Optimize memory consumption for simple GPOS tables

Sometimes GPOS tables are used for kerning and can grow quite
large if the font is unoptimized. In that case, allocating the
maximum size for each ValueRecord will have a great impact on
memory consumption. For GPOS tables which do not contain device
tables, we only allocate the memory actually need to store the
data instead.

While it would be possible to optimize memory for GPOS tables that
contain device tables as well, this is not a part of this patch.

Change-Id: Id665b2821675ef955c497c782f09f99af765b8a3
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

2 files changed, 170 insertions, 57 deletions

diff --git a/src/3rdparty/harfbuzz/src/harfbuzz-gpos-private.h b/src/3rdparty/harfbuzz/src/harfbuzz-gpos-private.h
index 63ba90797d..b363b81d87 100644
--- a/src/3rdparty/harfbuzz/src/harfbuzz-gpos-private.h
+++ b/src/3rdparty/harfbuzz/src/harfbuzz-gpos-private.h
@@ -39,6 +39,10 @@ HB_BEGIN_HEADER
 #define VR_X_ADVANCE_DEVICE   2
 #define VR_Y_ADVANCE_DEVICE   3
 
+#ifndef HB_SUPPORT_MULTIPLE_MASTER
+#  define HB_USE_FLEXIBLE_VALUE_RECORD
+#endif
+
 struct  HB_ValueRecord_
 {
   HB_Short    XPlacement;             /* horizontal adjustment for
@@ -242,7 +246,11 @@ typedef struct HB_Class2Record_  HB_Class2Record;
 
 struct  HB_Class1Record_
 {
-  HB_Class2Record*  Class2Record;    /* array of Class2Record tables */
+  hb_uint8 IsFlexible;
+  union {
+    HB_Class2Record*  Class2Record;    /* array of Class2Record tables */
+    HB_Short* ValueRecords;
+  } c2r;
 };
 
 typedef struct HB_Class1Record_  HB_Class1Record;
diff --git a/src/3rdparty/harfbuzz/src/harfbuzz-gpos.c b/src/3rdparty/harfbuzz/src/harfbuzz-gpos.c
index a21600579e..2a86cb21e9 100644
--- a/src/3rdparty/harfbuzz/src/harfbuzz-gpos.c
+++ b/src/3rdparty/harfbuzz/src/harfbuzz-gpos.c
@@ -194,6 +194,43 @@ HB_Error  HB_Done_GPOS_Table( HB_GPOSHeader* gpos )
 
 /* ValueRecord */
 
+static HB_Error  Get_FlexibleValueRecord( GPOS_Instance*   gpi,
+                                          HB_Short*        vr,
+                                          HB_UShort        format,
+                                          HB_Position      gd )
+{
+  HB_Error         error = HB_Err_Ok;
+
+  HB_16Dot16   x_scale, y_scale;
+
+  if ( !format )
+    return HB_Err_Ok;
+
+  x_scale = gpi->font->x_scale;
+  y_scale = gpi->font->y_scale;
+
+  /* design units -> fractional pixel */
+
+  if ( format & HB_GPOS_FORMAT_HAVE_X_PLACEMENT ) {
+    gd->x_pos += *vr * x_scale / 0x10000;
+    vr++;
+  }
+  if ( format & HB_GPOS_FORMAT_HAVE_Y_PLACEMENT ) {
+    gd->y_pos += *vr * y_scale / 0x10000;
+    vr++;
+  }
+  if ( format & HB_GPOS_FORMAT_HAVE_X_ADVANCE ) {
+    gd->x_advance += *vr * x_scale / 0x10000;
+    vr++;
+  }
+  if ( format & HB_GPOS_FORMAT_HAVE_Y_ADVANCE ) {
+    gd->y_advance += *vr * y_scale  / 0x10000;
+    vr++;
+  }
+
+  return error;
+}
+
 /* There is a subtle difference in the specs between a `table' and a
    `record' -- offsets for device tables in ValueRecords are taken from
    the parent table and not the parent record.                          */
@@ -1245,6 +1282,19 @@ static void  Free_PairPos1( HB_PairPosFormat1*  ppf1,
   }
 }
 
