/*-------------------------------------------------------------------------
This source file is a part of OGRE
(Object-oriented Graphics Rendering Engine)

For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2014 Torus Knot Software Ltd
Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in
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-------------------------------------------------------------------------*/

#ifndef _Font_H__
#define _Font_H__

#include "OgreOverlayPrerequisites.h"
#include "OgreResource.h"
#include "OgreCommon.h"
#include "OgreSharedPtr.h"

namespace Ogre
{
    /** \addtogroup Optional
    *  @{
    */
    /** \addtogroup Overlays
    *  @{
    */
    /** Enumerates the types of Font usable in the engine. */
    enum FontType
    {
        /// Generated from a truetype (.ttf) font
        FT_TRUETYPE = 1,
        /// Loaded from an image created by an artist
        FT_IMAGE = 2
    };


    /** Class representing a font in the system.
    @remarks
    This class is simply a way of getting a font texture into the OGRE system and
    to easily retrieve the texture coordinates required to accurately render them.
    Fonts can either be loaded from precreated textures, or the texture can be generated
    using a truetype font. You can either create the texture manually in code, or you
    can use a .fontdef script to define it (probably more practical since you can reuse
    the definition more easily)
    @note
    This class extends both Resource and ManualResourceLoader since it is
    both a resource in it's own right, but it also provides the manual load
    implementation for the Texture it creates.
    */
    class _OgreOverlayExport Font : public Resource, public ManualResourceLoader
    {
    protected:
        /// Command object for Font - see ParamCommand 
        class _OgreOverlayExport CmdType : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /// Command object for Font - see ParamCommand 
        class _OgreOverlayExport CmdSource : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        class _OgreOverlayExport CmdCharSpacer : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /// Command object for Font - see ParamCommand 
        class _OgreOverlayExport CmdSize : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /// Command object for Font - see ParamCommand 
        class _OgreOverlayExport CmdResolution : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };
        /// Command object for Font - see ParamCommand 
        class _OgreOverlayExport CmdCodePoints : public ParamCommand
        {
        public:
            String doGet(const void* target) const;
            void doSet(void* target, const String& val);
        };

        // Command object for setting / getting parameters
        static CmdType msTypeCmd;
        static CmdSource msSourceCmd;
        static CmdCharSpacer msCharacterSpacerCmd;
        static CmdSize msSizeCmd;
        static CmdResolution msResolutionCmd;
        static CmdCodePoints msCodePointsCmd;

        /// The type of font
        FontType mType;

        /// Source of the font (either an image name or a truetype font)
        String mSource;

        /** Add a gap between letters vertically and horizonally
            prevents nasty artifacts caused by fonts atypically wide or tall characters. */
        uint mCharacterSpacer;

        /// Size of the truetype font, in points
        Real mTtfSize;
        /// Resolution (dpi) of truetype font
        uint mTtfResolution;
        /// Max distance to baseline of this (truetype) font
        int mTtfMaxBearingY;


    public:
        typedef Ogre::uint32 CodePoint;
        typedef Ogre::FloatRect UVRect;
        /// Information about the position and size of a glyph in a texture
        struct GlyphInfo 
        {
            CodePoint codePoint;
            UVRect uvRect;
            Real aspectRatio;

            GlyphInfo(CodePoint id, const UVRect& rect, Real aspect)
                : codePoint(id), uvRect(rect), aspectRatio(aspect)
            {

            }
        };
        /// A range of code points, inclusive on both ends
        typedef std::pair<CodePoint, CodePoint> CodePointRange;
        typedef vector<CodePointRange>::type CodePointRangeList;
    protected:
        /// Map from unicode code point to texture coordinates
        typedef map<CodePoint, GlyphInfo>::type CodePointMap;
        CodePointMap mCodePointMap;

        /// The material which is generated for this font
        MaterialPtr mMaterial;

        /// Texture pointer
        TexturePtr mTexture;

        /// For TRUE_TYPE font only
        bool mAntialiasColour;

        /// Range of code points to generate glyphs for (truetype only)
        CodePointRangeList mCodePointRangeList;

        /// Internal method for loading from ttf
        void createTextureFromFont(void);

