Merge pull request #4237 from harfbuzz/layout-font-extents

[layout] Add hb_ot_layout_get_font_extents()

docs/harfbuzz-sections.txt

@@ -626,9 +626,13 @@ hb_ot_layout_feature_get_lookups
 hb_ot_layout_feature_get_name_ids
 hb_ot_layout_feature_with_variations_get_lookups
 hb_ot_layout_get_attach_points
+hb_ot_layout_get_font_extents
+hb_ot_layout_get_font_extents2
 hb_ot_layout_get_horizontal_baseline_tag_for_script
 hb_ot_layout_get_baseline
+hb_ot_layout_get_baseline2
 hb_ot_layout_get_baseline_with_fallback
+hb_ot_layout_get_baseline_with_fallback2
 hb_ot_layout_get_glyph_class
 hb_ot_layout_get_glyphs_in_class
 hb_ot_layout_get_ligature_carets

src/hb-ot-layout-base-table.hh

@@ -170,8 +170,8 @@ struct FeatMinMaxRecord
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
-			  minCoord.sanitize (c, this) &&
-			  maxCoord.sanitize (c, this)));
+			  minCoord.sanitize (c, base) &&
+			  maxCoord.sanitize (c, base)));
   }
 
   protected:
@@ -187,7 +187,6 @@ struct FeatMinMaxRecord
 				 * of MinMax table (may be NULL) */
   public:
   DEFINE_SIZE_STATIC (8);
-
 };
 
 struct MinMax
@@ -274,7 +273,7 @@ struct BaseLangSysRecord
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
-			  minMax.sanitize (c, this)));
+			  minMax.sanitize (c, base)));
   }
 
   protected:
@@ -297,7 +296,8 @@ struct BaseScript
   const BaseCoord &get_base_coord (int baseline_tag_index) const
   { return (this+baseValues).get_base_coord (baseline_tag_index); }
 
-  bool has_data () const { return baseValues; }
+  bool has_values () const { return baseValues; }
+  bool has_min_max () const { return defaultMinMax; /* TODO What if only per-language is present? */ }
 
   bool sanitize (hb_sanitize_context_t *c) const
   {
@@ -383,7 +383,7 @@ struct Axis
 		     const BaseCoord **coord) const
   {
     const BaseScript &base_script = (this+baseScriptList).get_base_script (script_tag);
-    if (!base_script.has_data ())
+    if (!base_script.has_values ())
     {
       *coord = nullptr;
       return false;
@@ -410,7 +410,7 @@ struct Axis
 		    const BaseCoord **max_coord) const
   {
     const BaseScript &base_script = (this+baseScriptList).get_base_script (script_tag);
-    if (!base_script.has_data ())
+    if (!base_script.has_min_max ())
     {
       *min_coord = *max_coord = nullptr;
       return false;
@@ -425,8 +425,8 @@ struct Axis
   {
     TRACE_SANITIZE (this);
     return_trace (likely (c->check_struct (this) &&
-			  (this+baseTagList).sanitize (c) &&
-			  (this+baseScriptList).sanitize (c)));
+			  baseTagList.sanitize (c, this) &&
+			  baseScriptList.sanitize (c, this)));
   }
 
   protected:
@@ -473,14 +473,13 @@ struct BASE
     return true;
   }
 
-  /* TODO: Expose this separately sometime? */
   bool get_min_max (hb_font_t      *font,
 		    hb_direction_t  direction,
 		    hb_tag_t        script_tag,
 		    hb_tag_t        language_tag,
 		    hb_tag_t        feature_tag,
 		    hb_position_t  *min,
-		    hb_position_t  *max)
+		    hb_position_t  *max) const
   {
     const BaseCoord *min_coord, *max_coord;
     if (!get_axis (direction).get_min_max (script_tag, language_tag, feature_tag,

src/hb-ot-layout.cc

@@ -2036,6 +2036,112 @@ hb_ot_layout_substitute_lookup (OT::hb_ot_apply_context_t *c,
 }
 
