source: trunk/doc/src/development/assistant-manual.qdoc@ 569

/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation ([email protected])
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at [email protected].
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \page assistant-manual.html
    \title Qt Assistant Manual
    \ingroup qttools

    \startpage {index.html}{Qt Reference Documentation}
    \nextpage Qt Assistant in More Detail

    \keyword Qt Assistant

    This document introduces \QA, a tool for presenting on-line
    documentation. The document is divided into the following sections:

    Table of contents:

    \list
    \o \l{The One-Minute Guide to Using Qt Assistant}
    \o \l{Qt Assistant in More Detail}
    \o \l{Using Qt Assistant as a Custom Help Viewer}
    \endlist

    \chapter The One-Minute Guide to Using Qt Assistant

    Once you have installed Qt, \QA should be ready to run:

    \list
    \o On Windows, \QA is available as a menu option on the Qt menu.
    \o On Mac OS X, \QA is installed in the /Developer/Applications/Qt directory.
    \o On Unix/Linux, open a terminal, type \c{assistant} and press \key{Enter}.
    \endlist

    When you start up \QA, you will be presented with a standard main window
    application, with a menu bar and toolbar. Below these, on the left hand
    side are navigation windows called \e{Contents}, \e{Index} and \e{Bookmarks}.
    On the right, taking up most of the space, is the \e{Documentation} window.
    By default, \QA loads the Qt reference documentation along with the manuals
    of other Qt tools, like \QD or \QL.

    \QA works in a similar way to a Web browser. If you click hyperlinks
    (cross-references), the \e{Documentation} window will present the relevant
    page. You can bookmark pages of particular interest and you can click the
    \gui{Previous} and \gui{Next} toolbar buttons to navigate within the pages
    you have visited.

    Although \QA can be used just like a Web browser to navigate through
    the documentation, \QA offers a powerful means of navigation that Web
    browsers do not provide. \QA uses an advanced full text search engine
    to index all the pages in each compressed help file so that you can
    search for particular words and phrases.

    To perform an index search, click the \gui{Index} tab on the Sidebar
    (or press \key{Alt+I}). In the \gui{'Look For'} line edit enter a word;
    e.g., 'homedirpath'. As you type, words are found and highlighted in a list
    beneath the line edit. If the highlighted text matches what you're
    looking for, double click it, (or press \key{Enter}) and the
    \e{Documentation} window will display the relevant page. You rarely have
    to type in the whole word before \QA finds a match. Note that for some
    words there may be more than one possible page that is relevant.

    \QA also provides full text searching for finding specific words in
    the documentation. To activate the full text search, either press \key(Alt+S)
    or click on the \gui{Search} tab in the \e{Documentation} window. Then
    enter the term you're looking for and hit the \gui{Search} button. All
    documents containing the specified term will then be listed in the list box
    below.
*/

/*!
    \page assistant-details.html
    \title Qt Assistant in More Detail

    \contentspage {Qt Assistant Manual}{Contents}
    \previouspage Qt Assistant Manual
    \nextpage Using Qt Assistant as a Custom Help Viewer

    \tableofcontents

    \img assistant-assistant.png

    \section1 Command Line Options

    \QA handles the following command line options:

    \table
        \header
            \o Command Line Option
            \o Brief Description
        \row
            \o -collectionFile <file.qhc>
            \o Uses the specified collection file instead of the default one.
        \row
            \o -showUrl <URL>
            \o Shows the document referenced by URL.
        \row
            \o -enableRemoteControl
            \o Enables \QA to be remotly controlled.
        \row
            \o -show <widget>
            \o Shows the specified dockwidget which can be "contents", "index",
            "bookmarks" or "search".
        \row
            \o -hide <widget>
            \o Hides the specified dockwidget which can be "contents", "index",
            "bookmarks" or "search.
        \row
            \o -activate <widget>
            \o Activates the specified dockwidget which can be "contents",
            "index", "bookmarks" or "search.
        \row
            \o -register <doc.qch>
            \o Registers the specified compressed help file in the given help
            collection.
        \row
            \o -unregister <doc.qch>
            \o Unregisters the specified compressed help file from the given
            collection file.
        \row
            \o -remove-search-index
            \o Purges the help search engine's index. This option is
               useful in case the associated index files get corrupted.
               \QA will re-index the documentation at the next start-up.
        \row
            \o -setCurrentFilter <filter>
            \o Sets the given filter as the active filter.
        \row
            \o -quiet
            \o Doesn't show any error, warning or success messages.
    \endtable