        /// @copydoc Resource::loadImpl
        virtual void loadImpl();
        /// @copydoc Resource::unloadImpl
        virtual void unloadImpl();
        /// @copydoc Resource::calculateSize
        size_t calculateSize(void) const { return 0; } // permanent resource is in the texture 
    public:

        /** Constructor.
        @see Resource
        */
        Font(ResourceManager* creator, const String& name, ResourceHandle handle,
            const String& group, bool isManual = false, ManualResourceLoader* loader = 0);
        virtual ~Font();

        /** Sets the type of font. Must be set before loading. */
        void setType(FontType ftype);

        /** Gets the type of font. */
        FontType getType(void) const;

        /** Sets the source of the font.
        @remarks
            If you have created a font of type FT_IMAGE, this method tells the
            Font which image to use as the source for the characters. So the parameter 
            should be the name of an appropriate image file. Note that when using an image
            as a font source, you will also need to tell the font where each character is
            located using setGlyphTexCoords (for each character).
        @par
            If you have created a font of type FT_TRUETYPE, this method tells the
            Font which .ttf file to use to generate the text. You will also need to call 
            setTrueTypeSize and setTrueTypeResolution, and call addCodePointRange
            as many times as required to define the range of glyphs you want to be
            available.
        @param source An image file or a truetype font, depending on the type of this font
        */
        void setSource(const String& source);

        /** Gets the source this font (either an image or a truetype font).
        */
        const String& getSource(void) const;

        /** Sets the spacing to allocate for font characters to overlap each other.
        @param charSpacer The size of the character spacer, in points.  Increasing it
            allows for more stretched-out fonts; decreasing it reduces memory and processing
            time.  The default is "5".
        */
        void setCharacterSpacer(uint charSpacer);
 
        /** Gets the spacing to allocate for font characters to overlap each other.
        @remarks Returns the size of the character spacer, in points.  A higher value
            allows for more stretched-out fonts.  A low value reduces memory and processing
            time.  The default is "5".
        */
        uint getCharacterSpacer(void) const;

        /** Sets the size of a truetype font (only required for FT_TRUETYPE). 
        @param ttfSize The size of the font in points. Note that the
            size of the font does not affect how big it is on the screen, just how large it is in
            the texture and thus how detailed it is.
        */
        void setTrueTypeSize(Real ttfSize);
        /** Gets the resolution (dpi) of the font used to generate the texture
        (only required for FT_TRUETYPE).
        @param ttfResolution The resolution in dpi
        */
        void setTrueTypeResolution(uint ttfResolution);

        /** Gets the point size of the font used to generate the texture.
        @remarks
            Only applicable for FT_TRUETYPE Font objects.
            Note that the size of the font does not affect how big it is on the screen, 
            just how large it is in the texture and thus how detailed it is.            
        */
        Real getTrueTypeSize(void) const;
        /** Gets the resolution (dpi) of the font used to generate the texture.
        @remarks
            Only applicable for FT_TRUETYPE Font objects.
        */
        uint getTrueTypeResolution(void) const;
        /** Gets the maximum baseline distance of all glyphs used in the texture.
        @remarks
            Only applicable for FT_TRUETYPE Font objects.
            The baseline is the vertical origin of horizontal based glyphs.  The bearingY
            attribute is the distance from the baseline (origin) to the top of the glyph's 
            bounding box.
        @note
            This value is only available after the font has been loaded.
        */
        int getTrueTypeMaxBearingY() const;


        /** Returns the texture coordinates of the associated glyph. 
            @remarks Parameter is a short to allow both ASCII and wide chars.
            @param id The code point (unicode)
            @return A rectangle with the UV coordinates, or null UVs if the
                code point was not present
        */
        inline const UVRect& getGlyphTexCoords(CodePoint id) const
        {
            CodePointMap::const_iterator i = mCodePointMap.find(id);
            if (i != mCodePointMap.end())
            {
                return i->second.uvRect;
            }
            else
            {
                static UVRect nullRect(0.0, 0.0, 0.0, 0.0);
                return nullRect;
            }
        }