+static HB_UInt Calculate_Class2RecordSize(HB_UShort format1, HB_UShort format2)
+{
+    // Return number of 16 bit values in two value records with given formats
+    return  (format1 & 0x01)       +  (format2 & 0x01)
+         + ((format1 & 0x02) >> 1) + ((format2 & 0x02) >> 1)
+         + ((format1 & 0x04) >> 2) + ((format2 & 0x04) >> 2)
+         + ((format1 & 0x08) >> 3) + ((format2 & 0x08) >> 3)
+         + ((format1 & 0x10) >> 4) + ((format2 & 0x10) >> 4)
+         + ((format1 & 0x20) >> 5) + ((format2 & 0x20) >> 5)
+         + ((format1 & 0x40) >> 6) + ((format2 & 0x40) >> 6)
+         + ((format1 & 0x80) >> 7) + ((format2 & 0x80) >> 7);
+}
+
 
 /* PairPosFormat2 */
 
@@ -1256,11 +1306,14 @@ static HB_Error  Load_PairPos2( HB_PairPosFormat2*  ppf2,
   HB_Error  error;
 
   HB_UShort          m, n, k, count1, count2;
-  HB_UInt           cur_offset, new_offset1, new_offset2, base_offset;
+  HB_UInt           cur_offset, new_offset1, new_offset2, base_offset, cls2_record_size = 0;
 
   HB_Class1Record*  c1r;
   HB_Class2Record*  c2r;
 
+  HB_Short* vr;
+
+  hb_uint8 use_flexible_value_records;
 
   base_offset = FILE_Pos() - 8L;
 
@@ -1276,6 +1329,13 @@ static HB_Error  Load_PairPos2( HB_PairPosFormat2*  ppf2,
   count1 = ppf2->Class1Count = GET_UShort();
   count2 = ppf2->Class2Count = GET_UShort();
 
+#ifndef HB_USE_FLEXIBLE_VALUE_RECORD
+  use_flexible_value_records = 0;
+#else
+  use_flexible_value_records = !((format1 & HB_GPOS_FORMAT_HAVE_DEVICE_TABLES) ||
+                                 (format2 & HB_GPOS_FORMAT_HAVE_DEVICE_TABLES));
+#endif
+
   FORGET_Frame();
 
   cur_offset = FILE_Pos();
@@ -1296,35 +1356,55 @@ static HB_Error  Load_PairPos2( HB_PairPosFormat2*  ppf2,
 
   c1r = ppf2->Class1Record;
 
+  if ( use_flexible_value_records )
+    cls2_record_size = Calculate_Class2RecordSize(format1, format2);
+
   for ( m = 0; m < count1; m++ )
   {
-    c1r[m].Class2Record = NULL;
-
-    if ( ALLOC_ARRAY( c1r[m].Class2Record, count2, HB_Class2Record ) )
-      goto Fail1;
-
-    c2r = c1r[m].Class2Record;
-
-    for ( n = 0; n < count2; n++ )
-    {
-      if ( format1 )
-      {
-	error = Load_ValueRecord( &c2r[n].Value1, format1,
-				  base_offset, stream );
-	if ( error )
-	  goto Fail0;
-      }
-      if ( format2 )
-      {
-	error = Load_ValueRecord( &c2r[n].Value2, format2,
-				  base_offset, stream );
-	if ( error )
-	{
-	  if ( format1 )
-	    Free_ValueRecord( &c2r[n].Value1, format1 );
-	  goto Fail0;
-	}
-      }
+    c1r[m].IsFlexible = use_flexible_value_records;
+    if ( use_flexible_value_records ) {
+        c1r[m].c2r.ValueRecords = NULL;
+
+        if ( ALLOC_ARRAY( c1r[m].c2r.ValueRecords, count2 * cls2_record_size, HB_UShort ) )
+          goto Fail1;
+
+        vr = c1r[m].c2r.ValueRecords;
+
+        if ( ACCESS_Frame( count2 * cls2_record_size * 2L ))
+            goto Fail1;
+
+        for ( n = 0; n < count2 * cls2_record_size; n++ )
+            vr[n] = GET_Short();
+
+        FORGET_Frame();
+    } else {
+        c1r[m].c2r.Class2Record = NULL;
+
+        if ( ALLOC_ARRAY( c1r[m].c2r.Class2Record, count2, HB_Class2Record ) )
+          goto Fail1;
+
+        c2r = c1r[m].c2r.Class2Record;
+        for ( n = 0; n < count2; n++ )
+        {
+            if ( format1 )
+            {
+                error = Load_ValueRecord( &c2r[n].Value1, format1,
+                                          base_offset, stream );
+                if ( error )
+                    goto Fail0;
+            }
+            if ( format2 )
+            {
+                error = Load_ValueRecord( &c2r[n].Value2, format2,
+                                          base_offset, stream );
+                if ( error )
+                {
+                    if ( format1 )
+                        Free_ValueRecord( &c2r[n].Value1, format1 );
+                    goto Fail0;
+                }
+            }
+        }
     }
 