    \section1 Tool Windows

    \img assistant-dockwidgets.png

    The tool windows provide four ways to navigate the documentation:

    \list
    \o The \gui{Contents} window presents a table of contents implemented as a
    tree view for the documentation that is available. If you click an item,
    its documentation will appear in the \e{Documentation} window. If you double
    click an item or click on the control to the left of it, the item's sub-items
    will appear. Click a sub-item to make its page appear in the \e{Documentation}
    window. Click on the control next to an open item to hide its sub-items.
    \o The \gui{Index} window is used to look up key words or phrases.
    See \l{The One-Minute Guide to Using Qt Assistant} for how to use this
    window.
    \o The \gui{Bookmarks} window lists any bookmarks you have made. Double
    click a bookmark to make its page appear in the \e{Documentation} window.
    The \gui{Bookmarks} window provides a context menu with \gui{Show Item},
    \gui{Delete Item} as well as \gui{Rename Item}. Click in the main menu
    \menu{Bookmark|Add Bookmark...} (or press \key{Ctrl+B}) to bookmark the
    page that is currently showing in the \e{Documentation} window. Right click
    a bookmark in the list to rename or delete the highlighted bookmark.
    \endlist

    If you want the \gui{Documentation} window to use as much space as possible,
    you can easily group, move or hide the tool windows. To group the windows,
    drag one on top of the other and release the mouse. If one or all tool
    windows are not shown, press \key{Alt+C}, \key{Alt+I} or \key{Alt+O} to show
    the required window.

    The tool windows can be docked into the main window, so you can drag them
    to the top, left, right or bottom of \e{Qt Assistant's} window, or you can
    drag them outside \QA to float them as independent windows.

    \section1 Documentation Window

    \img assistant-docwindow.png

    The \gui{Documentation} window lets you create a tab for each
    documentation page that you view. Click the \gui{Add Tab} button and a new
    tab will appear with the page name as the tab's caption. This makes it
    convenient to switch between pages when you are working with different
    documentation. You can delete a tab by clicking the \gui{Close Tab} button
    located on the right side of the \gui{Documentation} window.

    \section1 Toolbars

    \img assistant-toolbar.png

    The main toolbar provides fast access to the most common actions.

    \table
    \header \o Action \o Description \o Menu Item \o Shortcut
    \row \o \gui{Previous} \o Takes you to the previous page in the history.
         \o \menu{Go|Previous} \o \key{Alt+Left Arrow}
    \row \o \gui{Next} \o Takes you to the next page in the history.
         \o \menu{Go|Next} \o \key{Alt+Right Arrow}
    \row \o \gui{Home}
         \o Takes you to the home page as specified in the Preferences Dialog.
         \o \menu{Go|Home} \o \key{Ctrl+Home}.
    \row \o \gui{Sync with Table of Contents}
         \o Synchronizes the \gui{Contents} tool window with the page currently
            shown in the \gui{Documentation} window.
         \o \menu{Go|Sync with Table of Contents} \o
    \row \o \gui{Copy} \o Copies any selected text to the clipboard.
         \o \menu{Edit|Copy} \o \key{Ctrl+C}
    \row \o \gui{Print} \o Opens the \gui{Print} dialog.
         \o \menu{File|Print} \o \key{Ctrl+P}
    \row \o \gui{Find in Text} \o Opens the \gui{Find Text} dialog.
         \o \menu{Edit|Find in Text} \o \key{Ctrl+F}
    \row \o \gui{Zoom in}
         \o Increases the font size used to display text in the current tab.
         \o \menu{View|Zoom in} \o \key{Ctrl++}
    \row \o \gui{Zoom out}
         \o Decreases the font size used to display text in the current tab.
         \o \menu{View|Zoom out} \o \key{Ctrl+-}
    \row \o \gui{Normal Size}
         \o Resets the font size to its normal size in the current tab.
         \o \menu{View|Normal Size} \o \key{Ctrl+0}
    \endtable

    \img assistant-address-toolbar.png

    The address toolbar provides a fast way to enter a specific URL for a
    documentation file. By default, the address toolbar is not shown, so it
    has to be activated via \menu{View|Toolbars|Address Toolbar}.

