harfbuzz-ng roll

third_party/harfbuzz-ng/src/hb-ot-shape-fallback.cc

+/*
+ * Copyright © 2011,2012  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): Behdad Esfahbod
+ */
+
+#include "hb-ot-shape-fallback-private.hh"
+
+static unsigned int
+recategorize_combining_class (hb_codepoint_t u,
+                              unsigned int klass)
+{
+  if (klass >= 200)
+    return klass;
+
+  /* Thai / Lao need some per-character work. */
+  if ((u & ~0xFF) == 0x0E00)
+  {
+    if (unlikely (klass == 0))
+    {
+      switch (u)
+      {
+        case 0x0E31:
+        case 0x0E34:
+        case 0x0E35:
+        case 0x0E36:
+        case 0x0E37:
+        case 0x0E47:
+        case 0x0E4C:
+        case 0x0E4D:
+        case 0x0E4E:
+          klass = HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
+          break;
+
+        case 0x0EB1:
+        case 0x0EB4:
+        case 0x0EB5:
+        case 0x0EB6:
+        case 0x0EB7:
+        case 0x0EBB:
+        case 0x0ECC:
+        case 0x0ECD:
+          klass = HB_UNICODE_COMBINING_CLASS_ABOVE;
+          break;
+
+        case 0x0EBC:
+          klass = HB_UNICODE_COMBINING_CLASS_BELOW;
+          break;
+      }
+    } else {
+      /* Thai virama is below-right */
+      if (u == 0x0E3A)
+        klass = HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
+    }
+  }
+
+  switch (klass)
+  {
+
+    /* Hebrew */
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC10: /* sheva */
+    case HB_MODIFIED_COMBINING_CLASS_CCC11: /* hataf segol */
+    case HB_MODIFIED_COMBINING_CLASS_CCC12: /* hataf patah */
+    case HB_MODIFIED_COMBINING_CLASS_CCC13: /* hataf qamats */
+    case HB_MODIFIED_COMBINING_CLASS_CCC14: /* hiriq */
+    case HB_MODIFIED_COMBINING_CLASS_CCC15: /* tsere */
+    case HB_MODIFIED_COMBINING_CLASS_CCC16: /* segol */
+    case HB_MODIFIED_COMBINING_CLASS_CCC17: /* patah */
+    case HB_MODIFIED_COMBINING_CLASS_CCC18: /* qamats */
+    case HB_MODIFIED_COMBINING_CLASS_CCC20: /* qubuts */
+    case HB_MODIFIED_COMBINING_CLASS_CCC22: /* meteg */
+      return HB_UNICODE_COMBINING_CLASS_BELOW;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC23: /* rafe */
+      return HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC24: /* shin dot */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC25: /* sin dot */
+    case HB_MODIFIED_COMBINING_CLASS_CCC19: /* holam */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC26: /* point varika */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC21: /* dagesh */
+      break;
+
+
+    /* Arabic and Syriac */
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC27: /* fathatan */
+    case HB_MODIFIED_COMBINING_CLASS_CCC28: /* dammatan */
+    case HB_MODIFIED_COMBINING_CLASS_CCC30: /* fatha */
+    case HB_MODIFIED_COMBINING_CLASS_CCC31: /* damma */
+    case HB_MODIFIED_COMBINING_CLASS_CCC33: /* shadda */
+    case HB_MODIFIED_COMBINING_CLASS_CCC34: /* sukun */
+    case HB_MODIFIED_COMBINING_CLASS_CCC35: /* superscript alef */
+    case HB_MODIFIED_COMBINING_CLASS_CCC36: /* superscript alaph */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC29: /* kasratan */
+    case HB_MODIFIED_COMBINING_CLASS_CCC32: /* kasra */
+      return HB_UNICODE_COMBINING_CLASS_BELOW;
+
+
+    /* Thai */
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC103: /* sara u / sara uu */
+      return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC107: /* mai */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
+
+
+    /* Lao */
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC118: /* sign u / sign uu */
+      return HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC122: /* mai */
+      return HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT;
+
+
+    /* Tibetan */
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC129: /* sign aa */
+      return HB_UNICODE_COMBINING_CLASS_BELOW;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC130: /* sign i*/
+      return HB_UNICODE_COMBINING_CLASS_ABOVE;
+
+    case HB_MODIFIED_COMBINING_CLASS_CCC132: /* sign u */
+      return HB_UNICODE_COMBINING_CLASS_BELOW;
+
+  }
+
+  return klass;
+}
+
+void
+_hb_ot_shape_fallback_position_recategorize_marks (const hb_ot_shape_plan_t *plan,
+                                                   hb_font_t *font,
+                                                   hb_buffer_t  *buffer)
+{
+  unsigned int count = buffer->len;
