supercell-wx/scwx-qt/source/scwx/qt/ui/flow_layout.cpp

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#include <scwx/qt/ui/flow_layout.hpp>

#include <QWidget>

namespace scwx
{
namespace qt
{
namespace ui
{

FlowLayout::FlowLayout(QWidget* parent,
                       int      margin,
                       int      hSpacing,
                       int      vSpacing) :
    QLayout(parent), hSpace_(hSpacing), vSpace_(vSpacing)
{
   setContentsMargins(margin, margin, margin, margin);
}

FlowLayout::FlowLayout(int margin, int hSpacing, int vSpacing) :
    hSpace_(hSpacing), 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 (hSpace_ >= 0)
   {
      return hSpace_;
   }
   else
   {
      return smartSpacing(QStyle::PM_LayoutHorizontalSpacing);
   }
}

int FlowLayout::verticalSpacing() const
{
   if (vSpace_ >= 0)
   {
      return 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);
   }
   return nullptr;
}

Qt::Orientations FlowLayout::expandingDirections() const
{
   return {};
}

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;
   for (const QLayoutItem* item : std::as_const(itemList_))
   {
      size = size.expandedTo(item->minimumSize());
   }

   const QMargins margins = contentsMargins();
   size +=
      QSize(margins.left() + margins.right(), margins.top() + margins.bottom());
   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;

   for (QLayoutItem* item : std::as_const(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);
      }

      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, nullptr, pw);
   }
   else
   {
      return static_cast<QLayout*>(parent)->spacing();
   }
}

} // namespace ui
} // namespace qt
} // namespace scwx