    \img assistant-filter-toolbar.png

    The filter toolbar allows you to apply a filter to the currently installed
    documentation. As with the address toolbar, the filter toolbar is not visible
    by default and has to be activated via \menu{View|Toolbars|Filter Toolbar}.

    \section1 Menus

    \section2 File Menu

    \list
    \o \menu{File|Page Setup...} invokes a dialog allowing you to define
    page layout properties, such as margin sizes, page orientation and paper size.
    \o \menu{File|Print Preview...} provides a preview of the printed pages.
    \o \menu{File|Print...} opens the \l{#Print Dialog}{\gui{Print} dialog}.
    \o \menu{File|New Tab} opens a new empty tab in the \gui{Documentation}
    window.
    \o \menu{File|Close Tab} closes the current tab of the
    \gui{Documentation} window.
    \o \menu{File|Exit} closes the \QA application.
    \endlist

    \section2 Edit Menu

    \list
    \o \menu{Edit|Copy} copies any selected text to the clipboard.
    \o \menu{Edit|Find in Text} invokes the \l{#Find Text Control}{\gui{Find Text}
    control} at the lower end of the \gui{Documentation} window.
    \o \menu{Edit|Find Next} looks for the next occurance of the specified
    text in the \gui{Find Text} control.
    \o \menu{Edit|Find Previous} looks for the previous occurance of
    the specified text in the \l{#Find Text Control}{\gui{Find Text} control}.
    \o \menu{Edit|Preferences} invokes the \l{#Preferences Dialog}{\gui{Preferences} dialog}.
    \endlist

    \section2 View Menu

    \list
    \o \menu{View|Zoom in} increases the font size in the current tab.
    \o \menu{View|Zoom out} decreases the font size in the current tab.
    \o \menu{View|Normal Size} resets the font size in the current tab.
    \o \menu{View|Contents} toggles the display of the \gui{Contents} tool window.
    \o \menu{View|Index} toggles the display of the \gui{Index} tool window.
    \o \menu{View|Bookmarks} toggles the display of the \gui{Bookmarks} tool window.
    \o \menu{View|Search} toggles the display of the Search in the \gui{Documentation} window.
    \endlist

    \section2 Go Menu

    \list
    \o \menu{Go|Home} goes to the home page.
    \o \menu{Go|Back} displays the previous page in the history.
    \o \menu{Go|Forward} displays the next page in the history.
    \o \menu{Go|Sync with Table of Contents} syncs the \gui{Contents} tool window to the currently shown page.
    \o \menu{Go|Next Page} selects the next tab in the \gui{Documentation} window.
    \o \menu{Go|Previous Page} selects the previous tab in the \gui{Documentation} window.
    \endlist

    \section2 Bookmarks Menu

    \list
    \o \menu{Bookmarks|Add} adds the current page to the list of bookmarks.
    \endlist

    \section1 Dialogs

    \section2 Print Dialog

    This dialog is platform-specific. It gives access to various printer
    options and can be used to print the document shown in the current tab.

    \section2 Preferences Dialog

    \img assistant-preferences-fonts.png

    The \menu{Fonts} page allows you to change the font family and font sizes of the
    browser window displaying the documentation or the application itself.

    \img assistant-preferences-filters.png

    The \menu{Filters} page lets you create and remove documentation
    filters. To add a new filter, click the \gui{Add} button, specify a
    filter name in the pop-up dialog and click \gui{OK}, then select
    the filter attributes in the list box on the right hand side.
    You can delete a filter by selecting it and clicking the \gui{Remove}
    button.

    \img assistant-preferences-documentation.png

    The \menu{Documentation} page lets you install and remove compressed help
    files. Click the \gui{Install} button and choose the path of the compressed
    help file (*.qch) you would like to install.
    To delete a help file, select a documentation set in the list and click
    \gui{Remove}.

    \img assistant-preferences-options.png

    The \menu{Options} page lets you specify the homepage \QA will display when
    you click the \gui{Home} button in \QA's main user interface. You can specify
    the hompage by typing it here or clicking on one of the buttons below the
    textbox. \gui{Current Page} sets the currently displayed page as your home
    page while \gui{Restore to default} will reset your home page to the default
    home page.

