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<td align="right" valign="top" width="230"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></td></tr></table><h1 align="center">imageviewer.cpp Example File<br /><sup><sup>widgets/imageviewer/imageviewer.cpp</sup></sup></h1>
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<pre> /****************************************************************************
22
** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
24
** This file is part of the documentation of the Qt Toolkit.
26
** This file may be used under the terms of the GNU General Public
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** License version 2.0 as published by the Free Software Foundation
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** and appearing in the file LICENSE.GPL included in the packaging of
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** this file. Please review the following information to ensure GNU
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** General Public Licensing requirements will be met:
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** http://www.trolltech.com/products/qt/opensource.html
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** If you are unsure which license is appropriate for your use, please
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** review the following information:
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** http://www.trolltech.com/products/qt/licensing.html or contact the
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** sales department at sales@trolltech.com.
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** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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****************************************************************************/
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#include <QtGui>
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#include "imageviewer.h"
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ImageViewer::ImageViewer()
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imageLabel = new QLabel;
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imageLabel->setBackgroundRole(QPalette::Base);
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imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
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imageLabel->setScaledContents(true);
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scrollArea = new QScrollArea;
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scrollArea->setBackgroundRole(QPalette::Dark);
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scrollArea->setWidget(imageLabel);
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setCentralWidget(scrollArea);
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setWindowTitle(tr("Image Viewer"));
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void ImageViewer::open()
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QString fileName = QFileDialog::getOpenFileName(this,
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tr("Open File"), QDir::currentPath());
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if (!fileName.isEmpty()) {
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QImage image(fileName);
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QMessageBox::information(this, tr("Image Viewer"),
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tr("Cannot load %1.").arg(fileName));
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imageLabel->setPixmap(QPixmap::fromImage(image));
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printAct->setEnabled(true);
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fitToWindowAct->setEnabled(true);
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if (!fitToWindowAct->isChecked())
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imageLabel->adjustSize();
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void ImageViewer::print()
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Q_ASSERT(imageLabel->pixmap());
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QPrintDialog dialog(&printer, this);
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QPainter painter(&printer);
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QRect rect = painter.viewport();
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QSize size = imageLabel->pixmap()->size();
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size.scale(rect.size(), Qt::KeepAspectRatio);
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painter.setViewport(rect.x(), rect.y(), size.width(), size.height());
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painter.setWindow(imageLabel->pixmap()->rect());
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painter.drawPixmap(0, 0, *imageLabel->pixmap());
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void ImageViewer::zoomIn()
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void ImageViewer::zoomOut()
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void ImageViewer::normalSize()
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imageLabel->adjustSize();
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void ImageViewer::fitToWindow()
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bool fitToWindow = fitToWindowAct->isChecked();
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scrollArea->setWidgetResizable(fitToWindow);
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void ImageViewer::about()
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QMessageBox::about(this, tr("About Image Viewer"),
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tr("<p>The <b>Image Viewer</b> example shows how to combine QLabel "
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"and QScrollArea to display an image. QLabel is typically used "
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"for displaying a text, but it can also display an image. "
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"QScrollArea provides a scrolling view around another widget. "
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"If the child widget exceeds the size of the frame, QScrollArea "
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"automatically provides scroll bars. </p><p>The example "
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"demonstrates how QLabel's ability to scale its contents "
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"(QLabel::scaledContents), and QScrollArea's ability to "
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"automatically resize its contents "
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"(QScrollArea::widgetResizable), can be used to implement "
