[truetype] Do linear scaling for FT_LOAD_NO_HINTING (#50470).

* src/truetype/ttobs.h (TT_SizeRec): Add field `hinted_metrics' to
hold hinted metrics.
Make `metrics' a pointer so that `tt_glyph_load' can easily switch
between metrics.

* src/truetype/ttdriver.c (tt_size_request): Updated.
(tt_glyph_load): Use top-level metrics if FT_LOAD_NO_HINTING is
used.

* src/truetype/ttgload.c (TT_Hint_Glyph, TT_Process_Simple_Glyph,
TT_Process_Composite_Component, load_truetype_glyph,
compute_glyph_metrics, TT_Load_Glyph): Updated.

* src/truetype/ttinterp.c (TT_Load_Context): Updated.

* src/truetype/ttobjs.c (tt_size_reset): Updated.

* src/truetype/ttsubpix.c (sph_set_tweaks): Updated.

7 files changed, 55 insertions, 23 deletions

diff --git a/ChangeLog b/ChangeLog
index 05db1d150..886883868 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,28 @@
 2017-04-22  Werner Lemberg  <wl@gnu.org>
 
+	[truetype] Do linear scaling for FT_LOAD_NO_HINTING (#50470).
+
+	* src/truetype/ttobs.h (TT_SizeRec): Add field `hinted_metrics' to
+	hold hinted metrics.
+	Make `metrics' a pointer so that `tt_glyph_load' can easily switch
+	between metrics.
+
+	* src/truetype/ttdriver.c (tt_size_request): Updated.
+	(tt_glyph_load): Use top-level metrics if FT_LOAD_NO_HINTING is
+	used.
+
+	* src/truetype/ttgload.c (TT_Hint_Glyph, TT_Process_Simple_Glyph,
+	TT_Process_Composite_Component, load_truetype_glyph,
+	compute_glyph_metrics, TT_Load_Glyph): Updated.
+
+	* src/truetype/ttinterp.c (TT_Load_Context): Updated.
+
+	* src/truetype/ttobjs.c (tt_size_reset): Updated.
+
+	* src/truetype/ttsubpix.c (sph_set_tweaks): Updated.
+
+2017-04-22  Werner Lemberg  <wl@gnu.org>
+
 	Add new `slight' auto-hinting mode.
 
 	This mode uses fractional advance widths and doesn't scale glyphs
diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c
index 9bf0f84fc..c9f682e5e 100644
--- a/src/truetype/ttdriver.c
+++ b/src/truetype/ttdriver.c
@@ -361,9 +361,10 @@
 #ifdef TT_USE_BYTECODE_INTERPRETER
       /* for the `MPS' bytecode instruction we need the point size */
       {
-        FT_UInt  resolution = ttsize->metrics.x_ppem > ttsize->metrics.y_ppem
-                                ? req->horiResolution
-                                : req->vertResolution;
+        FT_UInt  resolution =
+                   ttsize->metrics->x_ppem > ttsize->metrics->y_ppem
+                     ? req->horiResolution
+                     : req->vertResolution;
 
 
         /* if we don't have a resolution value, assume 72dpi */
@@ -457,6 +458,11 @@
         load_flags |= FT_LOAD_NO_HINTING;
     }
 
+    /* use hinted metrics only if we load a glyph with hinting */
+    size->metrics = ( load_flags & FT_LOAD_NO_HINTING )
+                      ? &ttsize->metrics
+                      : &size->hinted_metrics;
+
     /* now load the glyph outline if necessary */
     error = TT_Load_Glyph( size, slot, glyph_index, load_flags );
 
diff --git a/src/truetype/ttgload.c b/src/truetype/ttgload.c
index 8962be560..c5d548f0b 100644
--- a/src/truetype/ttgload.c
+++ b/src/truetype/ttgload.c
@@ -778,8 +778,8 @@
     }
     else
     {
-      loader->exec->metrics.x_scale = loader->size->metrics.x_scale;
-      loader->exec->metrics.y_scale = loader->size->metrics.y_scale;
+      loader->exec->metrics.x_scale = loader->size->metrics->x_scale;
+      loader->exec->metrics.y_scale = loader->size->metrics->y_scale;
     }
 #endif
 
@@ -926,7 +926,7 @@
       TT_Driver  driver = (TT_Driver)FT_FACE_DRIVER( face );
 
       FT_String*  family         = face->root.family_name;
-      FT_UInt     ppem           = loader->size->metrics.x_ppem;
+      FT_UInt     ppem           = loader->size->metrics->x_ppem;
       FT_String*  style          = face->root.style_name;
       FT_UInt     x_scale_factor = 1000;
 #endif
@@ -955,9 +955,9 @@
         if ( ( loader->load_flags & FT_LOAD_NO_SCALE ) == 0 ||
              x_scale_factor != 1000                         )
         {
-          x_scale = FT_MulDiv( loader->size->metrics.x_scale,
+          x_scale = FT_MulDiv( loader->size->metrics->x_scale,
                                (FT_Long)x_scale_factor, 1000 );
-          y_scale = loader->size->metrics.y_scale;
+          y_scale = loader->size->metrics->y_scale;
 
