[autofit] Remove `slight' auto-hint mode again.

A poll on freetype-devel favoured changes directly applied to
`light'.

* include/freetype/freetype.h (FT_LOAD_TARGET_SLIGHT,
FT_RENDER_MODE_SLIGHT): Removed.

* src/autofit/afcjk.c (af_cjk_hints_init), src/autofit/aflatin.c
(af_latin_hints_init), src/autofit/aflatin2.c
(af_latin2_hints_init): Revert change from 2017-04-22.

* src/autofit/afloader.c (af_loader_load_glyph) Remove references to
FT_RENDER_MODE_SLIGHT.
[AF_CONFIG_OPTION_TT_SIZE_METRICS]: Enable TrueType-like metrics
unconditionally.

* src/base/ftadvanc.c (LOAD_ADVANCE_FAST_CHECK): Revert change from
2017-04-22.

* src/base/ftobjs.c (FT_Load_Glyph): Revert change from 2017-04-22.

* src/pshinter/pshalgo.c (ps_hints_apply): Revert change from
2017-04-22.

* src/smooth/ftsmooth.c (ft_smooth_render): Revert change from
2017-04-22.

* docs/CHANGES: Updated.

10 files changed, 32 insertions, 55 deletions

diff --git a/src/autofit/afcjk.c b/src/autofit/afcjk.c
index 86b8b4067..61e29cded 100644
--- a/src/autofit/afcjk.c
+++ b/src/autofit/afcjk.c
@@ -1398,12 +1398,9 @@
       other_flags |= AF_LATIN_HINTS_VERT_SNAP;
 
     /*
-     *  We adjust stems to full pixels unless in `light', `slight',
-     *  or `lcd' mode.
+     *  We adjust stems to full pixels unless in `light' or `lcd' mode.
      */
-    if ( mode != FT_RENDER_MODE_LIGHT  &&
-         mode != FT_RENDER_MODE_SLIGHT &&
-         mode != FT_RENDER_MODE_LCD    )
+    if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
       other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
 
     if ( mode == FT_RENDER_MODE_MONO )
diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index e03fdf01f..11fa523c8 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -2577,9 +2577,7 @@
     /*
      *  We adjust stems to full pixels unless in `light' or `lcd' mode.
      */
-    if ( mode != FT_RENDER_MODE_LIGHT  &&
-         mode != FT_RENDER_MODE_SLIGHT &&
-         mode != FT_RENDER_MODE_LCD    )
+    if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
       other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
 
     if ( mode == FT_RENDER_MODE_MONO )
@@ -2592,10 +2590,8 @@
      *  However, if warping is enabled (which only works in `light' hinting
      *  mode), advance widths get adjusted, too.
      */
-    if ( mode == FT_RENDER_MODE_LIGHT                      ||
-         mode == FT_RENDER_MODE_SLIGHT                     ||
-         mode == FT_RENDER_MODE_LCD                        ||
-         ( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
+    if ( mode == FT_RENDER_MODE_LIGHT || mode == FT_RENDER_MODE_LCD ||
+         ( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0          )
       scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;
 
 #ifdef AF_CONFIG_OPTION_USE_WARPER
diff --git a/src/autofit/aflatin2.c b/src/autofit/aflatin2.c
index 87ab91d8e..0607278b1 100644
--- a/src/autofit/aflatin2.c
+++ b/src/autofit/aflatin2.c
@@ -1560,9 +1560,7 @@
     /*
      *  We adjust stems to full pixels unless in `light' or `lcd' mode.
      */
-    if ( mode != FT_RENDER_MODE_LIGHT  &&
-         mode != FT_RENDER_MODE_SLIGHT &&
-         mode != FT_RENDER_MODE_LCD    )
+    if ( mode != FT_RENDER_MODE_LIGHT && mode != FT_RENDER_MODE_LCD )
       other_flags |= AF_LATIN_HINTS_STEM_ADJUST;
 
     if ( mode == FT_RENDER_MODE_MONO )
@@ -1572,10 +1570,8 @@
      *  In `light' or `lcd' mode we disable horizontal hinting completely.
      *  We also do it if the face is italic.
      */
-    if ( mode == FT_RENDER_MODE_LIGHT                      ||
-         mode == FT_RENDER_MODE_SLIGHT                     ||
-         mode == FT_RENDER_MODE_LCD                        ||
-         ( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0 )
+    if ( mode == FT_RENDER_MODE_LIGHT || mode == FT_RENDER_MODE_LCD ||
+         ( face->style_flags & FT_STYLE_FLAG_ITALIC ) != 0          )
       scaler_flags |= AF_SCALER_FLAG_NO_HORIZONTAL;
 
