extends QLayout to create flow layout
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#ifndef FLOWLAYOUT_H
#define FLOWLAYOUT_H
#include <QLayout>
#include <QRect>
#include <QWidgetItem>
class FlowLayout : public QLayout
{
public:
FlowLayout(QWidget *parent, int margin = -1, int hSpacing = -1, int vSpacing = -1);
FlowLayout(int margin = -1, int hSpacing = -1, int vSpacing = -1);
~FlowLayout();
void addItem(QLayoutItem *item);
int horizontalSpacing() const;
int verticalSpacing() const;
Qt::Orientations expandingDirections() const;
bool hasHeightForWidth() const;
int heightForWidth(int) const;
int count() const;
QLayoutItem *itemAt(int index) const;
QSize minimumSize() const;
void setGeometry(const QRect &rect);
QSize sizeHint() const;
QLayoutItem *takeAt(int index);
private:
int doLayout(const QRect &rect, bool testOnly) const;
int smartSpacing(QStyle::PixelMetric pm) const;
QList<QLayoutItem *> itemList;
int m_hSpace;
int m_vSpace;
};
#endif
#include <QtGui>
#include "flowlayout.h"
FlowLayout::FlowLayout(QWidget *parent, int margin, int hSpacing, int vSpacing)
: QLayout(parent), m_hSpace(hSpacing), m_vSpace(vSpacing)
{
setContentsMargins(margin, margin, margin, margin);
}
FlowLayout::FlowLayout(int margin, int hSpacing, int vSpacing)
: m_hSpace(hSpacing), m_vSpace(vSpacing)
{
setContentsMargins(margin, margin, margin, margin);
}
FlowLayout::~FlowLayout()
{
QLayoutItem *item;
while ((item = takeAt(0)))
delete item;
}
void FlowLayout::addItem(QLayoutItem *item)
{
itemList.append(item);
}
int FlowLayout::horizontalSpacing() const
{
if (m_hSpace >= 0) {
return m_hSpace;
} else {
return smartSpacing(QStyle::PM_LayoutHorizontalSpacing);
}
}
int FlowLayout::verticalSpacing() const
{
if (m_vSpace >= 0) {
return m_vSpace;
} else {
return smartSpacing(QStyle::PM_LayoutVerticalSpacing);
}
}
int FlowLayout::count() const
{
return itemList.size();
}
QLayoutItem *FlowLayout::itemAt(int index) const
{
return itemList.value(index);
}
QLayoutItem *FlowLayout::takeAt(int index)
{
if (index >= 0 && index < itemList.size())
return itemList.takeAt(index);
else
return 0;
}
Qt::Orientations FlowLayout::expandingDirections() const
{
return 0;
}
bool FlowLayout::hasHeightForWidth() const
{
return true;
}
int FlowLayout::heightForWidth(int width) const
{
int height = doLayout(QRect(0, 0, width, 0), true);
return height;
}
void FlowLayout::setGeometry(const QRect &rect)
{
QLayout::setGeometry(rect);
doLayout(rect, false);
}
QSize FlowLayout::sizeHint() const
{
return minimumSize();
}
QSize FlowLayout::minimumSize() const
{
QSize size;
QLayoutItem *item;
foreach (item, itemList)
size = size.expandedTo(item->minimumSize());
size += QSize(2*margin(), 2*margin());
return size;
}
int FlowLayout::doLayout(const QRect &rect, bool testOnly) const
{
int left, top, right, bottom;
getContentsMargins(&left, &top, &right, &bottom);
QRect effectiveRect = rect.adjusted(+left, +top, -right, -bottom);
int x = effectiveRect.x();
int y = effectiveRect.y();
int lineHeight = 0;
QLayoutItem *item;
foreach (item, itemList) {
QWidget *wid = item->widget();
int spaceX = horizontalSpacing();
if (spaceX == -1)
spaceX = wid->style()->layoutSpacing(
QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Horizontal);
int spaceY = verticalSpacing();
if (spaceY == -1)
spaceY = wid->style()->layoutSpacing(
QSizePolicy::PushButton, QSizePolicy::PushButton, Qt::Vertical);
int nextX = x + item->sizeHint().width() + spaceX;
if (nextX - spaceX > effectiveRect.right() && lineHeight > 0) {
x = effectiveRect.x();
y = y + lineHeight + spaceY;
nextX = x + item->sizeHint().width() + spaceX;
lineHeight = 0;
}
if (!testOnly)
item->setGeometry(QRect(QPoint(x, y), item->sizeHint()));
x = nextX;
lineHeight = qMax(lineHeight, item->sizeHint().height());
}
return y + lineHeight - rect.y() + bottom;
}
int FlowLayout::smartSpacing(QStyle::PixelMetric pm) const
{
QObject *parent = this->parent();
if (!parent) {
return -1;
} else if (parent->isWidgetType()) {
QWidget *pw = static_cast<QWidget *>(parent);
return pw->style()->pixelMetric(pm, 0, pw);
} else {
return static_cast<QLayout *>(parent)->spacing();
}
}
#ifndef WINDOW_H
#define WINDOW_H
#include <QWidget>
QT_BEGIN_NAMESPACE
class QLabel;
QT_END_NAMESPACE
class Window : public QWidget
{
Q_OBJECT
public:
Window();
};
#endif
#include <QtGui>
#include "flowlayout.h"
#include "window.h"
Window::Window()
{
FlowLayout *flowLayout = new FlowLayout;
flowLayout->addWidget(new QPushButton(tr("Short")));
flowLayout->addWidget(new QPushButton(tr("Longer")));
flowLayout->addWidget(new QPushButton(tr("Different text")));
flowLayout->addWidget(new QPushButton(tr("More text")));
flowLayout->addWidget(new QPushButton(tr("Even longer button text")));
setLayout(flowLayout);
setWindowTitle(tr("Flow Layout"));
}
#include <QApplication>
#include "window.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
Window window;
window.show();
return app.exec();
}
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