+  for (unsigned int i = 0; i < count; i++)
+    if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) {
+      unsigned int combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
+      combining_class = recategorize_combining_class (buffer->info[i].codepoint, combining_class);
+      _hb_glyph_info_set_modified_combining_class (&buffer->info[i], combining_class);
+    }
+}
+
+
+static void
+zero_mark_advances (hb_buffer_t *buffer,
+                    unsigned int start,
+                    unsigned int end)
+{
+  for (unsigned int i = start; i < end; i++)
+    if (_hb_glyph_info_get_general_category (&buffer->info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
+    {
+      buffer->pos[i].x_advance = 0;
+      buffer->pos[i].y_advance = 0;
+    }
+}
+
+static inline void
+position_mark (const hb_ot_shape_plan_t *plan,
+               hb_font_t *font,
+               hb_buffer_t  *buffer,
+               hb_glyph_extents_t &base_extents,
+               unsigned int i,
+               unsigned int combining_class)
+{
+  hb_glyph_extents_t mark_extents;
+  if (!font->get_glyph_extents (buffer->info[i].codepoint,
+                                &mark_extents))
+    return;
+
+  hb_position_t y_gap = font->y_scale / 16;
+
+  hb_glyph_position_t &pos = buffer->pos[i];
+  pos.x_offset = pos.y_offset = 0;
+
+
+  /* We dont position LEFT and RIGHT marks. */
+
+  /* X positioning */
+  switch (combining_class)
+  {
+    case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
+    case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
+      if (buffer->props.direction == HB_DIRECTION_LTR) {
+        pos.x_offset += base_extents.x_bearing - mark_extents.width / 2 - mark_extents.x_bearing;
+        break;
+      } else if (buffer->props.direction == HB_DIRECTION_RTL) {
+        pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width / 2 - mark_extents.x_bearing;
+        break;
+      }
+      /* Fall through */
+
+    default:
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
+    case HB_UNICODE_COMBINING_CLASS_BELOW:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE:
+      /* Center align. */
+      pos.x_offset += base_extents.x_bearing + (base_extents.width - mark_extents.width) / 2 - mark_extents.x_bearing;
+      break;
+
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
+    case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
+      /* Left align. */
+      pos.x_offset += base_extents.x_bearing - mark_extents.x_bearing;
+      break;
+
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
+    case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
+      /* Right align. */
+      pos.x_offset += base_extents.x_bearing + base_extents.width - mark_extents.width - mark_extents.x_bearing;
+      break;
+  }
+
+  /* Y positioning */
+  switch (combining_class)
+  {
+    case HB_UNICODE_COMBINING_CLASS_DOUBLE_BELOW:
+    case HB_UNICODE_COMBINING_CLASS_BELOW_LEFT:
+    case HB_UNICODE_COMBINING_CLASS_BELOW:
+    case HB_UNICODE_COMBINING_CLASS_BELOW_RIGHT:
+      /* Add gap, fall-through. */
+      base_extents.height -= y_gap;
+
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW_LEFT:
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_BELOW:
+      pos.y_offset += base_extents.y_bearing + base_extents.height - mark_extents.y_bearing;
+      base_extents.height += mark_extents.height;
+      break;
+
+    case HB_UNICODE_COMBINING_CLASS_DOUBLE_ABOVE:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE_LEFT:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE:
+    case HB_UNICODE_COMBINING_CLASS_ABOVE_RIGHT:
+      /* Add gap, fall-through. */
+      base_extents.y_bearing += y_gap;
+      base_extents.height -= y_gap;
+
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE:
+    case HB_UNICODE_COMBINING_CLASS_ATTACHED_ABOVE_RIGHT:
+      pos.y_offset += base_extents.y_bearing - (mark_extents.y_bearing + mark_extents.height);
+      base_extents.y_bearing -= mark_extents.height;
+      base_extents.height += mark_extents.height;
+      break;
+  }
+}
+
+static inline void
+position_around_base (const hb_ot_shape_plan_t *plan,
+                      hb_font_t *font,
+                      hb_buffer_t  *buffer,
+                      unsigned int base,
+                      unsigned int end)
+{
+  hb_direction_t horiz_dir = HB_DIRECTION_INVALID;
+  hb_glyph_extents_t base_extents;
