/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2003 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_TEXTURE2D
#define OSG_TEXTURE2D 1

#include <osg/Texture>

namespace osg {

/** Texture state class which encapsulates OpenGl texture functionality.*/
class SG_EXPORT Texture2D : public Texture
{

    public :
        
        Texture2D();

        Texture2D(Image* image);

        /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
        Texture2D(const Texture2D& text,const CopyOp& copyop=CopyOp::SHALLOW_COPY);
        
        META_StateAttribute(osg, Texture2D,TEXTURE);

        /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
        virtual int compare(const StateAttribute& rhs) const;

        virtual bool getModeUsage(ModeUsage& usage) const
        {
            usage.usesTextureMode(GL_TEXTURE_2D);
            return true;
        }

        /** Set the texture image. */
        void setImage(Image* image);

        /** Get the texture image. */
        Image* getImage() { return _image.get(); }

        /** Get the const texture image. */
        inline const Image* getImage() const { return _image.get(); }

        inline unsigned int& getModifiedTag(unsigned int contextID) const
        {
            // get the modified tag for the current contextID.
            return _modifiedTag[contextID];
        }

        /** Set the texture width and height. If width or height are zero then
          * the repsective size value is calculated from the source image sizes. */
        inline void setTextureSize(int width, int height) const
        {
            _textureWidth = width;
            _textureHeight = height;
        }

        int getTextureWidth() const { return _textureWidth; }
        int getTextureHeight() const { return _textureHeight; }

        // deprecated.
        inline void getTextureSize(int& width, int& height) const
        {
            width = _textureWidth;
            height = _textureHeight;
        }


        class SG_EXPORT SubloadCallback : public Referenced
        {
            public:
                virtual void load(const Texture2D& texture,State& state) const = 0;
                virtual void subload(const Texture2D& texture,State& state) const = 0;
        };
        
        void setSubloadCallback(SubloadCallback* cb) { _subloadCallback = cb;; }
        
        SubloadCallback* getSubloadCallback() { return _subloadCallback.get(); }

        const SubloadCallback* getSubloadCallback() const { return _subloadCallback.get(); }


        /** Set the number of mip map levels the the texture has been created with,
            should only be called within an osg::Texuture::apply() and custom OpenGL texture load.*/
        void setNumMipmapLevels(unsigned int num) const { _numMipmapLevels=num; }

        /** Get the number of mip map levels the the texture has been created with.*/
        unsigned int getNumMipmapLevels() const { return _numMipmapLevels; }
        

        /** Copy pixels into a 2D texture image.As per glCopyTexImage2D.
          * Creates an OpenGL texture object from the current OpenGL background
          * framebuffer contents at pos \a x, \a y with width \a width and
          * height \a height. \a width and \a height must be a power of two.
          */
        void copyTexImage2D(State& state, int x, int y, int width, int height );

        /** Copy a two-dimensional texture subimage. As per glCopyTexSubImage2D.
          * Updates portion of an existing OpenGL texture object from the current OpenGL background
          * framebuffer contents at pos \a x, \a y with width \a width and
          * height \a height. \a width and \a height must be a power of two,
          * and writing into the texture with offset \a xoffset and \a yoffset.
          */
        void copyTexSubImage2D(State& state, int xoffset, int yoffset, int x, int y, int width, int height );


        /** On first apply (unless already compiled), create the minmapped 
          * texture and bind it, subsequent apply will simple bind to texture.*/
        virtual void apply(State& state) const;

    protected :

        virtual ~Texture2D();

        virtual void computeInternalFormat() const;


        // not ideal that _image is mutable, but its required since
        // Image::ensureDimensionsArePowerOfTwo() can only be called
        // in a valid OpenGL context, a therefore within an Texture::apply
        // which is const...
        ref_ptr<Image> _image;

        // subloaded images can have different texture and image sizes.
        mutable GLsizei _textureWidth, _textureHeight;
        
        // number of mip map levels the the texture has been created with,        
        mutable GLsizei _numMipmapLevels;

        ref_ptr<SubloadCallback> _subloadCallback;

        typedef buffered_value<unsigned int> ImageModifiedTag;
        mutable ImageModifiedTag _modifiedTag;

};

}

#endif