screenshot.cpp Example File
desktop/screenshot/screenshot.cpp

 /****************************************************************************
 **
 ** Copyright (C) 2010 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 <QtGui>

 #include "screenshot.h"

 Screenshot::Screenshot()
 {
     screenshotLabel = new QLabel;
     screenshotLabel->setSizePolicy(QSizePolicy::Expanding,
                                    QSizePolicy::Expanding);
     screenshotLabel->setAlignment(Qt::AlignCenter);
     screenshotLabel->setMinimumSize(240, 160);

     createOptionsGroupBox();
     createButtonsLayout();

     mainLayout = new QVBoxLayout;
     mainLayout->addWidget(screenshotLabel);
     mainLayout->addWidget(optionsGroupBox);
     mainLayout->addLayout(buttonsLayout);
     setLayout(mainLayout);

     shootScreen();
     delaySpinBox->setValue(5);

     setWindowTitle(tr("Screenshot"));
     resize(300, 200);
 }

 void Screenshot::resizeEvent(QResizeEvent * /* event */)
 {
     QSize scaledSize = originalPixmap.size();
     scaledSize.scale(screenshotLabel->size(), Qt::KeepAspectRatio);
     if (!screenshotLabel->pixmap()
             || scaledSize != screenshotLabel->pixmap()->size())
         updateScreenshotLabel();
 }

 void Screenshot::newScreenshot()
 {
     if (hideThisWindowCheckBox->isChecked())
         hide();
     newScreenshotButton->setDisabled(true);

     QTimer::singleShot(delaySpinBox->value() * 1000, this, SLOT(shootScreen()));
 }

 void Screenshot::saveScreenshot()
 {
     QString format = "png";
     QString initialPath = QDir::currentPath() + tr("/untitled.") + format;

     QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
                                initialPath,
                                tr("%1 Files (*.%2);;All Files (*)")
                                .arg(format.toUpper())
                                .arg(format));
     if (!fileName.isEmpty())
         originalPixmap.save(fileName, format.toAscii());
 }

 void Screenshot::shootScreen()
 {
     if (delaySpinBox->value() != 0)
         qApp->beep();
     originalPixmap = QPixmap(); // clear image for low memory situations
                                 // on embedded devices.
     originalPixmap = QPixmap::grabWindow(QApplication::desktop()->winId());
     updateScreenshotLabel();

     newScreenshotButton->setDisabled(false);
     if (hideThisWindowCheckBox->isChecked())
         show();
 }

 void Screenshot::updateCheckBox()
 {
     if (delaySpinBox->value() == 0) {
         hideThisWindowCheckBox->setDisabled(true);
         hideThisWindowCheckBox->setChecked(false);
     }
     else
         hideThisWindowCheckBox->setDisabled(false);
 }

 void Screenshot::createOptionsGroupBox()
 {
     optionsGroupBox = new QGroupBox(tr("Options"));

     delaySpinBox = new QSpinBox;
     delaySpinBox->setSuffix(tr(" s"));
     delaySpinBox->setMaximum(60);
     connect(delaySpinBox, SIGNAL(valueChanged(int)), this, SLOT(updateCheckBox()));

     delaySpinBoxLabel = new QLabel(tr("Screenshot Delay:"));

     hideThisWindowCheckBox = new QCheckBox(tr("Hide This Window"));

     optionsGroupBoxLayout = new QGridLayout;
     optionsGroupBoxLayout->addWidget(delaySpinBoxLabel, 0, 0);
     optionsGroupBoxLayout->addWidget(delaySpinBox, 0, 1);
     optionsGroupBoxLayout->addWidget(hideThisWindowCheckBox, 1, 0, 1, 2);
     optionsGroupBox->setLayout(optionsGroupBoxLayout);
 }

 void Screenshot::createButtonsLayout()
 {
     newScreenshotButton = createButton(tr("New Screenshot"),
                                        this, SLOT(newScreenshot()));

     saveScreenshotButton = createButton(tr("Save Screenshot"),
                                         this, SLOT(saveScreenshot()));

     quitScreenshotButton = createButton(tr("Quit"), this, SLOT(close()));

     buttonsLayout = new QHBoxLayout;
     buttonsLayout->addStretch();
     buttonsLayout->addWidget(newScreenshotButton);
     buttonsLayout->addWidget(saveScreenshotButton);
     buttonsLayout->addWidget(quitScreenshotButton);
 }

 QPushButton *Screenshot::createButton(const QString &text, QWidget *receiver,
                                       const char *member)
 {
     QPushButton *button = new QPushButton(text);
     button->connect(button, SIGNAL(clicked()), receiver, member);
     return button;
 }

 void Screenshot::updateScreenshotLabel()
 {
     screenshotLabel->setPixmap(originalPixmap.scaled(screenshotLabel->size(),
                                                      Qt::KeepAspectRatio,
                                                      Qt::SmoothTransformation));
 }