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"zooming and scaling features. </p><p>In addition the example "
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"shows how to use QPainter to print an image.</p>"));
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void ImageViewer::createActions()
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openAct = new QAction(tr("&Open..."), this);
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openAct->setShortcut(tr("Ctrl+O"));
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connect(openAct, SIGNAL(triggered()), this, SLOT(open()));
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printAct = new QAction(tr("&Print..."), this);
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printAct->setShortcut(tr("Ctrl+P"));
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printAct->setEnabled(false);
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connect(printAct, SIGNAL(triggered()), this, SLOT(print()));
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exitAct = new QAction(tr("E&xit"), this);
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exitAct->setShortcut(tr("Ctrl+Q"));
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connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));
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zoomInAct = new QAction(tr("Zoom &In (25%)"), this);
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zoomInAct->setShortcut(tr("Ctrl++"));
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zoomInAct->setEnabled(false);
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connect(zoomInAct, SIGNAL(triggered()), this, SLOT(zoomIn()));
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zoomOutAct = new QAction(tr("Zoom &Out (25%)"), this);
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zoomOutAct->setShortcut(tr("Ctrl+-"));
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zoomOutAct->setEnabled(false);
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connect(zoomOutAct, SIGNAL(triggered()), this, SLOT(zoomOut()));
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normalSizeAct = new QAction(tr("&Normal Size"), this);
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normalSizeAct->setShortcut(tr("Ctrl+S"));
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normalSizeAct->setEnabled(false);
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connect(normalSizeAct, SIGNAL(triggered()), this, SLOT(normalSize()));
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fitToWindowAct = new QAction(tr("&Fit to Window"), this);
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fitToWindowAct->setEnabled(false);
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fitToWindowAct->setCheckable(true);
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fitToWindowAct->setShortcut(tr("Ctrl+F"));
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connect(fitToWindowAct, SIGNAL(triggered()), this, SLOT(fitToWindow()));
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aboutAct = new QAction(tr("&About"), this);
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connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
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aboutQtAct = new QAction(tr("About &Qt"), this);
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connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
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void ImageViewer::createMenus()
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fileMenu = new QMenu(tr("&File"), this);
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fileMenu->addAction(openAct);
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fileMenu->addAction(printAct);
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fileMenu->addSeparator();
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fileMenu->addAction(exitAct);
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viewMenu = new QMenu(tr("&View"), this);
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viewMenu->addAction(zoomInAct);
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viewMenu->addAction(zoomOutAct);
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viewMenu->addAction(normalSizeAct);
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viewMenu->addSeparator();
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viewMenu->addAction(fitToWindowAct);
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helpMenu = new QMenu(tr("&Help"), this);
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helpMenu->addAction(aboutAct);
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helpMenu->addAction(aboutQtAct);
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menuBar()->addMenu(fileMenu);
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menuBar()->addMenu(viewMenu);
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menuBar()->addMenu(helpMenu);
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void ImageViewer::updateActions()
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zoomInAct->setEnabled(!fitToWindowAct->isChecked());
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zoomOutAct->setEnabled(!fitToWindowAct->isChecked());
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normalSizeAct->setEnabled(!fitToWindowAct->isChecked());
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void ImageViewer::scaleImage(double factor)
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Q_ASSERT(imageLabel->pixmap());
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scaleFactor *= factor;
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imageLabel->resize(scaleFactor * imageLabel->pixmap()->size());
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adjustScrollBar(scrollArea->horizontalScrollBar(), factor);
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adjustScrollBar(scrollArea->verticalScrollBar(), factor);
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zoomInAct->setEnabled(scaleFactor < 3.0);
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zoomOutAct->setEnabled(scaleFactor > 0.333);
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void ImageViewer::adjustScrollBar(QScrollBar *scrollBar, double factor)
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scrollBar->setValue(int(factor * scrollBar->value()
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+ ((factor - 1) * scrollBar->pageStep()/2)));
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<td align="right" valign="top" width="230"><a href="http://www.trolltech.com"><img src="images/trolltech-logo.png" align="right" width="203" height="32" border="0" /></a></td></tr></table><h1 align="center">imageviewer.cpp Example File<br /><sup><sup>widgets/imageviewer/imageviewer.cpp</sup></sup></h1>
15
<pre> /****************************************************************************
