<?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>imagescaling.cpp Example File | Qt Concurrent 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="qtconcurrent-index.html">Qt Concurrent</a></td><td ><a href="qtconcurrent-imagescaling-example.html">Image Scaling Example</a></td><td >imagescaling.cpp Example File</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtconcurrent-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">imagescaling.cpp Example File</h1> <span class="subtitle">imagescaling/imagescaling.cpp</span> <!-- $$$imagescaling/imagescaling.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 "imagescaling.h"</span> <span class="preprocessor">#include <qmath.h></span> <span class="preprocessor">#include <functional></span> Images<span class="operator">::</span>Images(<span class="type">QWidget</span> <span class="operator">*</span>parent) : <span class="type">QWidget</span>(parent) { setWindowTitle(tr(<span class="string">"Image loading and scaling example"</span>)); resize(<span class="number">800</span><span class="operator">,</span> <span class="number">600</span>); imageScaling <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator"><</span><span class="type">QImage</span><span class="operator">></span>(<span class="keyword">this</span>); connect(imageScaling<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator"><</span><span class="type">QImage</span><span class="operator">></span><span class="operator">::</span>resultReadyAt<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>Images<span class="operator">::</span>showImage); connect(imageScaling<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator"><</span><span class="type">QImage</span><span class="operator">></span><span class="operator">::</span>finished<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>Images<span class="operator">::</span>finished); openButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QPushButton</span>(tr(<span class="string">"Open Images"</span>)); connect(openButton<span class="operator">,</span> <span class="operator">&</span><span class="type">QPushButton</span><span class="operator">::</span>clicked<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&</span>Images<span class="operator">::</span>open); cancelButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QPushButton</span>(tr(<span class="string">"Cancel"</span>)); cancelButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">false</span>); connect(cancelButton<span class="operator">,</span> <span class="operator">&</span><span class="type">QPushButton</span><span class="operator">::</span>clicked<span class="operator">,</span> imageScaling<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator"><</span><span class="type">QImage</span><span class="operator">></span><span class="operator">::</span>cancel); pauseButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QPushButton</span>(tr(<span class="string">"Pause/Resume"</span>)); pauseButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">false</span>); connect(pauseButton<span class="operator">,</span> <span class="operator">&</span><span class="type">QPushButton</span><span class="operator">::</span>clicked<span class="operator">,</span> imageScaling<span class="operator">,</span> <span class="operator">&</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator"><</span><span class="type">QImage</span><span class="operator">></span><span class="operator">::</span>togglePaused); <span class="type">QHBoxLayout</span> <span class="operator">*</span>buttonLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QHBoxLayout</span>(); buttonLayout<span class="operator">-</span><span class="operator">></span>addWidget(openButton); buttonLayout<span class="operator">-</span><span class="operator">></span>addWidget(cancelButton); buttonLayout<span class="operator">-</span><span class="operator">></span>addWidget(pauseButton); buttonLayout<span class="operator">-</span><span class="operator">></span>addStretch(); imagesLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QGridLayout</span>(); mainLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QVBoxLayout</span>(); mainLayout<span class="operator">-</span><span class="operator">></span>addLayout(buttonLayout); mainLayout<span class="operator">-</span><span class="operator">></span>addLayout(imagesLayout); mainLayout<span class="operator">-</span><span class="operator">></span>addStretch(); setLayout(mainLayout); } Images<span class="operator">::</span><span class="operator">~</span>Images() { imageScaling<span class="operator">-</span><span class="operator">></span>cancel(); imageScaling<span class="operator">-</span><span class="operator">></span>waitForFinished(); } <span class="type">void</span> Images<span class="operator">::</span>open() { <span class="comment">// Cancel and wait if we are already loading images.</span> <span class="keyword">if</span> (imageScaling<span class="operator">-</span><span class="operator">></span>isRunning()) { imageScaling<span class="operator">-</span><span class="operator">></span>cancel(); imageScaling<span class="operator">-</span><span class="operator">></span>waitForFinished(); } <span class="comment">// Show a file open dialog at QStandardPaths::PicturesLocation.</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> files <span class="operator">=</span> <span class="type">QFileDialog</span><span class="operator">::</span>getOpenFileNames(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Select Images"</span>)<span class="operator">,</span> <span class="type"><a href="../qtcore/qstandardpaths.html">QStandardPaths</a></span><span class="operator">::</span>writableLocation(<span class="type"><a href="../qtcore/qstandardpaths.html">QStandardPaths</a></span><span class="operator">::</span>PicturesLocation)<span class="operator">,</span> <span class="string">"*.jpg *.png"</span>); <span class="keyword">if</span> (files<span class="operator">.</span>isEmpty()) <span class="keyword">return</span>; <span class="keyword">const</span> <span class="type">int</span> imageSize <span class="operator">=</span> <span class="number">100</span>; <span class="comment">// Do a simple layout.</span> <a href="../qtcore/qtalgorithms.html#qDeleteAll">qDeleteAll</a>(labels); labels<span class="operator">.</span>clear(); <span class="type">int</span> dim <span class="operator">=</span> <a href="../qtcore/qtmath.html#qSqrt">qSqrt</a>(<span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span>(files<span class="operator">.</span>count())) <span class="operator">+</span> <span class="number">1</span>; <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> dim; <span class="operator">+</span><span class="operator">+</span>i) { <span class="keyword">for</span> (<span class="type">int</span> j <span class="operator">=</span> <span class="number">0</span>; j <span class="operator"><</span> dim; <span class="operator">+</span><span class="operator">+</span>j) { <span class="type">QLabel</span> <span class="operator">*</span>imageLabel <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QLabel</span>; imageLabel<span class="operator">-</span><span class="operator">></span>setFixedSize(imageSize<span class="operator">,</span>imageSize); imagesLayout<span class="operator">-</span><span class="operator">></span>addWidget(imageLabel<span class="operator">,</span>i<span class="operator">,</span>j); labels<span class="operator">.</span>append(imageLabel); } } std<span class="operator">::</span>function<span class="operator"><</span><span class="type">QImage</span>(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">&</span>)<span class="operator">></span> scale <span class="operator">=</span> <span class="operator">[</span>imageSize<span class="operator">]</span>(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&</span>imageFileName) { <span class="type">QImage</span> image(imageFileName); <span class="keyword">return</span> image<span class="operator">.</span>scaled(<span class="type"><a href="../qtcore/qsize.html">QSize</a></span>(imageSize<span class="operator">,</span> imageSize)<span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>IgnoreAspectRatio<span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>SmoothTransformation); }; <span class="comment">// Use mapped to run the thread safe scale function on the files.</span> imageScaling<span class="operator">-</span><span class="operator">></span>setFuture(<span class="type"><a href="qtconcurrent-module.html">QtConcurrent</a></span><span class="operator">::</span>mapped(files<span class="operator">,</span> scale)); openButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">false</span>); cancelButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">true</span>); pauseButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">true</span>); } <span class="type">void</span> Images<span class="operator">::</span>showImage(<span class="type">int</span> num) { labels<span class="operator">[</span>num<span class="operator">]</span><span class="operator">-</span><span class="operator">></span>setPixmap(<span class="type">QPixmap</span><span class="operator">::</span>fromImage(imageScaling<span class="operator">-</span><span class="operator">></span>resultAt(num))); } <span class="type">void</span> Images<span class="operator">::</span>finished() { openButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">true</span>); cancelButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">false</span>); pauseButton<span class="operator">-</span><span class="operator">></span>setEnabled(<span class="keyword">false</span>); } </pre> </div> <!-- @@@imagescaling/imagescaling.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>