QtHelp Module

Detailed Description

The QtHelp module provides classes for integrating online documentation in applications.

To import the module use, for example, the following statement:

from PyQt4 import QtHelp

Topics

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:

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.

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:

     <?xml version="1.0" encoding="utf-8" ?>
     <QHelpCollectionProject version="1.0">
         <docFiles>
             <register>
                 <file>doc.qch</file>
             </register>
         </docFiles>
     </QHelpCollectionProject>

For actually creating the collection file call:

     qcollectiongenerator mycollection.qhcp -o mycollection.qhc

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.

     ...
     <docFiles>
         <generate>
             <file>
                 <input>doc.qhp</input>
                 <output>doc.qch</output>
             </file>
         </generate>
         <register>
             <file>doc.qch</file>
         </register>
     </docFiles>
     ...

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.

Using Qt Help

Using Qt Assistant

Qt Assistant 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.

Using QHelpEngine API