<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>flowlayout.cpp Example File | Qt Widgets 5.12.6</title>
<link rel="stylesheet" type="text/css" href="style/offline-simple.css" />
<script type="text/javascript">
document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css");
// loading style sheet breaks anchors that were jumped to before
// so force jumping to anchor again
setTimeout(function() {
var anchor = location.hash;
// need to jump to different anchor first (e.g. none)
location.hash = "#";
setTimeout(function() {
location.hash = anchor;
}, 0);
}, 0);
</script>
</head>
<body>
<div class="header" id="qtdocheader">
<div class="main">
<div class="main-rounded">
<div class="navigationbar">
<table><tr>
<td >Qt 5.12</td><td ><a href="qtwidgets-index.html">Qt Widgets</a></td><td ><a href="qtwidgets-graphicsview-flowlayout-example.html">Graphics View Flow Layout Example</a></td><td >flowlayout.cpp Example File</td></tr></table><table class="buildversion"><tr>
<td id="buildversion" width="100%" align="right"><a href="qtwidgets-index.html">Qt 5.12.6 Reference Documentation</a></td>
</tr></table>
</div>
</div>
<div class="content">
<div class="line">
<div class="content mainContent">
<div class="sidebar"><div class="sidebar-content" id="sidebar-content"></div></div>
<h1 class="title">flowlayout.cpp Example File</h1>
<span class="subtitle">graphicsview/flowlayout/flowlayout.cpp</span>
<!-- $$$graphicsview/flowlayout/flowlayout.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">
<span class="comment">/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** 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:
** * 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 The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "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
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include "flowlayout.h"</span>
<span class="preprocessor">#include <qmath.h></span>
<span class="preprocessor">#include <QWidget></span>
FlowLayout<span class="operator">::</span>FlowLayout()
{
m_spacing<span class="operator">[</span><span class="number">0</span><span class="operator">]</span> <span class="operator">=</span> <span class="number">6</span>;
m_spacing<span class="operator">[</span><span class="number">1</span><span class="operator">]</span> <span class="operator">=</span> <span class="number">6</span>;
<span class="type"><a href="qsizepolicy.html">QSizePolicy</a></span> sp <span class="operator">=</span> sizePolicy();
sp<span class="operator">.</span>setHeightForWidth(<span class="keyword">true</span>);
setSizePolicy(sp);
}
<span class="type">void</span> FlowLayout<span class="operator">::</span>insertItem(<span class="type">int</span> index<span class="operator">,</span> <span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>item)
{
item<span class="operator">-</span><span class="operator">></span>setParentLayoutItem(<span class="keyword">this</span>);
<span class="keyword">if</span> (<span class="type"><a href="../qtcore/qtglobal.html#uint-typedef">uint</a></span>(index) <span class="operator">></span> <span class="type"><a href="../qtcore/qtglobal.html#uint-typedef">uint</a></span>(m_items<span class="operator">.</span>count()))
index <span class="operator">=</span> m_items<span class="operator">.</span>count();
m_items<span class="operator">.</span>insert(index<span class="operator">,</span> item);
invalidate();
}
<span class="type">int</span> FlowLayout<span class="operator">::</span>count() <span class="keyword">const</span>
{
<span class="keyword">return</span> m_items<span class="operator">.</span>count();
}
<span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>FlowLayout<span class="operator">::</span>itemAt(<span class="type">int</span> index) <span class="keyword">const</span>
{
<span class="keyword">return</span> m_items<span class="operator">.</span>value(index);
}
<span class="type">void</span> FlowLayout<span class="operator">::</span>removeAt(<span class="type">int</span> index)
{
m_items<span class="operator">.</span>removeAt(index);
invalidate();
}
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> FlowLayout<span class="operator">::</span>spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Orientation o) <span class="keyword">const</span>
{
<span class="keyword">return</span> m_spacing<span class="operator">[</span><span class="type">int</span>(o) <span class="operator">-</span> <span class="number">1</span><span class="operator">]</span>;
}
<span class="type">void</span> FlowLayout<span class="operator">::</span>setSpacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Orientations o<span class="operator">,</span> <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> spacing)
{
<span class="keyword">if</span> (o <span class="operator">&</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Horizontal)
m_spacing<span class="operator">[</span><span class="number">0</span><span class="operator">]</span> <span class="operator">=</span> spacing;
<span class="keyword">if</span> (o <span class="operator">&</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Vertical)
m_spacing<span class="operator">[</span><span class="number">1</span><span class="operator">]</span> <span class="operator">=</span> spacing;
}
<span class="type">void</span> FlowLayout<span class="operator">::</span>setGeometry(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span> <span class="operator">&</span>geom)
{
<span class="type"><a href="qgraphicslayout.html">QGraphicsLayout</a></span><span class="operator">::</span>setGeometry(geom);
doLayout(geom<span class="operator">,</span> <span class="keyword">true</span>);
}
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> FlowLayout<span class="operator">::</span>doLayout(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span> <span class="operator">&</span>geom<span class="operator">,</span> bool applyNewGeometry) <span class="keyword">const</span>
{
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> left<span class="operator">,</span> top<span class="operator">,</span> right<span class="operator">,</span> bottom;
