Dynamically resize spacing

[jpn]

I gave it a quick try and it seems to work at least for a top level widget:

#include <QtGui>
 
class Window : public QWidget
{
	Q_OBJECT
public:
	Window()
	{
		int spacing = 20;
 
		QSpinBox* spinbox = new QSpinBox(this);
		spinbox->setStyleSheet("background: red");
		spinbox->setValue(spacing);
 
		QLabel* label = new QLabel(this);
		label->setStyleSheet("background: blue");
		label->setNum(spacing);
 
		QVBoxLayout* layout = new QVBoxLayout(this);
		spacer = new QSpacerItem(spacing, spacing);
		layout->addWidget(spinbox);
		layout->addItem(spacer);
		layout->addWidget(label);
 
		connect(spinbox, SIGNAL(valueChanged(int)), label, SLOT(setNum(int)));
		connect(spinbox, SIGNAL(valueChanged(int)), this, SLOT(setSpacing(int)));
	}
 
private slots:
	void setSpacing(int spacing)
	{
		spacer->changeSize(spacing, spacing);
		layout()->invalidate();
	}
 
private:
	QSpacerItem* spacer;
};
 
int main(int argc, char* argv[])
{
	QApplication a(argc, argv);
	Window w;
	w.show();
	return a.exec();
}
 
#include "main.moc"

#include <QtGui>

class Window : public QWidget
{
	Q_OBJECT
public:
	Window()
	{
		int spacing = 20;

		QSpinBox* spinbox = new QSpinBox(this);
		spinbox->setStyleSheet("background: red");
		spinbox->setValue(spacing);

		QLabel* label = new QLabel(this);
		label->setStyleSheet("background: blue");
		label->setNum(spacing);

		QVBoxLayout* layout = new QVBoxLayout(this);
		spacer = new QSpacerItem(spacing, spacing);
		layout->addWidget(spinbox);
		layout->addItem(spacer);
		layout->addWidget(label);

		connect(spinbox, SIGNAL(valueChanged(int)), label, SLOT(setNum(int)));
		connect(spinbox, SIGNAL(valueChanged(int)), this, SLOT(setSpacing(int)));
	}

private slots:
	void setSpacing(int spacing)
	{
		spacer->changeSize(spacing, spacing);
		layout()->invalidate();
	}

private:
	QSpacerItem* spacer;
};

int main(int argc, char* argv[])
{
	QApplication a(argc, argv);
	Window w;
	w.show();
	return a.exec();
}

#include "main.moc"

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I suppose the spacing is not homogeneous over the layout? Otherwise you could simply use QBoxLayout::setSpacing().

[trskel]

It is a quite complex layout setup, with nested layouts (I'm sorry but I cannot post the code). There is a Q3ListView bellow and I want to set the spacer width to match that of one column of the list view. I think the resizing is done internally, but it never gets refreshed to the GUI. If I manually resize the window in the GUI, then magically everything gets to it's required size.

I finally solved it by calling hide() and then show(), forcing a full refresh. Not a very elegant solution but it works.