        /** Sets the texture coordinates of a glyph.
        @remarks
            You only need to call this if you're setting up a font loaded from a texture manually.
        @note
            Also sets the aspect ratio (width / height) of this character. textureAspect
            is the width/height of the texture (may be non-square)
        */
        inline void setGlyphTexCoords(CodePoint id, Real u1, Real v1, Real u2, Real v2, Real textureAspect)
        {
            CodePointMap::iterator i = mCodePointMap.find(id);
            if (i != mCodePointMap.end())
            {
                i->second.uvRect.left = u1;
                i->second.uvRect.top = v1;
                i->second.uvRect.right = u2;
                i->second.uvRect.bottom = v2;
                i->second.aspectRatio = textureAspect * (u2 - u1)  / (v2 - v1);
            }
            else
            {
                mCodePointMap.insert(
                    CodePointMap::value_type(id, 
                        GlyphInfo(id, UVRect(u1, v1, u2, v2), 
                            textureAspect * (u2 - u1)  / (v2 - v1))));
            }

        }
        /** Gets the aspect ratio (width / height) of this character. */
        inline Real getGlyphAspectRatio(CodePoint id) const
        {
            CodePointMap::const_iterator i = mCodePointMap.find(id);
            if (i != mCodePointMap.end())
            {
                return i->second.aspectRatio;
            }
            else
            {
                return 1.0;
            }
        }
        /** Sets the aspect ratio (width / height) of this character.
        @remarks
            You only need to call this if you're setting up a font loaded from a 
            texture manually.
        */
        inline void setGlyphAspectRatio(CodePoint id, Real ratio)
        {
            CodePointMap::iterator i = mCodePointMap.find(id);
            if (i != mCodePointMap.end())
            {
                i->second.aspectRatio = ratio;
            }
        }

        /** Gets the information available for a glyph corresponding to a
            given code point, or throws an exception if it doesn't exist;
        */
        const GlyphInfo& getGlyphInfo(CodePoint id) const;

        /** Adds a range of code points to the list of code point ranges to generate
            glyphs for, if this is a truetype based font.
        @remarks
            In order to save texture space, only the glyphs which are actually
            needed by the application are generated into the texture. Before this
            object is loaded you must call this method as many times as necessary
            to define the code point range that you need.
        */
        void addCodePointRange(const CodePointRange& range)
        {
            mCodePointRangeList.push_back(range);
        }

        /** Clear the list of code point ranges.
        */
        void clearCodePointRanges()
        {
            mCodePointRangeList.clear();
        }
        /** Get a const reference to the list of code point ranges to be used to
            generate glyphs from a truetype font.
        */
        const CodePointRangeList& getCodePointRangeList() const
        {
            return mCodePointRangeList;
        }
        /** Gets the material generated for this font, as a weak reference. 
        @remarks
            This will only be valid after the Font has been loaded. 
        */
        inline const MaterialPtr& getMaterial() const
        {
            return mMaterial;
        }
        /** Gets the material generated for this font, as a weak reference. 
        @remarks
            This will only be valid after the Font has been loaded. 
        */
        inline const MaterialPtr& getMaterial()
        {
            return mMaterial;
        }
        /** Sets whether or not the colour of this font is antialiased as it is generated
            from a true type font.
        @remarks
            This is valid only for a FT_TRUETYPE font. If you are planning on using 
            alpha blending to draw your font, then it is a good idea to set this to
            false (which is the default), otherwise the darkening of the font will combine
            with the fading out of the alpha around the edges and make your font look thinner
            than it should. However, if you intend to blend your font using a colour blending
            mode (add or modulate for example) then it's a good idea to set this to true, in
            order to soften your font edges.
        */
        inline void setAntialiasColour(bool enabled)
        {
            mAntialiasColour = enabled;
        }

        /** Gets whether or not the colour of this font is antialiased as it is generated
        from a true type font.
        */
        inline bool getAntialiasColour(void) const
        {
            return mAntialiasColour;
        }

        /** Implementation of ManualResourceLoader::loadResource, called
            when the Texture that this font creates needs to (re)load.
        */
        void loadResource(Resource* resource);
    };

    typedef SharedPtr<Font> FontPtr;
    /** @} */
    /** @} */
}

#endif
