source: GTP/trunk/App/Demos/Geom/OgreStuff/include/OgreResource.h @ 1812

Revision 1812, 10.6 KB checked in by gumbau, 18 years ago (diff)
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1/*
2-----------------------------------------------------------------------------
3This source file is part of OGRE
4    (Object-oriented Graphics Rendering Engine)
5For the latest info, see http://www.ogre3d.org/
6
7Copyright (c) 2000-2005 The OGRE Team
8Also see acknowledgements in Readme.html
9
10This program is free software; you can redistribute it and/or modify it under
11the terms of the GNU Lesser General Public License as published by the Free Software
12Foundation; either version 2 of the License, or (at your option) any later
13version.
14
15This program is distributed in the hope that it will be useful, but WITHOUT
16ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
18
19You should have received a copy of the GNU Lesser General Public License along with
20this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21Place - Suite 330, Boston, MA 02111-1307, USA, or go to
22http://www.gnu.org/copyleft/lesser.txt.
23-----------------------------------------------------------------------------
24*/
25#ifndef _Resource_H__
26#define _Resource_H__
27
28#include "OgrePrerequisites.h"
29#include "OgreString.h"
30#include "OgreSharedPtr.h"
31#include "OgreStringInterface.h"
32
33namespace Ogre {
34
35    typedef unsigned long ResourceHandle;
36
37
38        // Forward declaration
39        class ManualResourceLoader;
40
41        /** Abstract class reprensenting a loadable resource (e.g. textures, sounds etc)
42        @remarks
43            Resources are data objects that must be loaded and managed throughout
44                        an application. A resource might be a mesh, a texture, or any other
45                        piece of data - the key thing is that they must be identified by
46                        a name which is unique, must be loaded only once,
47                        must be managed efficiently in terms of retrieval, and they may
48                        also be unloadable to free memory up when they have not been used for
49                        a while and the memory budget is under stress.
50                @par
51                        All Resource instances must be a member of a resource group; see
52                        ResourceGroupManager for full details.
53        @par
54            Subclasses must implement:
55                        <ol>
56                        <li>A constructor, overriding the same parameters as the constructor
57                            defined by this class. Subclasses are not allowed to define
58                                constructors with other parameters; other settings must be
59                                settable through accessor methods before loading.</li>
60            <li>The loadImpl() and unloadImpl() methods - mSize must be set
61                                after loadImpl()</li>
62                        <li>StringInterface ParamCommand and ParamDictionary setups
63                            in order to allow setting of core parameters (prior to load)
64                                through a generic interface.</li>
65                        </ol>
66    */
67        class _OgreExport Resource : public StringInterface
68    {
69        public:
70                OGRE_AUTO_MUTEX // public to allow external locking
71    protected:
72                /// Creator
73                ResourceManager* mCreator;
74                /// Unique name of the resource
75        String mName;
76                /// The name of the resource group
77                String mGroup;
78                /// Numeric handle for more efficient look up than name
79        ResourceHandle mHandle;
80                /// Is the resource currently loaded?
81        bool mIsLoaded;
82                /// The size of the resource in bytes
83        size_t mSize;
84                /// Is this file manually loaded?
85                bool mIsManual;
86                /// Origin of this resource (e.g. script name) - optional
87                String mOrigin;
88                /// Optional manual loader; if provided, data is loaded from here instead of a file
89                ManualResourceLoader* mLoader;
90
91                /** Protected unnamed constructor to prevent default construction.
92                */
93                Resource()
94                        : mCreator(0), mHandle(0), mIsLoaded(false), mSize(0), mIsManual(0), mLoader(0)
95                {
96                }
97
98                /** Internal implementation of the 'load' action, only called if this
99                        resource is not being loaded from a ManualResourceLoader.
100                */
101                virtual void loadImpl(void) = 0;
102                /** Internal implementation of the 'unload' action; called regardless of
103                        whether this resource is being loaded from a ManualResourceLoader.
104                */
105                virtual void unloadImpl(void) = 0;
106                /** Calculate the size of a resource; this will only be called after 'load' */
107                virtual size_t calculateSize(void) const = 0;
108
109    public:
110                /** Standard constructor.
111                @param creator Pointer to the ResourceManager that is creating this resource
112                @param name The unique name of the resource
113                @param group The name of the resource group to which this resource belongs
114                @param isManual Is this resource manually loaded? If so, you should really
115                        populate the loader parameter in order that the load process
116                        can call the loader back when loading is required.
117                @param loader Pointer to a ManualResourceLoader implementation which will be called
118                        when the Resource wishes to load (should be supplied if you set
119                        isManual to true). You can in fact leave this parameter null
120                        if you wish, but the Resource will never be able to reload if
121                        anything ever causes it to unload. Therefore provision of a proper
122                        ManualResourceLoader instance is strongly recommended.
123                */
124                Resource(ResourceManager* creator, const String& name, ResourceHandle handle,
125                        const String& group, bool isManual = false, ManualResourceLoader* loader = 0);
126
127        /** Virtual destructor. Shouldn't need to be overloaded, as the resource
128            deallocation code should reside in unload()
129            @see
130                Resource::unload()
131        */
132        virtual ~Resource();
133
134        /** Loads the resource, if it is not already.