17
** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
19
** This file is part of the example classes of the Qt Toolkit.
21
** This file may be used under the terms of the GNU General Public
22
** License version 2.0 as published by the Free Software Foundation
23
** and appearing in the file LICENSE.GPL included in the packaging of
24
** this file. Please review the following information to ensure GNU
25
** General Public Licensing requirements will be met:
26
** http:<span class="comment">//www.trolltech.com/products/qt/opensource.html</span>
28
** If you are unsure which license is appropriate for your use, please
29
** review the following information:
30
** http:<span class="comment">//www.trolltech.com/products/qt/licensing.html or contact the</span>
31
** sales department at sales@trolltech.com.
33
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
34
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
36
****************************************************************************/
38
#include <QtGui>
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#include "imageviewer.h"
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ImageViewer::ImageViewer()
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imageLabel = new QLabel;
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imageLabel->setBackgroundRole(QPalette::Base);
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imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
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imageLabel->setScaledContents(true);
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scrollArea = new QScrollArea;
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scrollArea->setBackgroundRole(QPalette::Dark);
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scrollArea->setWidget(imageLabel);
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setCentralWidget(scrollArea);
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setWindowTitle(tr("Image Viewer"));
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void ImageViewer::open()
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QString fileName = QFileDialog::getOpenFileName(this,
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tr("Open File"), QDir::currentPath());
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if (!fileName.isEmpty()) {
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QImage image(fileName);
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QMessageBox::information(this, tr("Image Viewer"),
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tr("Cannot load %1.").arg(fileName));
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imageLabel->setPixmap(QPixmap::fromImage(image));
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printAct->setEnabled(true);
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fitToWindowAct->setEnabled(true);
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if (!fitToWindowAct->isChecked())
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imageLabel->adjustSize();
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void ImageViewer::print()
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Q_ASSERT(imageLabel->pixmap());
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QPrintDialog dialog(&printer, this);
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QPainter painter(&printer);
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QRect rect = painter.viewport();
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QSize size = imageLabel->pixmap()->size();
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size.scale(rect.size(), Qt::KeepAspectRatio);
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painter.setViewport(rect.x(), rect.y(), size.width(), size.height());
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painter.setWindow(imageLabel->pixmap()->rect());
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painter.drawPixmap(0, 0, *imageLabel->pixmap());
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void ImageViewer::zoomIn()
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void ImageViewer::zoomOut()
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void ImageViewer::normalSize()
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imageLabel->adjustSize();
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void ImageViewer::fitToWindow()
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bool fitToWindow = fitToWindowAct->isChecked();
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scrollArea->setWidgetResizable(fitToWindow);
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void ImageViewer::about()
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QMessageBox::about(this, tr("About Image Viewer"),
128
tr("<p>The <b>Image Viewer</b> example shows how to combine QLabel "
129
"and QScrollArea to display an image. QLabel is typically used "
130
"for displaying a text, but it can also display an image. "
131
"QScrollArea provides a scrolling view around another widget. "
132
"If the child widget exceeds the size of the frame, QScrollArea "
133
"automatically provides scroll bars. </p><p>The example "
134
"demonstrates how QLabel's ability to scale its contents "
135
"(QLabel::scaledContents), and QScrollArea's ability to "
136
"automatically resize its contents "
137
"(QScrollArea::widgetResizable), can be used to implement "
138
"zooming and scaling features. </p><p>In addition the example "
139
"shows how to use QPainter to print an image.</p>"));
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void ImageViewer::createActions()
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openAct = new QAction(tr("&Open..."), this);
