[truetype] Binary search through `hdmx` records.

The `hdmx` table is supposed to be sorted by ppem size, which
enables binary search.  We also drop the check for the sufficient
length of the record because it is now enforced when the table
is loaded.

* include/freetype/internal/tttypes.h (TT_FaceRec): Store the `hdmx`
record pointers sorted by ppem instead of ppem's themselves.
* src/truetype/ttpload.c (tt_face_load_hdmx): Prudently sort records.
(tt_face_get_device_metrics): Implement binary search to retrieve
advances.

include/freetype/internal/tttypes.h

@@ -1390,8 +1390,8 @@ FT_BEGIN_HEADER
    *   hdmx_record_size ::
    *     The size of a single hdmx record.
    *
-   *   hdmx_record_sizes ::
-   *     An array holding the ppem sizes available in the 'hdmx' table.
+   *   hdmx_records ::
+   *     A array of pointers to the 'hdmx' table records sorted by ppem.
    *
    *   sbit_table ::
    *     A pointer to the font's embedded bitmap location table.
@@ -1605,7 +1605,7 @@ FT_BEGIN_HEADER
     FT_ULong              hdmx_table_size;
     FT_UInt               hdmx_record_count;
     FT_ULong              hdmx_record_size;
-    FT_Byte*              hdmx_record_sizes;
+    FT_Byte**             hdmx_records;
 
     FT_Byte*              sbit_table;
     FT_ULong              sbit_table_size;
@@ -1769,6 +1769,9 @@ FT_BEGIN_HEADER
     /* since version 2.6.2 */
     FT_ListRec       composites;
 
+    /* since version 2.11.2 */
+    FT_Byte*         widthp;
+
   } TT_LoaderRec;
 
 

src/truetype/ttgload.c

@@ -2230,10 +2230,6 @@
                          FT_UInt    glyph_index )
   {
     TT_Face    face   = loader->face;
-#if defined TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY || \
-    defined TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
-    TT_Driver  driver = (TT_Driver)FT_FACE_DRIVER( face );
-#endif
 
     FT_BBox       bbox;
     FT_Fixed      y_scale;
@@ -2256,37 +2252,10 @@
 
     glyph->metrics.horiBearingX = bbox.xMin;
     glyph->metrics.horiBearingY = bbox.yMax;
-    glyph->metrics.horiAdvance  = SUB_LONG(loader->pp2.x, loader->pp1.x);
-
-    /* Adjust advance width to the value contained in the hdmx table   */
-    /* unless FT_LOAD_COMPUTE_METRICS is set or backward compatibility */
-    /* mode of the v40 interpreter is active.  See `ttinterp.h' for    */
-    /* details on backward compatibility mode.                         */
-    if ( IS_HINTED( loader->load_flags )                                &&
-         !( loader->load_flags & FT_LOAD_COMPUTE_METRICS )              &&
-#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
-         !( driver->interpreter_version == TT_INTERPRETER_VERSION_40  &&
-            ( loader->exec && loader->exec->backward_compatibility  ) ) &&
-#endif
-#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
-         !( driver->interpreter_version == TT_INTERPRETER_VERSION_38  &&
-            !SPH_OPTION_BITMAP_WIDTHS                                 &&
-            FT_LOAD_TARGET_MODE( loader->load_flags ) !=
-                                                 FT_RENDER_MODE_MONO  &&
-            ( loader->exec && !loader->exec->compatible_widths )      ) &&
-#endif
-         !face->postscript.isFixedPitch                                 )
-    {
-      FT_Byte*  widthp;
-
-
-      widthp = tt_face_get_device_metrics( face,
-                                           size->metrics->x_ppem,
-                                           glyph_index );
-
-      if ( widthp )
-        glyph->metrics.horiAdvance = *widthp * 64;
-    }
+    if ( loader->widthp )
+      glyph->metrics.horiAdvance = loader->widthp[glyph_index] * 64;
+    else
+      glyph->metrics.horiAdvance = SUB_LONG(loader->pp2.x, loader->pp1.x);
 
