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<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:
  **
  ** &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
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  **   * Neither the name of The Qt Company Ltd nor the names of its
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  **     from this software without specific prior written permission.
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  **
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  ** (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 &lt;qmath.h&gt;</span>

  <span class="preprocessor">#include &lt;functional&gt;</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">&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="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type">QImage</span><span class="operator">&gt;</span>(<span class="keyword">this</span>);
      connect(imageScaling<span class="operator">,</span> <span class="operator">&amp;</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type">QImage</span><span class="operator">&gt;</span><span class="operator">::</span>resultReadyAt<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&amp;</span>Images<span class="operator">::</span>showImage);
      connect(imageScaling<span class="operator">,</span> <span class="operator">&amp;</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type">QImage</span><span class="operator">&gt;</span><span class="operator">::</span>finished<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> <span class="operator">&amp;</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">&quot;Open Images&quot;</span>));
      connect(openButton<span class="operator">,</span> <span class="operator">&amp;</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">&amp;</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">&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> <span class="operator">&amp;</span><span class="type">QPushButton</span><span class="operator">::</span>clicked<span class="operator">,</span> imageScaling<span class="operator">,</span> <span class="operator">&amp;</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type">QImage</span><span class="operator">&gt;</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">&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> <span class="operator">&amp;</span><span class="type">QPushButton</span><span class="operator">::</span>clicked<span class="operator">,</span> imageScaling<span class="operator">,</span> <span class="operator">&amp;</span><span class="type"><a href="../qtcore/qfuturewatcher.html">QFutureWatcher</a></span><span class="operator">&lt;</span><span class="type">QImage</span><span class="operator">&gt;</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">&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">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">&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 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">&quot;Select Images&quot;</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">&quot;*.jpg *.png&quot;</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">&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">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">&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);
          }
      }

      std<span class="operator">::</span>function<span class="operator">&lt;</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">&amp;</span>)<span class="operator">&gt;</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">&amp;</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">&gt;</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">&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">QPixmap</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>);
  }

</pre>
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<!-- @@@imagescaling/imagescaling.cpp -->
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