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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"
#include "gsubgpos-context.hh"
#include "pairpos-graph.hh"
#ifndef GRAPH_GSUBGPOS_GRAPH_HH
#define GRAPH_GSUBGPOS_GRAPH_HH
namespace graph {
struct Lookup;
template<typename T>
struct ExtensionFormat1 : public OT::ExtensionFormat1<T>
{
void reset(unsigned type)
{
this->format = 1;
this->extensionLookupType = type;
this->extensionOffset = 0;
}
unsigned get_lookup_type () const
{
return this->extensionLookupType;
}
unsigned get_subtable_index (graph_t& graph, unsigned this_index) const
{
return graph.index_for_offset (this_index, &this->extensionOffset);
}
};
struct Lookup : public OT::Lookup
{
unsigned number_of_subtables () const
{
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 ();
}
bool is_extension (hb_tag_t table_tag) const
{
return lookupType == extension_type (table_tag);
}
bool make_extension (gsubgpos_graph_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,
"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 split_subtables_if_needed (gsubgpos_graph_context_t& c,
unsigned this_index)
{
unsigned type = lookupType;
bool is_ext = is_extension (c.table_tag);
if (c.table_tag != HB_OT_TAG_GPOS)
return true;
if (!is_ext && type != OT::Layout::GPOS_impl::PosLookupSubTable::Type::Pair)
return true;
// TODO check subtable type.
for (unsigned i = 0; i < subTable.len; i++)
{
unsigned subtable_index = c.graph.index_for_offset (this_index, &subTable[i]);
if (is_ext) {
unsigned ext_subtable_index = subtable_index;
ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
(ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*)
c.graph.object (ext_subtable_index).head;
subtable_index = extension->get_subtable_index (c.graph, ext_subtable_index);
type = extension->get_lookup_type ();
if (type != OT::Layout::GPOS_impl::PosLookupSubTable::Type::Pair)
continue;
}
PairPos* pairPos = (PairPos*) c.graph.object (subtable_index).head;
// TODO sanitize
pairPos->split_subtables (c, subtable_index);
}
return true;
}
bool make_subtable_extension (gsubgpos_graph_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 ext_index = c.create_node (extension_size);
if (ext_index == (unsigned) -1)
return false;
ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
(ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*) c.graph.object (ext_index).head;
extension->reset (type);
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;
}
private:
unsigned extension_type (hb_tag_t table_tag) const
{
switch (table_tag)
{
case HB_OT_TAG_GPOS: return 9;
case HB_OT_TAG_GSUB: return 7;
default: return 0;
}
}
};
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;
if (len < OT::GSUBGPOS::min_size) return false;
return len >= get_size ();
}
// TODO(garretrieger): add find subtable's method, could be templated locate a specific
// subtable type, maybe take the lookup map as a starting point?
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
}
}
unsigned get_lookup_list_index (graph_t& graph)
{
return graph.index_for_offset (graph.root_idx (),
get_lookup_list_field_offset());
}
template<typename Types>
void find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
unsigned lookup_list_idx = get_lookup_list_index (graph);
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 */
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