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/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** 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 Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/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.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page qtwebenginewidgets-qtwebkitportingguide.html
\title Porting from Qt WebKit to Qt WebEngine
\brief This guide gives an overview of the differences between the Qt WebKit
and Qt WebEngine APIs in applications.
This provides rough steps to follow when porting an application using
Qt WebKit's QWebView API to use Qt WebEngine's QWebEngineView.
\section1 Class Names
The Qt WebEngine equivalent of Qt WebKit C++ classes are prefixed by
"\e QWebEngine" instead of "\e QWeb".
\b {Qt WebKit}
\code
#include <QWebHistory>
#include <QWebHistoryItem>
#include <QWebPage>
#include <QWebView>
QWebHistory
QWebHistoryItem
QWebPage
QWebView
\endcode
\b {Qt WebEngine}
\code
#include <QWebEngineHistory>
#include <QWebEngineHistoryItem>
#include <QWebEnginePage>
#include <QWebEngineView>
QWebEngineHistory
QWebEngineHistoryItem
QWebEnginePage
QWebEngineView
\endcode
\section1 Qt Module Name
\section2 In qmake Project Files
\b {Qt WebKit}
\code
QT += webkitwidgets
\endcode
\b {Qt WebEngine}
\code
QT += webenginewidgets
\endcode
\section2 Including the Module in Source Files
\b {Qt WebKit}
\code
#include <QtWebKit/QtWebKit>
#include <QtWebKitWidgets/QtWebKitWidgets> // With Qt >= 4.8
\endcode
\b {Qt WebEngine}
\code
#include <QtWebEngineWidgets/QtWebEngineWidgets>
\endcode
\section1 QWebFrame has been Merged into QWebEnginePage
It is not possible to access sub-frames. Methods of the main QWebFrame are
now available directly through the QWebEnginePage itself.
\b {Qt WebKit}
\code
QWebPage page;
connect(page.mainFrame(), SIGNAL(urlChanged(const QUrl&)), SLOT(mySlotName()));
page.mainFrame()->load(url);
\endcode
\b {Qt WebEngine}
\code
QWebEnginePage page;
connect(&page, SIGNAL(urlChanged(const QUrl&)), SLOT(mySlotName()));
page.load(url);
\endcode
\section1 Some methods now return their result asynchronously
Since Qt WebEngine uses a multi-process architecture, applications needs
to return to the event loop where the result will be received asynchronously
from Qt WebEngine's render process. A function pointer, a functor or a lambda
expression must be provided to handle the result when it is available.
\b {Qt WebKit}
\code
QWebPage *page = new QWebPage;
QTextEdit *textEdit = new QTextEdit;
// *textEdit is modified immediately.
textEdit->setPlainText(page->toHtml());
textEdit->setPlainText(page->toPlainText());
\endcode
\b {Qt WebEngine (with a lambda function in C++11)}
\code
QWebEnginePage *page = new QWebEnginePage;
QTextEdit *textEdit = new QTextEdit;
// *textEdit must remain valid until the lambda function is called.
page->toHtml([textEdit](const QString &result){ textEdit->setPlainText(result); });
page->toPlainText([textEdit](const QString &result){ textEdit->setPlainText(result); });
\endcode
\b {Qt WebEngine (with a functor template wrapping a member function)}
\code
template<typename Arg, typename R, typename C>
struct InvokeWrapper {
R *receiver;
void (C::*memberFun)(Arg);
void operator()(Arg result) {
(receiver->*memberFun)(result);
}
};
template<typename Arg, typename R, typename C>
InvokeWrapper<Arg, R, C> invoke(R *receiver, void (C::*memberFun)(Arg))
{
InvokeWrapper<Arg, R, C> wrapper = {receiver, memberFun};
return wrapper;
}
QWebEnginePage *page = new QWebEnginePage;
QTextEdit *textEdit = new QTextEdit;
// *textEdit must remain valid until the functor is called.
