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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. ** $QT_END_LICENSE$ ** ****************************************************************************/ /*! \page qtwebengine-overview.html \title Qt WebEngine Overview The Qt WebEngine module provides a web browser engine that makes it easy to embed content from the World Wide Web into your Qt application on platforms that do not have a native web engine. Qt WebEngine provides C++ classes and QML types for rendering HTML, XHTML, and SVG documents, styled using Cascading Style Sheets (CSS) and scripted with JavaScript. HTML documents can be made fully editable by the user through the use of the \c{contenteditable} attribute on HTML elements. \section1 Qt WebEngine Architecture \image qtwebengine-architecture.png The functionality in Qt WebEngine is divided into the following modules: \list \li \l{Qt WebEngine Widgets Module} for creating widget-based web applications \li \l{Qt WebEngine Module} for creating Qt Quick based web applications \li \l{Qt WebEngine Core Module} for interacting with Chromium \endlist Page rendering and JavaScript execution are separated from the GUI process into the Qt WebEngine Process. It is a library that must be shipped with the application if the Qt libraries are bundled into the application. \section2 Qt WebEngine Widgets Module \image qtwebenginewidgets-model.png A \e {web engine view} is the main widget component of the Qt WebEngine module. It can be used in various applications to load web content. Within a view, a \e {web engine page} holds a main frame that is responsible for web content, the \e history of navigated links, and \e actions. The view and page are quite similar, as they provide a set of common functions. All pages belong to a \e {web engine profile} that contains shared \e settings, \e scripts, and \e cookies. Profiles can be used to isolate pages from each other. A typical use case is a dedicated profile for a \e {private browsing} mode, where no information is permanently saved. \note The Qt WebEngine Widgets module uses the \l{Qt Quick Scene Graph}{Qt Quick scene graph} to compose the elements of a web page into one view. This means that the UI process requires OpenGL ES 2.0 or OpenGL 2.0 for its rendering. \section2 Qt WebEngine Module \image qtwebengine-model.png The Qt WebEngine QML implementation contains the same elements as the Qt WebEngine Widgets implementation, except that there is no separately accessible web engine page. The supported page functionality is integrated into the web engine view. \section2 Qt WebEngine Core Module The Qt WebEngine core is based on the \l {Chromium Project}. Chromium provides its own network and painting engines and is developed tightly together with its dependent modules. \note Qt WebEngine is based on Chromium, but does not contain or use any services or add-ons that might be part of the Chrome browser that is built and delivered by Google. You can find more detailed information about the differences between Chromium and Chrome in this \l{https://chromium.googlesource.com/chromium/src/+/master/docs/chromium_browser_vs_google_chrome.md}{overview} that is part of the documentation in the \l {Chromium Project} upstream source tree. This version of Qt WebEngine is based on Chromium version 45.0.2554.101, with additional security fixes from newer versions. \section2 Qt WebEngine Process The Qt WebEngine Process is a separate executable that is used to render web pages and execute JavaScript. This mitigates security issues and isolates crashes caused by specific content. \section1 Embedding Web Content into Widget Based Applications Use the QWebEngineView class to display web pages in the simplest way. Because it is a widget, you can embed QWebEngineView into your forms and use its convenience functions to download and display web sites. \code QWebEngineView *view = new QWebEngineView(parent); view->load(QUrl("http://www.qt.io/")); view->show(); \endcode An instance of QWebEngineView has one QWebEnginePage. QWebEnginePage can have a QWebEngineHistory that provides access to the page's navigation history and several QAction objects that apply actions on the web page. In addition, a QWebEnginePage has the ability to run JavaScript code in the context of the page's main frame and to enable customization of handlers for specific events like showing custom authentication dialogs. Each QWebEnginePage belongs to a QWebEngineProfile that can have a QWebEngineSettings for specifying page settings, a QWebEngineScriptCollection for running scripts on the page, and a QWebEngineCookieStore for accessing the HTTP cookies of Chromium. A QWebEnginePage can also directly point to a script collection. For a widget based application, the web engine is automatically initialized, unless it is placed in a plugin. In that case, it must be initialized in the application main source file by using \l QtWebEngine::initialize, as illustrated by the following code snippet: \code int main(int argc, char **argv) { QApplication app(argc, argv); QtWebEngine::initialize(); QMainWindow window; window.show(); return app.exec(); } \endcode \section1 Embedding Web Content into Qt Quick Applications The WebEngineView QML type allows Qt Quick applications to render regions of dynamic web content. A \e{WebEngineView} type may share the screen with other QML types or encompass the full screen as specified within the Qt Quick application. To make sure that OpenGL context can be shared between the GUI and render processes, the web engine must be initialized by using \l QtWebEngine::initialize in the application main source file, as illustrated by the following code snippet: \quotefromfile webengine/minimal/main.cpp \skipto main \printuntil } An application can load pages into the WebEngineView, using either an URL or HTML string, and navigate within session history. By default, links to different pages load within the same WebEngineView object, but web sites may request them to be opened as a new tab, window, or dialog. The following sample QML application loads a web page using the \l{WebEngineView::}{url} property: \quotefromfile webengine/minimal/main.qml \skipto import \printuntil /^\}/ \section1 Script Injection Qt WebEngine does not allow direct access to the document object model (DOM) of a page. However, the DOM can be inspected and adapted by injecting scripts. The DOM of a page is constructed when the document is ready, typically when the page is completely loaded. Therefore, executing scripts as soon as a document is created is not suitable for DOM operations, where one has to wait until the DOM is ready. In addition, an injected script shares the same \e world as the other scripts executed on the page, which might lead to conflicts. To avoid this, the QWebEngineScript class and the WebEngineScript QML type provide implementations of the Chromium API for \e{Content Script Extensions}. They specify the script to run, the injection point, and the world where the script is run. This enables accessing the DOM to manipulate it within a world. \note Chromium extensions, such as \c @include, \c @match, and \c @exclude, are not supported. \section1 Managing Certificates Qt WebEngine uses its own network stack, and therefore QSslConfiguration is not used to open SSL connections. Instead, Qt WebEngine uses the root CA certificates from the operating system to validate the peer's certificate. The \l{WebEngineCertificateError::error} and \l{QWebEngineCertificateError::Error} enumerations provide information about the types of certificate errors that might occur. The errors can be handled by using the WebEngineView::certificateError QML method or by reimplementing the QWebEnginePage::certificateError function. \section1 Proxy Support If QNetworkProxy::applicationProxy is set, it will also be used for Qt WebEngine. Otherwise, Qt WebEngine automatically picks up the proxy configuration from OS X and Windows. On Linux, it acknowledges settings from KDE and Gnome. If a proxy requires authentication, QWebEnginePage::proxyAuthenticationRequired is emitted. For Qt Quick, a dialog is shown. \section1 High DPI Support To support High DPI devices, it is recommended that the application attribute Qt::AA_EnableHighDpiScaling is set to enable automatic scaling based on the pixel density of the monitor. In Qt WebEngine applications, the scaling affects the default zooming factor and scrollbar size. For example: \code int main(int argc, char *argv[]) { QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling); QApplication app(argc, argv); // ... } \endcode Qt WebEngine bundles images for normal and high-dpi resolutions into \e qtwebengine_resources_100p.pak and \e qtwebengine_resources_200p.pak files. Depending on the target resolutions, one or both of these files need to be deployed. For more information, see \l{High DPI Displays}. \section1 Using WebEngine Core Qt WebEngine Core provides an API shared by Qt WebEngine and Qt WebEngine Widgets for handling URL requests issued for the networking stack of Chromium and for accessing its HTTP cookies. Implementing the QWebEngineUrlRequestInterceptor interface and installing the interceptor on a profile enables intercepting, blocking, and modifying URL requests (QWebEngineUrlRequestInfo) before they reach the networking stack of Chromium. A QWebEngineUrlSchemeHandler can be registered for a profile to add support for custom URL schemes. Requests for the scheme are then issued to QWebEngineUrlSchemeHandler::requestStarted() as QWebEngineUrlRequestJob objects. The QWebEngineCookieStore class provides functions for accessing HTTP cookies of Chromium. The functions can be used to synchronize cookies with QNetworkAccessManager, as well as to set, delete, and intercept cookies during navigation. \section1 Platform Notes Qt WebEngine currently supports only Windows, Linux, and OS X. Due to Chromium build requirements it also often requires a newer compiler than the rest of Qt. See \l{Qt WebEngine Platform Notes} for further details. \section1 Related Modules Qt WebEngine supersedes the \l{http://doc.qt.io/archives/qt-5.3/qtwebkit-index.html}{Qt WebKit} module, which is based on the WebKit project, but has not been actively synchronized with the upstream WebKit code since Qt 5.2 and has been deprecated in Qt 5.5. For tips on how to change a Qt WebKit widgets application to use Qt WebEngine widgets, see \l{Porting from Qt WebKit to Qt WebEngine}. The \l{Qt WebView} module allows to use a native web browser on platforms where one is available. The \l{Qt WebChannel} module can be used to create a bi-directional communication channel between QObject objects on the C++ side and JavaScript on the QML side. \section1 License Information Qt WebEngine module is a snapshot of the integration of Chromium into Qt. Qt Commercial Edition licensees that wish to distribute applications that use the Qt WebEngine module need to be aware of their obligations under the GNU Library General Public License (LGPLv2). Developers using the Open Source Edition can choose to redistribute the module under the GNU LGPLv3 or GPLv2 and up. \legalese Chromium is licensed under the following license: Copyright (c) 2013 The Chromium Authors. All rights reserved. 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 Google Inc. 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. \endlegalese */