koreader/ft.c

/*
    KindlePDFViewer: FreeType font rastering for UI
    Copyright (C) 2011 Hans-Werner Hilse <hilse@web.de>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program 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/>.
*/
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <ft2build.h>
#include FT_FREETYPE_H
#include "blitbuffer.h"

/* for font access: */
#include <fitz/fitz.h>
#include <pdf/mupdf.h>

#include "ft.h"

FT_Library freetypelib;

static int newFace(lua_State *L) {
	const char *filename = luaL_checkstring(L, 1);
	int pxsize = luaL_optint(L, 2, 16*64);

	FT_Face *face = (FT_Face*) lua_newuserdata(L, sizeof(FT_Face));
	luaL_getmetatable(L, "ft_face");
	lua_setmetatable(L, -2);

	FT_Error error = FT_New_Face(freetypelib, filename, 0, face);
	if(error) {
		return luaL_error(L, "freetype error");
	}

	error = FT_Set_Pixel_Sizes(*face, 0, pxsize);
	if(error) {
		error = FT_Done_Face(*face);
		return luaL_error(L, "freetype error");
	}

	if((*face)->charmap == NULL) {
		//TODO
		//fprintf(stderr, "no unicode charmap found, to be implemented.\n");
	}
	return 1;
}

static int newBuiltinFace(lua_State *L) {
	const char *fontname = luaL_checkstring(L, 1);
	int pxsize = luaL_optint(L, 2, 16*64);

	unsigned int size;
	const char *fontdata = pdf_find_builtin_font(fontname, &size);
	if(fontdata == NULL) {
		return luaL_error(L, "no such built-in font");
	}

	FT_Face *face = (FT_Face*) lua_newuserdata(L, sizeof(FT_Face));
	luaL_getmetatable(L, "ft_face");
	lua_setmetatable(L, -2);

	FT_Error error = FT_New_Memory_Face(freetypelib, (FT_Byte*)fontdata, size, 0, face);
	if(error) {
		return luaL_error(L, "freetype error");
	}

	error = FT_Set_Pixel_Sizes(*face, 0, pxsize);
	if(error) {
		error = FT_Done_Face(*face);
		return luaL_error(L, "freetype error");
	}

	if((*face)->charmap == NULL) {
		//TODO
		//fprintf(stderr, "no unicode charmap found, to be implemented.\n");
	}
	return 1;
}


static int renderGlyph(lua_State *L) {
	FT_Face *face = (FT_Face*) luaL_checkudata(L, 1, "ft_face");
	int ch = luaL_checkint(L, 2);
	FT_Error error = FT_Load_Char(*face, ch, FT_LOAD_RENDER);
	if(error) {
		return luaL_error(L, "freetype error");
	}

	int w = ((*face)->glyph->bitmap.width + 1) & -2; // 2px steps
	int h = (*face)->glyph->bitmap.rows;

	lua_newtable(L);

	BlitBuffer *bb = (BlitBuffer*) lua_newuserdata(L, sizeof(BlitBuffer) + (w * h / 2) - 1);
	luaL_getmetatable(L, "blitbuffer");
	lua_setmetatable(L, -2);

	lua_setfield(L, -2, "bb");

	bb->w = w;
	bb->h = h;

	uint8_t *dst = bb->data;
	int y;
	int x;
	w = (*face)->glyph->bitmap.width;
	for(y = 0; y < h; y++) {
		uint8_t *src = (*face)->glyph->bitmap.buffer + y * (*face)->glyph->bitmap.pitch;
		for(x = 0; x < w; x+=2) {
			*dst = *src & 0xF0;
			src++;
			if(x+1 < w) {
				*dst |= (*src & 0xF0) >> 4;
				src++;
			}
			dst++;
		}
	}

	lua_pushinteger(L, (*face)->glyph->bitmap_left);
	lua_setfield(L, -2, "l");
	lua_pushinteger(L, (*face)->glyph->bitmap_top);
	lua_setfield(L, -2, "t");
	lua_pushinteger(L, (*face)->glyph->advance.x >> 6);
	lua_setfield(L, -2, "ax");

	return 1;
}

static int doneFace(lua_State *L) {
	FT_Face *face = (FT_Face*) luaL_checkudata(L, 1, "ft_face");
	FT_Error error = FT_Done_Face(*face);
	if(error) {
		return luaL_error(L, "freetype error when freeing face");
	}
	return 0;
}

static const struct luaL_reg ft_face_meth[] = {
	{"renderGlyph", renderGlyph},
	{"done", doneFace},
	{NULL, NULL}
};

static const struct luaL_reg ft_func[] = {
	{"newFace", newFace},
	{"newBuiltinFace", newBuiltinFace},
	{NULL, NULL}
};

int luaopen_ft(lua_State *L) {
	int error = FT_Init_FreeType(&freetypelib);
	if(error) {
		return luaL_error(L, "freetype error on initialization");
	}

	luaL_newmetatable(L, "ft_face");
	lua_pushstring(L, "__index");
	lua_pushvalue(L, -2);
	lua_settable(L, -3);
	luaL_register(L, NULL, ft_face_meth);

	luaL_register(L, "freetype", ft_func);
	return 1;
}