namespace {
/**
@page resprov_tutorial The Beginners Guide to resource loading with ResourceProviders
@author Paul D Turner

This tutorial introduces the CEGUI::ResourceProvider concept, explains how to
set up resource groups and directories in the DefaultResourceProvider and how to
specify the default resource groups to be used by various parts of the system.

<br>
@section resprov_tutorial_intro What is a ResourceProvider?
CEGUI uses a ResourceProvider object to provide a bridge between the CEGUI
library and external file loading systems - whether this might be the basic
underlying file system of the machine executing the code, or something a bit
more exotic such as the resource management sub-systems offered by the Ogre3D
and Irrlicht engines; by providing custom implementations of the
ResourceProvider interface, it is possible for CEGUI to seamlessly integrate
with all of these systems.

<br>
@section resprov_tutorial_default_rp DefaultResourceProvider Explained
CEGUI's default resource provider, DefaultResourceProvider, supplies some
basic functionality for those who do not yet have, or do not need, a more
sophisticated alternative.  As well as supplying the functions required by CEGUI
for actually loading file data, DefaultResourceProvider also has some
rudimentary support for 'resource groups'.  Here, a resource group is basically
a label given to a directory location on the system.  This allows one to have
logical grouping of files within directories and then to be able to refer to
those locations via a simple label rather than hard coded paths.  This then
means that should you need to change the location of some data files, you just
need to update the resource group location instead of updating path information
throughout your code and XML files.

For users of the Ogre3D library - or users with other custom resource providers
not derived from DefaultResourceProvider - <em>you should not follow the parts
of this tutorial that deal with defining resouce groups and their
directories</em> (you should especially ignore any example code that casts to
DefaultResouceProvider).  These users should follow the usual procedures for
using the underlying resouce system in use (for example, in Ogre3D you might set
up your resource locations in code using the Ogre::ResourceManager or via a
resources.cfg file).

This said, <em>all users</em> should follow the parts of this tutorial dealing
with setting the default resouce groups for the various resource classes, as
detailed in @ref resprov_tutorial_default_resource_groups.

@subsection resprov_tutorial_default_rp_groups Specifying Resource Groups and Directories
The DefaultResourceProvider allows you to define any number of named resource
groups and to specify a directory to be accessed by each of those groups.
What this means is that you can create a resource group, say
@c "imagesets", and assign a directory to that group, for example
@c "./mygame/datafiles/gui/imagesets/".  When loading an Imageset through the
ImagesetManager, you might then specify the resource group to be used as
@c "imagesets" and the system will look in the predefined location
@c "./mygame/datafiles/gui/imagesets/".  Note that at present each resource
group may only have a single directory associated with it.

A small code example is in order to clarify what has been said.  Instead of
loading resources by giving an explicit path, like this:
@code
Imageset& wlis = ImagesetManager::getSingleton().create(
    "./mygame/datafiles/gui/imagesets/WindowsLook.imageset");
@endcode

At initialisation time, you set up a resource group in the default resource
provider, like this:
@code
DefaultResourceProvider* rp = static_cast<DefaultResourceProvider*>(
    CEGUI::System::getSingleton().getResourceProvider());

rp->setResourceGroupDirectory("imagesets", "./mygame/datafiles/gui/imagesets/");
@endcode

Then later on in the code, when you need to load an imageset, just do this:
@code
Imageset& wlis = ImagesetManager::getSingleton().create(
    "WindowsLook.imageset", "imagesets");
@endcode

Note how when creating the imageset from a file we do not specify any path
information; the path information is obtained from the resource group specified,
in the example this is @c "imagesets".  We will later show you how you set
default resource groups for each of the resource types - then you do not have to
specify the group when you load a resource (unless you're loading it from a
group other than the default, of course).

Something important to consider is that when using this resource group approach,
data files that contain references to other data files should not contain
relative path information - they should, in general, just have the actual file
name of the file being referred to - this way the resource group system can be
put to better use, and it also makes it easier to move files around later -
since rather than having to 'fix up' all the relative paths, you just have to
update the resource group paths instead.

<br>
@section resprov_tutorial_default_resource_groups Specifying Default Resource Groups
Each of the core system classes that represents a loadable resource has static
members to set and get a default resource group.  This resource group will be
used when loading the specific data files needed by a given class - in the case
of the Imageset class, the default resource group should reference a directory
holding the imageset xml and texture image files.

