examples/qtconcurrent/imagescaling/imagescaling.cpp
changeset 0 1918ee327afb
child 4 3b1da2848fc7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/qtconcurrent/imagescaling/imagescaling.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,147 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "imagescaling.h"
+#include "math.h"
+
+#ifndef QT_NO_CONCURRENT
+
+const int imageSize = 100;
+
+QImage scale(const QString &imageFileName)
+{
+    QImage image(imageFileName);
+    return image.scaled(QSize(imageSize, imageSize), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+}
+
+Images::Images(QWidget *parent) 
+: QWidget(parent)
+{
+    setWindowTitle(tr("Image loading and scaling example"));
+    resize(800, 600);
+
+    imageScaling = new QFutureWatcher<QImage>(this);
+    connect(imageScaling, SIGNAL(resultReadyAt(int)), SLOT(showImage(int)));
+    connect(imageScaling, SIGNAL(finished()), SLOT(finished()));
+
+    openButton = new QPushButton(tr("Open Images"));
+    connect(openButton, SIGNAL(clicked()), SLOT(open()));
+
+    cancelButton = new QPushButton(tr("Cancel"));
+    cancelButton->setEnabled(false);
+    connect(cancelButton, SIGNAL(clicked()), imageScaling, SLOT(cancel()));
+   
+    pauseButton = new QPushButton(tr("Pause/Resume"));
+    pauseButton->setEnabled(false);
+    connect(pauseButton, SIGNAL(clicked()), imageScaling, SLOT(togglePaused()));
+   
+    QHBoxLayout *buttonLayout = new QHBoxLayout();
+    buttonLayout->addWidget(openButton);
+    buttonLayout->addWidget(cancelButton);
+    buttonLayout->addWidget(pauseButton);
+    buttonLayout->addStretch();
+
+    imagesLayout = new QGridLayout();
+
+    mainLayout = new QVBoxLayout();
+    mainLayout->addLayout(buttonLayout);
+    mainLayout->addLayout(imagesLayout);
+    mainLayout->addStretch();
+    setLayout(mainLayout);
+}
+
+Images::~Images()
+{
+    imageScaling->cancel();
+    imageScaling->waitForFinished();
+}
+
+void Images::open()
+{
+    // Cancel and wait if we are already loading images.
+    if (imageScaling->isRunning()) {
+        imageScaling->cancel();
+        imageScaling->waitForFinished();
+    }
+
+    // Show a file open dialog at QDesktopServices::PicturesLocation.
+    QStringList files = QFileDialog::getOpenFileNames(this, tr("Select Images"), 
+                            QDesktopServices::storageLocation(QDesktopServices::PicturesLocation),
+                            "*.jpg *.png");
+
+    if (files.count() == 0)
+        return;
+
+    // Do a simple layout.
+    qDeleteAll(labels);
+    labels.clear();
+
+    int dim = sqrt(qreal(files.count())) + 1;
+    for (int i = 0; i < dim; ++i) {
+        for (int j = 0; j < dim; ++j) {
+            QLabel *imageLabel = new QLabel;
+            imageLabel->setFixedSize(imageSize,imageSize);
+            imagesLayout->addWidget(imageLabel,i,j);
+            labels.append(imageLabel);
+        }
+    }
+
+    // Use mapped to run the thread safe scale function on the files.
+    imageScaling->setFuture(QtConcurrent::mapped(files, scale));
+
+    openButton->setEnabled(false);
+    cancelButton->setEnabled(true);
+    pauseButton->setEnabled(true);
+}
+
+void Images::showImage(int num)
+{
+    labels[num]->setPixmap(QPixmap::fromImage(imageScaling->resultAt(num)));
+}
+
+void Images::finished()
+{
+    openButton->setEnabled(true);
+    cancelButton->setEnabled(false);
+    pauseButton->setEnabled(false);
+}
+
+#endif // QT_NO_CONCURRENT
+