gls_font_base.h

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/*! \file
  \brief  The disti::GlsFontBase class and related classes.

  \par Copyright Information

  Copyright (c) 2015 by The DiSTI Corporation.<br>
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  NO WARRANTY. THE SOFTWARE IS PROVIDED "AS-IS," WITHOUT WARRANTY OF ANY KIND,
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*/
#ifndef _GLS_FONT_H
#define _GLS_FONT_H

#include <string>
#include <vector>
#include "gls_gl.h"
#include "vertex.h"

//---------------------------------------------------------------------------
//              MACROS FOR USE IN GENERATED SOURCE CODE
//---------------------------------------------------------------------------
#define BEGIN_CHAR_ATTR AttrCont_t attr
#define ADD_CHAR_ATTR(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16) \
    attr.push_back(CharAttr_t(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16))
#define END_CHAR_ATTR return attr


//===========================================================================
//                         BEGIN NAMESPACE
//===========================================================================
namespace disti
{

//---------------------------------------------------------------------------
//                        FORWARD REFERENCES
//---------------------------------------------------------------------------
class VertexNoColor;
class glsColor;
class Image;

typedef VertexNoColor Vector;

//===========================================================================
/**
* The GlsFontBase class provides a specific font face for use within the GL 
* Studio.  The font face is determined at construction time by the 
* parameters passed in by the creator of the GlsFontBase instance.  Specific
* instances should be wrapped in a singelton object wrapper, as there is
* no reason to have more than one instance of the exact same face (meaning
* font family, style, and point size.)
*
* Once instanced, a GlsFontRenderer object can be used to render characters in
* Open GL at specific locations and with several different text effects.
* 
* \sa GlsFontRenderer
*/
//===========================================================================
class GlsFontBase  
{
public:

    // Define the character type to use.
    typedef GLuint Char_t;

    //-----------------------------------------------------------------------
    /// Attributes of the specific font
    //-----------------------------------------------------------------------
    struct FontAttr_t
    {   
        std::string family;   /** Font family name. Eg. Arial */       
        std::string style;    /** Font style. Eg. Bold */ 
        GLuint ptSize;        /** Font point size */
        GLuint descender;     /** Font descender in positive pixels */
        Char_t firstChar;     /** First character code in the character set */
        Char_t lastChar;      /** Last character code in the character set */
        GLuint maxCharHeight; /** Maximum character height in pixels */
        GLuint maxCharWidth;  /** Maximum character width in pixels */
        GLint underlinePos;   /** Position of the underline for underlined text */
        GLuint underlineSize; /** thickness of the underline */

        /** Default constructor to initialize font data to known values */
        FontAttr_t() :
            ptSize       (0),
            descender    (0),
            firstChar    (32),
            lastChar     (127),
            maxCharHeight(0),
            maxCharWidth (0),
            underlinePos (0),
            underlineSize(0)
        {
        }
    };

    //-----------------------------------------------------------------------
    /// Character attributes. One item for each character in the set.
    //-----------------------------------------------------------------------
    struct CharAttr_t
    {
        GLfloat width;      /** Character width in pixels/points */
        GLfloat height;     /** Character height in pixels/points  */      
        GLfloat varTexX1;   /** Left most x position in the texture for variable width font spacing. (in texture coordinates) */
        GLfloat varTexX2;   /** Right most x position in the texture for variable width font spacing. (in texture coordinates) */
        GLfloat fixedTexX1; /** Left most x position in the texture for fixed width font spacing. (in texture coordinates) */
        GLfloat fixedTexX2; /** Right most x position in the texture for fixed width font spacing. (in texture coordinates) */
        GLfloat varTexY1;   /** Lowest y position in the texture for variable height font spacing. (in texture coordinates) */
        GLfloat varTexY2;   /** Upper most y position in the texture for variable height font spacing. (in texture coordinates) */
        GLfloat fixedTexY1; /** Lowest y position in the texture for fixed height font spacing. (in texture coordinates) */
        GLfloat fixedTexY2; /** Upper most y position in the texture for fixed height font spacing. (in texture coordinates) */

        // Glyph metrics for character placement
        // Additional information on the meaning of these parameters can
        // be found in the freetype library documentation.
        GLfloat horiBearingX; /** Distance from pen position to the left edge of the character (varTexX1) for horizontal strings. */
        GLfloat horiBearingY; /** Distance from pen position (ie the baseline) to the top edge of the character (varTexY2) for horizontal strings. */
        GLfloat horiAdvance;  /** Distance to advance the pen position after drawing this character for horizontal strings. */
        GLfloat vertBearingX; /** Distance from pen position (ie the center line) to the left edge of the character (varTexX1) for vertical strings. */
        GLfloat vertBearingY; /** Distance from pen position to the top edge of the character (varTexY2) for vertical strings. */ 
        GLfloat vertAdvance;  /** Distance to advance the pen position after drawing this character for vertical strings. */

        /// Default constructor to initialize character attribute data to known values
        CharAttr_t() : width        (0), 
                       height       (0), 
                       varTexX1     (0), 
                       varTexX2     (0),
                       fixedTexX1   (0), 
                       fixedTexX2   (0),
                       varTexY1     (0), 
                       varTexY2     (0),
                       fixedTexY1   (0), 
                       fixedTexY2   (0),
                       horiBearingX (0),
                       horiBearingY (0),
                       horiAdvance  (0),
                       vertBearingX (0),
                       vertBearingY (0),
                       vertAdvance  (0)
        {
        }

