SharpMuPDF/mupdf/source/xps/xps-glyphs.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 "xps-imp.h"

#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_ADVANCES_H

static inline int ishex(int a)
{
	return (a >= 'A' && a <= 'F') ||
		(a >= 'a' && a <= 'f') ||
		(a >= '0' && a <= '9');
}

static inline int unhex(int a)
{
	if (a >= 'A' && a <= 'F') return a - 'A' + 0xA;
	if (a >= 'a' && a <= 'f') return a - 'a' + 0xA;
	if (a >= '0' && a <= '9') return a - '0';
	return 0;
}

int
xps_count_font_encodings(fz_context *ctx, fz_font *font)
{
	FT_Face face = fz_font_ft_face(ctx, font);
	return face->num_charmaps;
}

void
xps_identify_font_encoding(fz_context *ctx, fz_font *font, int idx, int *pid, int *eid)
{
	FT_Face face = fz_font_ft_face(ctx, font);
	*pid = face->charmaps[idx]->platform_id;
	*eid = face->charmaps[idx]->encoding_id;
}

void
xps_select_font_encoding(fz_context *ctx, fz_font *font, int idx)
{
	FT_Face face = fz_font_ft_face(ctx, font);
	fz_ft_lock(ctx);
	FT_Set_Charmap(face, face->charmaps[idx]);
	fz_ft_unlock(ctx);
}

int
xps_encode_font_char(fz_context *ctx, fz_font *font, int code)
{
	FT_Face face = fz_font_ft_face(ctx, font);
	int gid;
	fz_ft_lock(ctx);
	gid = FT_Get_Char_Index(face, code);
	if (gid == 0 && face->charmap && face->charmap->platform_id == 3 && face->charmap->encoding_id == 0)
		gid = FT_Get_Char_Index(face, 0xF000 | code);
	fz_ft_unlock(ctx);
	return gid;
}

void
xps_measure_font_glyph(fz_context *ctx, xps_document *doc, fz_font *font, int gid, xps_glyph_metrics *mtx)
{
	int mask = FT_LOAD_NO_SCALE | FT_LOAD_IGNORE_TRANSFORM;
	FT_Face face = fz_font_ft_face(ctx, font);
	FT_Fixed hadv = 0, vadv = 0;

	fz_ft_lock(ctx);
	FT_Get_Advance(face, gid, mask, &hadv);
	FT_Get_Advance(face, gid, mask | FT_LOAD_VERTICAL_LAYOUT, &vadv);
	fz_ft_unlock(ctx);

	mtx->hadv = (float) hadv / face->units_per_EM;
	mtx->vadv = (float) vadv / face->units_per_EM;
	mtx->vorg = (float) face->ascender / face->units_per_EM;
}

static fz_font *
xps_lookup_font_imp(fz_context *ctx, xps_document *doc, char *name)
{
	xps_font_cache *cache;
	for (cache = doc->font_table; cache; cache = cache->next)
		if (!xps_strcasecmp(cache->name, name))
			return fz_keep_font(ctx, cache->font);
	return NULL;
}

static void
xps_insert_font(fz_context *ctx, xps_document *doc, char *name, fz_font *font)
{
	xps_font_cache *cache = fz_malloc_struct(ctx, xps_font_cache);
	cache->font = NULL;
	cache->name = NULL;

	fz_try(ctx)
	{
		cache->font = fz_keep_font(ctx, font);
		cache->name = fz_strdup(ctx, name);
		cache->next = doc->font_table;
	}
	fz_catch(ctx)
	{
		fz_drop_font(ctx, cache->font);
		fz_free(ctx, cache->name);
		fz_free(ctx, cache);
		fz_rethrow(ctx);
	}

	doc->font_table = cache;
}

/*
 * Some fonts in XPS are obfuscated by XOR:ing the first 32 bytes of the
 * data with the GUID in the fontname.
 */
static void
xps_deobfuscate_font_resource(fz_context *ctx, xps_document *doc, xps_part *part)
{
	unsigned char buf[33];
	unsigned char key[16];
	unsigned char *data;
	size_t size;
	char *p;
	int i;

	size = fz_buffer_storage(ctx, part->data, &data);
	if (size < 32)
	{
		fz_warn(ctx, "insufficient data for font deobfuscation");
		return;
	}