     /* set glyph dimensions */
     glyph->metrics.width  = SUB_LONG( bbox.xMax, bbox.xMin );
@@ -2720,11 +2689,64 @@
       if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 &&
            exec->GS.instruct_control & 4                            )
         exec->ignore_x_mode = 0;
-#endif
+
+      exec->iup_called = FALSE;
+#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */
+
+#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
+      /*
+       * Toggle backward compatibility according to what font wants, except
+       * when
+       *
+       * 1) we have a `tricky' font that heavily relies on the interpreter to
+       *    render glyphs correctly, for example DFKai-SB, or
+       * 2) FT_RENDER_MODE_MONO (i.e, monochome rendering) is requested.
+       *
+       * In those cases, backward compatibility needs to be turned off to get
+       * correct rendering.  The rendering is then completely up to the
+       * font's programming.
+       *
+       */
+      if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 &&
+           subpixel_hinting_lean                                    &&
+           !FT_IS_TRICKY( glyph->face )                             )
+        exec->backward_compatibility = !( exec->GS.instruct_control & 4 );
+      else
+        exec->backward_compatibility = FALSE;
+
+      exec->iupx_called = FALSE;
+      exec->iupy_called = FALSE;
+#endif /* TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL */
 
       exec->pedantic_hinting = FT_BOOL( load_flags & FT_LOAD_PEDANTIC );
       loader->exec = exec;
       loader->instructions = exec->glyphIns;
+
+      /* Use the hdmx table if any unless FT_LOAD_COMPUTE_METRICS */
+      /* is set or backward compatibility mode of the v38 or v40  */
+      /* interpreters is active.  See `ttinterp.h' for details on */
+      /* backward compatibility mode.                             */
+      if ( IS_HINTED( loader->load_flags )                                &&
+           !( loader->load_flags & FT_LOAD_COMPUTE_METRICS )              &&
+#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
+           !( driver->interpreter_version == TT_INTERPRETER_VERSION_40  &&
+              exec->backward_compatibility                              ) &&
+#endif
+#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
+           !( driver->interpreter_version == TT_INTERPRETER_VERSION_38  &&
+              !SPH_OPTION_BITMAP_WIDTHS                                 &&
+              FT_LOAD_TARGET_MODE( loader->load_flags ) !=
+                                                   FT_RENDER_MODE_MONO  &&
+              exec->compatible_widths                                   ) &&
+#endif
+           !face->postscript.isFixedPitch                                 )
+      {
+        loader->widthp = tt_face_get_device_metrics( face,
+                                                     size->metrics->x_ppem,
+                                                     0 );
+      }
+      else
+        loader->widthp = NULL;
     }
 
 #endif /* TT_USE_BYTECODE_INTERPRETER */
@@ -2923,6 +2945,15 @@
     if ( error )
       goto Exit;
 
+    /* done if we are only interested in the `hdmx` advance */
+    if ( load_flags & FT_LOAD_ADVANCE_ONLY         &&
+         !( load_flags & FT_LOAD_VERTICAL_LAYOUT ) &&
+         loader.widthp                             )
+    {
+      glyph->metrics.horiAdvance = loader.widthp[glyph_index] * 64;
+      goto Done;
+    }
+
     glyph->format        = FT_GLYPH_FORMAT_OUTLINE;
     glyph->num_subglyphs = 0;
     glyph->outline.flags = 0;
@@ -3001,6 +3032,7 @@
                 glyph->outline.n_points,
                 glyph->outline.flags ));
 
+  Done:
     tt_loader_done( &loader );
 
   Exit:

src/truetype/ttinterp.c

@@ -5260,10 +5260,15 @@
       }
     }
 
-    exc->GS.instruct_control &= ~(FT_Byte)Kf;
-    exc->GS.instruct_control |= (FT_Byte)L;
+    /* INSTCTRL should only be used in the CVT program */
+    if ( exc->iniRange == tt_coderange_cvt )
+    {
+      exc->GS.instruct_control &= ~(FT_Byte)Kf;
+      exc->GS.instruct_control |= (FT_Byte)L;
+    }
 
-    if ( K == 3 )
+    /* except to change the subpixel flags temporarily */
+    else if ( exc->iniRange == tt_coderange_glyph && K == 3 )
     {
 #ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
       /* INSTCTRL modifying flag 3 also has an effect */
@@ -7755,35 +7760,6 @@
 #endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */
 
