[SOLVED] Resizing Custom Widgets in a Layout Leaves Empty Space Between Widgets

  • Hello fellow Qt developers, right now I am working on resizing some custom widgets (Named "Pods") (Derive QFrame, member widgets: 2 scroll area both containing labels) within a vertical box layout. I use QWidget::resize(int,int) to adjust the size of the member widgets and the widget as it's QFrame base class. When I resize my widgets I notice that within the layout containing my custom widget there is empty space between each custom widget. I have looked through other threads and tried multiple things such as, updating geometries, setting layout size constraints, size policies and so on. So, please help me, it is appreciated. I could just post tons of code here and make a huge post, but instead you can provide the concepts and if you need code I can give it at request just ask for something specific such as the custom class header etc.

  • Did you also try to set the margins to zero in your layout(s)? QLayout::setContentsMargins(int left, int top, int right, int bottom). To me it sounds that your margins still have the default value (11 or 12 etc.) and changing size constraints or policies would not make the widgets closer as the margin values, I think.

  • Moderators

    The margins control the spacing around the children as suggested by @Varius and to modify the spacing between the items you can use setSpacing.

  • I appreciate the ideas guys, I have now tested both but neither appear to have yielded any positive result :( Any other ideas? Additionally, I have now noticed that some widget, extends out of the top level scroll area and blocks mouse interaction despite not being visible. Any ideas for that one?


    No dice.

  • Moderators

    It's hard to help without seeing the code that creates the widget. It could be anything really. You didn't add something to a layout or are trying to modify the size of something governed by a layout etc.

  • @Chris-Kawa Well, if you'd like I can provide code I just need to know what you want to see, and I am resizing a widget governed by a layout in using QWidget::resize(int,int), is this not correct?

  • Moderators

    It would be nice to see how this widget is created and how children elements are placed in it. Or(if it's large) you could prepare a minimal example that demonstrates the problem and describe the wanted behavior.

    I'm not sure I understand the part about the resize. Do you resize a widget that has a layout set or do you try to resize a widget that is inside a layout of its parent (because that's not right)?

  • @Chris-Kawa Okay, I'll provide a more thorough explanation and show some code (I probably should have from the beginning). So what I have is a mainwindow with a QScrollArea in it, in this scroll area I have an empty QWidget with a layout (Vertical Box) set, so that in practice whatever I put in the layout is displayed in the scroll area in a fashion like you would probably expect. This layout is filled with x amount of a custom class called Pod the .cpp file is as shown (I know, I am a messy programmer but whatever! Throws organization to the wind!)

    #include "pod.h"
    #include "mainwindow.h"
    Pod::Pod(int xI, int yI, int widthI, int heightI, QWidget *parent) : QFrame(parent), width(widthI),
        height(heightI), x(xI), y(yI)
        //this->setStyleSheet(".Pod {border: 3px solid orange; border-radius: 3px;}");
        TextLabel = new QLabel(this);
        TextLabel->setGeometry(QRect(0,0,(width * 0.6),height));
        Image = new QPixmap();
        ImageScroll = new QScrollArea(this);
        ImageScroll->setGeometry(QRect(TextLabel->width(),0,(width * 0.4),height));
        ImageLabel = new QLabel(this);
        ImageLabel->setGeometry(QRect(TextLabel->width(),0,(width * 0.4),height));
        ImageLabel->setStyleSheet("border: 2px solid #D50918; border-radius: 3px;");
        TextScroll = new QScrollArea(this);
        TextScroll->setGeometry(QRect(0,0,(width * 0.6),height));
        TextLabel->setStyleSheet("border: 3px solid orange; border-radius: 3px;");
    void Pod::setText(QString Text)
    void Pod::setImage(QByteArray Data)
        if (TextScroll->height() < ImageScroll->height())
            if (TextLabel->height() < Image->height() == false)
        this->resize(this->width,(ImageScroll->height() > TextScroll->height()) ? ImageScroll->height() : TextScroll->height());
    void Pod::setUrl(QUrl Url)
        qDebug() << "SetUrl Called";
        Download = new Downloader(Url,this);

    Well, that is a long post. I'm not sure if I should explain it (as you can probably figure it out from the code) but, this custom widget has 2 scroll areas in it which each contain a label. Does this information help?

