How to restrict QLayout from growing?

1
votes

I have a QWidget (window) with QHBoxLayout which contains two QPushButtons. If I make the window bigger (very wide) two things happen:

  1. The buttons grow to their maximum width
  2. The space between and around the buttons grows too.

But I need another behavior:

  1. The widget could grow and shrink as usual
  2. The space between and around the buttons should not grow (it must be constant).
  3. When the buttons reach their maximal width, the widget further grow must be restricted

How to reach the above behavior?

UPD:

I propose the following code:

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

    QWidget wgt;

    QPushButton* button1 = new QPushButton("Button1");
    QPushButton* button2 = new QPushButton("Button2");

    button1->setMinimumSize(150, 100);
    button1->setMaximumSize(250, 100);
    button2->setMinimumSize(150, 100);
    button2->setMaximumSize(250, 100);

    QHBoxLayout* pLayout = new QHBoxLayout(&wgt);
    pLayout->addWidget(button1);
    pLayout->addWidget(button2);

    wgt.setLayout(pLayout);

    wgt.setGeometry(400, 400, 800, 300);
    wgt.show();

    return app.exec();
}

I need that layout should be restricted from min to max (cant be less than min and cant be larger than max) + without stretching the space (it must have fixed size) between and around the buttons.

1
c++qtlayoutqt5

1 Answers

1
votes

Cause

When the window is resized, something must take the available space up. Since the buttons themselves are restricted in size, the space between them grows.

Solution

I would suggest you to add an invisible widget to serve as a placeholder. Then adjust the spacing of the layout accordingly.

Example

Here is an example I have prepared for you of how to change your code in order to achieve the desired effect:

QHBoxLayout* pLayout = new QHBoxLayout(&wgt);
pLayout->addWidget(button1);
pLayout->addSpacing(6);
pLayout->addWidget(button2);
pLayout->addWidget(new QWidget());
pLayout->setSpacing(0);

Alternative solution

In order to restrict the widget's size, use QWidget::setMinimumSize and QWidget::setMaximumSize:

wgt.setMinimumSize(button1->minimumWidth()
                   + button2->minimumWidth()
                   + pLayout->contentsMargins().left()
                   + pLayout->contentsMargins().right()
                   + pLayout->spacing(),
                   button1->minimumHeight()
                   + pLayout->contentsMargins().top()
                   + pLayout->contentsMargins().bottom()
                   + pLayout->spacing());
wgt.setMaximumSize(button1->maximumWidth()
                   + button2->maximumWidth()
                   + pLayout->contentsMargins().left()
                   + pLayout->contentsMargins().right()
                   + pLayout->spacing(),
                   button1->maximumHeight()
                   + pLayout->contentsMargins().top()
                   + pLayout->contentsMargins().bottom()
                   + pLayout->spacing());

If you know the exact dimensions in advance, this could be simplified to:

wgt.setMinimumWidth(324);
wgt.setMaximumWidth(524);
wgt.setFixedHeight(118);