From 359d163d25bbaa97b9a8d9647598b949e9ad789d Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 4 Feb 2025 17:11:46 +0000
Subject: [PATCH] Revert "[aat] Remove buffer-digest stuff"

This reverts commit 7642366593826c0e04ad58df83fa63ec53960486.
---
 src/hb-aat-layout-common.hh     |  1 +
 src/hb-aat-layout-kerx-table.hh |  5 +++++
 src/hb-aat-layout-morx-table.hh | 10 ++++++++++
 3 files changed, 16 insertions(+)

diff --git a/src/hb-aat-layout-common.hh b/src/hb-aat-layout-common.hh
index 6f8aae773..121c25f18 100644
--- a/src/hb-aat-layout-common.hh
+++ b/src/hb-aat-layout-common.hh
@@ -65,6 +65,7 @@ struct hb_aat_apply_context_t :
   const ankr *ankr_table;
   const OT::GDEF *gdef_table;
   const hb_sorted_vector_t<hb_aat_map_t::range_flags_t> *range_flags = nullptr;
+  hb_set_digest_t buffer_digest = hb_set_digest_t::full ();
   const hb_set_t *left_set = nullptr;
   const hb_set_t *right_set = nullptr;
   hb_aat_class_cache_t *machine_class_cache = nullptr;
diff --git a/src/hb-aat-layout-kerx-table.hh b/src/hb-aat-layout-kerx-table.hh
index fe8684cbd..72d696212 100644
--- a/src/hb-aat-layout-kerx-table.hh
+++ b/src/hb-aat-layout-kerx-table.hh
@@ -967,6 +967,11 @@ struct KerxTable
   {
     c->buffer->unsafe_to_concat ();
 
+    if (c->buffer->len < HB_AAT_BUFFER_DIGEST_THRESHOLD)
+      c->buffer_digest = c->buffer->digest ();
+    else
+      c->buffer_digest = hb_set_digest_t::full ();
+
     typedef typename T::SubTable SubTable;
 
     bool ret = false;
diff --git a/src/hb-aat-layout-morx-table.hh b/src/hb-aat-layout-morx-table.hh
index 58f9dd921..d05737a89 100644
--- a/src/hb-aat-layout-morx-table.hh
+++ b/src/hb-aat-layout-morx-table.hh
@@ -268,6 +268,7 @@ struct ContextualSubtable
       {
 	buffer->unsafe_to_break (mark, hb_min (buffer->idx + 1, buffer->len));
 	buffer->info[mark].codepoint = *replacement;
+	c->buffer_digest.add (*replacement);
 	if (has_glyph_classes)
 	  _hb_glyph_info_set_glyph_props (&buffer->info[mark],
 					  gdef.get_glyph_props (*replacement));
@@ -297,6 +298,7 @@ struct ContextualSubtable
       if (replacement)
       {
 	buffer->info[idx].codepoint = *replacement;
+	c->buffer_digest.add (*replacement);
 	if (has_glyph_classes)
 	  _hb_glyph_info_set_glyph_props (&buffer->info[idx],
 					  gdef.get_glyph_props (*replacement));
@@ -657,6 +659,7 @@ struct NoncontextualSubtable
       if (replacement)
       {
 	info[i].codepoint = *replacement;
+	c->buffer_digest.add (*replacement);
 	if (has_glyph_classes)
 	  _hb_glyph_info_set_glyph_props (&info[i],
 					  gdef.get_glyph_props (*replacement));
@@ -791,6 +794,8 @@ struct InsertionSubtable
 	  if (unlikely (!buffer->copy_glyph ())) return;
 	/* TODO We ignore KashidaLike setting. */
 	if (unlikely (!buffer->replace_glyphs (0, count, glyphs))) return;
+	for (unsigned int i = 0; i < count; i++)
+	  c->buffer_digest.add (glyphs[i]);
 	ret = true;
 	if (buffer->idx < buffer->len && !before)
 	  buffer->skip_glyph ();
@@ -1368,6 +1373,11 @@ struct mortmorx
 
     c->buffer->unsafe_to_concat ();
 
+    if (c->buffer->len < HB_AAT_BUFFER_DIGEST_THRESHOLD)
+      c->buffer_digest = c->buffer->digest ();
+    else
+      c->buffer_digest = hb_set_digest_t::full ();
+
     c->set_lookup_index (0);
     const Chain<Types> *chain = &firstChain;
     unsigned int count = chainCount;