Create example for WebEngine's Print To Pdf

Adds example command line tool 'html2pdf' that loads a URL into
QWebEnginePage and prints it to a pdf file.

Task-number: QTBUG-59823
Change-Id: I898e9a9ecdf819f417876f964d40e494f6095c99
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Michael Brüning <michael.bruning@qt.io>

5 files changed, 241 insertions, 0 deletions

diff --git a/examples/webenginewidgets/html2pdf/doc/images/html2pdf-example.png b/examples/webenginewidgets/html2pdf/doc/images/html2pdf-example.png
new file mode 100644
index 000000000..e8055f798
--- /dev/null
+++ b/examples/webenginewidgets/html2pdf/doc/images/html2pdf-example.png
diff --git a/examples/webenginewidgets/html2pdf/doc/src/html2pdf.qdoc b/examples/webenginewidgets/html2pdf/doc/src/html2pdf.qdoc
new file mode 100644
index 000000000..97301977f
--- /dev/null
+++ b/examples/webenginewidgets/html2pdf/doc/src/html2pdf.qdoc
@@ -0,0 +1,96 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: http://www.gnu.org/copyleft/fdl.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+    \example webenginewidgets/html2pdf
+    \title WebEngine Widgets Html2Pdf Example
+    \ingroup webengine-widgetexamples
+    \brief Converts web pages to PDF documents using Qt WebEngine
+
+    \image html2pdf-example.png
+
+    \e {Html2Pdf} demonstrates how to use Qt WebEngine to implement a
+    command-line application for converting web pages into PDF documents.
+
+    \include examples-run.qdocinc
+
+    \section1 The Conversion Process
+
+    In order to convert a web page into a PDF document we need to:
+
+    \list 1
+        \li Create a \l QWebEnginePage.
+        \li Tell the \l QWebEnginePage to begin loading the target URL and wait for it to finish.
+        \li Tell the \l QWebEnginePage to begin converting the loaded page into a PDF file and again wait for it to finish.
+        \li Once the conversion is finished, exit the program.
+    \endlist
+
+    This process is encapsulated in the \e {Html2PdfConverter} class:
+
+    \quotefromfile webenginewidgets/html2pdf/html2pdf.cpp
+    \skipto #include
+    \printuntil Html2PdfConverter
+    \printuntil /^\};/
+
+    In the constructor we create the \l QWebEnginePage and connect to its \l
+    QWebEnginePage::loadFinished and \l QWebEnginePage::pdfPrintingFinished
+    signals:
+
+    \skipto Html2PdfConverter::Html2PdfConverter
+    \printuntil /^\}/
+
+    The \c run() method will trigger the conversion process by asking \l
+    QWebEnginePage to start loading the target URL. We then enter the main event
+    loop:
+
+    \skipto Html2PdfConverter::run
+    \printuntil /^\}/
+
+    After the loading is finished we begin PDF generation. We ask the \l
+    QWebEnginePage::printToPdf method to write the output directly to disk:
+
+    \skipto Html2PdfConverter::loadFinished
+    \printuntil /^\}/
+
+    Once we receive the signal that the PDF conversion has finished, all that
+    remains is to report potential errors and exit the program:
+
+    \skipto Html2PdfConverter::pdfPrintingFinished
+    \printuntil /^\}/
+
+    \section1 The Main Function
+
+    Our \c main function is responsible for setting up a \l QApplication and
+    parsing command line arguments:
+
+    \skipto int main
+    \printuntil /^\}/
+
+    Note that to use Qt WebEngine Widgets we need to create a \l QApplication
+    and not a \l QCoreApplication, even though this is a command line
+    application.
+*/
diff --git a/examples/webenginewidgets/html2pdf/html2pdf.cpp b/examples/webenginewidgets/html2pdf/html2pdf.cpp
new file mode 100644
index 000000000..44e692a22
--- /dev/null
+++ b/examples/webenginewidgets/html2pdf/html2pdf.cpp
