text_paint.hpp

// By Emil Ernerfeldt 2014-2016
// LICENSE:
//   This software is dual-licensed to the public domain and under the following
//   license: you are granted a perpetual, irrevocable license to copy, modify,
//   publish, and distribute this file as you see fit.
// HISTORY:
//   Created in 2014-12 for Ghostel
//   Cleaned up as separate library 2016-02

/*
Library for drawing colored, multiline strings on iOS and OSX.

Requires Foundation and CoreText on both iOS and OSX.
Requires UIKit on iOS.
Requires AppKit on OSX.
*/

#pragma once

#include <limits>
#include <string>
#include <vector>

namespace text_paint {

struct Vec2 { float x, y; };
struct RGBAf { float r, g, b, a; };

enum class TextAlign
{
    LEFT,
    CENTER,
    RIGHT
};

struct AttributeString
{
    struct ColorRange
    {
        RGBAf  color;
        size_t length_bytes; 
    };

    struct FontRange
    {
        size_t      begin, end;
        std::string font;
    };

    std::string             utf8;
    std::vector<ColorRange> colors;
    std::vector<FontRange>  fonts;

    AttributeString() {}

    explicit AttributeString(const std::string& str, RGBAf color = {1, 1, 1, 1})
    {
        append(str, color);
    }

    void append(const std::string& str, RGBAf color = {1, 1, 1, 1})
    {
        auto pre_size = utf8.size();
        utf8 += str;
        colors.push_back(ColorRange{color, utf8.size() - pre_size});
    }

    void set_font_range(size_t begin, size_t end, std::string font)
    {
        fonts.emplace_back(FontRange{begin, end, std::move(font)});
    }
};

struct TextInfo
{
    std::string font      = "Noteworthy-Light";
    float       font_size = 22;
    TextAlign   alignment = TextAlign::LEFT;

    // Use max_size.x to set a max width for wrapping the text to.
    Vec2        max_size  = {std::numeric_limits<float>::infinity(), std::numeric_limits<float>::infinity()};
};

Vec2 text_size(const TextInfo& ti, const AttributeString& str);

void draw_text(
    uint8_t* bytes, size_t width, size_t height, bool rgba,
    const Vec2& pos, const TextInfo& ti, const AttributeString& str);

bool test();

} // namespace text_paint