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harfbuzz/src/hb-ot-glyf-table.hh

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/*
* Copyright © 2015 Google, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_OT_GLYF_TABLE_HH
#define HB_OT_GLYF_TABLE_HH
#include "hb-open-type.hh"
#include "hb-ot-head-table.hh"
#include "hb-subset-glyf.hh"
namespace OT {
/*
* loca -- Index to Location
* https://docs.microsoft.com/en-us/typography/opentype/spec/loca
*/
#define HB_OT_TAG_loca HB_TAG('l','o','c','a')
struct loca
{
friend struct glyf;
static constexpr hb_tag_t tableTag = HB_OT_TAG_loca;
bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
{
TRACE_SANITIZE (this);
return_trace (true);
}
protected:
UnsizedArrayOf<HBUINT8> dataZ; /* Location data. */
public:
DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always
* check the size externally, allow Null() object of it by
* defining it MIN() instead. */
};
/*
* glyf -- TrueType Glyph Data
* https://docs.microsoft.com/en-us/typography/opentype/spec/glyf
*/
#define HB_OT_TAG_glyf HB_TAG('g','l','y','f')
struct glyf
{
static constexpr hb_tag_t tableTag = HB_OT_TAG_glyf;
bool sanitize (hb_sanitize_context_t *c HB_UNUSED) const
{
TRACE_SANITIZE (this);
/* We don't check for anything specific here. The users of the
* struct do all the hard work... */
return_trace (true);
}
bool subset (hb_subset_plan_t *plan) const
{
hb_blob_t *glyf_prime = nullptr;
hb_blob_t *loca_prime = nullptr;
bool success = true;
bool use_short_loca = false;
if (hb_subset_glyf_and_loca (plan, &use_short_loca, &glyf_prime, &loca_prime)) {
success = success && plan->add_table (HB_OT_TAG_glyf, glyf_prime);
success = success && plan->add_table (HB_OT_TAG_loca, loca_prime);
success = success && _add_head_and_set_loca_version (plan, use_short_loca);
} else {
success = false;
}
hb_blob_destroy (loca_prime);
hb_blob_destroy (glyf_prime);
return success;
}
static bool
_add_head_and_set_loca_version (hb_subset_plan_t *plan, bool use_short_loca)
{
hb_blob_t *head_blob = hb_sanitize_context_t ().reference_table<head> (plan->source);
hb_blob_t *head_prime_blob = hb_blob_copy_writable_or_fail (head_blob);
hb_blob_destroy (head_blob);
if (unlikely (!head_prime_blob))
return false;
head *head_prime = (head *) hb_blob_get_data_writable (head_prime_blob, nullptr);
head_prime->indexToLocFormat.set (use_short_loca ? 0 : 1);
bool success = plan->add_table (HB_OT_TAG_head, head_prime_blob);
hb_blob_destroy (head_prime_blob);
return success;
}
struct GlyphHeader
{
HBINT16 numberOfContours; /* If the number of contours is
* greater than or equal to zero,
* this is a simple glyph; if negative,
* this is a composite glyph. */
FWORD xMin; /* Minimum x for coordinate data. */
FWORD yMin; /* Minimum y for coordinate data. */
FWORD xMax; /* Maximum x for coordinate data. */
FWORD yMax; /* Maximum y for coordinate data. */
DEFINE_SIZE_STATIC (10);
};
struct CompositeGlyphHeader
{
enum composite_glyph_flag_t {
ARG_1_AND_2_ARE_WORDS = 0x0001,
ARGS_ARE_XY_VALUES = 0x0002,
ROUND_XY_TO_GRID = 0x0004,
WE_HAVE_A_SCALE = 0x0008,
MORE_COMPONENTS = 0x0020,
WE_HAVE_AN_X_AND_Y_SCALE = 0x0040,
WE_HAVE_A_TWO_BY_TWO = 0x0080,
WE_HAVE_INSTRUCTIONS = 0x0100,
USE_MY_METRICS = 0x0200,
OVERLAP_COMPOUND = 0x0400,
SCALED_COMPONENT_OFFSET = 0x0800,
UNSCALED_COMPONENT_OFFSET = 0x1000
};
HBUINT16 flags;
GlyphID glyphIndex;
unsigned int get_size () const
{
unsigned int size = min_size;
// arg1 and 2 are int16
if (flags & ARG_1_AND_2_ARE_WORDS) size += 4;