    \section1 Find Text Control

    This control is used to find text in the current page. Enter the text you want
    to find in the line edit. The search is incremental, meaning that the most
    relevant result is shown as you enter characters into the line edit.

    If you check the \gui{Whole words only} checkbox, the search will only consider
    whole words; for example, if you search for "spin" with this checkbox checked it will
    not match "spinbox", but will match "spin". If you check the \gui{Case sensitive}
    checkbox then, for example, "spin" will match "spin" but not "Spin". You can
    search forwards or backwards from your current position in the page by clicking
    the \gui{Previous} or \gui{Next} buttons. To hide the find control, either click the
    \gui{Close} button or hit the \key{Esc} key.

    \section1 Filtering Help Contents

    \QA allows you to install any kind of documentation as long as it is organized
    in Qt compressed help files (*.qch). For example, it is possible to install the
    Qt reference documentation for Qt 4.4.0 and Qt 4.4.1 at the same time. In many
    respects, this is very convenient since only one version of \QA is needed.
    However, at the same time it becomes more complicated when performing tasks like
    searching the index because nearly every keyword is defined in Qt 4.4.0 as well
    as in Qt 4.4.1. This means that \QA will always ask the user to choose which one
    should be displayed.

    We use documentation filters to solve this issue. A filter is identified by its
    name, and contains a list of filter attributes. An attribute is just a string and
    can be freely chosen. Attributes are defined by the documentation itself, this
    means that every documentation set usually has one or more attributes.

    For example, the Qt 4.4.0 \QA documentation defines the attributes \c {assistant},
    \c{tools} and \c{4.4.0}, \QD defines \c{designer}, \c{tools} and \c{4.4.0}.
    The filter to display all tools would then define only the attribute
    \c{tools} since this attribute is part of both documentation sets.
    Adding the attribute \c{assistant} to the filter would then only show \QA
    documentation since the \QD documentation does not contain this
    attribute. Having an empty list of attributes in a filter will match all
    documentation; i.e., it is equivalent to requesting unfiltered documentation.

    \section1 Full Text Searching

    \img assistant-search.png

    \QA provides a powerful full text search engine. To search
    for certain words or text, click the \gui{Search} tab in the \gui{Documentation}
    window. Then enter the text you want to look for and press \key{Enter}
    or click the \gui{Search} button. The search is not case sensitive, so,
    for example, Foo, fOo and FOO are all treated as the same. The following are
    examples of common search patterns:

    \list
    \o \c deep -- lists all the documents that contain the word 'deep'
    \o \c{deep*} -- lists all the documents that contain a word beginning
    with 'deep'
    \o \c{deep copy} -- lists all documents that contain both 'deep' \e
    and 'copy'
    \o \c{"deep copy"} -- list all documents that contain the phrase 'deep copy'
    \endlist

    It is also possible to use the \gui{Advanced search} to get more flexibility.
    You can specify some words so that hits containing these are excluded from the
    result, or you can search for an exact phrase. Searching for similar words will
    give results like these:

    \list
    \o \c{QStin} -- lists all the documents with titles that are similar, such as \c{QString}
    \o \c{QSting} -- lists all the documents with titles that are similar, such as \c{QString}
    \o \c{QStrin} -- lists all the documents with titles that are similar, such as \c{QString}
    \endlist

    Options can be combined to improve the search results.

    The list of documents found is ordered according to the number of
    occurrences of the search text which they contain, with those containing
    the highest number of occurrences appearing first. Simply click any
    document in the list to display it in the \gui{Documentation} window.

    If the documentation has changed \mdash for example, if documents have been added
    or removed \mdash \QA will index them again.

*/

/*!
    \page assistant-custom-help-viewer.html
    \title Using Qt Assistant as a Custom Help Viewer

    \contentspage {Qt Assistant Manual}{Contents}
    \previouspage Qt Assistant in More Detail

    Using \QA as custom help viewer requires more than just being able to
    display custom documentation. It is equally important that the
    appearance of \QA can be customized so that it is seen as a
    application-specific help viewer rather than \QA. This is achieved by
    changing the window title or icon, as well as some application-specific
    menu texts and actions. The complete list of possible customizations
    can be found in the \l{Creating a Custom Help Collection File} section.