 #ifdef AF_CONFIG_OPTION_USE_WARPER
diff --git a/src/autofit/afloader.c b/src/autofit/afloader.c
index b3269d10b..ddf47ebcf 100644
--- a/src/autofit/afloader.c
+++ b/src/autofit/afloader.c
@@ -245,15 +245,14 @@
     if ( !size_internal->autohint_metrics.x_scale                          ||
          size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) )
     {
-      /* switching between LIGHT and SLIGHT (and vice versa) usually means */
-      /* different scaling values; this later on enforces recomputation of */
-      /* everything related to the current size                            */
+      /* switching between hinting modes usually means different scaling */
+      /* values; this later on enforces recomputation of everything      */
+      /* related to the current size                                     */
 
       size_internal->autohint_mode    = FT_LOAD_TARGET_MODE( load_flags );
       size_internal->autohint_metrics = size->metrics;
 
 #ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS
-      if ( size_internal->autohint_mode != FT_RENDER_MODE_SLIGHT )
       {
         FT_Size_Metrics*  size_metrics = &size_internal->autohint_metrics;
 
@@ -382,12 +381,11 @@
      *
      */
 
-    /* stem darkening only works well in `light' and `slight' modes */
-    if ( ( scaler.render_mode == FT_RENDER_MODE_LIGHT  ||
-           scaler.render_mode == FT_RENDER_MODE_SLIGHT ) &&
+    /* stem darkening only works well in `light' mode */
+    if ( scaler.render_mode == FT_RENDER_MODE_LIGHT    &&
          ( !face->internal->no_stem_darkening        ||
            ( face->internal->no_stem_darkening < 0 &&
-             !module->no_stem_darkening            ) )   )
+             !module->no_stem_darkening            ) ) )
       af_loader_embolden_glyph_in_slot( loader, face, style_metrics );
 
     loader->transformed = slot_internal->glyph_transformed;
@@ -435,8 +433,7 @@
 
       /* we now need to adjust the metrics according to the change in */
       /* width/positioning that occurred during the hinting process   */
-      if ( scaler.render_mode != FT_RENDER_MODE_LIGHT  &&
-           scaler.render_mode != FT_RENDER_MODE_SLIGHT )
+      if ( scaler.render_mode != FT_RENDER_MODE_LIGHT )
       {
         FT_Pos  old_rsb, old_lsb, new_lsb;
         FT_Pos  pp1x_uh, pp2x_uh;
@@ -494,9 +491,8 @@
         }
       }
       /* `light' mode uses integer advance widths */
-      /* (but sets `lsb_delta' and `rsb_delta'),  */
-      /* `slight' mode uses fractional values     */
-      else if ( scaler.render_mode == FT_RENDER_MODE_LIGHT )
+      /* but sets `lsb_delta' and `rsb_delta'     */
+      else
       {
         FT_Pos  pp1x = loader->pp1.x;
         FT_Pos  pp2x = loader->pp2.x;
@@ -508,11 +504,6 @@
         slot->lsb_delta = loader->pp1.x - pp1x;
         slot->rsb_delta = loader->pp2.x - pp2x;
       }
-      else
-      {
-        slot->lsb_delta = 0;
-        slot->rsb_delta = 0;
-      }
 
       break;
 
@@ -563,7 +554,6 @@
       /* to keep the original rounded advance width; ditto for     */
       /* digits if all have the same advance width                 */
       if ( scaler.render_mode != FT_RENDER_MODE_LIGHT                       &&
-           scaler.render_mode != FT_RENDER_MODE_SLIGHT                      &&
            ( FT_IS_FIXED_WIDTH( slot->face )                              ||
              ( af_face_globals_is_digit( loader->globals, glyph_index ) &&
                style_metrics->digits_have_same_width                    ) ) )
@@ -587,8 +577,7 @@
       slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance,
                                              style_metrics->scaler.y_scale );
 
-      if ( scaler.render_mode != FT_RENDER_MODE_SLIGHT )
-        slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance );
+      slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance );
       slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance );
 
       slot->format  = FT_GLYPH_FORMAT_OUTLINE;
diff --git a/src/base/ftadvanc.c b/src/base/ftadvanc.c
index 5f2e0b167..1557607fc 100644
--- a/src/base/ftadvanc.c
+++ b/src/base/ftadvanc.c
@@ -59,15 +59,14 @@
    /*                                                              */
    /*  - unscaled load                                             */
    /*  - unhinted load                                             */
-   /*  - light-hinted and slight-hinted load                       */
+   /*  - light-hinted load                                         */
    /*  - if a variations font, it must have an `HVAR' or `VVAR'    */
    /*    table (thus the old MM or GX fonts don't qualify; this    */
    /*    gets checked by the driver-specific functions)            */
 
