Qt 4.8: flowlayout.cpp Example File (layouts/flowlayout/flowlayout.cpp)

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# flowlayout.cpp Example File

layouts/flowlayout/flowlayout.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
     ** Contact: http://www.qt-project.org/legal
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** 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:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
     **     of its contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
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     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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     #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();
         }
     }