text_renderer.h

/********************************************************************
 * Copyright (C) 2015 Liangliang Nan <liangliang.nan@gmail.com>
 * https://3d.bk.tudelft.nl/liangliang/
 *
 * This file is part of Easy3D. If it is useful in your research/work,
 * I would be grateful if you show your appreciation by citing it:
 * ------------------------------------------------------------------
 *      Liangliang Nan.
 *      Easy3D: a lightweight, easy-to-use, and efficient C++ library
 *      for processing and rendering 3D data.
 *      Journal of Open Source Software, 6(64), 3255, 2021.
 * ------------------------------------------------------------------
 *
 * Easy3D is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 3
 * as published by the Free Software Foundation.
 *
 * Easy3D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ********************************************************************/
 
#ifndef EASY3D_RENDERER_TEXT_RENDERER_H
#define EASY3D_RENDERER_TEXT_RENDERER_H
 
#include <vector>
#include <string>
 
#include <easy3d/core/types.h>
 
 
namespace easy3d {

    class TextRenderer {
    public:
        explicit TextRenderer(float dpi_scale = 1.0f, int texture_size = 512, bool mipmaps = false);

        ~TextRenderer();

        bool add_font(const std::string &font_file);

        std::size_t num_fonts() const { return font_ids_.size(); }

        const std::vector<std::string> &font_names() const { return font_names_; }

        float draw(const std::string &text, float x, float y, float font_size,
                   int font_id = 0, const vec3 &font_color = vec3(0, 0, 0), bool upper_left = true
        ) const;
 
 
        // -------------------------------------------------------------------------------------------------------------
        // Multi-line text rendering

        enum Align {
            ALIGN_LEFT,     
            ALIGN_RIGHT,    
            ALIGN_CENTER    
        };

        Rect draw(const std::string &text, float x, float y, float font_size, Align align/* = ALIGN_LEFT*/,
                  int font_id = 0, const vec3 &font_color = vec3(0, 0, 0),
                  float line_spacing = 0.0f, bool upper_left = true
        ) const;
 
        // -------------------------------------------------------------------------------------------------------------

        void set_character_spacing(float spacing);

        float character_spacing() const;

        void set_kerning(bool kerning);

        bool kerning() const;

        float font_height(float font_size) const;

        float string_width(const std::string& str, float font_size) const;
        
        float string_height(const std::string& str, float font_size) const;
        
        Rect string_bounding_rect(const std::string& str, float x, float y, float font_size) const;
 
    private:
 
        void flush_draw(const vec3 &font_color) const;
 
        //if the text has newlines, it will be treated as if was called into drawing multiple lines
        Rect _get_bbox(const std::string &text, float size, float x, float y, Align align, float line_spacing) const;
 
    private:
        int texture_size_;
        void *stash_;
        std::vector<int> font_ids_;
        std::vector<std::string> font_names_;
    };
 
}
 
#endif  // EASY3D_RENDERER_TEXT_RENDERER_H