flowlayout.cpp

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#include "flowlayout.h"
 
#include <QtWidgets>
 
//! [1]
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);
}
 
//! [1]
 
//! [2]
FlowLayout::~FlowLayout()
{
    QLayoutItem* item;
    while ((item = takeAt(0)))
        delete item;
}
 
//! [2]
 
//! [3]
void
FlowLayout::addItem(QLayoutItem* item)
{
    itemList.append(item);
}
 
//! [3]
 
//! [4]
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);
    }
}
 
//! [4]
 
//! [5]
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);
    return nullptr;
}
 
//! [5]
 
//! [6]
Qt::Orientations
FlowLayout::expandingDirections() const
{
    return {};
}
 
//! [6]
 
//! [7]
bool
FlowLayout::hasHeightForWidth() const
{
    return true;
}
 
int
FlowLayout::heightForWidth(int width) const
{
    int height = doLayout(QRect(0, 0, width, 0), true);
    return height;
}
 
//! [7]
 
//! [8]
void
FlowLayout::setGeometry(const QRect& rect)
{
    QLayout::setGeometry(rect);
    doLayout(rect, false);
}
 
QSize
FlowLayout::sizeHint() const
{
    return minimumSize();
}
 
QSize
FlowLayout::minimumSize() const
{
    QSize size;
    for (const QLayoutItem* item : qAsConst(itemList))
        size = size.expandedTo(item->minimumSize());
 
    const QMargins margins = contentsMargins();
    size += QSize(margins.left() + margins.right(), margins.top() + margins.bottom());
    return size;
}
 
//! [8]
 
//! [9]
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;
    //! [9]
 
    //! [10]
    for (QLayoutItem* item : qAsConst(itemList))
    {
        const 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);
        //! [10]
        //! [11]
        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;
}
 
//! [11]
//! [12]
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, nullptr, pw);
    }
    else
    {
        return static_cast<QLayout*>(parent)->spacing();
    }
}
 
//! [12]