harfbuzz/src/graph/gsubgpos-graph.hh

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/*
* Copyright © 2022 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): Garret Rieger
*/
#include "graph.hh"
#include "hb-ot-layout-gsubgpos.hh"
#include "OT/Layout/GSUB/ExtensionSubst.hh"
#ifndef GRAPH_GSUBGPOS_GRAPH_HH
#define GRAPH_GSUBGPOS_GRAPH_HH
namespace graph {
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struct Lookup;
struct make_extension_context_t
{
hb_tag_t table_tag;
graph_t& graph;
hb_vector_t<char>& buffer;
hb_hashmap_t<unsigned, graph::Lookup*> lookups;
HB_INTERNAL make_extension_context_t (hb_tag_t table_tag_,
graph_t& graph_,
hb_vector_t<char>& buffer_);
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bool in_error () const
{
return buffer.in_error ();
}
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private:
HB_INTERNAL unsigned num_non_ext_subtables ();
};
template<typename T>
struct ExtensionFormat1 : public OT::ExtensionFormat1<T>
{
void reset(unsigned type)
{
this->format = 1;
this->extensionLookupType = type;
this->extensionOffset = 0;
}
};
struct Lookup : public OT::Lookup
{
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unsigned number_of_subtables () const
{
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return subTable.len;
}
bool sanitize (graph_t::vertex_t& vertex) const
{
int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
if (vertex_len < OT::Lookup::min_size) return false;
return vertex_len >= this->get_size ();
}
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bool is_extension (hb_tag_t table_tag) const
{
return lookupType == extension_type (table_tag);
}
bool make_extension (make_extension_context_t& c,
unsigned this_index)
{
unsigned type = lookupType;
unsigned ext_type = extension_type (c.table_tag);
if (!ext_type || is_extension (c.table_tag))
{
// NOOP
return true;
}
DEBUG_MSG (SUBSET_REPACK, nullptr,
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"Promoting lookup type %u (obj %u) to extension.",
type,
this_index);
for (unsigned i = 0; i < subTable.len; i++)
{
unsigned subtable_index = c.graph.index_for_offset (this_index, &subTable[i]);
if (!make_subtable_extension (c,
this_index,
subtable_index))
return false;
}
lookupType = ext_type;
return true;
}
bool make_subtable_extension (make_extension_context_t& c,
unsigned lookup_index,
unsigned subtable_index)
{
unsigned type = lookupType;
unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
unsigned start = c.buffer.length;
unsigned end = start + extension_size;
if (!c.buffer.resize (c.buffer.length + extension_size))
return false;
ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
(ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*) &c.buffer[start];
extension->reset (type);
unsigned ext_index = c.graph.new_node (&c.buffer.arrayZ[start],
&c.buffer.arrayZ[end]);
if (ext_index == (unsigned) -1) return false;
auto& lookup_vertex = c.graph.vertices_[lookup_index];
for (auto& l : lookup_vertex.obj.real_links.writer ())
{
if (l.objidx == subtable_index)
// Change lookup to point at the extension.
l.objidx = ext_index;
}
// Make extension point at the subtable.
auto& ext_vertex = c.graph.vertices_[ext_index];
auto& subtable_vertex = c.graph.vertices_[subtable_index];
auto* l = ext_vertex.obj.real_links.push ();
l->width = 4;
l->objidx = subtable_index;
l->is_signed = 0;
l->whence = 0;
l->position = 4;
l->bias = 0;
ext_vertex.parents.push (lookup_index);
subtable_vertex.remap_parent (lookup_index, ext_index);
return true;
}
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private:
unsigned extension_type (hb_tag_t table_tag) const
{
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switch (table_tag)
{
case HB_OT_TAG_GPOS: return 9;
case HB_OT_TAG_GSUB: return 7;
default: return 0;
}
}
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};
template <typename T>
struct LookupList : public OT::LookupList<T>
{
bool sanitize (const graph_t::vertex_t& vertex) const
{
int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
if (vertex_len < OT::LookupList<T>::min_size) return false;
return vertex_len >= OT::LookupList<T>::item_size * this->len;
}
};
struct GSTAR : public OT::GSUBGPOS
{
static GSTAR* graph_to_gstar (graph_t& graph)
{
const auto& r = graph.root ();
GSTAR* gstar = (GSTAR*) r.obj.head;
if (!gstar->sanitize (r))
return nullptr;
return gstar;
}
const void* get_lookup_list_field_offset () const
{
switch (u.version.major) {
case 1: return u.version1.get_lookup_list_offset ();
#ifndef HB_NO_BORING_EXPANSION
case 2: return u.version2.get_lookup_list_offset ();
#endif
default: return 0;
}
}
bool sanitize (const graph_t::vertex_t& vertex)
{
int64_t len = vertex.obj.tail - vertex.obj.head;
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if (len < OT::GSUBGPOS::min_size) return false;
return len >= get_size ();
}
void find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
switch (u.version.major) {
case 1: find_lookups<SmallTypes> (graph, lookups); break;
#ifndef HB_NO_BORING_EXPANSION
case 2: find_lookups<MediumTypes> (graph, lookups); break;
#endif
}
}
template<typename Types>
void find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
unsigned lookup_list_idx = graph.index_for_offset (graph.root_idx (),
get_lookup_list_field_offset());
const LookupList<Types>* lookupList =
(const LookupList<Types>*) graph.object (lookup_list_idx).head;
if (!lookupList->sanitize (graph.vertices_[lookup_list_idx]))
return;
for (unsigned i = 0; i < lookupList->len; i++)
{
unsigned lookup_idx = graph.index_for_offset (lookup_list_idx, &(lookupList->arrayZ[i]));
Lookup* lookup = (Lookup*) graph.object (lookup_idx).head;
if (!lookup->sanitize (graph.vertices_[lookup_idx])) continue;
lookups.set (lookup_idx, lookup);
}
}
};
}
#endif /* GRAPH_GSUBGPOS_GRAPH_HH */