SharpMuPDF/mupdf/source/pdf/pdf-unicode.c

// Copyright (C) 2004-2021 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF 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 Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#include "mupdf/fitz.h"
#include "mupdf/pdf.h"

#include <string.h>

/* Load or synthesize ToUnicode map for fonts */

static void
pdf_remap_cmap_range(fz_context *ctx, pdf_cmap *ucs_from_gid,
	unsigned int cpt, unsigned int gid, unsigned int n, pdf_cmap *ucs_from_cpt)
{
	unsigned int k;
	int ucsbuf[PDF_MRANGE_CAP];
	int ucslen;

	for (k = 0; k <= n; ++k)
	{
		ucslen = pdf_lookup_cmap_full(ucs_from_cpt, cpt + k, ucsbuf);
		if (ucslen == 1)
			pdf_map_range_to_range(ctx, ucs_from_gid, gid + k, gid + k, ucsbuf[0]);
		else if (ucslen > 1)
			pdf_map_one_to_many(ctx, ucs_from_gid, gid + k, ucsbuf, ucslen);
	}
}

static pdf_cmap *
pdf_remap_cmap(fz_context *ctx, pdf_cmap *gid_from_cpt, pdf_cmap *ucs_from_cpt)
{
	pdf_cmap *ucs_from_gid;
	unsigned int a, b, x;
	int i;

	ucs_from_gid = pdf_new_cmap(ctx);

	fz_try(ctx)
	{
		if (gid_from_cpt->usecmap)
			ucs_from_gid->usecmap = pdf_remap_cmap(ctx, gid_from_cpt->usecmap, ucs_from_cpt);

		pdf_add_codespace(ctx, ucs_from_gid, 0, 0x7fffffff, 4);

		for (i = 0; i < gid_from_cpt->rlen; ++i)
		{
			a = gid_from_cpt->ranges[i].low;
			b = gid_from_cpt->ranges[i].high;
			x = gid_from_cpt->ranges[i].out;
			pdf_remap_cmap_range(ctx, ucs_from_gid, a, x, b - a, ucs_from_cpt);
		}

		for (i = 0; i < gid_from_cpt->xlen; ++i)
		{
			a = gid_from_cpt->xranges[i].low;
			b = gid_from_cpt->xranges[i].high;
			x = gid_from_cpt->xranges[i].out;
			pdf_remap_cmap_range(ctx, ucs_from_gid, a, x, b - a, ucs_from_cpt);
		}

		/* Font encoding CMaps don't have one-to-many mappings, so we can ignore the mranges. */

		pdf_sort_cmap(ctx, ucs_from_gid);
	}
	fz_catch(ctx)
	{
		pdf_drop_cmap(ctx, ucs_from_gid);
		fz_rethrow(ctx);
	}

	return ucs_from_gid;
}

void
pdf_load_to_unicode(fz_context *ctx, pdf_document *doc, pdf_font_desc *font,
	const char **strings, char *collection, pdf_obj *cmapstm)
{
	unsigned int cpt;

	if (pdf_is_stream(ctx, cmapstm))
	{
		pdf_cmap *ucs_from_cpt = pdf_load_embedded_cmap(ctx, doc, cmapstm);
		fz_try(ctx)
			font->to_unicode = pdf_remap_cmap(ctx, font->encoding, ucs_from_cpt);
		fz_always(ctx)
			pdf_drop_cmap(ctx, ucs_from_cpt);
		fz_catch(ctx)
			fz_rethrow(ctx);
		font->size += pdf_cmap_size(ctx, font->to_unicode);
	}

	else if (pdf_is_name(ctx, cmapstm))
	{
		pdf_cmap *ucs_from_cpt = pdf_load_system_cmap(ctx, pdf_to_name(ctx, cmapstm));
		fz_try(ctx)
			font->to_unicode = pdf_remap_cmap(ctx, font->encoding, ucs_from_cpt);
		fz_always(ctx)
			pdf_drop_cmap(ctx, ucs_from_cpt);
		fz_catch(ctx)
			fz_rethrow(ctx);
		font->size += pdf_cmap_size(ctx, font->to_unicode);
	}

	else if (collection)
	{
		if (!strcmp(collection, "Adobe-CNS1"))
			font->to_unicode = pdf_load_system_cmap(ctx, "Adobe-CNS1-UCS2");
		else if (!strcmp(collection, "Adobe-GB1"))
			font->to_unicode = pdf_load_system_cmap(ctx, "Adobe-GB1-UCS2");
		else if (!strcmp(collection, "Adobe-Japan1"))
			font->to_unicode = pdf_load_system_cmap(ctx, "Adobe-Japan1-UCS2");
		else if (!strcmp(collection, "Adobe-Korea1"))
			font->to_unicode = pdf_load_system_cmap(ctx, "Adobe-Korea1-UCS2");
	}

	if (strings)
	{
		/* TODO one-to-many mappings */

		font->cid_to_ucs = Memento_label(fz_malloc_array(ctx, 256, unsigned short), "cid_to_ucs");
		font->cid_to_ucs_len = 256;
		font->size += 256 * sizeof *font->cid_to_ucs;

		for (cpt = 0; cpt < 256; cpt++)
		{
			if (strings[cpt])
				font->cid_to_ucs[cpt] = fz_unicode_from_glyph_name(strings[cpt]);
			else
				font->cid_to_ucs[cpt] = FZ_REPLACEMENT_CHARACTER;
		}
	}

	if (!font->to_unicode && !font->cid_to_ucs)
	{
		/* TODO: synthesize a ToUnicode if it's a freetype font with
		 * cmap and/or post tables or if it has glyph names. */
	}
}