    Another requirement of a custom help viewer is the ability to receive
    actions or commands from the application it provides help for. This is
    especially important when the application offers context sensitive help.
    When used in this way, the help viewer may need to change its contents
    depending on the state the application is currently in. This means that
    the application has to communicate the current state to the help viewer.
    The section about \l{Using Qt Assistant Remotely} explains how this can
    be done.

    \tableofcontents

    The \l{Simple Text Viewer Example}{Simple Text Viewer} example uses the
    techniques described in this document to show how to use \QA as a custom
    help viewer for an application.

    \warning In order to ship Qt Assistant in your application, it is crucial
    that you include the sqlite plugin. For more information on how to include
    plugins in your application, refer to the \l{Deploying Qt Applications}
    {deployment documentation}.

    \section1 Qt Help Collection Files

    The first important point to know about \QA is that it stores all
    settings related to its appearance \e and a list of installed
    documentation in a help collection file. This means, when starting \QA
    with different collection files, \QA may look totally different. This
    complete separation of settings makes it possible to deploy \QA as a
    custom help viewer for more than one application on one machine
    without risk of interference between different instances of \QA.

    To apply a certain help collection to \QA, specify the respective
    collection file on the command line when starting it. For example:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 8

    However, storing all settings in one collection file raises some problems.
    The collection file is usually installed in the same directory as the
    application itself, or one of its subdirectories. Depending on the
    directory and the operating system, the user may not have any permissions
    to modify this file which would happen when the user settings are stored.
    Also, it may not even be possible to give the user write permissions;
    e.g., when the file is located on a read-only medium like a CD-ROM.

    Even if it is possible to give everybody the right to store their settings
    in a globally available collection file, the settings from one user would
    be overwritten by another user when exiting \QA.

    To solve this dilemma, \QA creates user specific collection files which
    are more or less copied from the original collection file. The user-specific
    collection file will be saved in a subdirectory of the path returned by
    QDesktopServices::DataLocation. The subdirectory, or \e{cache directory}
    within this user-specific location, can be defined in the help collection
    project file. For example:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 7

    So, when calling

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 8

    \QA actually uses the collection file:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 9

    There is no need ever to start \QA with the user specific collection
    file. Instead, the collection file shipped with the application should
    always be used. Also, when adding or removing documentation from the
    collection file (see next section) always use the normal collection file.
    \QA will take care of synchronizing the user collection files when the
    list of installed documentation has changed.

    \section1 Displaying Custom Documentation

    Before \QA is able to show documentation, it has to know where it can
    find the actual documentation files, meaning that it has to know the
    location of the Qt compressed help file (*.qch). As already mentioned,
    \QA stores references to the compressed help files in the currently used
    collection file. So, when creating a new collection file you can list
    all compressed help files \QA should display.

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 5

    Sometimes, depending on the application for which \QA acts as a
    help viewer, more documentation needs to be added over time; for
    example, when installing more application components or plugins.
    This can be done manually by starting \QA, opening the \gui{Edit|Preferences}
    dialog and navigating to the \gui{Documentation} tab page. Then click
    the \gui{Add...} button, select a Qt compressed help file (*.qch)
    and press \gui{Open}. However, this approach has the disadvantage
    that every user has to do it manually to get access to the new
    documentation.

    The prefered way of adding documentation to an already existing collection
    file is to use the \c{-register} command line flag of \QA. When starting
    \QA with this flag, the documentation will be added and \QA will
    exit right away displaying a message if the registration was successful
    or not.

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 6

    The \c{-quiet} flag can be passed on to \QA to prevent it from writing
    out the status message.

    \bold{Note:} \QA will show the documentation in the contents view in the same
    order as it was registered.


    \section1 Changing the Appearance of Qt Assistant

    The appearance of \QA can be changed by passing different command line options
    on startup. However, these command line options only allow to show or hide
    specific widgets, like the contents or index view. Other customizations, such
    as changing the application title or icon, or disabling the filter functionality,
    can be done by creating a custom help collection file.

