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diff --git a/doc/src/frameworks-technologies/qthelp.qdoc b/doc/src/frameworks-technologies/qthelp.qdoc new file mode 100644 index 0000000..2529631 --- /dev/null +++ b/doc/src/frameworks-technologies/qthelp.qdoc @@ -0,0 +1,382 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** 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 1.0, 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 are unsure which license is appropriate for your use, please +** contact the sales department at http://qt.nokia.com/contact. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \group helpsystem + \title Help System + \ingroup groups + + \brief Classes used to provide online-help for applications. + + \keyword help system + + These classes provide for all forms of online-help in your application, + with three levels of detail: + + \list 1 + \o Tool Tips and Status Bar message - flyweight help, extremely brief, + entirely integrated in the user interface, requiring little + or no user interaction to invoke. + \o What's This? - lightweight, but can be + a three-paragraph explanation. + \o Online Help - can encompass any amount of information, + but is typically slower to call up, somewhat separated + from the user's work, and often users feel that using online + help is a digression from their real task. + \endlist + +*/ + +/*! + \page qthelp-framework.html + \title The Qt Help Framework + \brief Integrating Documentation in Applications + \ingroup frameworks-technologies + + \section1 Topics + + \tableofcontents + + \section1 Overview + The Qt help system includes tools for generating and viewing + Qt help files. In addition it provides classes for accessing + help contents programatically to be able to integrate online + help into Qt applications. + + The actual help data, meaning the table of contents, index + keywords or html documents, is contained in Qt compressed help + files. So, one such a help file represents usually one manual + or documentation set. Since most products are more comprehensive + and consist of a number of tools, one manual is rarely enough. + Instead, more manuals which should be accessible at the same + time, exist. Ideally, it should also be possible to reference + certain points of interest of one manual to another. + Therefore, the Qt help system operates on help collection files + which include any number of compressed help files. + + However, having collection files to merge many documentation + sets may lead to some problems. For example, one index keyword + may be defined in different documentations. So, when only seeing + it in the index and activating it, you cannot be sure that + the expected documentation will be shown. Therefore, the Qt + help system offers the possibiltiy to filter the help contents + after certain attributes. This requires however, that the + attributes have been assigned to the help contents before the + generation of the compressed help file. + + As already mentioned, the Qt compressed help file contains all + data, so there is no need any longer to ship all single html + files. Instead, only the compressed help file and optionally the + collection file has to be distributed. The collection file is + optional since any existing collection file, e.g. from an older + release could be used. + + So, in general, there are four files interacting with the help + system, two used for generating Qt help and two meant for + distribution: + + \table + \header + \o Name + \o Extension + \o Brief Description + \row + \o \l {Qt Help Project} + \o .qhp + \o The input file for the help generator consisting of the table + of contents, indices and references to the actual documentation + files (*.html); it also defines a unique namespace for the + documentation. + + \row + \o Qt Compressed Help + \o .qch + \o The output file of the help generator. This binary file contains + all information specified in the help project file along with all + compressed documentation files. + + \row + \o \l {Qt Help Collection Project} + \o .qhcp + \o The input file for the help collection generator. It contains + references to compressed help files which should be included in + the collection; it also may contain other information for + customizing Qt Assistant. + + \row + \o Qt Help Collection + \o .qhc + \o The output of the help collection generator. This is the file + QHelpEngine operates on. It contains references to any number of + compressed help files as well as additional information, such as + custom filters. + \endtable + + \section1 Generating Qt Help + + Building help files for the Qt help system assumes that the html + documentation files already exist, i.e. the Qt help system does + not offer the possibility to create html files like e.g. Doxygen. + + Once the html documentents are in place, a \l {Qt Help Project} file + has to be created. After specifying all relevant information in + this file, it needs to be compiled by calling: + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 2 + + The file 'doc.qch' contains then all html files in compressed + form along with the table of contents and index keywords. To + test if the generated file is correct, open Qt Assistant and + install the file via the Settings|Documentation page. + + \target Qt Help Collection Project + \section2 Creating a Qt Help Collection + + The first step is to create a Qt Help Collection Project file. + Since a Qt help collection stores primarily references to + compressed help files, the project 'mycollection.qhcp' file + looks unsurprisingly simple: + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 3 + + For actually creating the collection file call: + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 4 + + Instead of running two tools, one for generating the compressed + help and one for generating the collection file, it is also + possible to just run the qcollectiongenerator tool with a + slightly modified project file instructing the generator to + create the compressed help first. + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 5 + + Of course, it is possible to specify more than one file in the + 'generate' or 'register' section, so any number of compressed + help files can be generated and registered in one go. + + \section1 Using Qt Help + + Accessing the help contents can be done in two ways: Using Qt + Assistant as documentation browser or using the QHelpEngine + API for embedding the help contents directly in an application. + + \section2 Using Qt Assistant + + \QA operates on a collection file which can be specified + before start up. If no collection file is given, a default one + will be created and used. In either case, it is possible to + register any Qt compressed help file and access the help contents. + + When using Assistant as the help browser for an application, it + would be desirable that it can be customized to fit better to the + application and doesn't look like an independent, standalone + help browser. To achieve this, several additional properties can + be set in an Qt help collection file, to change e.g. the title + or application icon of Qt Assistant. For more information on + this topic have a look at the \l{assistant-manual.html} + {Qt Assistant manual}. + + \section2 