// arg1 and 2 are int8
else size += 2;
// One x 16 bit (scale)
if (flags & WE_HAVE_A_SCALE) size += 2;
// Two x 16 bit (xscale, yscale)
else if (flags & WE_HAVE_AN_X_AND_Y_SCALE) size += 4;
// Four x 16 bit (xscale, scale01, scale10, yscale)
else if (flags & WE_HAVE_A_TWO_BY_TWO) size += 8;
return size;
}
struct Iterator
{
const char *glyph_start;
const char *glyph_end;
const CompositeGlyphHeader *current;
bool move_to_next ()
{
if (current->flags & CompositeGlyphHeader::MORE_COMPONENTS)
{
const CompositeGlyphHeader *possible =
&StructAfter<CompositeGlyphHeader, CompositeGlyphHeader> (*current);
if (!in_range (possible))
return false;
current = possible;
return true;
}
return false;
}
bool in_range (const CompositeGlyphHeader *composite) const
{
return (const char *) composite >= glyph_start
&& ((const char *) composite + CompositeGlyphHeader::min_size) <= glyph_end
&& ((const char *) composite + composite->get_size ()) <= glyph_end;
}
};
static bool get_iterator (const char * glyph_data,
unsigned int length,
CompositeGlyphHeader::Iterator *iterator /* OUT */)
{
if (length < GlyphHeader::static_size)
return false; /* Empty glyph; zero extents. */
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph_data, 0);
if (glyph_header.numberOfContours < 0)
{
const CompositeGlyphHeader *possible =
&StructAfter<CompositeGlyphHeader, GlyphHeader> (glyph_header);
iterator->glyph_start = glyph_data;
iterator->glyph_end = (const char *) glyph_data + length;
if (!iterator->in_range (possible))
return false;
iterator->current = possible;
return true;
}
return false;
}
DEFINE_SIZE_MIN (4);
};
struct accelerator_t
{
void init (hb_face_t *face)
{
memset (this, 0, sizeof (accelerator_t));
const OT::head &head = *face->table.head;
if (head.indexToLocFormat > 1 || head.glyphDataFormat != 0)
/* Unknown format. Leave num_glyphs=0, that takes care of disabling us. */
return;
short_offset = 0 == head.indexToLocFormat;
loca_table = hb_sanitize_context_t ().reference_table<loca> (face);
glyf_table = hb_sanitize_context_t ().reference_table<glyf> (face);
num_glyphs = MAX (1u, loca_table.get_length () / (short_offset ? 2 : 4)) - 1;
}
void fini ()
{
loca_table.destroy ();
glyf_table.destroy ();
}
/*
* Returns true if the referenced glyph is a valid glyph and a composite glyph.
* If true is returned a pointer to the composite glyph will be written into
* composite.
*/
bool get_composite (hb_codepoint_t glyph,
CompositeGlyphHeader::Iterator *composite /* OUT */) const
{
if (unlikely (!num_glyphs))
return false;
unsigned int start_offset, end_offset;
if (!get_offsets (glyph, &start_offset, &end_offset))
return false; /* glyph not found */
return CompositeGlyphHeader::get_iterator ((const char *) this->glyf_table + start_offset,
end_offset - start_offset,
composite);
}
enum simple_glyph_flag_t {
FLAG_ON_CURVE = 0x01,
FLAG_X_SHORT = 0x02,
FLAG_Y_SHORT = 0x04,
FLAG_REPEAT = 0x08,
FLAG_X_SAME = 0x10,
FLAG_Y_SAME = 0x20,
FLAG_RESERVED1 = 0x40,
FLAG_RESERVED2 = 0x80
};
/* based on FontTools _g_l_y_f.py::trim */
bool remove_padding (unsigned int start_offset,
unsigned int *end_offset) const
{
if (*end_offset - start_offset < GlyphHeader::static_size) return true;
const char *glyph = ((const char *) glyf_table) + start_offset;
const char * const glyph_end = glyph + (*end_offset - start_offset);
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyph, 0);
int16_t num_contours = (int16_t) glyph_header.numberOfContours;
if (num_contours < 0)
/* Trimming for composites not implemented.
