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Forum Update on Monday, May 27th 2025

Adding widgets dynamically to layout, causes to them to be misplaced

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  • M mrjj
    14 Mar 2018, 16:18

    @Petross404_Petros-S
    Hi
    Normally layouts will "contract". I have yet to experience
    one that leaves a hole if i remove widget. Maybe boxlayout.

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    Petross404_Petros S
    wrote on 14 Mar 2018, 16:20 last edited by Petross404_Petros S
    #18

    @mrjj

    Maybe boxlayout.

    You mean I should try boxlayout? Designer doesn't have one though...

    @Global-Moderators Please, correct my title. I meant to write "...causes them to be misplaced".

    M 1 Reply Last reply 14 Mar 2018, 17:46
    0
    • P Petross404_Petros S
      14 Mar 2018, 16:20

      @mrjj

      Maybe boxlayout.

      You mean I should try boxlayout? Designer doesn't have one though...

      @Global-Moderators Please, correct my title. I meant to write "...causes them to be misplaced".

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      mrjj
      Lifetime Qt Champion
      wrote on 14 Mar 2018, 17:46 last edited by mrjj
      #19

      @Petross404_Petros-S
      no, no i mean maybe box layout would / might/perhaps leave a hole but all other layouts would
      contract if you remove a widget.

      There is something else wrong.
      Do you use TakeAt to remove from layout ?
      https://doc.qt.io/qt-5.10/qboxlayout.html#takeAt
      Its the only valid way to remove a widget.

      P 1 Reply Last reply 14 Mar 2018, 17:57
      0
      • M mrjj
        14 Mar 2018, 17:46

        @Petross404_Petros-S
        no, no i mean maybe box layout would / might/perhaps leave a hole but all other layouts would
        contract if you remove a widget.

        There is something else wrong.
        Do you use TakeAt to remove from layout ?
        https://doc.qt.io/qt-5.10/qboxlayout.html#takeAt
        Its the only valid way to remove a widget.

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        Petross404_Petros S
        wrote on 14 Mar 2018, 17:57 last edited by Petross404_Petros S
        #20

        Well, one thing I know is that the custom widget's size constraints had to set to a minimum. It used quite a lot of space so it was centered on top of another layout/widget. Now it's loaded where it should, but after it's deletion there still is a void space.

        That's the code:

        void QtDice::enableUserWidget()
        {
        	userwidget = new UserWidget(this);
        	m_ui->gridLayout_Widget->addWidget(userwidget);
        }
        
        void QtDice::deleteUserWidget()
        {
        	m_ui->gridLayout_Widget->removeWidget(userwidget);
        	userwidget->setParent(nullptr);
        	delete userwidget;
        }
        

        Other suspects could be the main form (i.e. the QtDice qmainwindow) and it's size policies or the vertical spacer. I tried almost every combination and I am out of ideas.

        Do you use TakeAt to remove from layout ?

        Ebook Mastering Qt5, suggested the QLayout::removeWidget, so...

        M 1 Reply Last reply 14 Mar 2018, 18:04
        0
        • P Petross404_Petros S
          14 Mar 2018, 17:57

          Well, one thing I know is that the custom widget's size constraints had to set to a minimum. It used quite a lot of space so it was centered on top of another layout/widget. Now it's loaded where it should, but after it's deletion there still is a void space.

          That's the code:

          void QtDice::enableUserWidget()
          {
          	userwidget = new UserWidget(this);
          	m_ui->gridLayout_Widget->addWidget(userwidget);
          }
          
          void QtDice::deleteUserWidget()
          {
          	m_ui->gridLayout_Widget->removeWidget(userwidget);
          	userwidget->setParent(nullptr);
          	delete userwidget;
          }
          

          Other suspects could be the main form (i.e. the QtDice qmainwindow) and it's size policies or the vertical spacer. I tried almost every combination and I am out of ideas.

          Do you use TakeAt to remove from layout ?

          Ebook Mastering Qt5, suggested the QLayout::removeWidget, so...