        CharAttr_t(GLfloat w, 
                   GLfloat h,
                   GLfloat vTexX1,
                   GLfloat vTexX2,
                   GLfloat fTexX1,
                   GLfloat fTexX2,
                   GLfloat vTexY1,
                   GLfloat vTexY2,
                   GLfloat fTexY1,
                   GLfloat fTexY2,
                   GLfloat horiBearingX_,
                   GLfloat horiBearingY_,
                   GLfloat horiAdvance_,
                   GLfloat vertBearingX_,
                   GLfloat vertBearingY_,
                   GLfloat vertAdvance_ ) : 
            width        (w), 
            height       (h),
            varTexX1     (vTexX1), 
            varTexX2     (vTexX2),
            fixedTexX1   (fTexX1), 
            fixedTexX2   (fTexX2),
            varTexY1     (vTexY1), 
            varTexY2     (vTexY2),
            fixedTexY1   (fTexY1), 
            fixedTexY2   (fTexY2),
            horiBearingX (horiBearingX_),
            horiBearingY (horiBearingY_),
            horiAdvance  (horiAdvance_),
            vertBearingX (vertBearingX_),
            vertBearingY (vertBearingY_),
            vertAdvance  (vertAdvance_)
        {
        }
    }; // end struct CharAttr_t

    typedef std::vector<CharAttr_t> AttrCont_t;

    /** Class Constructor. */
    GLS_EXPORT GlsFontBase(
        const FontAttr_t& fontAttr, 
        const AttrCont_t& charAttributes, 
              Image*      texture);

    /** 
    * Access the attributes of the font.
    * \return all the attributes of the font.
    */
    const FontAttr_t& Attributes() const
    {
        return _attr;
    }

    /**
    * NOTE: This function will only return char attributes for pre-generated ASCII fonts.
    * Users should call CharAttrUnicode for GlsUnicodeFontBase fonts or CharAttrRuntime for GlsRuntimeFontBase fonts.
    * \param c The character to retrieve attributes for.
    * \returns The attributes for the character. 
    */
    const CharAttr_t& CharAttr(Char_t c) const
    {
        return _charAttr[CharAttrIndex(c)];
    }

    /** 
    * Calculates an index for the specified character depending on the set of characters the texture map was generated for.
    * NOTE: This function will only return char attributes for pre-generated ASCII fonts.
    * Users should call CharAttrUnicode for GlsUnicodeFontBase fonts or CharAttrRuntime for GlsRuntimeFontBase fonts.
    * \param c  specifies for which character the index is calculated for
    * \return the index of the specified character
    */
    GLuint CharAttrIndex(Char_t c) const
    {
        return (_attr.firstChar <= c && c <= _attr.lastChar) 
            ? GLuint(c - _attr.firstChar) : 0;     
    }

    /** 
    * Access the character attributes of the font.
    * \return the attributes of all the characters in the font.
    */
    const AttrCont_t& CharAttributes() const
    {
        return _charAttr;
    }

    /** 
    * \return The font family string
    */
    std::string Family() const
    {
        return _attr.family;
    }

    /**
    * \return The unique lookup key for this font.
    */
    std::string Key() const
    {
        return _key;
    }

    /** 
    * Builds a unique lookup key for a specific font, style, and size.
    * \param name   Name of the font
    * \param style  Style of the font
    * \param ptSize Point size of the font
    */
    static GLS_EXPORT std::string Key(
        const std::string& name,
        const std::string& style,
        GLuint ptSize);

    /**
    * \return maximum height in pixels of the characters in the set
    */
    GLfloat MaxCharHeight() const
    {
        return GLfloat(_attr.maxCharHeight);
    }

    /**
    * \return maximum width in pixels of the characters in the set
    */
    GLfloat MaxCharWidth() const
    {
        return GLfloat(_attr.maxCharWidth);
    }

    /**
    * \return maximum height in pixels of the characters in the set
    */
    GLuint PtSize() const
    {
        return _attr.ptSize;
    }

    /**
    * Return the style description
    */
    std::string Style() const
    {
        return _attr.style;
    }

    /**
    * \return a pointer to the font's texture image.
    */
    Image* Texture() const
    {
        return _texture;
    }

protected:

    /** 
    * Class Destructor. This is protected so that no one can delete a font
    * except via the font manager GlsFontMan.
    * It is not vitual because we want to avoid calling destructors on unloaded font code, 
    * and it is not needed.
    */
    GLS_EXPORT ~GlsFontBase();

    friend class GlsFontMan;

    /** Attributes of the font. */
    FontAttr_t _attr;      

    /** Proportional character attributes used when proportional character spacing is turned on. */
    AttrCont_t _charAttr;  

    /** Unique key used as a lookup key to find fonts within maps. */
    std::string _key;      

    /** Texture of all characters in the set. */
    Image* _texture;

private:

    //-----------------------------------------------------------------------
    // Prevent copies
    //-----------------------------------------------------------------------
    GlsFontBase(const GlsFontBase&);
    GlsFontBase& operator=(const GlsFontBase&);

}; // end class GlsFontBase

} // end namespace disti

#endif