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>

2 files changed, 96 insertions, 0 deletions

diff --git a/examples/webenginewidgets/html2pdf/doc/images/html2pdf-example.png b/examples/webenginewidgets/html2pdf/doc/images/html2pdf-example.png
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diff --git a/examples/webenginewidgets/html2pdf/doc/src/html2pdf.qdoc b/examples/webenginewidgets/html2pdf/doc/src/html2pdf.qdoc
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+/****************************************************************************
+**
+** 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.
+*/