 
-#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
-    exc->iup_called = FALSE;
-#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */
-
-#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
-    /*
-     * Toggle backward compatibility according to what font wants, except
-     * when
-     *
-     * 1) we have a `tricky' font that heavily relies on the interpreter to
-     *    render glyphs correctly, for example DFKai-SB, or
-     * 2) FT_RENDER_MODE_MONO (i.e, monochome rendering) is requested.
-     *
-     * In those cases, backward compatibility needs to be turned off to get
-     * correct rendering.  The rendering is then completely up to the
-     * font's programming.
-     *
-     */
-    if ( SUBPIXEL_HINTING_MINIMAL          &&
-         exc->subpixel_hinting_lean        &&
-         !FT_IS_TRICKY( &exc->face->root ) )
-      exc->backward_compatibility = !( exc->GS.instruct_control & 4 );
-    else
-      exc->backward_compatibility = FALSE;
-
-    exc->iupx_called = FALSE;
-    exc->iupy_called = FALSE;
-#endif
-
     /* We restrict the number of twilight points to a reasonable,     */
     /* heuristic value to avoid slow execution of malformed bytecode. */
     num_twilight_points = FT_MAX( 30,

src/truetype/ttpload.c

@@ -498,6 +498,14 @@
   }
 
 
+  FT_COMPARE_DEF( int )
+  compare_ppem( const void*  a,
+                const void*  b )
+  {
+    return **(FT_Byte**)a - **(FT_Byte**)b;
+  }
+
+
   /**************************************************************************
    *
    * @Function:
@@ -574,20 +582,21 @@
       goto Fail;
     }
 
-    if ( FT_QNEW_ARRAY( face->hdmx_record_sizes, num_records ) )
+    if ( FT_QNEW_ARRAY( face->hdmx_records, num_records ) )
       goto Fail;
 
-    /* XXX: We do not check if the records are sorted by ppem */
-    /* and cannot use binary search later.                    */
     for ( nn = 0; nn < num_records; nn++ )
     {
       if ( p + record_size > limit )
         break;
-
-      face->hdmx_record_sizes[nn] = p[0];
-      p                          += record_size;
+      face->hdmx_records[nn] = p;
+      p                     += record_size;
     }
 
+    /* The records must be already sorted by ppem but it does not */
+    /* hurt to make sure so that the binary search works later.   */
+    ft_qsort( face->hdmx_records, nn, sizeof ( FT_Byte* ), compare_ppem );
+
     face->hdmx_record_count = nn;
     face->hdmx_table_size   = table_size;
     face->hdmx_record_size  = record_size;
@@ -611,7 +620,7 @@
     FT_Memory  memory = stream->memory;
 
 
-    FT_FREE( face->hdmx_record_sizes );
+    FT_FREE( face->hdmx_records );
     FT_FRAME_RELEASE( face->hdmx_table );
   }
 
@@ -619,27 +628,34 @@
   /**************************************************************************
    *
    * Return the advance width table for a given pixel size if it is found
-   * in the font's `hdmx' table (if any).
+   * in the font's `hdmx' table (if any).  The records must be sorted for
+   * the binary search to work properly.
    */
   FT_LOCAL_DEF( FT_Byte* )
   tt_face_get_device_metrics( TT_Face  face,
                               FT_UInt  ppem,
                               FT_UInt  gindex )
   {
-    FT_UInt   nn;
-    FT_Byte*  result      = NULL;
-    FT_ULong  record_size = face->hdmx_record_size;
-    FT_Byte*  record      = FT_OFFSET( face->hdmx_table, 8 );
+    FT_UInt   min    = 0;
+    FT_UInt   max    = face->hdmx_record_count;
+    FT_UInt   mid;
+    FT_Byte*  result = NULL;
 
 
-    for ( nn = 0; nn < face->hdmx_record_count; nn++ )
-      if ( face->hdmx_record_sizes[nn] == ppem )
+    while ( min < max )
+    {
+      mid = ( min + max ) >> 1;
+
+      if ( face->hdmx_records[mid][0] > ppem )
+        max = mid;
+      else if ( face->hdmx_records[mid][0] < ppem )
+        min = mid + 1;
+      else
       {
-        gindex += 2;
-        if ( gindex < record_size )
-          result = record + nn * record_size + gindex;
+        result = face->hdmx_records[mid] + 2 + gindex;
         break;
       }
+    }
 
     return result;
   }