page->toHtml(invoke(textEdit, &QTextEdit::setPlainText));
page->toPlainText(invoke(textEdit, &QTextEdit::setPlainText));
\endcode
\b {Qt WebEngine (with a regular functor)}
\code
struct SetPlainTextFunctor {
QTextEdit *textEdit;
SetPlainTextFunctor(QTextEdit *textEdit) : textEdit(textEdit) { }
void operator()(const QString &result) {
textEdit->setPlainText(result);
}
};
QWebEnginePage *page = new QWebEnginePage;
QTextEdit *textEdit = new QTextEdit;
// *textEdit must remain valid until the functor is called.
page->toHtml(SetPlainTextFunctor(textEdit));
page->toPlainText(SetPlainTextFunctor(textEdit));
\endcode
\section1 Qt WebEngine does not Interact with QNetworkAccessManager
Some classes of Qt Network such as QAuthenticator were reused for their interface
but, unlike Qt WebKit, Qt WebEngine has its own HTTP implementation and can't
go through a QNetworkAccessManager.
Signals and methods of QNetworkAccessManager that are still supported were
moved to QWebEnginePage directly.
\b {Qt WebKit}
\code
QNetworkAccessManager qnam;
QWebPage page;
page.setNetworkAccessManager(&qnam);
connect(&qnam, SIGNAL(authenticationRequired(QNetworkReply*,QAuthenticator*)), this, SLOT(authenticate(QNetworkReply*,QAuthenticator*)));
\endcode
\b {Qt WebEngine}
\code
QWebEnginePage page;
connect(&page, SIGNAL(authenticationRequired(QNetworkReply*,QAuthenticator*)), this, SLOT(authenticate(QNetworkReply*,QAuthenticator*)));
\endcode
\section1 Notes about Individual Methods
\section2 evaluateJavaScript
QWebFrame::evaluateJavaScript was renamed and moved as QWebEnginePage::runJavaScript.
It is currently only possible to run JavaScript on the main frame of a page and the
result is returned asynchronously to the provided functor.
\b {Qt WebKit}
\code
QWebPage *page = new QWebPage;
qDebug() << page->mainFrame()->evaluateJavaScript("'Java' + 'Script'");
\endcode
\b {Qt WebEngine (with lambda expressions in C++11)}
\code
QWebEnginePage *page = new QWebEnginePage;
page->runJavaScript("'Java' + 'Script'", [](const QVariant &result){ qDebug() << result; });
\endcode
\section2 setHtml and setContent
QWebEnginePage::setHtml and QWebEnginePage::setContent perform asynchronously
the same way as a normal HTTP load would, unlike their QWebPage counterparts.
\section2 setContentEditable
QWebPage::setContentEditable has no equivalent since any document element can be made editable through
the contentEditable attribute in the latest HTML standard. Therefore, QWebEnginePage::runJavaScript
is all that is needed.
\b {Qt WebKit}
\code
QWebPage page;
page.setContentEditable(true);
\endcode
\b {Qt WebEngine}
\code
QWebEnginePage page;
page.runJavascript("document.documentElement.contentEditable = true");
\endcode
\section1 Unavailable Qt WebKit APIs
Qt WebKit classes and methods in this list will not be available in Qt WebEngine.
\table
\row
\li QGraphicsWebView
\li Qt WebEngine requires hardware acceleration. Since we couldn't support
a web view class in a QGraphicsView unless it is attached to a QGLWidget
viewport, this feature is out of scope.
\row
\li QWebElement
\li Qt WebEngine uses a multi-process architecture and this means that
any access to the internal structure of the page has to be done
asynchronously, any query result must be returned through callbacks.
The QWebElement API was designed for synchronous access and this
would require a complete redesign.
\row
\li QWebDatabase
\li The Web SQL Database feature that this API was wrapping in Qt WebKit
was dropped from the HTML5 standard.
\row
\li QWebPluginFactory, QWebPage::setPalette, QWebView::setRenderHints
\li Qt WebEngine renders web pages using Skia and isn't using QPainter
or Qt for this purpose. The HTML5 standard also now offers much
better alternatives that were not available when native controls
plugins were introduced in Qt WebKit.
\row
\li QWebHistoryInterface
\li Visited links are persisted automatically by Qt WebEngine.
\endtable
*/
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