  • Lifetime Qt Champion


    If I've read Pod's code correctly, there's no layout on it, so you have to do all the placing/resizing for the widgets in it by hand. A QGridLayout might be a better alternative for that.

    Hope it helps

  • @SGaist Are you meaning to say apply a layout directly to the widget as in QWidget::setLayout(QLayout *)? I've just checked the documentation and I'm not quite sure what effect this has/what it does. Could you please elaborate a little bit more?

    Edit: After reading your post again and thinking about it a bit more, do you mean that I should have a layout as a member of Pod? If this is correct in what you are saying, I think I have not explained correctly, The spacing issue is not within the pods themselves but rather between pods.

  • Lifetime Qt Champion

    If you manage all your pods like the widgets inside them, then you need to do all the mathematics to ensure they are placed and spaced correctly. That's why I suggest using a layout manager inside them and also to handle them

  • @SGaist @Chris-Kawa ..... Still not seeing your point, and yes now that I think about it it probably would have been better to have another layout as a member of Pod. But, as for managing placing and spacing, I don't get it, I just construct the object in a QList<Pod *> named PodList and subsequently place it into the layout, then they need not be moved again. I'm not sure if I've mentioned this previously but, the issue with the empty space comes in when I resize TextLabel, ImageLabel and their scroll areas.

        QList<Pod*> PodList;
        for (int p=0; p!=NumPods; p++)
            PodList.insert(p,new Pod(0,0,400,150,this));

    *MainLayout is the layout in the highest level scroll area

    Here I'll also include a picture to provide additional context to my issue

  • Lifetime Qt Champion

    Since you don't use a layout manager, you also need to take into account the position of your widgets when you resize

  • @SGaist Okay. But, if I've adjusted the size of the widgets inside the v box layout, shouldn't it resize to fit its children (OR is there a fixed space within the layout that I can position Pods in)? As evidently it doesn't, how can I create this behavior? And yes, I've tried setting size policy to fixed size.

  • Lifetime Qt Champion

    If the children of your widgets are not themselves handled by a layout manager, then no, they won't do anything automatically

  • @SGaist What? If a widget and all its children in a position above that of another widget were to uniformly decrease in size so that they take up less vertical space expanding downwards but maintain the same position of being in the top left, just like why? Why would this empty space exist the widgets have all decreased in size meaning that they have retracted from their position leaving space which I would have assumed would be removed so that the widgets in the next index position underneath could shift upwards. In other terms, if the size decreases as to retract from a position then shouldn't the layout adjust its allocated space for this widget? I've never had a problem with this before... And one last thing, as an answer to your statement, could I just apply a newly constructed layout to the widgets without setting anything and it would work?

    I'm sorry if I do sound a bit rude... I appreciate the help you and others on this form willingly provide, even if I am being difficult.

  • Lifetime Qt Champion

    Widgets in a layout manager are evenly distributed unless you modify their stretch factor (by default 0 IIRC). In the case of a vertical layout, if you add a stretch with a higher value at the last position you should have all your widgets pushed against one another to the top.

    QVBoxLayout *layout = new QVBoxLayout(this);

  • @SGaist ! I solved it! I appreciate the help and suggestions, but, in the end it turns out that the VBox layout was splitting up the available space its parent inside the topmost level of scroll area. Put more simply, remember the scroll area with the widget that had a layout set to it so that the layout would display inside the scroll area? Well, it turns out I just had to resize that blank widget.

    EDIT: How do I mark this thread as solved?

  • Lifetime Qt Champion

    Good !

    However, I'm not sure I'm following you on that one. Where did you put that resize ?

    If you can't from the Topic Tools menu, then just edit the thread title and prepend [solved]

  • @SGaist I'll give an example

    QScrollArea * Scroll = new QScrollArea();
    QWidget * Widget = new QWidget();
    QVBoxLayout * Layout = new QVBoxLayout();
    //Layout is now displayed inside the scroll area
    //Place things inside Layout
    TheCombinedTotalofAllPodHeights); //Or the largest height out of the two scroll areas in my case

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