           /* compensate for any scaling by de/emboldening; */
           /* the amount was determined via experimentation */
@@ -977,8 +977,8 @@
         /* scale the glyph */
         if ( ( loader->load_flags & FT_LOAD_NO_SCALE ) == 0 )
         {
-          x_scale = loader->size->metrics.x_scale;
-          y_scale = loader->size->metrics.y_scale;
+          x_scale = loader->size->metrics->x_scale;
+          y_scale = loader->size->metrics->y_scale;
 
           do_scale = TRUE;
         }
@@ -1136,8 +1136,8 @@
 
       if ( !( loader->load_flags & FT_LOAD_NO_SCALE ) )
       {
-        FT_Fixed  x_scale = loader->size->metrics.x_scale;
-        FT_Fixed  y_scale = loader->size->metrics.y_scale;
+        FT_Fixed  x_scale = loader->size->metrics->x_scale;
+        FT_Fixed  y_scale = loader->size->metrics->y_scale;
 
 
         x = FT_MulFix( x, x_scale );
@@ -1470,8 +1470,8 @@
 
     if ( ( loader->load_flags & FT_LOAD_NO_SCALE ) == 0 )
     {
-      x_scale = loader->size->metrics.x_scale;
-      y_scale = loader->size->metrics.y_scale;
+      x_scale = loader->size->metrics->x_scale;
+      y_scale = loader->size->metrics->y_scale;
     }
     else
     {
@@ -2038,7 +2038,7 @@
 
     y_scale = 0x10000L;
     if ( ( loader->load_flags & FT_LOAD_NO_SCALE ) == 0 )
-      y_scale = size->metrics.y_scale;
+      y_scale = size->metrics->y_scale;
 
     if ( glyph->format != FT_GLYPH_FORMAT_COMPOSITE )
       FT_Outline_Get_CBox( &glyph->outline, &bbox );
@@ -2070,7 +2070,7 @@
 
 
       widthp = tt_face_get_device_metrics( face,
-                                           size->metrics.x_ppem,
+                                           size->metrics->x_ppem,
                                            glyph_index );
 
 #ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
@@ -2637,11 +2637,11 @@
           if ( !glyph->metrics.horiAdvance && glyph->linearHoriAdvance )
             glyph->metrics.horiAdvance =
               FT_MulFix( glyph->linearHoriAdvance,
-                         size->metrics.x_scale );
+                         size->metrics->x_scale );
           if ( !glyph->metrics.vertAdvance && glyph->linearVertAdvance )
             glyph->metrics.vertAdvance =
               FT_MulFix( glyph->linearVertAdvance,
-                         size->metrics.y_scale );
+                         size->metrics->y_scale );
         }
 
         return FT_Err_Ok;
@@ -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/ttinterp.c b/src/truetype/ttinterp.c
index fed377d97..0c51f756d 100644
--- a/src/truetype/ttinterp.c
+++ b/src/truetype/ttinterp.c
@@ -402,7 +402,7 @@
       exec->IDefs      = size->instruction_defs;
       exec->pointSize  = size->point_size;
       exec->tt_metrics = size->ttmetrics;
-      exec->metrics    = size->metrics;
+      exec->metrics    = *size->metrics;
 
       exec->maxFunc    = size->max_func;
       exec->maxIns     = size->max_ins;
diff --git a/src/truetype/ttobjs.c b/src/truetype/ttobjs.c
index 27e0931a3..64011e86e 100644
--- a/src/truetype/ttobjs.c
+++ b/src/truetype/ttobjs.c
@@ -1220,7 +1220,7 @@
 
     size->ttmetrics.valid = FALSE;
 
-    size_metrics = &size->metrics;
+    size_metrics = &size->hinted_metrics;
 
     /* copy the result from base layer */
     *size_metrics = size->root.metrics;
@@ -1280,6 +1280,8 @@
       size->ttmetrics.y_ratio = 0x10000L;
     }
 
+    size->metrics = size_metrics;
+
 #ifdef TT_USE_BYTECODE_INTERPRETER
     size->cvt_ready = -1;
 #endif /* TT_USE_BYTECODE_INTERPRETER */
diff --git a/src/truetype/ttobjs.h b/src/truetype/ttobjs.h
index 65929e592..cdacee75e 100644
--- a/src/truetype/ttobjs.h
+++ b/src/truetype/ttobjs.h
@@ -278,7 +278,8 @@ FT_BEGIN_HEADER
 
     /* we have our own copy of metrics so that we can modify */
     /* it without affecting auto-hinting (when used)         */
-    FT_Size_Metrics    metrics;
+    FT_Size_Metrics*   metrics;        /* for the current rendering mode */
+    FT_Size_Metrics    hinted_metrics; /* for the hinted rendering mode  */
 
     TT_Size_Metrics    ttmetrics;
 
diff --git a/src/truetype/ttsubpix.c b/src/truetype/ttsubpix.c
index f8502d2f7..1c8cf0110 100644
--- a/src/truetype/ttsubpix.c
+++ b/src/truetype/ttsubpix.c
@@ -906,7 +906,7 @@
   {
     TT_Face     face   = loader->face;
     FT_String*  family = face->root.family_name;
-    FT_UInt     ppem   = loader->size->metrics.x_ppem;
+    FT_UInt     ppem   = loader->size->metrics->x_ppem;
     FT_String*  style  = face->root.style_name;