableListWidget signals to:

                    class JEditableListWidget(QtWidgets.QListWidget):
                        # class variable for "editStarted" signal, including item
                        editStarted = QtCore.pyqtSignal(QtWidgets.QListWidgetItem, name='editStarted')
                        # class variable for "editFinished" signal, including item
                        editFinished = QtCore.pyqtSignal(QtWidgets.QListWidgetItem, name='editFinished')
                    

                    The extra first parameter of QtWidgets.QListWidgetItem declares the signal as forwarding the item as a parameter.

                    Now how do I pass that? I believe that (a) I will need a lambda for the signal and (b) I need to know what item is being edited. I think where I had:

                    styledItemDelegate.editStarted.connect(self.editStarted)
                    

                    I now need something like:

                    styledItemDelegate.editStarted.connect(lambda: self.editStarted(someItemWidget))
                    

                    [Actually I suspect it might be more like:

                    styledItemDelegate.editStarted.connect(lambda: self.editStarted.emit(someItemWidget))
                    

                    ]
                    Could you tell me:

                    • Is this how you would do it in C++ (e.g. with a lambda)? (If not, I may be doing it wrong.) Could you show me your C++ for how you would do this and I will attempt to figure it to PyQt? (Also, I believe your code omitted an emit because I know that's a NO-OP in C++; but could you include it wherever it should be, because in PyQt you can see we have to use emit as a function.)

                    • How do I calculate what the someItemWidget will be, from inside my JEditableListWidget?

                    1 Reply Last reply
                    0
                    • VRoninV Offline
                      VRoninV Offline
                      VRonin
                      wrote on last edited by
                      #11

                      It's actually super easy.
                      In the delegate:

                      • add an argument of type QtCore.QModelIndex to the signals.
                      • remove self.closeEditor.connect(self.editFinished)
                      • change self.editStarted.emit() to self.editStarted.emit(index)
                      • add
                      def destroyEditor(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                              self.editFinished.emit(index)
                              return super().destroyEditor(editor, index)
                      

                      Now in JEditableListWidget you can connect a slot that accepts a QtCore.QModelIndex. To find the corresponding QListWidgetItem you can just call item(index.row())

                      "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                      ~Napoleon Bonaparte

                      On a crusade to banish setIndexWidget() from the holy land of Qt

                      JonBJ 2 Replies Last reply
                      4
                      • VRoninV VRonin

                        It's actually super easy.
                        In the delegate:

                        • add an argument of type QtCore.QModelIndex to the signals.
                        • remove self.closeEditor.connect(self.editFinished)
                        • change self.editStarted.emit() to self.editStarted.emit(index)
                        • add
                        def destroyEditor(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                                self.editFinished.emit(index)
                                return super().destroyEditor(editor, index)
                        

                        Now in JEditableListWidget you can connect a slot that accepts a QtCore.QModelIndex. To find the corresponding QListWidgetItem you can just call item(index.row())

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by
                        #12

                        @VRonin
                        TVM. I'll implement next week. You're passing the QtCore.QModelIndex available in the JEditableListStyledItemDelegate class up the signal chain to indicate which QListWidgetItem was acted upon. I thought the JEditableListWidget class would know which item in the list was being edited, but seemingly not?

                        1 Reply Last reply
                        0
                        • VRoninV VRonin

                          It's actually super easy.
                          In the delegate:

                          • add an argument of type QtCore.QModelIndex to the signals.
                          • remove self.closeEditor.connect(self.editFinished)
                          • change self.editStarted.emit() to self.editStarted.emit(index)
                          • add
                          def destroyEditor(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                                  self.editFinished.emit(index)
                                  return super().destroyEditor(editor, index)
                          

                          Now in JEditableListWidget you can connect a slot that accepts a QtCore.QModelIndex. To find the corresponding QListWidgetItem you can just call item(index.row())

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by JonB
                          #13

                          @VRonin
                          Well, I followed your principle of having the QStyledItemDelegate emit signals with the QModelIndex as a parameter.

                          I diverged from yours slightly. Given that I'm now overriding destroyEditor() so as to access the index, it seems to me that I might as well be consistent and override createEditor() for beginning editing. So the following two overrides:

                          class JEditableListStyledItemDelegate(QtWidgets.QStyledItemDelegate):
                              # class variable for "editStarted" signal, with QModelIndex parameter
                              editStarted = QtCore.pyqtSignal(QtCore.QModelIndex, name='editStarted')
                              # class variable for "editFinished" signal, with QModelIndex parameter
                              editFinished = QtCore.pyqtSignal(QtCore.QModelIndex, name='editFinished')
                          
                              def createEditor(self, parent: QtWidgets.QWidget, option: QtWidgets.QStyleOptionViewItem, index: QtCore.QModelIndex):
                                  editor = super().createEditor(parent, option, index)
                                  if editor is not None:
                                      self.editStarted.emit(index)
                                  return editor
                          
                              def destroyEditor(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                                  self.editFinished.emit(index)
                                  return super().destroyEditor(editor, index)
                          

                          The above seems to give me fairly reliable signals for what I want, e.g. disable other buttons for doing things to QListWidget (add row, delete row) while the user is editing a row.