     continue;
@@ -1345,17 +1425,21 @@ static HB_Error  Load_PairPos2( HB_PairPosFormat2*  ppf2,
 Fail1:
   for ( k = 0; k < m; k++ )
   {
-    c2r = c1r[k].Class2Record;
-
-    for ( n = 0; n < count2; n++ )
-    {
-      if ( format1 )
-	Free_ValueRecord( &c2r[n].Value1, format1 );
-      if ( format2 )
-	Free_ValueRecord( &c2r[n].Value2, format2 );
-    }
-
-    FREE( c2r );
+      if ( !use_flexible_value_records ) {
+        c2r = c1r[k].c2r.Class2Record;
+
+        for ( n = 0; n < count2; n++ )
+        {
+          if ( format1 )
+        Free_ValueRecord( &c2r[n].Value1, format1 );
+          if ( format2 )
+        Free_ValueRecord( &c2r[n].Value2, format2 );
+        }
+
+        FREE( c2r );
+      } else {
+          FREE( c1r[k].c2r.ValueRecords );
+      }
   }
 
   FREE( c1r );
@@ -1387,17 +1471,21 @@ static void  Free_PairPos2( HB_PairPosFormat2*  ppf2,
 
     for ( m = 0; m < count1; m++ )
     {
-      c2r = c1r[m].Class2Record;
-
-      for ( n = 0; n < count2; n++ )
-      {
-	if ( format1 )
-	  Free_ValueRecord( &c2r[n].Value1, format1 );
-	if ( format2 )
-	  Free_ValueRecord( &c2r[n].Value2, format2 );
-      }
-
-      FREE( c2r );
+        if ( !c1r[m].IsFlexible ) {
+            c2r = c1r[m].c2r.Class2Record;
+
+            for ( n = 0; n < count2; n++ )
+            {
+                if ( format1 )
+                    Free_ValueRecord( &c2r[n].Value1, format1 );
+                if ( format2 )
+                    Free_ValueRecord( &c2r[n].Value2, format2 );
+            }
+
+            FREE( c2r );
+        } else {
+            FREE( c1r[m].c2r.ValueRecords );
+        }
     }
 
     FREE( c1r );
@@ -1544,6 +1632,10 @@ static HB_Error  Lookup_PairPos2( GPOS_Instance*       gpi,
 
   HB_Class1Record*  c1r;
   HB_Class2Record*  c2r;
+  HB_Short*         vr;
+
+  HB_UShort         vr1_size;
+  HB_UShort         vr2_size;
 
 
   error = _HB_OPEN_Get_Class( &ppf2->ClassDef1, IN_GLYPH( first_pos ),
@@ -1558,14 +1650,27 @@ static HB_Error  Lookup_PairPos2( GPOS_Instance*       gpi,
   c1r = &ppf2->Class1Record[cl1];
   if ( !c1r )
     return ERR(HB_Err_Invalid_SubTable);
-  c2r = &c1r->Class2Record[cl2];
 
-  error = Get_ValueRecord( gpi, &c2r->Value1, format1, POSITION( first_pos ) );
-  if ( error )
-    return error;
-  return Get_ValueRecord( gpi, &c2r->Value2, format2, POSITION( buffer->in_pos ) );
-}
+  if ( !c1r->IsFlexible ) {
+      c2r = &c1r->c2r.Class2Record[cl2];
 
+      error = Get_ValueRecord( gpi, &c2r->Value1, format1, POSITION( first_pos ) );
+      if ( error )
+          return error;
+      return Get_ValueRecord( gpi, &c2r->Value2, format2, POSITION( buffer->in_pos ) );
+  } else {
+      vr1_size = Calculate_Class2RecordSize( format1, 0 );
+      vr2_size = Calculate_Class2RecordSize( format2, 0 );
+
+      vr = c1r->c2r.ValueRecords + (cl2 * ( vr1_size + vr2_size ));
+
+      error = Get_FlexibleValueRecord( gpi, vr, format1, POSITION( first_pos ) );
+      if ( error )
+          return error;
+      vr += vr1_size; // Skip to second record
+      return Get_FlexibleValueRecord( gpi, vr, format2, POSITION( buffer->in_pos ) );
+  }
+}
 
 static HB_Error  Lookup_PairPos( GPOS_Instance*    gpi,
 				 HB_GPOS_SubTable* st,