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// Copyright (c) 2010-2026, Lawrence Livermore National Security, LLC. Produced
// at the Lawrence Livermore National Laboratory. All Rights reserved. See files
// LICENSE and NOTICE for details. LLNL-CODE-443271.
//
// This file is part of the GLVis visualization tool and library. For more
// information and source code availability see https://glvis.org.
//
// GLVis is free software; you can redistribute it and/or modify it under the
// terms of the BSD-3 license. We welcome feedback and contributions, see file
// CONTRIBUTING.md for details.
#ifndef GLVIS_FONT_HPP
#define GLVIS_FONT_HPP
#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_GLYPH_H
#include <string>
#include <iostream>
#include "gl/platform_gl.hpp"
class GlVisFont
{
public:
struct glyph
{
std::uint32_t w, h;
std::int32_t bear_x, bear_y;
float adv_x, adv_y;
float tex_x;
};
private:
bool init;
bool font_init;
GLenum alpha_channel;
glyph font_chars[256];
float tex_w;
float tex_h;
std::uint32_t font_tex;
FT_Library library;
FT_Face face;
bool face_has_kerning;
public:
bool LoadFont(const std::string& path, int font_index, int font_size);
const glyph &GetTexChar(char c) const
{
return font_chars[(std::uint8_t) c];
}
/// Get the width and height of the bounding box containing the rendered text
void getObjectSize(const std::string& text, int& w, int& h);
GlVisFont()
: init(false),
font_init(false),
face_has_kerning(false)
{
if (FT_Init_FreeType(&library))
{
std::cout << "GLVis: Can not initialize FreeType library!" << std::endl;
}
init = true;
}
~GlVisFont()
{
if (init)
{
FT_Done_FreeType(library);
}
}
float GetKerning(char cprev, char c)
{
if (!face_has_kerning || cprev == '\0')
{
return 0;
}
FT_UInt glyph_prev = FT_Get_Char_Index(face, cprev);
FT_UInt glyph_curr = FT_Get_Char_Index(face, c);
FT_Vector delta;
FT_Get_Kerning(face, glyph_prev, glyph_curr,
FT_KERNING_DEFAULT, &delta);
return delta.x / 64.f;
}
bool isFontLoaded() { return font_init; }
float getFontLineSpacing() const { return face->size->metrics.height/64.f; }
float getFontDescender() const { return face->size->metrics.descender/64.f; }
float getAtlasWidth() { return tex_w; }
float getAtlasHeight() { return tex_h; }
unsigned getFontTex() { return font_tex; }
void setAlphaChannel(GLenum alpha) { alpha_channel = alpha; }
};
#endif // GLVIS_FONT_HPP
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