getContentsMargins(<span class="operator">&</span>left<span class="operator">,</span> <span class="operator">&</span>top<span class="operator">,</span> <span class="operator">&</span>right<span class="operator">,</span> <span class="operator">&</span>bottom);
<span class="keyword">const</span> <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> maxw <span class="operator">=</span> geom<span class="operator">.</span>width() <span class="operator">-</span> left <span class="operator">-</span> right;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> x <span class="operator">=</span> <span class="number">0</span>;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> y <span class="operator">=</span> <span class="number">0</span>;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> maxRowHeight <span class="operator">=</span> <span class="number">0</span>;
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> pref;
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> m_items<span class="operator">.</span>count(); <span class="operator">+</span><span class="operator">+</span>i) {
<span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>item <span class="operator">=</span> m_items<span class="operator">.</span>at(i);
pref <span class="operator">=</span> item<span class="operator">-</span><span class="operator">></span>effectiveSizeHint(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>PreferredSize);
maxRowHeight <span class="operator">=</span> <a href="../qtcore/qtglobal.html#qMax">qMax</a>(maxRowHeight<span class="operator">,</span> pref<span class="operator">.</span>height());
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> next_x;
next_x <span class="operator">=</span> x <span class="operator">+</span> pref<span class="operator">.</span>width();
<span class="keyword">if</span> (next_x <span class="operator">></span> maxw) {
<span class="keyword">if</span> (x <span class="operator">=</span><span class="operator">=</span> <span class="number">0</span>) {
pref<span class="operator">.</span>setWidth(maxw);
} <span class="keyword">else</span> {
x <span class="operator">=</span> <span class="number">0</span>;
next_x <span class="operator">=</span> pref<span class="operator">.</span>width();
}
y <span class="operator">+</span><span class="operator">=</span> maxRowHeight <span class="operator">+</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Vertical);
maxRowHeight <span class="operator">=</span> <span class="number">0</span>;
}
<span class="keyword">if</span> (applyNewGeometry)
item<span class="operator">-</span><span class="operator">></span>setGeometry(<span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span>(<span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span>(left <span class="operator">+</span> x<span class="operator">,</span> top <span class="operator">+</span> y)<span class="operator">,</span> pref));
x <span class="operator">=</span> next_x <span class="operator">+</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Horizontal);
}
maxRowHeight <span class="operator">=</span> <a href="../qtcore/qtglobal.html#qMax">qMax</a>(maxRowHeight<span class="operator">,</span> pref<span class="operator">.</span>height());
<span class="keyword">return</span> top <span class="operator">+</span> y <span class="operator">+</span> maxRowHeight <span class="operator">+</span> bottom;
}
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> FlowLayout<span class="operator">::</span>minSize(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> <span class="operator">&</span>constraint) <span class="keyword">const</span>
{
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> size(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span>);
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> left<span class="operator">,</span> top<span class="operator">,</span> right<span class="operator">,</span> bottom;
getContentsMargins(<span class="operator">&</span>left<span class="operator">,</span> <span class="operator">&</span>top<span class="operator">,</span> <span class="operator">&</span>right<span class="operator">,</span> <span class="operator">&</span>bottom);
<span class="keyword">if</span> (constraint<span class="operator">.</span>width() <span class="operator">></span><span class="operator">=</span> <span class="number">0</span>) { <span class="comment">// height for width</span>
<span class="keyword">const</span> <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> height <span class="operator">=</span> doLayout(<span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span>(<span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span>(<span class="number">0</span><span class="operator">,</span><span class="number">0</span>)<span class="operator">,</span> constraint)<span class="operator">,</span> <span class="keyword">false</span>);
size <span class="operator">=</span> <span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span>(constraint<span class="operator">.</span>width()<span class="operator">,</span> height);
} <span class="keyword">else</span> <span class="keyword">if</span> (constraint<span class="operator">.</span>height() <span class="operator">></span><span class="operator">=</span> <span class="number">0</span>) { <span class="comment">// width for height?</span>
<span class="comment">// not supported</span>
} <span class="keyword">else</span> {
<span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>item;
foreach (item<span class="operator">,</span> m_items)
size <span class="operator">=</span> size<span class="operator">.</span>expandedTo(item<span class="operator">-</span><span class="operator">></span>effectiveSizeHint(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>MinimumSize));
size <span class="operator">+</span><span class="operator">=</span> <span class="type"><a href="../qtcore/qsize.html">QSize</a></span>(left <span class="operator">+</span> right<span class="operator">,</span> top <span class="operator">+</span> bottom);
}
<span class="keyword">return</span> size;
}