	p = strrchr(part->name, '/');
	if (!p)
		p = part->name;

	for (i = 0; i < 32 && *p; p++)
	{
		if (ishex(*p))
			buf[i++] = *p;
	}
	buf[i] = 0;

	if (i != 32)
	{
		fz_warn(ctx, "cannot extract GUID from obfuscated font part name");
		return;
	}

	for (i = 0; i < 16; i++)
		key[i] = unhex(buf[i*2+0]) * 16 + unhex(buf[i*2+1]);

	for (i = 0; i < 16; i++)
	{
		data[i] ^= key[15-i];
		data[i+16] ^= key[15-i];
	}
}

static void
xps_select_best_font_encoding(fz_context *ctx, xps_document *doc, fz_font *font)
{
	static struct { int pid, eid; } xps_cmap_list[] =
	{
		{ 3, 10 },		/* Unicode with surrogates */
		{ 3, 1 },		/* Unicode without surrogates */
		{ 3, 5 },		/* Wansung */
		{ 3, 4 },		/* Big5 */
		{ 3, 3 },		/* Prc */
		{ 3, 2 },		/* ShiftJis */
		{ 3, 0 },		/* Symbol */
		{ 1, 0 },
		{ -1, -1 },
	};

	int i, k, n, pid, eid;

	n = xps_count_font_encodings(ctx, font);
	for (k = 0; xps_cmap_list[k].pid != -1; k++)
	{
		for (i = 0; i < n; i++)
		{
			xps_identify_font_encoding(ctx, font, i, &pid, &eid);
			if (pid == xps_cmap_list[k].pid && eid == xps_cmap_list[k].eid)
			{
				xps_select_font_encoding(ctx, font, i);
				return;
			}
		}
	}

	fz_warn(ctx, "cannot find a suitable cmap");
}

fz_font *
xps_lookup_font(fz_context *ctx, xps_document *doc, char *base_uri, char *font_uri, char *style_att)
{
	char partname[1024];
	char fakename[1024];
	char *subfont;
	int subfontid = 0;
	xps_part *part;
	fz_font *font;

	xps_resolve_url(ctx, doc, partname, base_uri, font_uri, sizeof partname);
	subfont = strrchr(partname, '#');
	if (subfont)
	{
		subfontid = atoi(subfont + 1);
		*subfont = 0;
	}

	/* Make a new part name for font with style simulation applied */
	fz_strlcpy(fakename, partname, sizeof fakename);
	if (style_att)
	{
		if (!strcmp(style_att, "BoldSimulation"))
			fz_strlcat(fakename, "#Bold", sizeof fakename);
		else if (!strcmp(style_att, "ItalicSimulation"))
			fz_strlcat(fakename, "#Italic", sizeof fakename);
		else if (!strcmp(style_att, "BoldItalicSimulation"))
			fz_strlcat(fakename, "#BoldItalic", sizeof fakename);
	}

	font = xps_lookup_font_imp(ctx, doc, fakename);
	if (!font)
	{
		fz_buffer *buf = NULL;
		fz_var(buf);

		fz_try(ctx)
		{
			part = xps_read_part(ctx, doc, partname);
		}
		fz_catch(ctx)
		{
			if (fz_caught(ctx) == FZ_ERROR_TRYLATER)
			{
				if (doc->cookie)
				{
					doc->cookie->incomplete = 1;
					fz_ignore_error(ctx);
				}
				else
					fz_rethrow(ctx);
			}
			else
			{
				fz_rethrow_if(ctx, FZ_ERROR_SYSTEM);
				fz_report_error(ctx);
				fz_warn(ctx, "cannot find font resource part '%s'", partname);
			}
			return NULL;
		}

