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[repack] WIP implement extension promotion mechanism.

This commit is contained in:
Garret Rieger 2022-07-19 23:33:16 +00:00
parent d9295d88a7
commit c20b85cfed
4 changed files with 216 additions and 5 deletions
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38
src/graph/graph.hh
View File

@ -199,7 +199,7 @@ struct graph_t
return vertices_.length - 1;
}
const hb_serialize_context_t::object_t& object(unsigned i) const
const hb_serialize_context_t::object_t& object (unsigned i) const
{
return vertices_[i].obj;
}
@ -368,6 +368,8 @@ struct graph_t
*/
bool assign_spaces ()
{
update_parents ();
hb_set_t visited;
hb_set_t roots;
find_space_roots (visited, roots);
@ -632,6 +634,40 @@ struct graph_t
return true;
}
/*
* Adds a new node to the graph, not connected to anything.
*/
unsigned new_node (char* head, char* tail)
{
positions_invalid = true;
distance_invalid = true;
parents_invalid = true; // TODO: remove
auto* clone = vertices_.push ();
if (vertices_.in_error ()) {
return -1;
}
clone->obj.head = head;
clone->obj.tail = tail;
clone->distance = 0;
clone->space = 0;
unsigned clone_idx = vertices_.length - 2;
// The last object is the root of the graph, so swap back the root to the end.
// The root's obj idx does change, however since it's root nothing else refers to it.
// all other obj idx's will be unaffected.
hb_swap (vertices_[vertices_.length - 2], *clone);
// Since the root moved, update the parents arrays of all children on the root.
for (const auto& l : root ().obj.all_links ())
vertices_[l.objidx].remap_parent (root_idx () - 1, root_idx ());
return clone_idx;
}
/*
* Raises the sorting priority of all children.
*/

174
src/graph/gsubgpos-graph.hh Normal file
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@ -0,0 +1,174 @@
/*
* 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
*/
#ifndef GRAPH_GSUBGPOS_GRAPH_HH
#define GRAPH_GSUBGPOS_GRAPH_HH
#include "graph.hh"
#include "hb-ot-layout-gsubgpos.hh"
#include "OT/Layout/GSUB/ExtensionSubst.hh"
namespace graph {
struct GSTAR : public OT::GSUBGPOS
{
const void* get_lookup_list_field_offset () const
{
switch (u.version.major) {
case 1: return &(u.version1.lookupList);
#ifndef HB_NO_BORING_EXPANSION
case 2: return &(u.version2.lookupList);
#endif
default: return 0;
}
}
};
struct Lookup : public OT::Lookup
{
unsigned extension_type (hb_tag_t table_tag)
{
switch (table_tag)
{
case HB_OT_TAG_GPOS: return 9;
case HB_OT_TAG_GSUB: return 7;
default: return 0;
}
}
bool make_extension (hb_tag_t table_tag,
graph_t& graph,
unsigned this_index,
hb_vector_t<char>& buffer)
{
// TODO: use a context_t?
unsigned ext_type = extension_type (table_tag);
unsigned type = lookupType;
if (!ext_type || type == ext_type)
{
// NOOP
printf("Already extension (obj %u).\n", this_index);
return true;
}
printf("Promoting lookup type %u (obj %u) to extension.\n",
type,
this_index);
for (unsigned i = 0; i < subTable.len; i++)
{
unsigned subtable_index = graph.index_for_offset (this_index, &subTable[i]);
if (!make_subtable_extension (graph,
this_index,
subtable_index,
buffer))
return false;
}
lookupType = ext_type;
return true;
}
bool make_subtable_extension (graph_t& graph,
unsigned lookup_index,
unsigned subtable_index,
hb_vector_t<char>& buffer)
{
printf(" Promoting subtable %u in lookup %u to extension.\n", subtable_index, lookup_index);
unsigned type = lookupType;
unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
unsigned start = buffer.length;
unsigned end = start + extension_size;
if (!buffer.resize (buffer.length + extension_size))
return false;
OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
(OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*) &buffer[start];
extension->format = 1;
extension->extensionLookupType = type;
extension->extensionOffset = 0;
unsigned ext_index = graph.new_node (&buffer[start], &buffer[end]);
if (ext_index == (unsigned) -1) return false;
auto& lookup_vertex = 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.
printf(" Changing %d to %d\n", l.objidx, ext_index);
l.objidx = ext_index;
}
}
// Make extension point at the subtable.
// TODO: update extension parents array.
auto& ext_vertex = graph.vertices_[ext_index];
auto& subtable_vertex = 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;
subtable_vertex.remap_parent (lookup_index, ext_index);
return true;
}
};
static inline void
find_lookups (graph_t& graph,
hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
{
// TODO: move this into GSTAR?
// TODO: template on types, based on gstar version.
const GSTAR* gstar = (const GSTAR*) graph.root ().obj.head;
unsigned lookup_list_idx = graph.index_for_offset (graph.root_idx (),
gstar->get_lookup_list_field_offset());
const OT::LookupList<SmallTypes>* lookupList =
(const OT::LookupList<SmallTypes>*) graph.object (lookup_list_idx).head;
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;
lookups.set (lookup_idx, lookup);
}
}
}
#endif /* GRAPH_GSUBGPOS_GRAPH_HH */

2
src/hb-ot-layout-gsubgpos.hh
View File

@ -3850,7 +3850,7 @@ struct ExtensionFormat1
return_trace (dest_offset.serialize_subset (c, src_offset, this, get_type ()));
}
protected:
public: // TODO
HBUINT16 format; /* Format identifier. Set to 1. */
HBUINT16 extensionLookupType; /* Lookup type of subtable referenced
* by ExtensionOffset (i.e. the

7
src/hb-repacker.hh
View File

@ -44,7 +44,7 @@ using graph::graph_t;
*/
static inline
void _make_extensions (graph_t& sorted_graph)
void _make_extensions (hb_tag_t table_tag, graph_t& sorted_graph, hb_vector_t<char>& buffer)
{
// TODO: Move this into graph or gsubgpos graph?
hb_hashmap_t<unsigned, graph::Lookup*> lookups;
@ -52,7 +52,7 @@ void _make_extensions (graph_t& sorted_graph)
for (auto p : lookups.iter ())
{
p.second->make_extension (sorted_graph, p.first);
p.second->make_extension (table_tag, sorted_graph, p.first, buffer);
}
}
@ -182,12 +182,13 @@ hb_resolve_overflows (const T& packed,
return graph::serialize (sorted_graph);
}
hb_vector_t<char> extension_buffer;
if ((table_tag == HB_OT_TAG_GPOS
|| table_tag == HB_OT_TAG_GSUB)
&& will_overflow)
{
_make_extensions (table_tag, sorted_graph, extension_buffer);
DEBUG_MSG (SUBSET_REPACK, nullptr, "Assigning spaces to 32 bit subgraphs.");
_make_extensions (sorted_graph);
if (sorted_graph.assign_spaces ())
sorted_graph.sort_shortest_distance ();
}