layout sizeHint qwidget

Question

I am creating a widget which contains a chess table and six buttons which are displayed in 2 rows beneath the chess table. The button rows are wider than the chess table. Chess table and buttons are in a QGridLayout. Chess table has its own sizeHint calculated from the size of the squares. After some operations I delete the buttons and resize the widget that contains everything to its sizeHint (`resize(sizeHint())`). The widget resizes properly in the vertical direction but in the horizontal direction it remains as wide as if the button rows were there. What is the problem ? If I construct the widget only with the chess table the layout sizes the widget properly. I am adding the code: In the constructor of the window: ``` renderArea = new RenderArea(m_row,m_col,m_grid); formLayout = new QGridLayout; formLayout->addWidget(renderArea,0,0,1,3); setLayout(formLayout); ``` In the function that adds the buttons: ``` addPlaneButton = new QPushButton(tr("Add plane")); cancelButton = new QPush…

Accepted Answer

You must `activate()` the layout before for its `sizeHint()`, and subsequently the widget's `sizeHint()`, to be updated immediately after modifying the laid out widgets.

The calls to `layout->removeWidget()` are redundant. Simply `delete` the unneeded widgets. Qt handles all memory allocation in QWidget hierarchies. Deleting a QWidget without telling anyone on the Qt end of things is safe. There are sane exceptions of course: you can't delete a widget whose method is somewhere on the call stack, for example.

If you don't want to bother with calling `resize()`, you can set the appropriate size constraint on the widget's layout. For example:

`layout->setSizeConstraint(QLayout::SetFixedSize);`

This ensures that the widget will size itself only large enough to fit the contents per the `sizeHint()`.

Taking points 1 and 2 into account, the function that 'deletes everything besides the chess table' might look like the below:

```
void removeButtons() {
    delete addPlaneButton;
    delete cancelButton;
    delete movePlaneButton;
    delete deletePlaneButton;
    delete rotatePlaneButton;
    delete doneButton;
    delete infoLabel;
    delete statusLabel;

formLayout->activate();
    resize(sizeHint());
}
```

layout sizeHint qwidget

Solution

Problem