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openAct->setShortcut(tr("Ctrl+O"));
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connect(openAct, SIGNAL(triggered()), this, SLOT(open()));
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printAct = new QAction(tr("&Print..."), this);
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printAct->setShortcut(tr("Ctrl+P"));
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printAct->setEnabled(false);
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connect(printAct, SIGNAL(triggered()), this, SLOT(print()));
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exitAct = new QAction(tr("E&xit"), this);
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exitAct->setShortcut(tr("Ctrl+Q"));
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connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));
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zoomInAct = new QAction(tr("Zoom &In (25%)"), this);
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zoomInAct->setShortcut(tr("Ctrl++"));
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zoomInAct->setEnabled(false);
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connect(zoomInAct, SIGNAL(triggered()), this, SLOT(zoomIn()));
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zoomOutAct = new QAction(tr("Zoom &Out (25%)"), this);
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zoomOutAct->setShortcut(tr("Ctrl+-"));
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zoomOutAct->setEnabled(false);
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connect(zoomOutAct, SIGNAL(triggered()), this, SLOT(zoomOut()));
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normalSizeAct = new QAction(tr("&Normal Size"), this);
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normalSizeAct->setShortcut(tr("Ctrl+S"));
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normalSizeAct->setEnabled(false);
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connect(normalSizeAct, SIGNAL(triggered()), this, SLOT(normalSize()));
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fitToWindowAct = new QAction(tr("&Fit to Window"), this);
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fitToWindowAct->setEnabled(false);
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fitToWindowAct->setCheckable(true);
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fitToWindowAct->setShortcut(tr("Ctrl+F"));
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connect(fitToWindowAct, SIGNAL(triggered()), this, SLOT(fitToWindow()));
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aboutAct = new QAction(tr("&About"), this);
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connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
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aboutQtAct = new QAction(tr("About &Qt"), this);
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connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
185
void ImageViewer::createMenus()
187
fileMenu = new QMenu(tr("&File"), this);
188
fileMenu->addAction(openAct);
189
fileMenu->addAction(printAct);
190
fileMenu->addSeparator();
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fileMenu->addAction(exitAct);
193
viewMenu = new QMenu(tr("&View"), this);
194
viewMenu->addAction(zoomInAct);
195
viewMenu->addAction(zoomOutAct);
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viewMenu->addAction(normalSizeAct);
197
viewMenu->addSeparator();
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viewMenu->addAction(fitToWindowAct);
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helpMenu = new QMenu(tr("&Help"), this);
201
helpMenu->addAction(aboutAct);
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helpMenu->addAction(aboutQtAct);
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menuBar()->addMenu(fileMenu);
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menuBar()->addMenu(viewMenu);
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menuBar()->addMenu(helpMenu);
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void ImageViewer::updateActions()
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zoomInAct->setEnabled(!fitToWindowAct->isChecked());
212
zoomOutAct->setEnabled(!fitToWindowAct->isChecked());
213
normalSizeAct->setEnabled(!fitToWindowAct->isChecked());
216
void ImageViewer::scaleImage(double factor)
218
Q_ASSERT(imageLabel->pixmap());
219
scaleFactor *= factor;
220
imageLabel->resize(scaleFactor * imageLabel->pixmap()->size());
222
adjustScrollBar(scrollArea->horizontalScrollBar(), factor);
223
adjustScrollBar(scrollArea->verticalScrollBar(), factor);
225
zoomInAct->setEnabled(scaleFactor < 3.0);
226
zoomOutAct->setEnabled(scaleFactor > 0.333);
229
void ImageViewer::adjustScrollBar(QScrollBar *scrollBar, double factor)
231
scrollBar->setValue(int(factor * scrollBar->value()
232
+ ((factor - 1) * scrollBar->pageStep()/2)));
239
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<p /><address><hr /><div align="center">
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<table width="100%" cellspacing="0" border="0"><tr class="address">
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<td width="30%">Copyright © 2006 <a href="trolltech.html">Trolltech</a></td>
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<td width="40%" align="center"><a href="trademarks.html">Trademarks</a></td>
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<td width="30%" align="right"><div align="right">Qt 4.1.4</div></td>
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<td width="30%" align="right"><div align="right">Qt 4.2.0</div></td>
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</tr></table></div></address></body>
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