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> FlowLayout<span class="operator">::</span>prefSize() <span class="keyword">const</span>
{
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> left<span class="operator">,</span> right;
getContentsMargins(<span class="operator">&</span>left<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="operator">&</span>right<span class="operator">,</span> <span class="number">0</span>);
<span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>item;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> maxh <span class="operator">=</span> <span class="number">0</span>;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> totalWidth <span class="operator">=</span> <span class="number">0</span>;
foreach (item<span class="operator">,</span> m_items) {
<span class="keyword">if</span> (totalWidth <span class="operator">></span> <span class="number">0</span>)
totalWidth <span class="operator">+</span><span class="operator">=</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Horizontal);
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> pref <span class="operator">=</span> item<span class="operator">-</span><span class="operator">></span>effectiveSizeHint(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>PreferredSize);
totalWidth <span class="operator">+</span><span class="operator">=</span> pref<span class="operator">.</span>width();
maxh <span class="operator">=</span> <a href="../qtcore/qtglobal.html#qMax">qMax</a>(maxh<span class="operator">,</span> pref<span class="operator">.</span>height());
}
maxh <span class="operator">+</span><span class="operator">=</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Vertical);
<span class="keyword">const</span> <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> goldenAspectRatio <span class="operator">=</span> <span class="number">1.61803399</span>;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> w <span class="operator">=</span> <a href="../qtcore/qtmath.html#qSqrt">qSqrt</a>(totalWidth <span class="operator">*</span> maxh <span class="operator">*</span> goldenAspectRatio) <span class="operator">+</span> left <span class="operator">+</span> right;
<span class="keyword">return</span> minSize(<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span>(w<span class="operator">,</span> <span class="operator">-</span><span class="number">1</span>));
}
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> FlowLayout<span class="operator">::</span>maxSize() <span class="keyword">const</span>
{
<span class="type"><a href="qgraphicslayoutitem.html">QGraphicsLayoutItem</a></span> <span class="operator">*</span>item;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> totalWidth <span class="operator">=</span> <span class="number">0</span>;
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> totalHeight <span class="operator">=</span> <span class="number">0</span>;
foreach (item<span class="operator">,</span> m_items) {
<span class="keyword">if</span> (totalWidth <span class="operator">></span> <span class="number">0</span>)
totalWidth <span class="operator">+</span><span class="operator">=</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Horizontal);
<span class="keyword">if</span> (totalHeight <span class="operator">></span> <span class="number">0</span>)
totalHeight <span class="operator">+</span><span class="operator">=</span> spacing(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>Vertical);
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> pref <span class="operator">=</span> item<span class="operator">-</span><span class="operator">></span>effectiveSizeHint(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>PreferredSize);
totalWidth <span class="operator">+</span><span class="operator">=</span> pref<span class="operator">.</span>width();
totalHeight <span class="operator">+</span><span class="operator">=</span> pref<span class="operator">.</span>height();
}
<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> left<span class="operator">,</span> top<span class="operator">,</span> right<span class="operator">,</span> bottom;
getContentsMargins(<span class="operator">&</span>left<span class="operator">,</span> <span class="operator">&</span>top<span class="operator">,</span> <span class="operator">&</span>right<span class="operator">,</span> <span class="operator">&</span>bottom);
<span class="keyword">return</span> <span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span>(left <span class="operator">+</span> totalWidth <span class="operator">+</span> right<span class="operator">,</span> top <span class="operator">+</span> totalHeight <span class="operator">+</span> bottom);
}
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> FlowLayout<span class="operator">::</span>sizeHint(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>SizeHint which<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> <span class="operator">&</span>constraint) <span class="keyword">const</span>
{
<span class="type"><a href="../qtcore/qsizef.html">QSizeF</a></span> sh <span class="operator">=</span> constraint;
<span class="keyword">switch</span> (which) {
<span class="keyword">case</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>PreferredSize:
sh <span class="operator">=</span> prefSize();
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>MinimumSize:
sh <span class="operator">=</span> minSize(constraint);
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>MaximumSize:
sh <span class="operator">=</span> maxSize();
<span class="keyword">break</span>;
<span class="keyword">default</span>:
<span class="keyword">break</span>;
}
<span class="keyword">return</span> sh;
}
</pre>
</div>
<!-- @@@graphicsview/flowlayout/flowlayout.cpp -->
</div>
</div>
</div>
</div>
</div>
<div class="footer">
<p>
<acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd.
Documentation contributions included herein are the copyrights of
their respective owners.<br/> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br/> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property
of their respective owners. </p>
</div>
</body>
</html>
