Creating flow layout

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

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+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
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+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
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+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
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+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#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 : qAsConst(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 : 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);
+      }
+
+      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