		/* deobfuscate if necessary */
		if (strstr(part->name, ".odttf"))
			xps_deobfuscate_font_resource(ctx, doc, part);
		if (strstr(part->name, ".ODTTF"))
			xps_deobfuscate_font_resource(ctx, doc, part);

		fz_var(font);
		fz_try(ctx)
		{
			font = fz_new_font_from_buffer(ctx, NULL, part->data, subfontid, 1);
			xps_select_best_font_encoding(ctx, doc, font);
			xps_insert_font(ctx, doc, fakename, font);
		}
		fz_always(ctx)
		{
			xps_drop_part(ctx, doc, part);
		}
		fz_catch(ctx)
		{
			fz_drop_font(ctx, font);
			fz_warn(ctx, "cannot load font resource '%s'", partname);
			return NULL;
		}

		if (style_att)
		{
			fz_font_flags_t *flags = fz_font_flags(font);
			int bold = !!strstr(style_att, "Bold");
			int italic = !!strstr(style_att, "Italic");
			flags->fake_bold = bold;
			flags->is_bold = bold;
			flags->fake_italic = italic;
			flags->is_italic = italic;
		}
	}
	return font;
}

/*
 * Parse and draw an XPS <Glyphs> element.
 *
 * Indices syntax:

 GlyphIndices	= GlyphMapping ( ";" GlyphMapping )
 GlyphMapping	= ( [ClusterMapping] GlyphIndex ) [GlyphMetrics]
 ClusterMapping = "(" ClusterCodeUnitCount [":" ClusterGlyphCount] ")"
 ClusterCodeUnitCount	= * DIGIT
 ClusterGlyphCount		= * DIGIT
 GlyphIndex		= * DIGIT
 GlyphMetrics	= "," AdvanceWidth ["," uOffset ["," vOffset]]
 AdvanceWidth	= ["+"] RealNum
 uOffset		= ["+" | "-"] RealNum
 vOffset		= ["+" | "-"] RealNum
 RealNum		= ((DIGIT ["." DIGIT]) | ("." DIGIT)) [Exponent]
 Exponent		= ( ("E"|"e") ("+"|"-") DIGIT )

 */

static char *
xps_parse_digits(char *s, int *digit)
{
	*digit = 0;
	while (*s >= '0' && *s <= '9')
	{
		*digit = *digit * 10 + (*s - '0');
		s ++;
	}
	return s;
}

static char *
xps_parse_real_num(char *s, float *number, int *override)
{
	char *tail;
	float v;
	v = fz_strtof(s, &tail);
	*override = tail != s;
	if (*override)
		*number = v;
	return tail;
}

static char *
xps_parse_cluster_mapping(char *s, int *code_count, int *glyph_count)
{
	if (*s == '(')
		s = xps_parse_digits(s + 1, code_count);
	if (*s == ':')
		s = xps_parse_digits(s + 1, glyph_count);
	if (*s == ')')
		s ++;
	return s;
}

static char *
xps_parse_glyph_index(char *s, int *glyph_index)
{
	if (*s >= '0' && *s <= '9')
		s = xps_parse_digits(s, glyph_index);
	return s;
}

static char *
xps_parse_glyph_metrics(char *s, float *advance, float *uofs, float *vofs, int bidi_level)
{
	int override;
	if (*s == ',')
	{
		s = xps_parse_real_num(s + 1, advance, &override);
		if (override && (bidi_level & 1))
			*advance = -*advance;
	}
	if (*s == ',')
		s = xps_parse_real_num(s + 1, uofs, &override);
	if (*s == ',')
		s = xps_parse_real_num(s + 1, vofs, &override);
	return s;
}

fz_text *
xps_parse_glyphs_imp(fz_context *ctx, xps_document *doc, fz_matrix ctm,
	fz_font *font, float size, float originx, float originy,
	int is_sideways, int bidi_level,
	char *indices, char *unicode)
{
	xps_glyph_metrics mtx;
	fz_text *text;
	fz_matrix tm;
	float x = originx;
	float y = originy;
	char *us = unicode;
	char *is = indices;
	size_t un = 0;

	if (!unicode && !indices)
		fz_warn(ctx, "glyphs element with neither characters nor indices");

	if (us)
	{
		if (us[0] == '{' && us[1] == '}')
			us = us + 2;
		un = strlen(us);
	}

	if (is_sideways)
		tm = fz_pre_scale(fz_rotate(90), -size, size);
	else
		tm = fz_scale(size, -size);

	text = fz_new_text(ctx);

	fz_try(ctx)
	{
		while ((us && un > 0) || (is && *is))
		{
			int char_code = FZ_REPLACEMENT_CHARACTER;
			int code_count = 1;
			int glyph_count = 1;

			if (is && *is)
			{
				is = xps_parse_cluster_mapping(is, &code_count, &glyph_count);
			}

			if (code_count < 1)
				code_count = 1;
			if (glyph_count < 1)
				glyph_count = 1;

