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<h1 class="title">imagescaling.cpp Example File</h1>
<span class="small-subtitle">qtconcurrent/imagescaling/imagescaling.cpp</span>
<!-- $$$qtconcurrent/imagescaling/imagescaling.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp"> <span class="comment">/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** 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:
**
** &quot;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
** &quot;AS IS&quot; 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.&quot;
**
** $QT_END_LICENSE$
**
****************************************************************************/</span>
<span class="preprocessor">#include &quot;imagescaling.h&quot;</span>
<span class="preprocessor">#include &quot;math.h&quot;</span>
<span class="preprocessor">#ifndef QT_NO_CONCURRENT</span>
<span class="keyword">const</span> <span class="type">int</span> imageSize <span class="operator">=</span> <span class="number">100</span>;
<span class="type"><a href="qimage.html">QImage</a></span> scale(<span class="keyword">const</span> <span class="type"><a href="qstring.html">QString</a></span> <span class="operator">&amp;</span>imageFileName)
{
<span class="type"><a href="qimage.html">QImage</a></span> image(imageFileName);
<span class="keyword">return</span> image<span class="operator">.</span>scaled(<span class="type"><a href="qsize.html">QSize</a></span>(imageSize<span class="operator">,</span> imageSize)<span class="operator">,</span> <span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>IgnoreAspectRatio<span class="operator">,</span> <span class="type"><a href="qt.html">Qt</a></span><span class="operator">::</span>SmoothTransformation);
}
Images<span class="operator">::</span>Images(<span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>parent)
: <span class="type"><a href="qwidget.html">QWidget</a></span>(parent)
{
setWindowTitle(tr(<span class="string">&quot;Image loading and scaling example&quot;</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="qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type"><a href="qimage.html">QImage</a></span><span class="operator">&gt;</span>(<span class="keyword">this</span>);
connect(imageScaling<span class="operator">,</span> SIGNAL(resultReadyAt(<span class="type">int</span>))<span class="operator">,</span> SLOT(showImage(<span class="type">int</span>)));
connect(imageScaling<span class="operator">,</span> SIGNAL(finished())<span class="operator">,</span> SLOT(finished()));
openButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qpushbutton.html">QPushButton</a></span>(tr(<span class="string">&quot;Open Images&quot;</span>));
connect(openButton<span class="operator">,</span> SIGNAL(clicked())<span class="operator">,</span> SLOT(open()));
cancelButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qpushbutton.html">QPushButton</a></span>(tr(<span class="string">&quot;Cancel&quot;</span>));
cancelButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">false</span>);
connect(cancelButton<span class="operator">,</span> SIGNAL(clicked())<span class="operator">,</span> imageScaling<span class="operator">,</span> SLOT(cancel()));
pauseButton <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qpushbutton.html">QPushButton</a></span>(tr(<span class="string">&quot;Pause/Resume&quot;</span>));
pauseButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">false</span>);
connect(pauseButton<span class="operator">,</span> SIGNAL(clicked())<span class="operator">,</span> imageScaling<span class="operator">,</span> SLOT(togglePaused()));
<span class="type"><a href="qhboxlayout.html">QHBoxLayout</a></span> <span class="operator">*</span>buttonLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qhboxlayout.html">QHBoxLayout</a></span>();
buttonLayout<span class="operator">-</span><span class="operator">&gt;</span>addWidget(openButton);
buttonLayout<span class="operator">-</span><span class="operator">&gt;</span>addWidget(cancelButton);
buttonLayout<span class="operator">-</span><span class="operator">&gt;</span>addWidget(pauseButton);
buttonLayout<span class="operator">-</span><span class="operator">&gt;</span>addStretch();
imagesLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qgridlayout.html">QGridLayout</a></span>();
mainLayout <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qvboxlayout.html">QVBoxLayout</a></span>();
mainLayout<span class="operator">-</span><span class="operator">&gt;</span>addLayout(buttonLayout);
mainLayout<span class="operator">-</span><span class="operator">&gt;</span>addLayout(imagesLayout);
mainLayout<span class="operator">-</span><span class="operator">&gt;</span>addStretch();
setLayout(mainLayout);
}
Images<span class="operator">::</span><span class="operator">~</span>Images()
{
imageScaling<span class="operator">-</span><span class="operator">&gt;</span>cancel();
imageScaling<span class="operator">-</span><span class="operator">&gt;</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">&gt;</span>isRunning()) {
imageScaling<span class="operator">-</span><span class="operator">&gt;</span>cancel();
imageScaling<span class="operator">-</span><span class="operator">&gt;</span>waitForFinished();
}
<span class="comment">// Show a file open dialog at QDesktopServices::PicturesLocation.</span>
<span class="type"><a href="qstringlist.html">QStringList</a></span> files <span class="operator">=</span> <span class="type"><a href="qfiledialog.html">QFileDialog</a></span><span class="operator">::</span>getOpenFileNames(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">&quot;Select Images&quot;</span>)<span class="operator">,</span>
<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>storageLocation(<span class="type"><a href="qdesktopservices.html">QDesktopServices</a></span><span class="operator">::</span>PicturesLocation)<span class="operator">,</span>
<span class="string">&quot;*.jpg *.png&quot;</span>);
<span class="keyword">if</span> (files<span class="operator">.</span>count() <span class="operator">=</span><span class="operator">=</span> <span class="number">0</span>)
<span class="keyword">return</span>;
<span class="comment">// Do a simple layout.</span>
<a href="qtalgorithms.html#qDeleteAll">qDeleteAll</a>(labels);
labels<span class="operator">.</span>clear();
<span class="type">int</span> dim <span class="operator">=</span> sqrt(<span class="type"><a href="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">&lt;</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">&lt;</span> dim; <span class="operator">+</span><span class="operator">+</span>j) {
<span class="type"><a href="qlabel.html">QLabel</a></span> <span class="operator">*</span>imageLabel <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qlabel.html">QLabel</a></span>;
imageLabel<span class="operator">-</span><span class="operator">&gt;</span>setFixedSize(imageSize<span class="operator">,</span>imageSize);
imagesLayout<span class="operator">-</span><span class="operator">&gt;</span>addWidget(imageLabel<span class="operator">,</span>i<span class="operator">,</span>j);
labels<span class="operator">.</span>append(imageLabel);
}
}
<span class="comment">// Use mapped to run the thread safe scale function on the files.</span>
imageScaling<span class="operator">-</span><span class="operator">&gt;</span>setFuture(<span class="type"><a href="qtconcurrent.html">QtConcurrent</a></span><span class="operator">::</span>mapped(files<span class="operator">,</span> scale));
openButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">false</span>);
cancelButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">true</span>);
pauseButton<span class="operator">-</span><span class="operator">&gt;</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">&gt;</span>setPixmap(<span class="type"><a href="qpixmap.html">QPixmap</a></span><span class="operator">::</span>fromImage(imageScaling<span class="operator">-</span><span class="operator">&gt;</span>resultAt(num)));
}
<span class="type">void</span> Images<span class="operator">::</span>finished()
{
openButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">true</span>);
cancelButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">false</span>);
pauseButton<span class="operator">-</span><span class="operator">&gt;</span>setEnabled(<span class="keyword">false</span>);
}
<span class="preprocessor">#endif // QT_NO_CONCURRENT</span></pre>
</div>
<!-- @@@qtconcurrent/imagescaling/imagescaling.cpp -->
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