NouVeL/ADVect/Graphics.cpp

#include "Graphics.h"

#include <iostream>

#include <locale>
#include <codecvt>

namespace {
	FT_Library library;
	FT_Error error;
	FT_Face face;
	SDL_Color colors[256];
	std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
}

namespace ADVect::Graphics {
	void Init() {
		error = FT_Init_FreeType(&library);
		if (error) {
			std::cerr << "FreeType init error: " << error << std::endl;
		}

		error = FT_New_Face(library, "SourceHanSans-Regular.ttc", 0, &face);
		if (error == FT_Err_Unknown_File_Format) {
			std::cerr << "FreeType Unknown_File_Format: " << error << std::endl;
		}
		else if (error)	{
			std::cerr << "FreeType font loading error: " << error << std::endl;
		}

		error = FT_Set_Char_Size(face, 0, 20 * 64, 72, 72);
		if (error == FT_Err_Unknown_File_Format) {
			std::cerr << "FreeType Set_Char_Size error: " << error << std::endl;
		}

		for (int i = 0; i < 256; i++)
		{
			colors[i].r = colors[i].g = colors[i].b = i;
		}
	}

	void Destroy() {
		FT_Done_Face(face);
		FT_Done_FreeType(library);
	}

	void RenderString(const std::string& s, SDL_Surface* surface, int pos_x, int pos_y) {
		std::wstring w = converter.from_bytes(s);

		FT_GlyphSlot slot = face->glyph;

		for (const auto& c : w) {
			error = FT_Load_Char(face, c, FT_LOAD_RENDER);
			if (error)
				continue;

			SDL_Surface* glyph = SDL_CreateRGBSurfaceFrom(
				slot->bitmap.buffer,
				slot->bitmap.width,
				slot->bitmap.rows,
				8,
				slot->bitmap.pitch,
				0, 0, 0, 255);

			SDL_SetPaletteColors(glyph->format->palette, colors, 0, 256);

			SDL_SetSurfaceBlendMode(glyph, SDL_BlendMode::SDL_BLENDMODE_NONE);
			SDL_Rect pos = { pos_x + slot->bitmap_left, pos_y - slot->bitmap_top, 0, 0 };
			SDL_BlitSurface(glyph, nullptr, surface, &pos);
			SDL_FreeSurface(glyph);

			pos_x += slot->advance.x >> 6;
			pos_y += slot->advance.y >> 6;
		}
	}
}