			/* TODO: add code chars with cluster mappings for text extraction */

			while (code_count--)
			{
				if (us && un > 0)
				{
					int t = fz_chartorune(&char_code, us);
					us += t; un -= t;
				}
			}

			while (glyph_count--)
			{
				int glyph_index = -1;
				float u_offset = 0;
				float v_offset = 0;
				float advance;
				int dir;

				if (is && *is)
					is = xps_parse_glyph_index(is, &glyph_index);

				if (glyph_index == -1)
					glyph_index = xps_encode_font_char(ctx, font, char_code);

				xps_measure_font_glyph(ctx, doc, font, glyph_index, &mtx);
				if (is_sideways)
					advance = mtx.vadv * 100;
				else if (bidi_level & 1)
					advance = -mtx.hadv * 100;
				else
					advance = mtx.hadv * 100;

				if (fz_font_flags(font)->fake_bold)
					advance *= 1.02f;

				if (is && *is)
				{
					is = xps_parse_glyph_metrics(is, &advance, &u_offset, &v_offset, bidi_level);
					if (*is == ';')
						is ++;
				}

				if (bidi_level & 1)
					u_offset = -mtx.hadv * 100 - u_offset;

				u_offset = u_offset * 0.01f * size;
				v_offset = v_offset * 0.01f * size;

				if (is_sideways)
				{
					tm.e = x + u_offset + (mtx.vorg * size);
					tm.f = y - v_offset + (mtx.hadv * 0.5f * size);
				}
				else
				{
					tm.e = x + u_offset;
					tm.f = y - v_offset;
				}

				dir = bidi_level & 1 ? FZ_BIDI_RTL : FZ_BIDI_LTR;
				fz_show_glyph(ctx, text, font, tm, glyph_index, char_code, is_sideways, bidi_level, dir, FZ_LANG_UNSET);

				x += advance * 0.01f * size;
			}
		}
	}
	fz_catch(ctx)
	{
		fz_drop_text(ctx, text);
		fz_rethrow(ctx);
	}

	return text;
}

void
xps_parse_glyphs(fz_context *ctx, xps_document *doc, fz_matrix ctm,
		char *base_uri, xps_resource *dict, fz_xml *root)
{
	fz_device *dev = doc->dev;

	fz_xml *node;

	char *fill_uri;
	char *opacity_mask_uri;

	char *bidi_level_att;
	char *fill_att;
	char *font_size_att;
	char *font_uri_att;
	char *origin_x_att;
	char *origin_y_att;
	char *is_sideways_att;
	char *indices_att;
	char *unicode_att;
	char *style_att;
	char *transform_att;
	char *clip_att;
	char *opacity_att;
	char *opacity_mask_att;

	fz_xml *transform_tag = NULL;
	fz_xml *clip_tag = NULL;
	fz_xml *fill_tag = NULL;
	fz_xml *opacity_mask_tag = NULL;

	char *fill_opacity_att = NULL;

	fz_font *font;

	float font_size = 10;
	int is_sideways = 0;
	int bidi_level = 0;

	fz_text *text = NULL;
	fz_rect area;

	/*
	 * Extract attributes and extended attributes.
	 */

	bidi_level_att = fz_xml_att(root, "BidiLevel");
	fill_att = fz_xml_att(root, "Fill");
	font_size_att = fz_xml_att(root, "FontRenderingEmSize");
	font_uri_att = fz_xml_att(root, "FontUri");
	origin_x_att = fz_xml_att(root, "OriginX");
	origin_y_att = fz_xml_att(root, "OriginY");
	is_sideways_att = fz_xml_att(root, "IsSideways");
	indices_att = fz_xml_att(root, "Indices");
	unicode_att = fz_xml_att(root, "UnicodeString");
	style_att = fz_xml_att(root, "StyleSimulations");
	transform_att = fz_xml_att(root, "RenderTransform");
	clip_att = fz_xml_att(root, "Clip");
	opacity_att = fz_xml_att(root, "Opacity");
	opacity_mask_att = fz_xml_att(root, "OpacityMask");