* If removing hints it falls out of that. */
return true;
else if (num_contours > 0)
{
/* simple glyph w/contours, possibly trimmable */
glyph += GlyphHeader::static_size + 2 * num_contours;
if (unlikely (glyph + 2 >= glyph_end)) return false;
uint16_t nCoordinates = (uint16_t) StructAtOffset<HBUINT16> (glyph - 2, 0) + 1;
uint16_t nInstructions = (uint16_t) StructAtOffset<HBUINT16> (glyph, 0);
glyph += 2 + nInstructions;
if (unlikely (glyph + 2 >= glyph_end)) return false;
unsigned int coordBytes = 0;
unsigned int coordsWithFlags = 0;
while (glyph < glyph_end)
{
uint8_t flag = (uint8_t) *glyph;
glyph++;
unsigned int repeat = 1;
if (flag & FLAG_REPEAT)
{
if (glyph >= glyph_end)
{
DEBUG_MSG(SUBSET, nullptr, "Bad flag");
return false;
}
repeat = ((uint8_t) *glyph) + 1;
glyph++;
}
unsigned int xBytes, yBytes;
xBytes = yBytes = 0;
if (flag & FLAG_X_SHORT) xBytes = 1;
else if ((flag & FLAG_X_SAME) == 0) xBytes = 2;
if (flag & FLAG_Y_SHORT) yBytes = 1;
else if ((flag & FLAG_Y_SAME) == 0) yBytes = 2;
coordBytes += (xBytes + yBytes) * repeat;
coordsWithFlags += repeat;
if (coordsWithFlags >= nCoordinates)
break;
}
if (coordsWithFlags != nCoordinates)
{
DEBUG_MSG(SUBSET, nullptr, "Expect %d coords to have flags, got flags for %d", nCoordinates, coordsWithFlags);
return false;
}
glyph += coordBytes;
if (glyph < glyph_end)
*end_offset -= glyph_end - glyph;
}
return true;
}
bool get_offsets (hb_codepoint_t glyph,
unsigned int *start_offset /* OUT */,
unsigned int *end_offset /* OUT */) const
{
if (unlikely (glyph >= num_glyphs))
return false;
if (short_offset)
{
const HBUINT16 *offsets = (const HBUINT16 *) loca_table->dataZ.arrayZ;
*start_offset = 2 * offsets[glyph];
*end_offset = 2 * offsets[glyph + 1];
}
else
{
const HBUINT32 *offsets = (const HBUINT32 *) loca_table->dataZ.arrayZ;
*start_offset = offsets[glyph];
*end_offset = offsets[glyph + 1];
}
if (*start_offset > *end_offset || *end_offset > glyf_table.get_length ())
return false;
return true;
}
bool get_instruction_offsets (unsigned int start_offset,
unsigned int end_offset,
unsigned int *instruction_start /* OUT */,
unsigned int *instruction_end /* OUT */) const
{
if (end_offset - start_offset < GlyphHeader::static_size)
{
*instruction_start = 0;
*instruction_end = 0;
return true; /* Empty glyph; no instructions. */
}
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
int16_t num_contours = (int16_t) glyph_header.numberOfContours;
if (num_contours < 0)
{
CompositeGlyphHeader::Iterator composite_it;
if (unlikely (!CompositeGlyphHeader::get_iterator (
(const char*) this->glyf_table + start_offset,
end_offset - start_offset, &composite_it))) return false;
const CompositeGlyphHeader *last;
do {
last = composite_it.current;
} while (composite_it.move_to_next ());
if ((uint16_t) last->flags & CompositeGlyphHeader::WE_HAVE_INSTRUCTIONS)
*instruction_start = ((char *) last - (char *) glyf_table->dataZ.arrayZ) + last->get_size ();
else
*instruction_start = end_offset;
*instruction_end = end_offset;
if (unlikely (*instruction_start > *instruction_end))
{
DEBUG_MSG(SUBSET, nullptr, "Invalid instruction offset, %d is outside [%d, %d]", *instruction_start, start_offset, end_offset);
return false;
}
}
else
{
unsigned int instruction_length_offset = start_offset + GlyphHeader::static_size + 2 * num_contours;
if (unlikely (instruction_length_offset + 2 > end_offset))
{
DEBUG_MSG(SUBSET, nullptr, "Glyph size is too short, missing field instructionLength.");
return false;
}
const HBUINT16 &instruction_length = StructAtOffset<HBUINT16> (glyf_table, instruction_length_offset);
unsigned int start = instruction_length_offset + 2;
unsigned int end = start + (uint16_t) instruction_length;
if (unlikely (end > end_offset)) // Out of bounds of the current glyph
{
DEBUG_MSG(SUBSET, nullptr, "The instructions array overruns the glyph's boundaries.");
return false;
}
*instruction_start = start;
*instruction_end = end;
}
return true;
}
bool get_extents (hb_codepoint_t glyph, hb_glyph_extents_t *extents) const
{
unsigned int start_offset, end_offset;
if (!get_offsets (glyph, &start_offset, &end_offset))
return false;
if (end_offset - start_offset < GlyphHeader::static_size)
return true; /* Empty glyph; zero extents. */
const GlyphHeader &glyph_header = StructAtOffset<GlyphHeader> (glyf_table, start_offset);
extents->x_bearing = MIN (glyph_header.xMin, glyph_header.xMax);
extents->y_bearing = MAX (glyph_header.yMin, glyph_header.yMax);
extents->width = MAX (glyph_header.xMin, glyph_header.xMax) - extents->x_bearing;
extents->height = MIN (glyph_header.yMin, glyph_header.yMax) - extents->y_bearing;
return true;
}
private:
bool short_offset;
unsigned int num_glyphs;
hb_blob_ptr_t<loca> loca_table;
hb_blob_ptr_t<glyf> glyf_table;
};
protected:
UnsizedArrayOf<HBUINT8> dataZ; /* Glyphs data. */
public:
DEFINE_SIZE_MIN (0); /* In reality, this is UNBOUNDED() type; but since we always
* check the size externally, allow Null() object of it by
* defining it MIN() instead. */
};
struct glyf_accelerator_t : glyf::accelerator_t {};
} /* namespace OT */
#endif /* HB_OT_GLYF_TABLE_HH */
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