 #ifndef HB_NO_BASE
+
+static void
+choose_base_tags (hb_script_t    script,
+		  hb_language_t  language,
+		  hb_tag_t      *script_tag,
+		  hb_tag_t      *language_tag)
+{
+  hb_tag_t script_tags[HB_OT_MAX_TAGS_PER_SCRIPT];
+  unsigned script_count = ARRAY_LENGTH (script_tags);
+
+  hb_tag_t language_tags[HB_OT_MAX_TAGS_PER_LANGUAGE];
+  unsigned language_count = ARRAY_LENGTH (language_tags);
+
+  hb_ot_tags_from_script_and_language (script, language,
+				       &script_count, script_tags,
+				       &language_count, language_tags);
+
+  *script_tag = script_count ? script_tags[script_count - 1] : HB_OT_TAG_DEFAULT_SCRIPT;
+  *language_tag = language_count ? language_tags[language_count - 1] : HB_OT_TAG_DEFAULT_LANGUAGE;
+}
+
+/**
+ * hb_ot_layout_get_font_extents:
+ * @font: a font
+ * @direction: text direction.
+ * @script_tag:  script tag.
+ * @language_tag: language tag.
+ * @extents: (out) (nullable): font extents if found.
+ *
+ * Fetches script/language-specific font extents.  These values are
+ * looked up in the `BASE` table's `MinMax` records.
+ *
+ * If no such extents are found, the default extents for the font are
+ * fetched. As such, the return value of this function can for the
+ * most part be ignored.  Note that the per-script/language extents
+ * do not have a line-gap value, and the line-gap is set to zero in
+ * that case.
+ *
+ * Return value: `true` if found script/language-specific font extents.
+ *
+ * XSince: REPLACEME
+ **/
+hb_bool_t
+hb_ot_layout_get_font_extents (hb_font_t         *font,
+			       hb_direction_t     direction,
+			       hb_tag_t           script_tag,
+			       hb_tag_t           language_tag,
+			       hb_font_extents_t *extents)
+{
+  hb_position_t min, max;
+  if (font->face->table.BASE->get_min_max (font, direction, script_tag, language_tag, HB_TAG_NONE,
+					   &min, &max))
+  {
+    if (extents)
+    {
+      extents->ascender  = max;
+      extents->descender = min;
+      extents->line_gap  = 0;
+    }
+    return true;
+  }
+
+  hb_font_get_extents_for_direction (font, direction, extents);
+  return false;
+}
+
+/**
+ * hb_ot_layout_get_font_extents2:
+ * @font: a font
+ * @direction: text direction.
+ * @script:  script.
+ * @language: (nullable): language.
+ * @extents: (out) (nullable): font extents if found.
+ *
+ * Fetches script/language-specific font extents.  These values are
+ * looked up in the `BASE` table's `MinMax` records.
+ *
+ * If no such extents are found, the default extents for the font are
+ * fetched. As such, the return value of this function can for the
+ * most part be ignored.  Note that the per-script/language extents
+ * do not have a line-gap value, and the line-gap is set to zero in
+ * that case.
+ *
+ * This function is like hb_ot_layout_get_font_extents() but takes
+ * #hb_script_t and #hb_language_t instead of OpenType #hb_tag_t.
+ *
+ * Return value: `true` if found script/language-specific font extents.
+ *
+ * XSince: REPLACEME
+ **/
+hb_bool_t
+hb_ot_layout_get_font_extents2 (hb_font_t         *font,
+				hb_direction_t     direction,
+				hb_script_t        script,
+				hb_language_t      language,
+				hb_font_extents_t *extents)
+{
+  hb_tag_t script_tag, language_tag;
+  choose_base_tags (script, language, &script_tag, &language_tag);
+  return hb_ot_layout_get_font_extents (font,
+					direction,
+					script_tag,
+					language_tag,
+					extents);
+}
+
 /**
  * hb_ot_layout_get_horizontal_baseline_tag_for_script:
  * @script: a script tag.
@@ -2133,6 +2239,42 @@ hb_ot_layout_get_baseline (hb_font_t                   *font,
   return font->face->table.BASE->get_baseline (font, baseline_tag, direction, script_tag, language_tag, coord);
 }
 
