BackendFontFreeType.hpp

//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2025 Bruno Van de Velde (vdv_b@tgui.eu)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
 
#ifndef TGUI_BACKEND_FONT_FREETYPE_HPP
#define TGUI_BACKEND_FONT_FREETYPE_HPP
 
#include <TGUI/Config.hpp>
#include <TGUI/Backend/Font/BackendFont.hpp>
 
#include <unordered_map>

 
using FT_Library = struct FT_LibraryRec_*;
using FT_Face = struct FT_FaceRec_*;
using FT_Stroker = struct FT_StrokerRec_*;

 
namespace tgui
{
    class TGUI_API BackendFontFreeType : public BackendFont
    {
    public:

        ~BackendFontFreeType() override;

        bool loadFromMemory(std::unique_ptr<std::uint8_t[]> data, std::size_t sizeInBytes) override;
        using BackendFont::loadFromMemory;

        TGUI_NODISCARD bool hasGlyph(char32_t codePoint) const override;

        TGUI_NODISCARD FontGlyph getGlyph(char32_t codePoint, unsigned int characterSize, bool bold, float outlineThickness = 0) override;

        TGUI_NODISCARD float getKerning(char32_t first, char32_t second, unsigned int characterSize, bool bold) override;

        TGUI_NODISCARD float getLineSpacing(unsigned int characterSize) override;

        TGUI_NODISCARD float getFontHeight(unsigned int characterSize) override;

        TGUI_NODISCARD float getAscent(unsigned int characterSize) override;

        TGUI_NODISCARD float getDescent(unsigned int characterSize) override;

        TGUI_NODISCARD float getUnderlinePosition(unsigned int characterSize) override;

        TGUI_NODISCARD float getUnderlineThickness(unsigned int characterSize) override;

        TGUI_NODISCARD std::shared_ptr<BackendTexture> getTexture(unsigned int characterSize, unsigned int& textureVersion) override;

        TGUI_NODISCARD Vector2u getTextureSize(unsigned int characterSize) override;

        void setSmooth(bool smooth) override;

        void setFontScale(float scale) override;

    protected:
 
        struct Glyph
        {
            float     advance = 0;   
            float     lsbDelta = 0;  
            float     rsbDelta = 0;  
            FloatRect bounds;        
            UIntRect  textureRect;   
        };

        // Loads a glyph with freetype
        TGUI_NODISCARD Glyph loadGlyph(char32_t codePoint, unsigned int characterSize, bool bold, float outlineThickness);

        // Returns a cached glyph or calls loadGlyph to load it when this is the first time the glyph is requested
        TGUI_NODISCARD Glyph getInternalGlyph(char32_t codePoint, unsigned int characterSize, bool bold, float outlineThickness);

        // Reserves space in the texture to place the glyph
        TGUI_NODISCARD UIntRect findAvailableGlyphRect(unsigned int width, unsigned int height);

        // Sets the character size on which the freetype operations are performed
        bool setCurrentSize(unsigned int characterSize);

        // Destroys freetype resources
        void cleanup();

    protected:
 
        struct Row
        {
            Row(unsigned int rowTop, unsigned int rowHeight) : width(0), top(rowTop), height(rowHeight) {}
 
            unsigned int width;  
            unsigned int top;    
            unsigned int height; 
        };
 
        FT_Library  m_library = nullptr;  // Handle to the freetype library
        FT_Face     m_face    = nullptr;  // Contains the font (typeface and style)
        FT_Stroker  m_stroker = nullptr;  // Used for rendering outlines
 
        std::unordered_map<unsigned int, float> m_cachedLineSpacing;
        std::unordered_map<unsigned int, float> m_cachedFontHeights;
        std::unordered_map<unsigned int, float> m_cachedAscents;
        std::unordered_map<unsigned int, float> m_cachedDescents;
 
        std::unordered_map<std::uint64_t, Glyph> m_glyphs;
        unsigned int     m_nextRow = 3; 
        std::vector<Row> m_rows;
 
        std::unique_ptr<std::uint8_t[]> m_fileContents;
        std::unique_ptr<std::uint8_t[]> m_pixels;
        std::shared_ptr<BackendTexture> m_texture;
        unsigned int m_textureSize = 0;
        unsigned int m_textureVersion = 0;
    };

 
    using BackendFontFreetype TGUI_DEPRECATED("Use BackendFontFreeType instead (capital T)") = BackendFontFreeType;
}

 
#endif // TGUI_BACKEND_FONT_FREETYPE_HPP