          M Offline
          M Offline
          mrjj
          Lifetime Qt Champion
          wrote on 14 Mar 2018, 18:04 last edited by
          #21

          @Petross404_Petros-S
          Oh, yes, removeWidget seems better in this case and you do change parent.
          Hmm, i would also suspect spacer.
          Sorry i cant spot it. All seems pretty dandy with code shown.

          P 1 Reply Last reply 14 Mar 2018, 18:19
          0
          • M mrjj
            14 Mar 2018, 18:04

            @Petross404_Petros-S
            Oh, yes, removeWidget seems better in this case and you do change parent.
            Hmm, i would also suspect spacer.
            Sorry i cant spot it. All seems pretty dandy with code shown.

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            Petross404_Petros S
            wrote on 14 Mar 2018, 18:19 last edited by
            #22

            @mrjj Yeah, it's ok, thank you very much!

            For the moment I just create unconditionally the userwidget and all that clicking the checkbox does, is to enable or disable it. But it's always visible.

            It's not what I like, but it gives the functionality I am working on without an ugly ui. Until I find and post what the missing part of this puzzle is, I will leave this as UNSOLVED.

            1 Reply Last reply
            1
            • S Offline
              S Offline
              SGaist
              Lifetime Qt Champion
              wrote on 14 Mar 2018, 21:31 last edited by
              #23

              What about hiding it while the condition to use it are not met ?

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

              P 1 Reply Last reply 15 Mar 2018, 14:11
              0
              • M Offline
                M Offline
                MCam
                wrote on 15 Mar 2018, 12:30 last edited by
                #24

                Why use an empty QVBoxLayout as a placeholder for your userwidget? Why not just simply put your userwidget into the layout of your Mainwindow?

                I guess you are using another QVBoxLayout as the Layout of your Mainwindow so you could use:

                m_ui->yourmainlayoutname->insertWidget( 1, userwidget);
                

                On a sidenote: You don't need to put your textlabel-placeholder for your dice into a QGridLayout too, just put it into your Mainwindow-Layout and maybe set stretch-factors to your likeing.

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                • S SGaist
                  14 Mar 2018, 21:31

                  What about hiding it while the condition to use it are not met ?

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                  Petross404_Petros S
                  wrote on 15 Mar 2018, 14:11 last edited by
                  #25

                  @SGaist One reason is that I want to learn about creating custom widgets or working with spacers and layouts.
                  @MCam Aren't the widgets supposed to be -pretty much- always on top of a layout?

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                    Petross404_Petros S
                    wrote on 15 Mar 2018, 18:17 last edited by
                    #26

                    So, at first the window is at it's most minimum size. After enabling the widget it resizes a little, but after closing the widget again, the window doesn't resize back but rather the QLabel that shows the red dice expands.

                    I can't find some way to alter this. I have tried every combination for QLabel about it's SizePolicy but nothing changed.

                    M 1 Reply Last reply 16 Mar 2018, 11:29
                    0
                    • P Petross404_Petros S
                      15 Mar 2018, 18:17

                      So, at first the window is at it's most minimum size. After enabling the widget it resizes a little, but after closing the widget again, the window doesn't resize back but rather the QLabel that shows the red dice expands.

                      I can't find some way to alter this. I have tried every combination for QLabel about it's SizePolicy but nothing changed.

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                      MCam
                      wrote on 16 Mar 2018, 11:29 last edited by
                      #27

                      @Petross404_Petros-S
                      This is the default behavior of the layout-system here but you can get what you want by readjusting the size of your MainWindow after deleting the userwidget. In your case you have two QWidgets involved: your QtDice-MainWindow and its centralWidget(). So you need to adjust both of them!

                      Try adding

                      centralWidget()->adjustSize();
                      adjustSize();
                      

                      after removing the userwidget.

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                      1
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                        Petross404_Petros S
                        wrote on 16 Mar 2018, 11:40 last edited by Petross404_Petros S
                        #28

                        @MCam Thank you, I was using plain adjustSize() that's why it didn't resize. Although there is problem that remains even when resizing both layouts :

                        After unmaximising the window, adjustSize gives this result. I will mark the thread as solved because I can make the window to not be able to get maximized, but for completeness shake it would be nice if this result could be avoided.

                        Either way, you saved my day and I thank you very much for that :)

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                        16 Mar 2018, 11:29

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