qt-everywhere-src-5.15.1/qtwebengine/examples/webenginewidgets/contentmanipulation/doc/src/contentmanipulation.qdoc

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/*!
    \example webenginewidgets/contentmanipulation
    \title WebEngine Content Manipulation Example
    \ingroup webengine-widgetexamples
    \brief Demonstrates how to load and manipulate web content.

    \image contentmanipulation-example.png

    \e{Content Manipulation} shows how to use JQuery with \l {Qt WebEngine Widgets} to
    create a web browser with special effects and content manipulation.

    In the application, we call \l {QWebEnginePage::runJavaScript()} to
    execute jQuery JavaScript code. We implement a QMainWindow with a QWebEngineView
    as a central widget to build up the browser itself.

    \include examples-run.qdocinc

    \section1 MainWindow Class Definition

    The \c MainWindow class inherits QMainWindow. It implements a number of
    slots to perform actions on both the application and on the web content:

    \quotefromfile webenginewidgets/contentmanipulation/mainwindow.h
    \skipto class MainWindow :
    \printuntil /^\}/

    We also declare a QString that contains jQuery, a QWebEngineView
    that displays the web content, and a QLineEdit that acts as the
    address bar.

    \section1 MainWindow Class Implementation

    We start by implementing the constructor. The first part of the constructor sets the value of
    \c progress to 0. This value will be used later in the code to visualize the loading of a
    web page:

    \quotefromfile webenginewidgets/contentmanipulation/mainwindow.cpp
    \skipto MainWindow::MainWindow
    \printuntil progress

    Next, the jQuery library is loaded by using a QFile and reading the file
    content. The jQuery library is a JavaScript library that provides different
    functions for manipulating HTML:

    \printuntil file.close()

    The second part of the constructor creates a QWebEngineView and connects
    slots to the view's signals:

    \printuntil MainWindow::finishLoading

    Furthermore, we create a QLineEdit as the browser's address bar. We then set the vertical
    QSizePolicy to fill the available area in the browser at all times. We add the
    QLineEdit to a QToolBar together with a set of navigation actions from
    QWebEngineView::pageAction():

    \printuntil addWidget(locationEdit)

    The third part of the constructor implements two QMenu widgets and assigns
    a set of actions to them:

    \printuntil removeEmbeddedElements

    The last line sets the QWebEngineView as the central widget in the QMainWindow:

    \printuntil }

    When the page is loaded, \c adjustLocation() is triggered by the \c loadFinished() signal in
    QWebEngineView to update the address bar:

    \skipto adjustLocation()
    \printuntil }

    In \c changeLocation(), we create a QUrl object, and then use it to load the page into the
    QWebEngineView. When the new web page has finished loading, \c adjustLocation() will be
    run once more to update the address bar:

    \printuntil }

    The \c adjustTitle() method sets the window title and displays the loading progress:

    \printuntil }
    \printuntil }

    This slot is triggered by the \c titleChanged() signal in QWebEngineView.

    When a web page has loaded, the \c finishLoading() method is triggered by the
    \c loadFinished() signal in QWebEngineView. The method then updates the
    progress in the title bar and calls \c runJavaScript()
    to evaluate the jQuery library against the current web page:

    \printuntil }

    This means that the JavaScript can be viewed as a
    part of the content loaded into the QWebEngineView, and therefore needs to be
    loaded every time a new page is loaded. Once the jQuery library is loaded,
    we can start executing the different jQuery functions in the browser.

    The \c rotateImages() function is then called explicitly to make sure
    that the images of the newly loaded page respect the state of the toggle
    action.

    The first jQuery-based function, \c highlightAllLinks(), is designed to
    highlight all links in the current webpage. The JavaScript code looks
    for web elements named \e {a}, which is the tag for a hyperlink.
    For each such element, the background color is set to be yellow by
    using CSS:

    \printuntil }
    \printuntil }

    The \c rotateImages() function rotates the images on the current
    web page. This JavaScript code relies on CSS transforms. It
    looks up all \e {img} elements and rotates the images 180 degrees
    and then back again:

    \printuntil runJavaScript(code);
    \printuntil }

    The remaining methods remove different elements from the current web
    page. The \c removeGifImages() removes all GIF images on the page by looking up
    the \e {src} attribute of all the elements on the web page. Any element with
    a \e {gif} file as its source is removed:

    \printuntil }

    The \c removeInlineFrames() method removes all \e {iframe} or inline elements:

    \printuntil }

    The \c removeObjectElements() method removes all \e {object} elements:

    \printuntil }

    The \c removeEmbeddedElements() method removes any elements using the \e {embed} tag, such as
    plugins embedded on the page:

    \printuntil }
*/