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QTableView clicked() versus doubleClicked()

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  • PerdrixP Perdrix

    To answer my own question! This seems to work:

    	void StackingDlg::tableView_selectionChanged([[maybe_unused]] const QItemSelection& selected, [[maybe_unused]] const QItemSelection& deselected)
    	{
    
    		QItemSelectionModel * qsm = ui->tableView->selectionModel();
    		QModelIndexList selectedRows = qsm->selectedRows();
    		qDebug() << "Number of selected rows: " << selectedRows.count();
    		//
    		// If only one row is selected, we want to know the filename
    		//
    		if (1 == selectedRows.count())
    		{
    			QModelIndex& ndx = selectedRows[0];
    			qDebug() << "  Selected row: " << ndx.row();
    

    though there's one remaining oddity.

    When I click on the single row, the row is highlighted to show it's selected, and the image loading is started in another thread, and the table view is disabled.

    On completion of the loading, the table view is enabled again, but the highlight is lost until I click on somewhere else in the window (not the rows of the tableview).

    I changed that code to NOT disable the table view and the highlight did not go away.

    Is there a way to prevent USER interaction with a control but allow internal events to continue processing?

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

    @Perdrix said in QTableView clicked() versus doubleClicked():

    and the image loading is started in another thread, and the table view is disabled.

    Just asking: do you really need a separate thread for this "image loading" and having this "disabling" and consequent "focus losing"? Maybe you do, but have you tried without bothering?

    PerdrixP 1 Reply Last reply
    0
    • JonBJ JonB

      @Perdrix said in QTableView clicked() versus doubleClicked():

      and the image loading is started in another thread, and the table view is disabled.

      Just asking: do you really need a separate thread for this "image loading" and having this "disabling" and consequent "focus losing"? Maybe you do, but have you tried without bothering?

      PerdrixP Offline
      PerdrixP Offline
      Perdrix
      wrote on last edited by
      #14

      @JonB Separate thread? Yes - it can take quite a while for some of these images.

      JonBJ 1 Reply Last reply
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      • M mpergand

        @Perdrix said in QTableView clicked() versus doubleClicked():

        the table view is enabled again, but the highlight is lost

        Because the table lost the focus, set it again with:

        tableView->setFocus(Qt::OtherFocusReason);
        
        PerdrixP Offline
        PerdrixP Offline
        Perdrix
        wrote on last edited by
        #15

        @mpergand said in QTableView clicked() versus doubleClicked():

        tableView->setFocus(Qt::OtherFocusReason);

        Woohoo! That worked a treat.

        Thanks
        David

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        • PerdrixP Perdrix

          @JonB Separate thread? Yes - it can take quite a while for some of these images.

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by
          #16

          @Perdrix said in QTableView clicked() versus doubleClicked():

          it can take quite a while for some of these images.

          Just because I am interested: do you mean (it takes much time) to load the image (once generated if that is what you are doing) into the UI, or do you mean to generate an image to load?

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          • PerdrixP Offline
            PerdrixP Offline
            Perdrix
            wrote on last edited by
            #17

            Large images that take a while to load from file.

            1 Reply Last reply
            1
            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #18

              Do you want to show the full image size ?
              Otherwise creating a cache with small versions of them might be a better solution in terms of speed and only load the real version when really needed.

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              1 Reply Last reply
              1
              • PerdrixP Offline
                PerdrixP Offline
                Perdrix
                wrote on last edited by
                #19

                Still need to load them - I am caching once loaded.

                1 Reply Last reply
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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #20

                  Hence my suggestion, have a "pre-processing" phase where you create thumbnails to show quickly and load the complete file in the background. Once it's done notify your application and do what you need with it.

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                  • PerdrixP Offline
                    PerdrixP Offline
                    Perdrix
                    wrote on last edited by Perdrix
                    #21

                    No I can't do thumbnails as I don't know a-priori what files are involved and there might be 100s of them.

                    Now back to the problem - selectionChanged works fine to detect the newly selected row to trigger image loading.

                    Unfortunately, double clicking on a editable cell still results in selectionChanged driving the image loading to start.

                    What it doesn't do is open the editor on the cell that was double clicked!

                    I had a quick look at the code of mouseDoubleClickEvent in QAbstractItemView.cpp, and I think it is written so that it should always open the editor. I suspect that the way mousePressedEvent() is written means that the double click event isn't generated if the selection change is driven from there (I don't think it should be driven from there - rather it should be driven from a mouseClickedEvent()) which isn't present. I do see code in mousPressedEvent() that is intended to open the editor, but don't quite "get" why that wasn't invoked.

                    David

                    M 1 Reply Last reply
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                    • PerdrixP Perdrix

                      No I can't do thumbnails as I don't know a-priori what files are involved and there might be 100s of them.

                      Now back to the problem - selectionChanged works fine to detect the newly selected row to trigger image loading.

                      Unfortunately, double clicking on a editable cell still results in selectionChanged driving the image loading to start.

                      What it doesn't do is open the editor on the cell that was double clicked!

                      I had a quick look at the code of mouseDoubleClickEvent in QAbstractItemView.cpp, and I think it is written so that it should always open the editor. I suspect that the way mousePressedEvent() is written means that the double click event isn't generated if the selection change is driven from there (I don't think it should be driven from there - rather it should be driven from a mouseClickedEvent()) which isn't present. I do see code in mousPressedEvent() that is intended to open the editor, but don't quite "get" why that wasn't invoked.

                      David

                      M Offline
                      M Offline
                      mpergand
                      wrote on last edited by
                      #22

                      @Perdrix said in QTableView clicked() versus doubleClicked():

                      What it doesn't do is open the editor on the cell that was double clicked!

                      Check editTriggers is set to QAbstractItemView::DoubleClicked

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                      • PerdrixP Offline
                        PerdrixP Offline
                        Perdrix
                        wrote on last edited by
                        #23

                        It must be set because I can d-click the cell later (after the image has loaded) and it opens the editor just fine

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                        • SGaistS Offline
                          SGaistS Offline
                          SGaist
                          Lifetime Qt Champion
                          wrote on last edited by
                          #24

                          Did you keep any custom code / event filter after changing to use the selection model ?

                          Interested in AI ? www.idiap.ch
                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                          PerdrixP 1 Reply Last reply
                          0
                          • SGaistS SGaist

                            Did you keep any custom code / event filter after changing to use the selection model ?

                            PerdrixP Offline
                            PerdrixP Offline
                            Perdrix
                            wrote on last edited by
                            #25

                            @SGaist No Sir

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                            • SGaistS Offline
                              SGaistS Offline
                              SGaist
                              Lifetime Qt Champion
                              wrote on last edited by
                              #26

                              Then please share a minimal compilable example that shows this behaviour.

                              Interested in AI ? www.idiap.ch
                              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                              • PerdrixP Offline
                                PerdrixP Offline
                                Perdrix
                                wrote on last edited by
                                #27

                                It behaves as I would expect and hope on Qt 6.4.0 😊

                                David

                                1 Reply Last reply
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