	for (node = fz_xml_down(root); node; node = fz_xml_next(node))
	{
		if (fz_xml_is_tag(node, "Glyphs.RenderTransform"))
			transform_tag = fz_xml_down(node);
		if (fz_xml_is_tag(node, "Glyphs.OpacityMask"))
			opacity_mask_tag = fz_xml_down(node);
		if (fz_xml_is_tag(node, "Glyphs.Clip"))
			clip_tag = fz_xml_down(node);
		if (fz_xml_is_tag(node, "Glyphs.Fill"))
			fill_tag = fz_xml_down(node);
	}

	fill_uri = base_uri;
	opacity_mask_uri = base_uri;

	xps_resolve_resource_reference(ctx, doc, dict, &transform_att, &transform_tag, NULL);
	xps_resolve_resource_reference(ctx, doc, dict, &clip_att, &clip_tag, NULL);
	xps_resolve_resource_reference(ctx, doc, dict, &fill_att, &fill_tag, &fill_uri);
	xps_resolve_resource_reference(ctx, doc, dict, &opacity_mask_att, &opacity_mask_tag, &opacity_mask_uri);

	/*
	 * Check that we have all the necessary information.
	 */

	if (!font_size_att || !font_uri_att || !origin_x_att || !origin_y_att) {
		fz_warn(ctx, "missing attributes in glyphs element");
		return;
	}

	if (!indices_att && !unicode_att)
		return; /* nothing to draw */

	if (is_sideways_att)
		is_sideways = !strcmp(is_sideways_att, "true");

	if (bidi_level_att)
		bidi_level = atoi(bidi_level_att);

	/*
	 * Find and load the font resource.
	 */

	font = xps_lookup_font(ctx, doc, base_uri, font_uri_att, style_att);
	if (!font)
		font = fz_new_base14_font(ctx, "Times-Roman");

	fz_var(text);

	fz_try(ctx)
	{
		/*
		 * Set up graphics state.
		 */

		ctm = xps_parse_transform(ctx, doc, transform_att, transform_tag, ctm);

		if (clip_att || clip_tag)
			xps_clip(ctx, doc, ctm, dict, clip_att, clip_tag);

		font_size = fz_atof(font_size_att);

		text = xps_parse_glyphs_imp(ctx, doc, ctm, font, font_size,
				fz_atof(origin_x_att), fz_atof(origin_y_att),
				is_sideways, bidi_level, indices_att, unicode_att);

		area = fz_bound_text(ctx, text, NULL, ctm);

		xps_begin_opacity(ctx, doc, ctm, area, opacity_mask_uri, dict, opacity_att, opacity_mask_tag);

		/* If it's a solid color brush fill/stroke do a simple fill */

		if (fz_xml_is_tag(fill_tag, "SolidColorBrush"))
		{
			fill_opacity_att = fz_xml_att(fill_tag, "Opacity");
			fill_att = fz_xml_att(fill_tag, "Color");
			fill_tag = NULL;
		}

		if (fill_att)
		{
			float samples[FZ_MAX_COLORS];
			fz_colorspace *colorspace;

			xps_parse_color(ctx, doc, base_uri, fill_att, &colorspace, samples);
			if (fill_opacity_att)
				samples[0] *= fz_atof(fill_opacity_att);
			xps_set_color(ctx, doc, colorspace, samples);

			fz_fill_text(ctx, dev, text, ctm, doc->colorspace, doc->color, doc->alpha, fz_default_color_params);
		}

		/* If it's a complex brush, use the charpath as a clip mask */

		if (fill_tag)
		{
			fz_clip_text(ctx, dev, text, ctm, area);
			xps_parse_brush(ctx, doc, ctm, area, fill_uri, dict, fill_tag);
			fz_pop_clip(ctx, dev);
		}

		xps_end_opacity(ctx, doc, opacity_mask_uri, dict, opacity_att, opacity_mask_tag);

		if (clip_att || clip_tag)
			fz_pop_clip(ctx, dev);
	}
	fz_always(ctx)
	{
		fz_drop_text(ctx, text);
		fz_drop_font(ctx, font);
	}
	fz_catch(ctx)
		fz_rethrow(ctx);
}