For each of the resource consuming classes, the static members are named the
same (special exception is the xerces based XML paser - see below):
@code
const String& getDefaultResourceGroup();
void setDefaultResourceGroup(const String& groupname);
@endcode

The following is a list of the core resource loading classes and the resources that they load:
- @c CEGUI::Imageset          : Imageset xml and texture image files. 
- @c CEGUI::Font              : Font xml and freetype loadable font files.
- @c CEGUI::Scheme            : Scheme xml files.
- @c CEGUI::WindowManager     : Window layout xml files.
- @c CEGUI::WidgetLookManager : LookNFeel xml files
- @c CEGUI::ScriptModule      : Script files in whichever scripted langauge.

There is one special exception, as mentioned above, this is the Xerces-C++ based
XML parser.  For this there is a special resource group setting to specify where
the .xsd schema files - used for XML schema validation - can be found.  For this
special case, you instead use the PropertySet interface and access a property
named @c SchemaDefaultResourceGroup.  The use of the property interface mainly
serves to eliminate the need to link directly with the xerces xml based parser
module just to set the default schema resource group.

Because you may not know ahead of time which XML parser module is actually being
used - and therefore may not know whether the property exists - you should check
the existence of the propery before setting it.  This is better than checking
the XML parser ID string for "Xerces" because it allows you to seamlessly work
with any future parser module that may also offer validation (so long as it
exposes the same property).

For example:
@code
// setup default group for validation schemas
CEGUI::XMLParser* parser = CEGUI::System::getSingleton().getXMLParser();
if (parser->isPropertyPresent("SchemaDefaultResourceGroup"))
    parser->setProperty("SchemaDefaultResourceGroup", "schemas");
@endcode

One final thing to consider, is that the ResourceProvider class also has a
default resource group.  This should be considered a global or master default;
it is used whenever a specific resource loading class has no default of it's own
specified.  This would prove useful if you have all your data in a single
directory.

<br>
@section resprov_tutorial_example A final, Complete Example
To close, we will show how you might perform the initialisation of resource
groups and their target directories to access the data files within the
datafiles directory that comes with CEGUI, and how we assign the default groups
to be used for all of the resource types.

After initialising the core CEGUI::System object as usual, we then specify a set
of resource groups and their target directories (this assumes the working
directory will be the 'bin' directory within the CEGUI package:
@code
// initialise the required dirs for the DefaultResourceProvider
CEGUI::DefaultResourceProvider* rp = static_cast<CEGUI::DefaultResourceProvider*>
    (CEGUI::System::getSingleton().getResourceProvider());

rp->setResourceGroupDirectory("schemes", "../datafiles/schemes/");
rp->setResourceGroupDirectory("imagesets", "../datafiles/imagesets/");
rp->setResourceGroupDirectory("fonts", "../datafiles/fonts/");
rp->setResourceGroupDirectory("layouts", "../datafiles/layouts/");
rp->setResourceGroupDirectory("looknfeels", "../datafiles/looknfeel/");
rp->setResourceGroupDirectory("lua_scripts", "../datafiles/lua_scripts/");

// This is only really needed if you are using Xerces and need to
// specify the schemas location
rp->setResourceGroupDirectory("schemas", "../datafiles/xml_schemas/");
@endcode
Now that is done, we have a nice set of resource groups defined with their
target directories set.  Finally, to get the system to use these directories, we
set the default resource groups to be used:
@code
// set the default resource groups to be used
CEGUI::Imageset::setDefaultResourceGroup("imagesets");
CEGUI::Font::setDefaultResourceGroup("fonts");
CEGUI::Scheme::setDefaultResourceGroup("schemes");
CEGUI::WidgetLookManager::setDefaultResourceGroup("looknfeels");
CEGUI::WindowManager::setDefaultResourceGroup("layouts");
CEGUI::ScriptModule::setDefaultResourceGroup("lua_scripts");

// setup default group for validation schemas
CEGUI::XMLParser* parser = CEGUI::System::getSingleton().getXMLParser();
if (parser->isPropertyPresent("SchemaDefaultResourceGroup"))
    parser->setProperty("SchemaDefaultResourceGroup", "schemas");
@endcode

@section resprov_tutorial_conclusion Conclusion
This has been a brief introduction to the ResouceProvider system used by CEGUI.
You have seen how to create and use resource groups with CEGUI's
DefaultResourceProvider, and how to specify default resource groups for each
resource type used by CEGUI.
*/
}
