BackendFontFreeType.hpp

 
//
// TGUI - Texus' Graphical User Interface
// Copyright (C) 2012-2023 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>
#if TGUI_BUILD_AS_CXX_MODULE
 import tgui;
#else
 #include <TGUI/Backend/Font/BackendFont.hpp>
#endif
 
#if !TGUI_EXPERIMENTAL_USE_STD_MODULE
 #include <unordered_map>
#endif
 
 
using FT_Library = struct FT_LibraryRec_*;
using FT_Face = struct FT_FaceRec_*;
using FT_Stroker = struct FT_StrokerRec_*;
 
 
TGUI_MODULE_EXPORT namespace tgui
{
 class 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;
 };
 
}
 
 
#endif // TGUI_BACKEND_FONT_FREETYPE_HPP