+  if (!font->get_glyph_extents (buffer->info[base].codepoint,
+                                &base_extents))
+  {
+    /* If extents don't work, zero marks and go home. */
+    zero_mark_advances (buffer, base + 1, end);
+    return;
+  }
+  base_extents.x_bearing += buffer->pos[base].x_offset;
+  base_extents.y_bearing += buffer->pos[base].y_offset;
+
+  unsigned int lig_id = get_lig_id (buffer->info[base]);
+  unsigned int num_lig_components = get_lig_num_comps (buffer->info[base]);
+
+  hb_position_t x_offset = 0, y_offset = 0;
+  if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
+    x_offset -= buffer->pos[base].x_advance;
+    y_offset -= buffer->pos[base].y_advance;
+  }
+
+  hb_glyph_extents_t component_extents = base_extents;
+  unsigned int last_lig_component = (unsigned int) -1;
+  unsigned int last_combining_class = 255;
+  hb_glyph_extents_t cluster_extents;
+  for (unsigned int i = base + 1; i < end; i++)
+    if (_hb_glyph_info_get_modified_combining_class (&buffer->info[i]))
+    {
+      if (num_lig_components > 1) {
+        unsigned int this_lig_id = get_lig_id (buffer->info[i]);
+        unsigned int this_lig_component = get_lig_comp (buffer->info[i]) - 1;
+        /* Conditions for attaching to the last component. */
+        if (!lig_id || lig_id != this_lig_id || this_lig_component >= num_lig_components)
+          this_lig_component = num_lig_components - 1;
+        if (last_lig_component != this_lig_component)
+        {
+          last_lig_component = this_lig_component;
+          last_combining_class = 255;
+          component_extents = base_extents;
+          if (unlikely (horiz_dir == HB_DIRECTION_INVALID)) {
+            if (HB_DIRECTION_IS_HORIZONTAL (plan->props.direction))
+              horiz_dir = plan->props.direction;
+            else
+              horiz_dir = hb_script_get_horizontal_direction (plan->props.script);
+          }
+          if (horiz_dir == HB_DIRECTION_LTR)
+            component_extents.x_bearing += (this_lig_component * component_extents.width) / num_lig_components;
+          else
+            component_extents.x_bearing += ((num_lig_components - 1 - this_lig_component) * component_extents.width) / num_lig_components;
+          component_extents.width /= num_lig_components;
+        }
+      }
+
+      unsigned int this_combining_class = _hb_glyph_info_get_modified_combining_class (&buffer->info[i]);
+      if (last_combining_class != this_combining_class)
+      {
+        last_combining_class = this_combining_class;
+        cluster_extents = component_extents;
+      }
+
+      position_mark (plan, font, buffer, cluster_extents, i, this_combining_class);
+
+      buffer->pos[i].x_advance = 0;
+      buffer->pos[i].y_advance = 0;
+      buffer->pos[i].x_offset += x_offset;
+      buffer->pos[i].y_offset += y_offset;
+
+    } else {
+      if (HB_DIRECTION_IS_FORWARD (buffer->props.direction)) {
+        x_offset -= buffer->pos[i].x_advance;
+        y_offset -= buffer->pos[i].y_advance;
+      } else {
+        x_offset += buffer->pos[i].x_advance;
+        y_offset += buffer->pos[i].y_advance;
+      }
+    }
+}
+
+static inline void
+position_cluster (const hb_ot_shape_plan_t *plan,
+                  hb_font_t *font,
+                  hb_buffer_t  *buffer,
+                  unsigned int start,
+                  unsigned int end)
+{
+  if (end - start < 2)
+    return;
+
+  /* Find the base glyph */
+  for (unsigned int i = start; i < end; i++)
+    if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[i])))
+    {
+      /* Find mark glyphs */
+      unsigned int j;
+      for (j = i + 1; j < end; j++)
+        if (!HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&buffer->info[j])))
+          break;
+
+      position_around_base (plan, font, buffer, i, j);
+
+      i = j - 1;
+    }
+}
+
+void
+_hb_ot_shape_fallback_position (const hb_ot_shape_plan_t *plan,
+                                hb_font_t *font,
+                                hb_buffer_t  *buffer)
+{
+  unsigned int start = 0;
+  unsigned int last_cluster = buffer->info[0].cluster;
+  unsigned int count = buffer->len;
+  for (unsigned int i = 1; i < count; i++)
+    if (buffer->info[i].cluster != last_cluster) {
+      position_cluster (plan, font, buffer, start, i);
+      start = i;
+      last_cluster = buffer->info[i].cluster;
+    }
+  position_cluster (plan, font, buffer, start, count);
+}