imageviewer.cpp Example File
widgets/imageviewer/imageviewer.cpp/**************************************************************************** ** ** Copyright (C) 2015 The Qt Company Ltd. ** Contact: http://www.qt.io/licensing/ ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:BSD$ ** You may use this file under the terms of the BSD license as follows: ** ** "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 ** the documentation and/or other materials provided with the ** distribution. ** * Neither the name of The Qt Company Ltd nor the names of its ** contributors may be used to endorse or promote products derived ** from this software without specific prior written permission. ** ** ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include <QtWidgets> #ifndef QT_NO_PRINTER #include <QPrintDialog> #endif #include "imageviewer.h" ImageViewer::ImageViewer() { imageLabel = new QLabel; imageLabel->setBackgroundRole(QPalette::Base); imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored); imageLabel->setScaledContents(true); scrollArea = new QScrollArea; scrollArea->setBackgroundRole(QPalette::Dark); scrollArea->setWidget(imageLabel); setCentralWidget(scrollArea); createActions(); createMenus(); resize(QGuiApplication::primaryScreen()->availableSize() * 3 / 5); } bool ImageViewer::loadFile(const QString &fileName) { QImageReader reader(fileName); reader.setAutoTransform(true); const QImage image = reader.read(); if (image.isNull()) { QMessageBox::information(this, QGuiApplication::applicationDisplayName(), tr("Cannot load %1.").arg(QDir::toNativeSeparators(fileName))); setWindowFilePath(QString()); imageLabel->setPixmap(QPixmap()); imageLabel->adjustSize(); return false; } imageLabel->setPixmap(QPixmap::fromImage(image)); scaleFactor = 1.0; printAct->setEnabled(true); fitToWindowAct->setEnabled(true); updateActions(); if (!fitToWindowAct->isChecked()) imageLabel->adjustSize(); setWindowFilePath(fileName); return true; } void ImageViewer::open() { QStringList mimeTypeFilters; foreach (const QByteArray &mimeTypeName, QImageReader::supportedMimeTypes()) mimeTypeFilters.append(mimeTypeName); mimeTypeFilters.sort(); const QStringList picturesLocations = QStandardPaths::standardLocations(QStandardPaths::PicturesLocation); QFileDialog dialog(this, tr("Open File"), picturesLocations.isEmpty() ? QDir::currentPath() : picturesLocations.last()); dialog.setAcceptMode(QFileDialog::AcceptOpen); dialog.setMimeTypeFilters(mimeTypeFilters); dialog.selectMimeTypeFilter("image/jpeg"); while (dialog.exec() == QDialog::Accepted && !loadFile(dialog.selectedFiles().first())) {} } void ImageViewer::print() { Q_ASSERT(imageLabel->pixmap()); #if !defined(QT_NO_PRINTER) && !defined(QT_NO_PRINTDIALOG) QPrintDialog dialog(&printer, this); if (dialog.exec()) { QPainter painter(&printer); QRect rect = painter.viewport(); QSize size = imageLabel->pixmap()->size(); size.scale(rect.size(), Qt::KeepAspectRatio); painter.setViewport(rect.x(), rect.y(), size.width(), size.height()); painter.setWindow(imageLabel->pixmap()->rect()); painter.drawPixmap(0, 0, *imageLabel->pixmap()); } #endif } void ImageViewer::zoomIn() { scaleImage(1.25); } void ImageViewer::zoomOut() { scaleImage(0.8); } void ImageViewer::normalSize() { imageLabel->adjustSize(); scaleFactor = 1.0; } void ImageViewer::fitToWindow() { bool fitToWindow = fitToWindowAct->isChecked(); scrollArea->setWidgetResizable(fitToWindow); if (!fitToWindow) { normalSize(); } updateActions(); } void ImageViewer::about() { QMessageBox::about(this, tr("About Image Viewer"), tr("<p>The <b>Image Viewer</b> example shows how to combine QLabel " "and QScrollArea to display an image. QLabel is typically used " "for displaying a text, but it can also display an image. " "QScrollArea provides a scrolling view around another widget. " "If the child widget exceeds the size of the frame, QScrollArea " "automatically provides scroll bars. </p><p>The example " "demonstrates how QLabel's ability to scale its contents " "(QLabel::scaledContents), and QScrollArea's ability to " "automatically resize its contents " "(QScrollArea::widgetResizable), can be used to implement " "zooming and scaling features. </p><p>In addition the example " "shows how to use QPainter to print an image.</p>")); } void ImageViewer::createActions() { openAct = new QAction(tr("&Open..."), this); openAct->setShortcut(tr("Ctrl+O")); connect(openAct, SIGNAL(triggered()), this, SLOT(open())); printAct = new QAction(tr("&Print..."), this); printAct->setShortcut(tr("Ctrl+P")); printAct->setEnabled(false); connect(printAct, SIGNAL(triggered()), this, SLOT(print())); exitAct = new QAction(tr("E&xit"), this); exitAct->setShortcut(tr("Ctrl+Q")); connect(exitAct, SIGNAL(triggered()), this, SLOT(close())); zoomInAct = new QAction(tr("Zoom &In (25%)"), this); zoomInAct->setShortcut(tr("Ctrl++")); zoomInAct->setEnabled(false); connect(zoomInAct, SIGNAL(triggered()), this, SLOT(zoomIn())); zoomOutAct = new QAction(tr("Zoom &Out (25%)"), this); zoomOutAct->setShortcut(tr("Ctrl+-")); zoomOutAct->setEnabled(false); connect(zoomOutAct, SIGNAL(triggered()), this, SLOT(zoomOut())); normalSizeAct = new QAction(tr("&Normal Size"), this); normalSizeAct->setShortcut(tr("Ctrl+S")); normalSizeAct->setEnabled(false); connect(normalSizeAct, SIGNAL(triggered()), this, SLOT(normalSize())); fitToWindowAct = new QAction(tr("&Fit to Window"), this); fitToWindowAct->setEnabled(false); fitToWindowAct->setCheckable(true); fitToWindowAct->setShortcut(tr("Ctrl+F")); connect(fitToWindowAct, SIGNAL(triggered()), this, SLOT(fitToWindow())); aboutAct = new QAction(tr("&About"), this); connect(aboutAct, SIGNAL(triggered()), this, SLOT(about())); aboutQtAct = new QAction(tr("About &Qt"), this); connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt())); } void ImageViewer::createMenus() { fileMenu = new QMenu(tr("&File"), this); fileMenu->addAction(openAct); fileMenu->addAction(printAct); fileMenu->addSeparator(); fileMenu->addAction(exitAct); viewMenu = new QMenu(tr("&View"), this); viewMenu->addAction(zoomInAct); viewMenu->addAction(zoomOutAct); viewMenu->addAction(normalSizeAct); viewMenu->addSeparator(); viewMenu->addAction(fitToWindowAct); helpMenu = new QMenu(tr("&Help"), this); helpMenu->addAction(aboutAct); helpMenu->addAction(aboutQtAct); menuBar()->addMenu(fileMenu); menuBar()->addMenu(viewMenu); menuBar()->addMenu(helpMenu); } void ImageViewer::updateActions() { zoomInAct->setEnabled(!fitToWindowAct->isChecked()); zoomOutAct->setEnabled(!fitToWindowAct->isChecked()); normalSizeAct->setEnabled(!fitToWindowAct->isChecked()); } void ImageViewer::scaleImage(double factor) { Q_ASSERT(imageLabel->pixmap()); scaleFactor *= factor; imageLabel->resize(scaleFactor * imageLabel->pixmap()->size()); adjustScrollBar(scrollArea->horizontalScrollBar(), factor); adjustScrollBar(scrollArea->verticalScrollBar(), factor); zoomInAct->setEnabled(scaleFactor < 3.0); zoomOutAct->setEnabled(scaleFactor > 0.333); } void ImageViewer::adjustScrollBar(QScrollBar *scrollBar, double factor) { scrollBar->setValue(int(factor * scrollBar->value() + ((factor - 1) * scrollBar->pageStep()/2))); }