COLRv1: use ClipBoxes for extents

This is a first step; ultimatively, we
should compute the extents is ClipBoxes
are missing.

src/hb-ot-color-colr-table.hh

@@ -928,6 +928,24 @@ struct ClipBox
     }
   }
 
+  bool get_extents (hb_glyph_extents_t *extents) const
+  {
+    switch (u.format) {
+    case 1:
+      extents->x_bearing = u.format1.xMin;
+      extents->y_bearing = u.format1.yMax;
+      extents->width = u.format1.xMax - u.format1.xMin;
+      extents->height = u.format1.yMin - u.format1.yMax;
+      return true;
+    case 2:
+      // TODO
+      return false;
+    default:
+      // This shouldn't happen
+      return false;
+    }
+  }
+
   protected:
   union {
   HBUINT8		format;         /* Format identifier */
@@ -953,6 +971,11 @@ struct ClipRecord
     return_trace (c->check_struct (this) && clipBox.sanitize (c, base));
   }
 
+  bool get_extents (hb_glyph_extents_t *extents, const void *base) const
+  {
+    return (base+clipBox).get_extents (extents);
+  }
+
   public:
   HBUINT16		startGlyphID;  // first gid clip applies to
   HBUINT16		endGlyphID;    // last gid clip applies to, inclusive
@@ -1052,6 +1075,17 @@ struct ClipList
     return_trace (c->check_struct (this) && clips.sanitize (c, this));
   }
 
+  bool
+  get_extents (hb_codepoint_t gid, hb_glyph_extents_t *extents) const
+  {
+    for (const ClipRecord& record : clips.iter ())
+    {
+      if (record.startGlyphID <= gid && gid <= record.endGlyphID)
+        return record.get_extents (extents, this);
+    }
+    return false;
+  }
+
   HBUINT8			format;  // Set to 1.
   SortedArray32Of<ClipRecord>	clips;  // Clip records, sorted by startGlyphID
   public:
@@ -1513,6 +1547,21 @@ struct COLR
     return_trace (true);
   }
 
+  bool
+  get_extents (hb_font_t *font, hb_codepoint_t glyph, hb_glyph_extents_t *extents) const
+  {
+    if ((this+clipList).get_extents (glyph, extents))
+      {
+        extents->x_bearing = font->em_scale_x (extents->x_bearing);
+        extents->y_bearing = font->em_scale_x (extents->y_bearing);
+        extents->width = font->em_scale_x (extents->width);
+        extents->height = font->em_scale_x (extents->height);
+        return true;
+      }
+
+    return false;
+  }
+
   protected:
   HBUINT16	version;	/* Table version number (starts at 0). */
   HBUINT16	numBaseGlyphs;	/* Number of Base Glyph Records. */

src/hb-ot-font.cc

@@ -45,6 +45,7 @@
 #include "hb-ot-vorg-table.hh"
 #include "hb-ot-color-cbdt-table.hh"
 #include "hb-ot-color-sbix-table.hh"
+#include "hb-ot-color-colr-table.hh"
 
 
 /**
@@ -349,6 +350,9 @@ hb_ot_get_glyph_extents (hb_font_t *font,
 #if !defined(HB_NO_OT_FONT_BITMAP) && !defined(HB_NO_COLOR)
   if (ot_face->sbix->get_extents (font, glyph, extents)) return true;
   if (ot_face->CBDT->get_extents (font, glyph, extents)) return true;
+#endif
+#if !defined(HB_NO_COLOR)
+  if (ot_face->COLR->get_extents (font, glyph, extents)) return true;
 #endif
   if (ot_face->glyf->get_extents (font, glyph, extents)) return true;
 #ifndef HB_NO_OT_FONT_CFF