Qt - remove all widgets from layout?

This doesn't seem easy. Basically, I add QPushButtons through a function to a layout, and when the function executes, I want to clear the layout first (removing all QPushButtons and whatever else is in there), because more buttons just get appended to the scrollview.

header

QVBoxLayout* _layout;

cpp

void MainWindow::removeButtonsThenAddMore(const QString &item) {

//remove buttons/widgets

QVBoxLayout* _layout = new QVBoxLayout(this);

QPushButton button = new QPushButton(item);
_layout->addWidget(button);

QPushButton button = new QPushButton("button");
_layout->addWidget(button);

QWidget* widget = new QWidget();
widget->setLayout(_layout);

QScrollArea* scroll = new QScrollArea();
scroll->setWidget(widget);
scroll->show();

}

Edit Report

1 Answer

Untried: Why not create a new layout, swap it with the old layout and delete the old layout? This should delete all items that were owned by the layout and leave the others.

Edit: After studying the comments to my answer, the documentation and the Qt sources I found a better solution:

If you still have Qt3 support enabled, you can use QLayout::deleteAllItems() which is basically the same as hint in the documentation for QLayout::takeAt:

The following code fragment shows a safe way to remove all items from a layout:

QLayoutItem *child;
while ((child = layout->takeAt(0)) != 0) {
  ...
  delete child;
}

Edit: After further research it looks like both version above are equivalent: only sublayouts and widget without parents are deleted. Widgets with parent are treated in a special way. It looks like TeL's solution should work, you only should be careful not to delete any top-level widgets. Another way would be to use the widget hierarchy to delete widgets: Create a special widget without parent and create all your removeable widgets as child of this special widget. After cleaning the layout delete this special widget.

answered 2010-11-25T09:16:32.123

Qt - remove all widgets from layout?

1 Answer

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