    \section2 Creating a Custom Help Collection File

    The help collection file (*.qhc) used by \QA is created when running the
    \c qcollectiongenerator tool on a help collection project file (*.qhcp).
    The project file format is XML and supports the following tags:

    \table
        \header
            \o Tag
            \o Brief Description
        \row
            \o \c{<title>}
            \o This property is used to specify a window title for \QA.
        \row
            \o \c{<homePage>}
            \o This tag specifies which page should be display when
            pressing the home button in \QA's main user interface.
        \row
            \o \c{<startPage>}
            \o This tag specifies which page \QA should initially
            display when the help collection is used.
        \row
            \o \c{<currentFilter>}
            \o This tag specifies the \l{Qt Assistant in More Detail#Preferences Dialog}{filter}
            that is initially used.
            If this filter is not specified, the documentation will not be filtered. This has
            no impact if only one documentation set is installed.
        \row
            \o \c{<applicationIcon>}
            \o This tag describes an icon that will be used instead of the normal \QA
            application icon. This is specified as a relative path from the directory
            containing the collection file.
        \row
            \o \c{<enableFilterFunctionality>}
            \o This tag is used to enable or disable user accessible filter functionality,
            making it possible to prevent the user from changing any filter when running \QA.
            It does not mean that the internal filter functionality is completely disabled.
            Set the value to \c{false} if you want to disable the filtering. If the filter
            toolbar should be shown by default, set the attribute \c{visible} to \c{true}.
        \row
            \o \c{<enableDocumentationManager>}
            \o This tag is used to specify whether the documentation manager should be shown
            in the preferences dialog. Disabling the Documentation Manager allows you to limit
            \QA to display a specific documentation set or make it impossible for the end user
            to accidentally remove or install documentation. To hide the documentation manager,
            set the tag value to \c{false}.
        \row
            \o \c{<enableAddressBar>}
            \o This tag describes if the address bar can be shown. By default it is
            enabled; if you want to disable it set the tag value to \c{false}. If the
            address bar functionality is enabled, the address bar can be shown by setting the
            tag attribute \c{visible} to \c{true}.
        \row
            \o \c{<aboutMenuText>, <text>}
            \o The \c{aboutMenuText} tag lists texts for different languages which will
            later appear in the \menu{Help} menu; e.g., "About Application". A text is
            specified within the \c{text} tags; the \c{language} attribute takes the two
            letter language name. The text is used as the default text if no language
            attribute is specified.
        \row
            \o \c{<aboutDialog>, <file>, <icon>}
            \o The \c{aboutDialog} tag can be used to specify the text for the \gui{About}
            dialog that can be opened from the \menu{Help} menu. The text is taken from the
            file in the \c{file} tags. It is possible to specify a different file or any
            language. The icon defined by the \c{icon} tags is applied to any language.
        \row
            \o \c{<cacheDirectory>}
            \o Specified as a path relative to the directory given by
            QDesktopServices::DataLocation, the cache path is used to store index files
            needed for the full text search and a copy of the collection file.
            The copy is needed because \QA stores all its settings in the collection file;
            i.e., it must be writable for the user.
    \endtable

    In addition to those \QA specific tags, the tags for generating and registering
    documentation can be used. See \l{The Qt Help Framework#Creating a Qt Help Collection}
    {Qt Help Collection} documentation for more information.

    An example of a help collection file that uses all the available tags is shown below:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 1

    To create the binary collection file, run the \c qcollectiongenerator tool:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 10

    To test the generated collection file, start \QA in the following way:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 8

    \section1 Using Qt Assistant Remotely

    Even though the help viewer is a standalone application, it will mostly
    be launched by the application it provides help for. This approach
    gives the application the possibility to ask for specific help contents
    to be displayed as soon as the help viewer is started. Another advantage
    with this approach is that the application can communicate with the
    help viewer process and can therefore request other help contents to be
    shown depending on the current state of the application.

    So, to use \QA as the custom help viewer of your application, simply
    create a QProcess and specify the path to the Assistant executable. In order
    to make Assistant listen to your application, turn on its remote control
    functionality by passing the \c{-enableRemoteControl} command line option.

    \warning The trailing '\0' must be appended separately to the QByteArray,
    e.g., \c{QByteArray("command" + '\0')}.