+/**
+ * hb_ot_layout_get_baseline2:
+ * @font: a font
+ * @baseline_tag: a baseline tag
+ * @direction: text direction.
+ * @script:  script.
+ * @language: (nullable): language, currently unused.
+ * @coord: (out) (nullable): baseline value if found.
+ *
+ * Fetches a baseline value from the face.
+ *
+ * This function is like hb_ot_layout_get_baseline() but takes
+ * #hb_script_t and #hb_language_t instead of OpenType #hb_tag_t.
+ *
+ * Return value: `true` if found baseline value in the font.
+ *
+ * XSince: REPLACEME
+ **/
+hb_bool_t
+hb_ot_layout_get_baseline2 (hb_font_t                   *font,
+			    hb_ot_layout_baseline_tag_t  baseline_tag,
+			    hb_direction_t               direction,
+			    hb_script_t                  script,
+			    hb_language_t                language,
+			    hb_position_t               *coord        /* OUT.  May be NULL. */)
+{
+  hb_tag_t script_tag, language_tag;
+  choose_base_tags (script, language, &script_tag, &language_tag);
+  return hb_ot_layout_get_baseline (font,
+				    baseline_tag,
+				    direction,
+				    script_tag,
+				    language_tag,
+				    coord);
+}
+
 /**
  * hb_ot_layout_get_baseline_with_fallback:
  * @font: a font
@@ -2355,6 +2497,41 @@ hb_ot_layout_get_baseline_with_fallback (hb_font_t                   *font,
   }
 }
 
+/**
+ * hb_ot_layout_get_baseline_with_fallback2:
+ * @font: a font
+ * @baseline_tag: a baseline tag
+ * @direction: text direction.
+ * @script:  script.
+ * @language: (nullable): language, currently unused.
+ * @coord: (out): baseline value if found.
+ *
+ * Fetches a baseline value from the face, and synthesizes
+ * it if the font does not have it.
+ *
+ * This function is like hb_ot_layout_get_baseline_with_fallback() but takes
+ * #hb_script_t and #hb_language_t instead of OpenType #hb_tag_t.
+ *
+ * XSince: REPLACEME
+ **/
+void
+hb_ot_layout_get_baseline_with_fallback2 (hb_font_t                   *font,
+					  hb_ot_layout_baseline_tag_t  baseline_tag,
+					  hb_direction_t               direction,
+					  hb_script_t                  script,
+					  hb_language_t                language,
+					  hb_position_t               *coord        /* OUT */)
+{
+  hb_tag_t script_tag, language_tag;
+  choose_base_tags (script, language, &script_tag, &language_tag);
+  hb_ot_layout_get_baseline_with_fallback (font,
+					   baseline_tag,
+					   direction,
+					   script_tag,
+					   language_tag,
+					   coord);
+}
+
 #endif
 
 

src/hb-ot-layout.h

@@ -447,6 +447,20 @@ hb_ot_layout_feature_get_characters (hb_face_t      *face,
  * BASE
  */
 
+HB_EXTERN hb_bool_t
+hb_ot_layout_get_font_extents (hb_font_t         *font,
+			       hb_direction_t     direction,
+			       hb_tag_t           script_tag,
+			       hb_tag_t           language_tag,
+			       hb_font_extents_t *extents);
+
+HB_EXTERN hb_bool_t
+hb_ot_layout_get_font_extents2 (hb_font_t         *font,
+				hb_direction_t     direction,
+				hb_script_t        script,
+				hb_language_t      language,
+				hb_font_extents_t *extents);
+
 /**
  * hb_ot_layout_baseline_tag_t:
  * @HB_OT_LAYOUT_BASELINE_TAG_ROMAN: The baseline used by alphabetic scripts such as Latin, Cyrillic and Greek.
@@ -499,6 +513,14 @@ hb_ot_layout_get_baseline (hb_font_t                   *font,
 			   hb_tag_t                     language_tag,
 			   hb_position_t               *coord        /* OUT.  May be NULL. */);
 
+HB_EXTERN hb_bool_t
+hb_ot_layout_get_baseline2 (hb_font_t                   *font,
+			    hb_ot_layout_baseline_tag_t  baseline_tag,
+			    hb_direction_t               direction,
+			    hb_script_t                  script,
+			    hb_language_t                language,
+			    hb_position_t               *coord        /* OUT.  May be NULL. */);
+
 HB_EXTERN void
 hb_ot_layout_get_baseline_with_fallback (hb_font_t                   *font,
 					 hb_ot_layout_baseline_tag_t  baseline_tag,
@@ -507,6 +529,14 @@ hb_ot_layout_get_baseline_with_fallback (hb_font_t                   *font,
 					 hb_tag_t                     language_tag,
 					 hb_position_t               *coord        /* OUT */);
 
+HB_EXTERN void
+hb_ot_layout_get_baseline_with_fallback2 (hb_font_t                   *font,
+					  hb_ot_layout_baseline_tag_t  baseline_tag,
+					  hb_direction_t               direction,
+					  hb_script_t                  script,
+					  hb_language_t                language,
+					  hb_position_t               *coord        /* OUT */);
+
 HB_END_DECLS
 