                          Seem reasonable to you? Thanks for all your input.

                          VRoninV 1 Reply Last reply
                          2
                          • JonBJ JonB

                            @VRonin
                            Well, I followed your principle of having the QStyledItemDelegate emit signals with the QModelIndex as a parameter.

                            I diverged from yours slightly. Given that I'm now overriding destroyEditor() so as to access the index, it seems to me that I might as well be consistent and override createEditor() for beginning editing. So the following two overrides:

                            class JEditableListStyledItemDelegate(QtWidgets.QStyledItemDelegate):
                                # class variable for "editStarted" signal, with QModelIndex parameter
                                editStarted = QtCore.pyqtSignal(QtCore.QModelIndex, name='editStarted')
                                # class variable for "editFinished" signal, with QModelIndex parameter
                                editFinished = QtCore.pyqtSignal(QtCore.QModelIndex, name='editFinished')
                            
                                def createEditor(self, parent: QtWidgets.QWidget, option: QtWidgets.QStyleOptionViewItem, index: QtCore.QModelIndex):
                                    editor = super().createEditor(parent, option, index)
                                    if editor is not None:
                                        self.editStarted.emit(index)
                                    return editor
                            
                                def destroyEditor(self, editor: QtWidgets.QWidget, index: QtCore.QModelIndex):
                                    self.editFinished.emit(index)
                                    return super().destroyEditor(editor, index)
                            

                            The above seems to give me fairly reliable signals for what I want, e.g. disable other buttons for doing things to QListWidget (add row, delete row) while the user is editing a row.

                            Seem reasonable to you? Thanks for all your input.

                            VRoninV Offline
                            VRoninV Offline
                            VRonin
                            wrote on last edited by
                            #14

                            @JonB said in QListWidget item editing:

                            Given that I'm now overriding destroyEditor() so as to access the index, it seems to me that I might as well be consistent and override createEditor() for beginning editing.

                            Only doubt I have is if the delegate recycles the editor. Try going from editing 1 cell to editing another one directly and see if both create and destroy are called or it just calls setEditorData

                            "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                            ~Napoleon Bonaparte

                            On a crusade to banish setIndexWidget() from the holy land of Qt

                            JonBJ 1 Reply Last reply
                            1
                            • VRoninV VRonin

                              @JonB said in QListWidget item editing:

                              Given that I'm now overriding destroyEditor() so as to access the index, it seems to me that I might as well be consistent and override createEditor() for beginning editing.

                              Only doubt I have is if the delegate recycles the editor. Try going from editing 1 cell to editing another one directly and see if both create and destroy are called or it just calls setEditorData

                              JonBJ Offline
                              JonBJ Offline
                              JonB
                              wrote on last edited by JonB
                              #15

                              @VRonin
                              OK, thanks! You should have said that concern was why you had overridden different/"inconsistent" methods, I had no idea why! Tried with direct click to edit another item, all is well, does call destroy and then create.

                              So I shall mark what I did as the solution to my original question. TVM.

                              P.S.
                              Your Xmas hat looks good. But a lot of others are also wearing them...! :)

                              mrjjM VRoninV 2 Replies Last reply
                              1
                              • JonBJ JonB

                                @VRonin
                                OK, thanks! You should have said that concern was why you had overridden different/"inconsistent" methods, I had no idea why! Tried with direct click to edit another item, all is well, does call destroy and then create.

                                So I shall mark what I did as the solution to my original question. TVM.

                                P.S.
                                Your Xmas hat looks good. But a lot of others are also wearing them...! :)

                                mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by
                                #16

                                @JonB said in QListWidget item editing:

                                Your Xmas hat looks good. But a lot of others are also wearing them...! :)

                                Well that is is on purpose :)

                                1 Reply Last reply
                                1
                                • JonBJ JonB

                                  @VRonin
                                  OK, thanks! You should have said that concern was why you had overridden different/"inconsistent" methods, I had no idea why! Tried with direct click to edit another item, all is well, does call destroy and then create.

                                  So I shall mark what I did as the solution to my original question. TVM.

                                  P.S.
                                  Your Xmas hat looks good. But a lot of others are also wearing them...! :)

                                  VRoninV Offline
                                  VRoninV Offline
                                  VRonin
                                  wrote on last edited by
                                  #17

                                  @JonB said in QListWidget item editing:

                                  Your Xmas hat looks good

                                  All credit goes to @mrjj

                                  "La mort n'est rien, mais vivre vaincu et sans gloire, c'est mourir tous les jours"
                                  ~Napoleon Bonaparte

                                  On a crusade to banish setIndexWidget() from the holy land of Qt

                                  1 Reply Last reply
                                  1

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