    The following example shows how this can be done:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 2

    Once \QA is running, you can send commands by using the stdin channel of
    the process. The code snippet below shows how to tell \QA to show a certain
    page in the documentation.

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 3

    The following commands can be used to control \QA:

    \table
        \header
            \o Command
            \o Brief Description
        \row
            \o \c{show <Widget>}
            \o Shows the dock widget specified by <Widget>. If the widget
            is already shown and this command is sent again, the widget will be
            activated, meaning that it will be raised and given the input focus.
            Possible values for <Widget> are "contents", "index", "bookmarks" or "search".
        \row
            \o \c{hide <Widget>}
            \o Hides the dock widget specified by <Widget>. Possible values for
            <Widget> are "contents", "index", "bookmarks" and "search".
        \row
            \o \c{setSource <Url>}
            \o Displays the given <Url>. The URL can be absolute or relative
            to the currently displayed page. If the URL is absolute, it has to
            be a valid Qt help system URL; i.e., starting with "qthelp://".
        \row
            \o \c{activateKeyword <Keyword>}
            \o Inserts the specified <Keyword> into the line edit of the
            index dock widget and activates the corresponding item in the
            index list. If such an item has more than one link associated
            with it, a topic chooser will be shown.
        \row
            \o \c{activateIdentifier <Id>}
            \o Displays the help contents for the given <Id>. An ID is unique
            in each namespace and has only one link associated to it, so the
            topic chooser will never pop up.
        \row
            \o \c{syncContents}
            \o Selects the item in the contents widget which corresponds to
            the currently displayed page.
        \row
            \o \c{setCurrentFilter}
            \o Selects the specified filter and updates the visual representation
            accordingly.
        \row
            \o \c{expandToc <Depth>}
            \o Expands the table of contents tree to the given depth. If depth
            is less than 1, the tree will be collapsed completely.
    \endtable

    If you want to send several commands within a short period of time, it is
    recommended that you write only a single line to the stdin of the process
    instead of one line for every command. The commands have to be separated by
    a semicolon, as shown in the following example:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 4

    \section1 Compatibility with Old Formats

    In older versions of Qt, the help system was based on Document Content File
    (DCF) and Qt Assistant Documentation Profile (ADP) formats. In contrast,
    Qt Assistant and the help system used in Qt 4.4 use the formats described
    earlier in this manual.

    Unfortunately, the old file formats are not compatible with the new ones.
    In general, the differences are not that big \mdash in most cases is the old
    format is just a subset of the new one. One example is the \c namespace tag in
    the Qt Help Project format, which was not part of the old format, but plays a vital
    role in the new one. To help you to move to the new file format, we have created
    a conversion wizard.

    The wizard is started by executing \c qhelpconverter. It guides you through the
    conversion of different parts of the file and generates a new \c qch or \c qhcp
    file.

    Once the wizard is finished and the files created, run the \c qhelpgenerator
    or the \c qcollectiongenerator tool to generate the binary help files used by \QA.
*/

/*
\section2 Modifying \QA with Command Line Options

    Different help collections can be shown by simply passing the help collection
    path to \QA. For example:

    \snippet doc/src/snippets/code/doc_src_assistant-manual.qdoc 0

    Other available options the can be passed on the command line.

    \table
        \header
            \o Command Line Option
            \o Brief Description
        \row
            \o -collectionFile <file.qhc>
            \o Uses the specified collection file instead of the default one.
        \row
            \o -showUrl URL
            \o Shows the document referenced by URL.
        \row
            \o -enableRemoteControl
            \o Enables \QA to be remotly controlled.
        \row
            \o -show <widget>
            \o Shows the specified dockwidget which can be "contents", "index",
            "bookmarks" or "search".
        \row
            \o -hide <widget>
            \o Hides the specified dockwidget which can be "contents", "index",
            "bookmarks" or "search.
        \row
            \o -activate <widget>
            \o Activates the specified dockwidget which can be "contents",
            "index", "bookmarks" or "search.
        \row
            \o -register <doc.qch>
            \o Registers the specified compressed help file in the given help
            collection.
        \row
            \o -unregister <doc.qch>
            \o Unregisters the specified compressed help file from the given
            collection file.
        \row
            \o -quiet
            \o Doesn't show any error, warning or success messages.
    \endtable
    */