Using QHelpEngine API + + Instead of showing the help in an external application like the + Qt Assistant, it is also possible to embed the online help in + the application. The contents can then be retrieved via the + QHelpEngine class and can be displayed in nearly any form. + Showing it in a QTextBrowser is probably the most common way, but + embedding it in What's This help is also perfectly possible. + + Retrieving help data from the file engine does not involve a + lot of code. The first step is to create an instance of the + help engine. Then we ask the engine for the links assigned to + the identifier, in this case "MyDialog::ChangeButton". If a link + was found, meaning at least one help document exists to this topic, + we get the actual help contents by calling fileData() and display + the document to the user. + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 6 + + For further information on how to use the API, have a look at + the QHelpEngine class reference. +*/ + +/*! + \page qthelpproject.html + \title Qt Help Project + + A Qt help project collects all data necessary to generate a + compressed help file. Along with the actual help data, like + the table of contents, index keywords and help documents, it + contains some extra information like a namespace to identify + the help file. One help project stands for one documentation, + e.g. the Qt Assistant manual. + + \section1 Qt Help Project File Format + + The file format is XML-based. For a better understanding of + the format we'll discuss the following example: + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 7 + + \section2 Namespace + + To enable the QHelpEngine to retrieve the proper documentation to + a given link, every documentation set has to have a unique + identifier. A unique identifier makes is also possible for the + help collection to keep track of a documentation set without relying + on its file name. The Qt help system uses a namespace as identifier + which is defined by the mandatory namespace tags. In the example + above, the namespace is "mycompany.com.myapplication.1_0". + + \target Virtual Folders + \section2 Virtual Folders + + Having a namespace for every documentation naturally means that + the documentation sets are quite separated. From the help engines + point of view this is beneficial, but from the documentors view + it is often desirable to cross reference certain topic from one + manual to another without having to specify absolute links. To + solve this problem, the help system introduced the concept of + virtual folders. + + A virtual folder will become the root directory of all files + referenced in a compressed help file. When two documentations + share the same virtual folder, they can use relative paths when + defining hyperlinks pointing to the other documentation. If a + file is contained in both documentations or manuals, the one + from the current manual has precedence over the other. + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 8 + + The above example specifies 'doc' as virtual folder. If another + manual, e.g. for a small helper tool for 'My Application' + specifies the same folder, it is sufficient to write + 'doc.html#section1' to reference the first section in the + 'My Application' manual. + + The virtual folder tag is mandatory and the folder must not + contain any '/'. + + \target Custom Filters + \section2 Custom Filters + + Next in the Qt help project file are the optional definitions of + custom filters. A custom filter contains a list of filter + attributes which will be used later to display only the documentation + which has all those attributes assigned to. So, when setting the + current filter in the QHelpEngine to "My Application 1.0" only + the documentation which has "myapp" and "1.0" set as filter + attributes will be shown. + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 9 + + It is possible to define any number of custom filters in a help + project file. Important to know is, that the filter attributes have + not to be specified in the same project file; they can be defined + in any other help file. The definition of a filter attributes + takes place by specifying them in a filter section. + + \target Filter Section + \section2 Filter Section + + A filter section contains the actual documentation. One Qt help project + file may contain more than one filter sections. Every filter section + consists of four parts, the filter attributes section, the table of + contents, the keywords and the files list. In theory all parts are + optional but not specifying anything there will result in an empty + documentation. + + \section3 Filter Attributes + + Every filter section should have filter attributes assigned to it, to + enable documentation filtering. If no filter attribute is defined, the + documentation will only be shown if no filtering occurs, meaning the + current custom filter in the QHelpEngine does not contain any filter + attributes. + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 10 + + In this case, the filter attributes 'myapp' and '1.0' are assigned + to the filter section, i.e. all contents specified in this section + will only be shown if the current custom filter has 'myapp' or '1.0' + or both as filter attributes. + + \section3 Table of contents + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 11 + + One section tag represents one item in the table of contents. The + sections can be nested to any degree, but from a users perspective + it should not be more than four or five levels. A section is defined + by its title and reference. The reference, like all file references in a Qt + help project, are relative to the help project file itself. + \note The referenced files must be inside the same directory (or within a + subdirectory) as the help project file. An absolute file path is not supported + either. + + \section3 Keywords + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 12 + + The keyword section lists all keywords of this filter section. A + keyword consists basically of a name and a file reference. If the + attribute 'name' is used then the keyword specified there will appear in + the visible index, i.e. it will be accessible through the QHelpIndexModel. + If 'id' is used, the keyword does not appear in the index and is + only accessible via the linksForIdentifier() function of the + QHelpEngineCore. 'name' and 'id' can be specified at the same time. + + \section3 Files + + \snippet doc/src/snippets/code/doc_src_qthelp.qdoc 13 + + Finally, the actual documentation files have to be listed. Make sure + that all files neccessary to display the help are mentioned, i.e. + stylesheets or similar files need to be there as well. The files, like all + file references in a Qt help project, are relative to the help project file + itself. As the example shows, files (but not directories) can also be + specified as patterns using wildcards. All listed files will be compressed + and written to the Qt compressed help file. So, in the end, one single Qt + help file contains all documentation files along with the contents and + indices. \note The referenced files must be inside the same directory + (or within a subdirectory) as the help project file. An absolute file path + is not supported either. +*/ |