@@ -0,0 +1,136 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://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 <QApplication>
+#include <QCommandLineParser>
+#include <QFile>
+#include <QWebEnginePage>
+
+#include <functional>
+
+using namespace std;
+using namespace std::placeholders;
+
+class Html2PdfConverter : public QObject
+{
+    Q_OBJECT
+public:
+    explicit Html2PdfConverter(QString inputPath, QString outputPath);
+    int run();
+
+private slots:
+    void loadFinished(bool ok);
+    void pdfPrintingFinished(const QString &filePath, bool success);
+
+private:
+    QString m_inputPath;
+    QString m_outputPath;
+    QScopedPointer<QWebEnginePage> m_page;
+};
+
+Html2PdfConverter::Html2PdfConverter(QString inputPath, QString outputPath)
+    : m_inputPath(move(inputPath))
+    , m_outputPath(move(outputPath))
+    , m_page(new QWebEnginePage)
+{
+    connect(m_page.data(), &QWebEnginePage::loadFinished,
+            this, &Html2PdfConverter::loadFinished);
+    connect(m_page.data(), &QWebEnginePage::pdfPrintingFinished,
+            this, &Html2PdfConverter::pdfPrintingFinished);
+}
+
+int Html2PdfConverter::run()
+{
+    m_page->load(QUrl::fromUserInput(m_inputPath));
+    return QApplication::exec();
+}
+
+void Html2PdfConverter::loadFinished(bool ok)
+{
+    if (!ok) {
+        QTextStream(stderr)
+            << tr("failed to load URL '%1'").arg(m_inputPath) << "\n";
+        QCoreApplication::exit(1);
+        return;
+    }
+
+    m_page->printToPdf(m_outputPath);
+}
+
+void Html2PdfConverter::pdfPrintingFinished(const QString &filePath, bool success)
+{
+    if (!success) {
+        QTextStream(stderr)
+            << tr("failed to print to output file '%1'").arg(filePath) << "\n";
+        QCoreApplication::exit(1);
+    } else {
+        QCoreApplication::quit();
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    QApplication app(argc, argv);
+    QCoreApplication::setApplicationName("html2pdf");
+    QCoreApplication::setApplicationVersion(QT_VERSION_STR);
+
+    QCommandLineParser parser;
+    parser.setApplicationDescription(
+        QCoreApplication::translate("main", "Converts the web page INPUT into the PDF file OUTPUT."));
+    parser.addHelpOption();
+    parser.addVersionOption();
+    parser.addPositionalArgument(
+        QCoreApplication::translate("main", "INPUT"),
+        QCoreApplication::translate("main", "Input URL for PDF conversion."));
+    parser.addPositionalArgument(
+        QCoreApplication::translate("main", "OUTPUT"),
+        QCoreApplication::translate("main", "Output file name for PDF conversion."));
+
+    parser.process(QCoreApplication::arguments());
+
+    const QStringList requiredArguments = parser.positionalArguments();
+    if (requiredArguments.size() != 2)
+        parser.showHelp(1);
+
+    Html2PdfConverter converter(requiredArguments.at(0), requiredArguments.at(1));
+    return converter.run();
+}
+
+#include "html2pdf.moc"
diff --git a/examples/webenginewidgets/html2pdf/html2pdf.pro b/examples/webenginewidgets/html2pdf/html2pdf.pro
new file mode 100644
index 000000000..f041d23db
--- /dev/null
+++ b/examples/webenginewidgets/html2pdf/html2pdf.pro
@@ -0,0 +1,8 @@
+TEMPLATE = app
+
+QT += webenginewidgets
+
+SOURCES += html2pdf.cpp
+
+target.path = $$[QT_INSTALL_EXAMPLES]/webenginewidgets/html2pdf
+INSTALLS += target
diff --git a/examples/webenginewidgets/webenginewidgets.pro b/examples/webenginewidgets/webenginewidgets.pro
index 78db442b9..61b294d7a 100644
--- a/examples/webenginewidgets/webenginewidgets.pro
+++ b/examples/webenginewidgets/webenginewidgets.pro
@@ -5,6 +5,7 @@ SUBDIRS += \
     contentmanipulation \
     cookiebrowser \
     demobrowser \
+    html2pdf \
     markdowneditor \
     simplebrowser \
     videoplayer