135                @remarks
136                        If the resource is loaded from a file, loading is automatic. If not,
137                        if for example this resource gained it's data from procedural calls
138                        rather than loading from a file, then this resource will not reload
139                        on it's own
140                       
141        */
142        virtual void load(void);
143
144                /** Reloads the resource, if it is already loaded.
145                @remarks
146                        Calls unload() and then load() again, if the resource is already
147                        loaded. If it is not loaded already, then nothing happens.
148                */
149                virtual void reload(void);
150
151        /** Returns true if the Resource is reloadable, false otherwise.
152        */
153        bool isReloadable(void) const
154        {
155            return !mIsManual || mLoader;
156        }
157
158        /** Is this resource manually loaded?
159                */
160                bool isManuallyLoaded(void) const
161                {
162                        return mIsManual;
163                }
164
165                /** Unloads the resource; this is not permanent, the resource can be
166                        reloaded later if required.
167        */
168                virtual void unload(void);
169
170        /** Retrieves info about the size of the resource.
171        */
172        size_t getSize(void) const
173        {
174            return mSize;
175        }
176
177        /** 'Touches' the resource to indicate it has been used.
178        */
179        virtual void touch(void);
180
181        /** Gets resource name.
182        */
183        const String& getName(void) const
184        {
185            return mName;
186        }
187
188        ResourceHandle getHandle(void) const
189        {
190            return mHandle;
191        }
192
193        /** Returns true if the Resource has been loaded, false otherwise.
194        */
195        bool isLoaded(void) const
196        {
197                        OGRE_LOCK_AUTO_MUTEX
198            return mIsLoaded;
199        }
200
201                /// Gets the group which this resource is a member of
202                const String& getGroup(void) { return mGroup; }
203
204                /** Change the resource group ownership of a Resource.
205                @remarks
206                        This method is generally reserved for internal use, although
207                        if you really know what you're doing you can use it to move
208                        this resource from one group to another.
209                @param newGroup Name of the new group
210                */
211                void changeGroupOwnership(const String& newGroup);
212
213                /// Gets the manager which created this resource
214                ResourceManager* getCreator(void) { return mCreator; }
215                /** Get the origin of this resource, e.g. a script file name.
216                @remarks
217                        This property will only contain something if the creator of
218                        this resource chose to populate it. Script loaders are advised
219                        to populate it.
220                */
221                const String& getOrigin(void) const { return mOrigin; }
222                /// Notify this resource of it's origin
223                void _notifyOrigin(const String& origin) { mOrigin = origin; }
224
225    };
226
227        /** Shared pointer to a Resource.
228        @remarks
229                This shared pointer allows many references to a resource to be held, and
230                when the final reference is removed, the resource will be destroyed.
231                Note that the ResourceManager which created this Resource will be holding
232                at least one reference, so this resource will not get destroyed until
233                someone removes the resource from the manager - this at least gives you
234                strong control over when resources are freed. But the nature of the
235                shared pointer means that if anyone refers to the removed resource in the
236                meantime, the resource will remain valid.
237        @par
238                You may well see references to ResourcePtr (i.e. ResourcePtr&) being passed
239                around internally within Ogre. These are 'weak references' ie they do
240                not increment the reference count on the Resource. This is done for
241                efficiency in temporary operations that shouldn't need to incur the
242                overhead of maintaining the reference count; however we don't recommend
243                you do it yourself since these references are not guaranteed to remain valid.
244        */
245        typedef SharedPtr<Resource> ResourcePtr;
246
247        /** Interface describing a manual resource loader.
248        @remarks
249                Resources are usually loaded from files; however in some cases you
250                want to be able to set the data up manually instead. This provides
251                some problems, such as how to reload a Resource if it becomes
252                unloaded for some reason, either because of memory constraints, or
253                because a device fails and some or all of the data is lost.
254        @par
255                This interface should be implemented by all classes which wish to
256                provide manual data to a resource. They provide a pointer to themselves
257                when defining the resource (via the appropriate ResourceManager),
258                and will be called when the Resource tries to load.
259                They should implement the loadResource method such that the Resource
260                is in the end set up exactly as if it had loaded from a file,
261                although the implementations will likely differ between subclasses
262                of Resource, which is why no generic algorithm can be stated here.
263        @note
264                The loader must remain valid for the entire life of the resource,
265                so that if need be it can be called upon to re-load the resource
266                at any time.
267        */
268        class _OgreExport ManualResourceLoader
269        {
270        public:
271                ManualResourceLoader() {}
272                virtual ~ManualResourceLoader() {}
273
274                /** Called when a resource wishes to load.
275                @param resource The resource which wishes to load
276                */
277                virtual void loadResource(Resource* resource) = 0;
278        };
279}
280
281#endif
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