// Copyright (C) 2019 The Qt Company Ltd. // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only /*! \example webenginewidgets/printme \title WebEngine Widgets PrintMe Example \ingroup webengine-widgetexamples \brief Demonstrates how to print web pages using Qt WebEngine Widgets. \image printme-example.png \e PrintMe demonstrates how to use the \l{QWebEnginePage} and \l{QPrintDialog} classes to print a web page. Further, it shows how to implement print preview by using the \l{QPrintPreviewDialog} class. For completeness, it also illustrates how to trigger a printing request within JavaScript. \include examples-run.qdocinc \section1 Simple HTML Page In this example, we create an internal HTML page that is added as a resource collection file (.qrc). The page shows only a small HTML message box that explains how to trigger printing by using keyboard shortcuts or clicking a button. The button has the JavaScript \c{onclick} event attribute that calls the JavaScript \c{window.print()} function. \quotefromfile webenginewidgets/printme/data/index.html \skipto \section1 Main Function In the \c main function, we first instantiate a QWebEngineView and set the URL to our internal HTML page. Next, we create a \c PrintHandler instance and pass the requested page. For convenience, we also create keyboard shortcuts that can be used to call a print dialog or print preview dialog. \quotefromfile webenginewidgets/printme/main.cpp \skipto QWebEngineView view \printto return \section1 Print Handler In the \c{PrintHandler} class, we first implement \c{printPreview()}, where we instantiate \l{QPrintPreviewDialog}. We need the \l{QPrintPreviewDialog::paintRequested} handle to generate a set of preview pages. \quotefromfile webenginewidgets/printme/printhandler.cpp \skipto PrintHandler::printPreview( \printuntil /^\}/ Now we can implement the \c{PrintHandler::printDocument()} slot, which is called in response to the \l{QPrintPreviewDialog::paintRequested} signal. To do actual painting on a printer, we call the \l QWebEngineView::print() function. Because this call is asynchronous, we need to use a local event loop. We begin the local event loop by calling \l{QEventLoop::exec()}. \quotefromfile webenginewidgets/printme/printhandler.cpp \skipto PrintHandler::printDocument( \printuntil /^\}/ To get notified about the result of printing job, we implement \c{PrintHandler::printFinished()} slot as handler of \l QWebEngineView::printFinished() signal. We check for \c{success} and report any errors that occurred. \quotefromfile webenginewidgets/printme/printhandler.cpp \skipto PrintHandler::printFinished( \printuntil /^\}/ The last function we implement, \c{PrintHandler::print()}, is trivial, because it simply opens \l{QPrintDialog} and calls the previously implemented \c{PrintHandler::printDocument()}. \quotefromfile webenginewidgets/printme/printhandler.cpp \skipto PrintHandler::print( \printuntil /^\}/ */