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

/****************************************************************************
**
** Copyright (C) 2016 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 https://www.qt.io/terms-conditions. For further
** information use the contact form at https://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: https://www.gnu.org/licenses/fdl-1.3.html.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \example webenginewidgets/spellchecker
    \title WebEngine Widgets Spellchecker Example
    \ingroup webengine-widgetexamples
    \brief Integrates a spellchecker into a simple HTML form.

    \image spellchecker-example.png

    \e {Spellchecker} demonstrates how to integrate spellchecking support into
    an HTML form that enables users to submit spellchecked messages.

    \include examples-run.qdocinc

    \section1 Dictionaries

    To be able to check the spelling, we need to provide the spellchecker with
    dictionaries. The \QWE spellchecker supports dictionaries provided by the
    \l {Hunspell project} on all platforms and native dictionaries provided by macOS.
    In this example, we want to support the English and German languages.

    For Hunspell dictionaries to be supported they have to be compiled into a special binary format.
    A Hunspell dictionary consists of two files:

    \list

        \li A \c .dic file that is a dictionary containing words for the
            language
        \li An \c .aff file that defines the meaning of special flags in the
            dictionary
    \endlist

    These two files can be converted into the \c bdic format by using the
    \c qwebengine_convert_dict tool that is shipped together with Qt.

    In this example, we are going to compile en_US and de_DE dictionaries.
    However, the real full dictionaries would take too much space for the
    purposes of this example. Therefore, we have created two dummy dictionaries
    that contain the following words and can be used to demonstrate the
    conversion process:

    \list
        \li English dictionary: I, you, he, she, it, we, they, love, loves, qt
        \li German dictionary: ich, du, er, sie, es, wir, ihr, sie, Sie, liebe,
            liebst, liebt, lieben, liebt, qt
    \endlist

    Each word in a dictionary can be prefixed with \c q. For more information
    about how to create \c dic and \c aff files, see the Hunspell dictionary
    file format specification in the \l{Hunspell Project}.

    See the \l {Spellchecker}{Spellchecker feature documentation} for how
    dictionary files are searched.

    We specify the QMAKE_EXTRA_COMPILERS parameter in the project file to add a
    conversion step to the build process:

    \quotefromfile webenginewidgets/spellchecker/spellchecker.pro
    \skipto CONVERT_TOOL
    \printuntil QMAKE_EXTRA_COMPILERS

    To set up a dictionary, we run \c qwebengine_convert_dict passing the
    file path of the dictionary \c dic and \c bdic files. The \c aff file and
    optional \c delta file are also picked up by the \c convert process.
    The output \c bdic file is placed into the \e qtwebengine_dictionaries local
    directory (or Resources directory), which the application binary will run from.

    \section1 Setting the Spellchecker

    The constructor of our class is trivial.

    \quotefromfile webenginewidgets/spellchecker/webview.cpp
    \skipto WebView::WebView
    \printuntil }
    We define simple mapping between our dictionary filenames and
    the actual language display name. We will use that mapping to display names
    of dictionaries in the context menu. Spellchecking is disabled by default.
    Therefore we also enable spellchecker and set the \e English dictionary.
    When \QWE's spellcheck service initializes, it will try to load the
    \c bdict dictionaries and to check them for consistency.
    Any errors are logged by using the qWarning() function.

    \section1 Switching the Spellchecking Language

    The current language used for spellchecking is defined per profile, and can
    get set using the QWebEngineProfile::setSpellCheckLanguage method. When the
    user clicks on an underlined misspelled word, the default context menu
    displays up to four suggestions. Selecting one will replace the misspelled
    word. We could reimplement a number of suggestions, by overriding
    QWebEngineView::contextMenuEvent and using
    QWebEngineContextMenuData::spellCheckerSuggestions, but we will demonstrate
    how to add langague options in the context menu instead:

    \quotefromfile webenginewidgets/spellchecker/webview.cpp
    \skipto void WebView::contextMenuEvent
    \printuntil menu->popup
    \printline }

    Above, we get the QWebEngineContextMenuData instance using the
    QWebEnginePage::contextMenuData method. We use it to be notified when the
    user clicks on an editable field and show the \uicontrol {Check Spelling}
    item in the context menu. Moreover, if spellchecking is enabled, we also
    add the \uicontrol {Select Language} submenu with the supported languages.
    When an action is triggered, we set the language with the
    QWebEngineProfile::setSpellCheckLanguage call.
*/