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     2 **

     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

     4 ** All rights reserved.

     5 ** Contact: Nokia Corporation (qt-info@nokia.com)

     6 **

     7 ** This file is part of the examples of the Qt Toolkit.

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     9 ** $QT_BEGIN_LICENSE:LGPL$

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    12 ** You may use this file in accordance with the terms and conditions

    13 ** contained in the Technology Preview License Agreement accompanying

    14 ** this package.

    15 **

    16 ** GNU Lesser General Public License Usage

    17 ** Alternatively, this file may be used under the terms of the GNU Lesser

    18 ** General Public License version 2.1 as published by the Free Software

    19 ** Foundation and appearing in the file LICENSE.LGPL included in the

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    21 ** ensure the GNU Lesser General Public License version 2.1 requirements

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    38 ** $QT_END_LICENSE$

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    40 ****************************************************************************/

    41 #include "imagescaling.h"

    42 #include "math.h"

    43 

    44 #ifndef QT_NO_CONCURRENT

    45 

    46 const int imageSize = 100;

    47 

    48 QImage scale(const QString &imageFileName)

    49 {

    50     QImage image(imageFileName);

    51     return image.scaled(QSize(imageSize, imageSize), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

    52 }

    53 

    54 Images::Images(QWidget *parent) 

    55 : QWidget(parent)

    56 {

    57     setWindowTitle(tr("Image loading and scaling example"));

    58     resize(800, 600);

    59 

    60     imageScaling = new QFutureWatcher<QImage>(this);

    61     connect(imageScaling, SIGNAL(resultReadyAt(int)), SLOT(showImage(int)));

    62     connect(imageScaling, SIGNAL(finished()), SLOT(finished()));

    63 

    64     openButton = new QPushButton(tr("Open Images"));

    65     connect(openButton, SIGNAL(clicked()), SLOT(open()));

    66 

    67     cancelButton = new QPushButton(tr("Cancel"));

    68     cancelButton->setEnabled(false);

    69     connect(cancelButton, SIGNAL(clicked()), imageScaling, SLOT(cancel()));

    70    

    71     pauseButton = new QPushButton(tr("Pause/Resume"));

    72     pauseButton->setEnabled(false);

    73     connect(pauseButton, SIGNAL(clicked()), imageScaling, SLOT(togglePaused()));

    74    

    75     QHBoxLayout *buttonLayout = new QHBoxLayout();

    76     buttonLayout->addWidget(openButton);

    77     buttonLayout->addWidget(cancelButton);

    78     buttonLayout->addWidget(pauseButton);

    79     buttonLayout->addStretch();

    80 

    81     imagesLayout = new QGridLayout();

    82 

    83     mainLayout = new QVBoxLayout();

    84     mainLayout->addLayout(buttonLayout);

    85     mainLayout->addLayout(imagesLayout);

    86     mainLayout->addStretch();

    87     setLayout(mainLayout);

    88 }

    89 

    90 Images::~Images()

    91 {

    92     imageScaling->cancel();

    93     imageScaling->waitForFinished();

    94 }

    95 

    96 void Images::open()

    97 {

    98     // Cancel and wait if we are already loading images.

    99     if (imageScaling->isRunning()) {

   100         imageScaling->cancel();

   101         imageScaling->waitForFinished();

   102     }

   103 

   104     // Show a file open dialog at QDesktopServices::PicturesLocation.

   105     QStringList files = QFileDialog::getOpenFileNames(this, tr("Select Images"), 

   106                             QDesktopServices::storageLocation(QDesktopServices::PicturesLocation),

   107                             "*.jpg *.png");

   108 

   109     if (files.count() == 0)

   110         return;

   111 

   112     // Do a simple layout.

   113     qDeleteAll(labels);

   114     labels.clear();

   115 

   116     int dim = sqrt(qreal(files.count())) + 1;

   117     for (int i = 0; i < dim; ++i) {

   118         for (int j = 0; j < dim; ++j) {

   119             QLabel *imageLabel = new QLabel;

   120             imageLabel->setFixedSize(imageSize,imageSize);

   121             imagesLayout->addWidget(imageLabel,i,j);

   122             labels.append(imageLabel);

   123         }

   124     }

   125 

   126     // Use mapped to run the thread safe scale function on the files.

   127     imageScaling->setFuture(QtConcurrent::mapped(files, scale));

   128 

   129     openButton->setEnabled(false);

   130     cancelButton->setEnabled(true);

   131     pauseButton->setEnabled(true);

   132 }

   133 

   134 void Images::showImage(int num)

   135 {

   136     labels[num]->setPixmap(QPixmap::fromImage(imageScaling->resultAt(num)));

   137 }

   138 

   139 void Images::finished()

   140 {

   141     openButton->setEnabled(true);

   142     cancelButton->setEnabled(false);

   143     pauseButton->setEnabled(false);

   144 }

   145 

   146 #endif // QT_NO_CONCURRENT

   147