-#define LOAD_ADVANCE_FAST_CHECK( face, flags )                           \
-          ( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING )         || \
-            ( FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT  ||   \
-              FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_SLIGHT ) )
+#define LOAD_ADVANCE_FAST_CHECK( face, flags )                      \
+          ( flags & ( FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING )    || \
+            FT_LOAD_TARGET_MODE( flags ) == FT_RENDER_MODE_LIGHT )
 
 
   /* documentation is in ftadvanc.h */
diff --git a/src/base/ftobjs.c b/src/base/ftobjs.c
index cbc771322..539116e85 100644
--- a/src/base/ftobjs.c
+++ b/src/base/ftobjs.c
@@ -668,8 +668,8 @@
      * - Then, auto-hint if FT_LOAD_FORCE_AUTOHINT is set or if we don't
      *   have a native font hinter.
      *
-     * - Otherwise, auto-hint for LIGHT or SLIGHT hinting mode or if there
-     *   isn't any hinting bytecode in the TrueType/OpenType font.
+     * - Otherwise, auto-hint for LIGHT hinting mode or if there isn't
+     *   any hinting bytecode in the TrueType/OpenType font.
      *
      * - Exception: The font is `tricky' and requires the native hinter to
      *   load properly.
@@ -702,9 +702,8 @@
         /* 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  ||
-                 mode == FT_RENDER_MODE_SLIGHT )              &&
-               !FT_DRIVER_HINTS_LIGHTLY( driver )             ) ||
+        if ( ( mode == FT_RENDER_MODE_LIGHT       &&
+               !FT_DRIVER_HINTS_LIGHTLY( driver ) )             ||
              ( FT_IS_SFNT( face )                             &&
                ttface->num_locations                          &&
                ttface->max_profile.maxSizeOfInstructions == 0 &&
diff --git a/src/pshinter/pshalgo.c b/src/pshinter/pshalgo.c
index 27cb229eb..9ad1a3a02 100644
--- a/src/pshinter/pshalgo.c
+++ b/src/pshinter/pshalgo.c
@@ -2149,8 +2149,7 @@
       glyph->do_vert_snapping = FT_BOOL( hint_mode == FT_RENDER_MODE_MONO  ||
                                          hint_mode == FT_RENDER_MODE_LCD_V );
 
-      glyph->do_stem_adjust = FT_BOOL( hint_mode != FT_RENDER_MODE_LIGHT  &&
-                                       hint_mode != FT_RENDER_MODE_SLIGHT );
+      glyph->do_stem_adjust   = FT_BOOL( hint_mode != FT_RENDER_MODE_LIGHT );
 
       for ( dimension = 0; dimension < 2; dimension++ )
       {
diff --git a/src/smooth/ftsmooth.c b/src/smooth/ftsmooth.c
index 52e61e559..435854e67 100644
--- a/src/smooth/ftsmooth.c
+++ b/src/smooth/ftsmooth.c
@@ -433,8 +433,7 @@
                     FT_Render_Mode    mode,
                     const FT_Vector*  origin )
   {
-    if ( mode == FT_RENDER_MODE_LIGHT  ||
-         mode == FT_RENDER_MODE_SLIGHT )
+    if ( mode == FT_RENDER_MODE_LIGHT )
       mode = FT_RENDER_MODE_NORMAL;
 
     return ft_smooth_render_generic( render, slot, mode, origin,
diff --git a/src/truetype/ttgload.c b/src/truetype/ttgload.c
index c5d548f0b..9c1e109c3 100644
--- a/src/truetype/ttgload.c
+++ b/src/truetype/ttgload.c
@@ -2737,7 +2737,7 @@
     /* TrueType glyphs at all sizes using the bytecode interpreter. */
     /*                                                              */
     if ( !( load_flags & FT_LOAD_NO_SCALE ) &&
-         size->metrics->y_ppem < 24          )
+         size->metrics->y_ppem < 24         )
       glyph->outline.flags |= FT_OUTLINE_HIGH_PRECISION;
 
   Exit:
diff --git a/src/truetype/ttobjs.c b/src/truetype/ttobjs.c
index 64011e86e..d20e3da07 100644
--- a/src/truetype/ttobjs.c
+++ b/src/truetype/ttobjs.c
@@ -1234,6 +1234,7 @@
     /*                                                               */
     if ( face->header.Flags & 8 )
     {
+      /* the TT spec always asks for ROUND, not FLOOR or CEIL */
       size_metrics->ascender = FT_PIX_ROUND(
                                  FT_MulFix( face->root.ascender,
                                             size_metrics->y_scale ) );
@@ -1252,6 +1253,8 @@
 
     if ( face->header.Flags & 8 )
     {
+      /* base scaling values on integer ppem values, */
+      /* as mandated by the TrueType specification   */
       size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6,
                                          face->root.units_per_EM );
       size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6,