 #endif /* HB_OT_LAYOUT_H */

src/hb-ot-tag.cc

@@ -412,7 +412,7 @@ parse_private_use_subtag (const char     *private_use_subtag,
 /**
  * hb_ot_tags_from_script_and_language:
  * @script: an #hb_script_t to convert.
- * @language: an #hb_language_t to convert.
+ * @language: (nullable): an #hb_language_t to convert.
  * @script_count: (inout) (optional): maximum number of script tags to retrieve (IN)
  * and actual number of script tags retrieved (OUT)
  * @script_tags: (out) (optional): array of size at least @script_count to store the

test/api/Makefile.am

@@ -33,6 +33,7 @@ noinst_PROGRAMS = $(TEST_PROGS)
 TEST_PROGS = \
 	test-aat-layout \
 	test-baseline \
+	test-base-minmax \
 	test-be-glyph-advance \
 	test-be-num-glyphs \
 	test-blob \

test/api/meson.build

@@ -6,6 +6,7 @@ endif
 tests = [
   'test-aat-layout.c',
   'test-baseline.c',
+  'test-base-minmax.c',
   'test-be-glyph-advance.c',
   'test-be-num-glyphs.c',
   'test-blob.c',

test/api/test-base-minmax.c

@@ -0,0 +1,66 @@
+/*
+ * Copyright © 2023  Behdad Esfahbod
+ *
+ *  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.
+ */
+
+#include "hb-test.h"
+
+#include <hb-ot.h>
+
+/* Unit tests for hb-ot-layout.h font extents */
+
+static void
+test_ot_layout_font_extents (void)
+{
+  hb_face_t *face = hb_test_open_font_file ("fonts/base-minmax.ttf");
+  hb_font_t *font = hb_font_create (face);
+
+  hb_font_extents_t extents;
+
+  g_assert (hb_ot_layout_get_font_extents2 (font, HB_DIRECTION_LTR,
+					    HB_SCRIPT_LATIN, HB_LANGUAGE_INVALID,
+					    &extents));
+  g_assert_cmpint (extents.ascender, ==, 2000);
+
+  g_assert (hb_ot_layout_get_font_extents2 (font, HB_DIRECTION_LTR,
+					    HB_SCRIPT_LATIN, hb_language_from_string ("xx", -1),
+					    &extents));
+  g_assert_cmpint (extents.ascender, ==, 2000);
+
+  g_assert (!hb_ot_layout_get_font_extents2 (font, HB_DIRECTION_LTR,
+					     HB_SCRIPT_ARABIC, HB_LANGUAGE_INVALID,
+					     &extents));
+  g_assert_cmpint (extents.ascender, ==, 3000);
+
+  hb_font_destroy (font);
+  hb_face_destroy (face);
+}
+
+int
+main (int argc, char **argv)
+{
+  hb_test_init (&argc, &argv);
+
+  hb_test_add (test_ot_layout_font_extents);
+
+  return hb_test_run();
+}

test/api/test-baseline.c

@@ -41,6 +41,12 @@ test_ot_layout_base (void)
 				       &position));
   g_assert_cmpint (46, ==, position);
 
+  g_assert (hb_ot_layout_get_baseline2 (font, HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT, HB_DIRECTION_TTB,
+					HB_SCRIPT_HAN,
+					hb_language_from_string ("en", -1),
+					&position));
+  g_assert_cmpint (46, ==, position);
+
   g_assert (!hb_ot_layout_get_baseline (font, HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT, HB_DIRECTION_TTB,
 				        HB_TAG ('h','a','n','i'),
 				        HB_TAG ('E','N','G',' '),
@@ -63,6 +69,12 @@ test_ot_layout_base_with_fallback (void)
 					   &position);
   g_assert_cmpint (46, ==, position);
 
+  hb_ot_layout_get_baseline_with_fallback2 (font, HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT, HB_DIRECTION_TTB,
+					    HB_SCRIPT_HAN,
+					    hb_language_from_string ("en", -1),
+					    &position);
+  g_assert_cmpint (46, ==, position);
+
   hb_ot_layout_get_baseline_with_fallback (font, HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT, HB_DIRECTION_TTB,
 					   HB_TAG ('h','a','n','i'),
 					   HB_TAG ('E','N','G',' '),