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c++qtresizeqdialogqtwidgets

Enable resizing on QWidget

I want a resize feature in a QWidget using Qt, like the one shown in the image below.

enter image description here

I have used following tried following ways:

using QSizeGrip, setSizeGripEnabled

Solution

  • For completeness I'm showing two examples: with and without the Qt Designer.

    Example using Qt Designer

    designer

    Check the sizeGripEnabled property:

    properties

    Preview from within the Qt Designer (Form > Preview...):

    preview

    Minimal application to show the dialog:

    #include <QtWidgets/QApplication>
#include <QDialog>
#include "ui_DialogButtonBottom.h"

class Dialog : public QDialog {
public:
  Dialog(QWidget* parent = nullptr) :
    QDialog(parent) {
    ui.setupUi(this);
  }

private:
  Ui::Dialog ui;
};

int main(int argc, char* argv[])
{
  QApplication a(argc, argv);

  Dialog dlg;
  return dlg.exec();
}

    Resut

    result

    Without Qt Designer

    #include <QtWidgets/QApplication>
#include <QDialog>

class Dialog : public QDialog {
public:
  Dialog(QWidget* parent = nullptr) :
    QDialog(parent) {
    setWindowTitle("Example");
    setSizeGripEnabled(true);
  }
};

int main(int argc, char* argv[])
{
  QApplication a(argc, argv);

  Dialog dlg;
  return dlg.exec();
}

    Result

    result

    Update to include Frameless mode

    Adding the Frameless windows hint doesn't change anything: it works correctly. Obviously, there is no frame so resize/move methods provided by the windows manager are not available.

    #include <QtWidgets/QApplication>
#include <QDialog>

class Dialog : public QDialog {
public:
  Dialog(QWidget* parent = nullptr, Qt::WindowFlags flags = 0) :
    QDialog(parent, flags) {
    setWindowTitle("Example");
    setSizeGripEnabled(true);
  }
};

int main(int argc, char* argv[])
{
  QApplication a(argc, argv);

  Dialog dlg(nullptr, Qt::FramelessWindowHint); // frameless
  return dlg.exec();
}

    Result

    frameless

    As all the options are working straightforwardly, I'd suggest you to carefully review your code/UI design for things like setting a maximum/minimum size (if both are the same, the grip will still be available but won't change the size at all).