[subset] Add drop tables to subset input.

src/hb-subset-input.cc

@@ -45,6 +45,7 @@ hb_subset_input_create_or_fail ()
   input->unicodes = hb_set_create ();
   input->glyphs = hb_set_create ();
   input->name_ids = hb_set_create ();
+  input->drop_tables = hb_set_create ();
   input->drop_hints = false;
   input->drop_layout = true;
   input->desubroutinize = false;
@@ -83,6 +84,7 @@ hb_subset_input_destroy (hb_subset_input_t *subset_input)
   hb_set_destroy (subset_input->unicodes);
   hb_set_destroy (subset_input->glyphs);
   hb_set_destroy (subset_input->name_ids);
+  hb_set_destroy (subset_input->drop_tables);
 
   free (subset_input);
 }
@@ -117,6 +119,12 @@ hb_subset_input_nameid_set (hb_subset_input_t *subset_input)
   return subset_input->name_ids;
 }
 
+HB_EXTERN hb_set_t *
+hb_subset_input_drop_tables_set (hb_subset_input_t *subset_input)
+{
+  return subset_input->drop_tables;
+}
+
 HB_EXTERN void
 hb_subset_input_set_drop_hints (hb_subset_input_t *subset_input,
 				hb_bool_t drop_hints)

src/hb-subset-input.hh

@@ -41,6 +41,7 @@ struct hb_subset_input_t
   hb_set_t *unicodes;
   hb_set_t *glyphs;
   hb_set_t *name_ids;
+  hb_set_t *drop_tables;
 
   bool drop_hints : 1;
   bool drop_layout : 1;

src/hb-subset-plan.cc

@@ -241,6 +241,8 @@ hb_subset_plan_create (hb_face_t           *face,
   plan->retain_gids = input->retain_gids;
   plan->unicodes = hb_set_create ();
   plan->name_ids = hb_set_reference (input->name_ids);
+  plan->drop_tables = hb_set_reference (input->drop_tables);
+
   /* TODO Clean this up... */
   if (hb_set_is_empty (plan->name_ids))
     hb_set_add_range (plan->name_ids, 0, 0x7FFF);
@@ -279,6 +281,7 @@ hb_subset_plan_destroy (hb_subset_plan_t *plan)
 
   hb_set_destroy (plan->unicodes);
   hb_set_destroy (plan->name_ids);
+  hb_set_destroy (plan->drop_tables);
   hb_face_destroy (plan->source);
   hb_face_destroy (plan->dest);
   hb_map_destroy (plan->codepoint_to_glyph);

src/hb-subset-plan.hh

@@ -47,9 +47,12 @@ struct hb_subset_plan_t
   // For each cp that we'd like to retain maps to the corresponding gid.
   hb_set_t *unicodes;
 
-  //name_ids we would like to retain
+  // name_ids we would like to retain
   hb_set_t *name_ids;
 
+  // Tables which should be dropped.
+  hb_set_t *drop_tables;
+
   // The glyph subset
   hb_map_t *codepoint_to_glyph;
 

src/hb-subset.cc

@@ -237,6 +237,9 @@ _subset_table (hb_subset_plan_t *plan,
 static bool
 _should_drop_table (hb_subset_plan_t *plan, hb_tag_t tag)
 {
+  if (plan->drop_tables->has (tag))
+    return true;
+
   switch (tag) {
     case HB_TAG ('c', 'v', 'a', 'r'): /* hint table, fallthrough */
     case HB_TAG ('c', 'v', 't', ' '): /* hint table, fallthrough */

src/hb-subset.h

@@ -57,6 +57,9 @@ hb_subset_input_glyph_set (hb_subset_input_t *subset_input);
 HB_EXTERN hb_set_t *
 hb_subset_input_nameid_set (hb_subset_input_t *subset_input);
 
+HB_EXTERN hb_set_t *
+hb_subset_input_drop_tables_set (hb_subset_input_t *subset_input);
+
 HB_EXTERN void
 hb_subset_input_set_drop_hints (hb_subset_input_t *subset_input,
 				hb_bool_t drop_hints);

test/api/Makefile.am

@@ -42,6 +42,7 @@ TEST_PROGS = \
 	test-shape \
 	test-subset \
 	test-subset-cmap \
+	test-subset-drop-tables \
 	test-subset-glyf \
 	test-subset-hdmx \
 	test-subset-hmtx \
@@ -57,6 +58,7 @@ TEST_PROGS = \
 
 test_subset_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la
 test_subset_cmap_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la
+test_subset_drop_tables_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la
 test_subset_glyf_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la
 test_subset_hdmx_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la
 test_subset_hmtx_LDADD = $(LDADD) $(top_builddir)/src/libharfbuzz-subset.la

test/api/test-subset-drop-tables.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright © 2019  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 "hb-test.h"
+#include "hb-subset-test.h"
+
+/* Unit tests for hb-subset.cc drop tables functionality */
+
+static void
+test_subset_drop_tables (void)
+{
+  hb_face_t *face = hb_test_open_font_file ("fonts/Roboto-Regular.abc.ttf");
+
+  hb_set_t *codepoints = hb_set_create();
+  hb_set_add (codepoints, 97);
+  hb_set_add (codepoints, 99);
+  hb_subset_input_t *input = hb_subset_test_create_input (codepoints);
+  hb_set_add (hb_subset_input_drop_tables_set (input), HB_TAG ('h', 'd', 'm', 'x'));
+  hb_set_add (hb_subset_input_drop_tables_set (input), HB_TAG ('h', 'm', 't', 'x'));
+  hb_set_destroy (codepoints);
+
+  hb_face_t* subset = hb_subset (face, input);
+
+  hb_blob_t *hdmx = hb_face_reference_table (subset, HB_TAG ('h', 'd', 'm', 'x'));
+  hb_blob_t *hmtx = hb_face_reference_table (subset, HB_TAG ('h', 'm', 't', 'x'));
+  hb_blob_t *cmap = hb_face_reference_table (subset, HB_TAG ('c', 'm', 'a', 'p'));
+  g_assert (!hb_blob_get_length (hdmx));
+  g_assert (!hb_blob_get_length (hmtx));
+  g_assert ( hb_blob_get_length (cmap));
+  hb_blob_destroy (hdmx);
+  hb_blob_destroy (hmtx);
+  hb_blob_destroy (cmap);
+
+  hb_face_destroy (subset);
+  hb_subset_input_destroy (input);
+  hb_face_destroy (face);
+}
+
+
+int
+main (int argc, char **argv)
+{
+  hb_test_init (&argc, &argv);
+
+  hb_test_add (test_subset_drop_tables);
+
+  return hb_test_run();
+}