Allow native CFF hinter in FT_RENDER_MODE_LIGHT.

Both the native CFF hinter and the auto-hinter now have a very
similar rendering style.

* include/freetype/freetype.h: Mention that FT_LOAD_TARGET_LIGHT no
longer implies FT_LOAD_FORCE_AUTOHINT.

* include/freetype/ftmodapi.h (FT_MODULE_DRIVER_HINTS_LIGHTLY): New
macro.

* include/freetype/internal/ftobjs.h (FT_DRIVER_HINTS_LIGHTLY): New
macro.

* src/cff/cffdrivr.c (cff_driver_class): Use it.

* src/base/ftobjs.c (FT_Load_Glyph): Update auto-hinter selection
logic.

ChangeLog

@@ -1,3 +1,24 @@
+2015-11-10  Jan Alexander Steffens (heftig)  <jan.steffens@gmail.com>
+
+	Allow native CFF hinter in FT_RENDER_MODE_LIGHT.
+
+	Both the native CFF hinter and the auto-hinter now have a very
+	similar rendering style.
+
+	* include/freetype/freetype.h: Mention that FT_LOAD_TARGET_LIGHT no
+	longer implies FT_LOAD_FORCE_AUTOHINT.
+
+	* include/freetype/ftmodapi.h (FT_MODULE_DRIVER_HINTS_LIGHTLY): New
+	macro.
+
+	* include/freetype/internal/ftobjs.h (FT_DRIVER_HINTS_LIGHTLY): New
+	macro.
+
+	* src/cff/cffdrivr.c (cff_driver_class): Use it.
+
+	* src/base/ftobjs.c (FT_Load_Glyph): Update auto-hinter selection
+	logic.
+
 2015-11-09  Werner Lemberg  <wl@gnu.org>
 
 	* src/cid/cidload.c (cid_face_open): Fix GDBytes guard (#46408).

include/freetype/freetype.h

@@ -2821,9 +2821,6 @@ FT_BEGIN_HEADER
    *   have specified (e.g., the TrueType bytecode interpreter).  You can set
    *   @FT_LOAD_FORCE_AUTOHINT to ensure that the auto-hinter is used.
    *
-   *   Also note that @FT_LOAD_TARGET_LIGHT is an exception, in that it
-   *   always implies @FT_LOAD_FORCE_AUTOHINT.
-   *
    * @values:
    *   FT_LOAD_TARGET_NORMAL ::
    *     This corresponds to the default hinting algorithm, optimized for
@@ -2835,8 +2832,6 @@ FT_BEGIN_HEADER
    *     generated glyphs are more fuzzy but better resemble its original
    *     shape.  A bit like rendering on Mac OS~X.
    *
-   *     As a special exception, this target implies @FT_LOAD_FORCE_AUTOHINT.
-   *
    *   FT_LOAD_TARGET_MONO ::
    *     Strong hinting algorithm that should only be used for monochrome
    *     output.  The result is probably unpleasant if the glyph is rendered

include/freetype/ftmodapi.h

@@ -111,12 +111,14 @@ FT_BEGIN_HEADER
 #define FT_MODULE_HINTER              4  /* this module is a glyph hinter */
 #define FT_MODULE_STYLER              8  /* this module is a styler       */
 
-#define FT_MODULE_DRIVER_SCALABLE     0x100   /* the driver supports      */
+#define FT_MODULE_DRIVER_SCALABLE      0x100  /* the driver supports      */
                                               /* scalable fonts           */
-#define FT_MODULE_DRIVER_NO_OUTLINES  0x200   /* the driver does not      */
+#define FT_MODULE_DRIVER_NO_OUTLINES   0x200  /* the driver does not      */
                                               /* support vector outlines  */
-#define FT_MODULE_DRIVER_HAS_HINTER   0x400   /* the driver provides its  */
+#define FT_MODULE_DRIVER_HAS_HINTER    0x400  /* the driver provides its  */
                                               /* own hinter               */
+#define FT_MODULE_DRIVER_HINTS_LIGHTLY 0x800  /* the driver's hinter      */
+                                              /* produces LIGHT hints     */
 
 
   /* deprecated values */
@@ -125,9 +127,10 @@ FT_BEGIN_HEADER
 #define ft_module_hinter              FT_MODULE_HINTER
 #define ft_module_styler              FT_MODULE_STYLER
 
-#define ft_module_driver_scalable     FT_MODULE_DRIVER_SCALABLE
-#define ft_module_driver_no_outlines  FT_MODULE_DRIVER_NO_OUTLINES
-#define ft_module_driver_has_hinter   FT_MODULE_DRIVER_HAS_HINTER
+#define ft_module_driver_scalable       FT_MODULE_DRIVER_SCALABLE
+#define ft_module_driver_no_outlines    FT_MODULE_DRIVER_NO_OUTLINES
+#define ft_module_driver_has_hinter     FT_MODULE_DRIVER_HAS_HINTER
+#define ft_module_driver_hints_lightly  FT_MODULE_DRIVER_HINTS_LIGHTLY
 
 
   typedef FT_Pointer  FT_Module_Interface;

include/freetype/internal/ftobjs.h

@@ -506,6 +506,9 @@ FT_BEGIN_HEADER
 #define FT_DRIVER_HAS_HINTER( x )  ( FT_MODULE_CLASS( x )->module_flags & \
                                      FT_MODULE_DRIVER_HAS_HINTER )
 
+#define FT_DRIVER_HINTS_LIGHTLY( x )  ( FT_MODULE_CLASS( x )->module_flags & \
+                                        FT_MODULE_DRIVER_HINTS_LIGHTLY )
+
 
   /*************************************************************************/
   /*                                                                       */

src/base/ftobjs.c

@@ -686,7 +686,8 @@
         /* check the size of the `fpgm' and `prep' tables, too --    */
         /* the assumption is that there don't exist real TTFs where  */
         /* both `fpgm' and `prep' tables are missing                 */
-        if ( mode == FT_RENDER_MODE_LIGHT                       ||
+        if ( ( mode == FT_RENDER_MODE_LIGHT                   &&
+               !FT_DRIVER_HINTS_LIGHTLY( driver ) )             ||
              face->internal->ignore_unpatented_hinter           ||
              ( FT_IS_SFNT( face )                             &&
                ttface->num_locations                          &&

src/cff/cffdrivr.c

@@ -870,9 +870,10 @@
   FT_DEFINE_DRIVER(
     cff_driver_class,
 
-      FT_MODULE_FONT_DRIVER       |
-      FT_MODULE_DRIVER_SCALABLE   |
-      FT_MODULE_DRIVER_HAS_HINTER,
+      FT_MODULE_FONT_DRIVER          |
+      FT_MODULE_DRIVER_SCALABLE      |
+      FT_MODULE_DRIVER_HAS_HINTER    |
+      FT_MODULE_DRIVER_HINTS_LIGHTLY,
 
       sizeof ( CFF_DriverRec ),
       "cff",