Proposal: Feature control for variable COLRv1

* include/freetype/ftdriver.h (variable-color-v1 property): Add documentation
for variable-colr-v1 property.
* src/truetype/ttdriver.c (tt_property_set): Ingest variable-control property
when called, set to enable_variable_colrv1 driver flag.
* src/truetype/ttobjs.h (TT_DriverRec): Add enable_variable_colrv1 flag.

2 files changed, 19 insertions, 0 deletions

diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c
index 31dcb3c6f..dc063bbb3 100644
--- a/src/truetype/ttdriver.c
+++ b/src/truetype/ttdriver.c
@@ -108,6 +108,23 @@
       return error;
     }
 
+    if ( !ft_strcmp( property_name, "TEMPORARY-enable-variable-colrv1" ) )
+    {
+      /* This flag is temporary and can't be set with environment variables. */
+      if ( !value_is_string )
+      {
+        FT_Bool*  bv = (FT_Bool*)value;
+
+        if ( *bv == TRUE || *bv == FALSE)
+          driver->enable_variable_colrv1 = *bv;
+        else
+          error = FT_ERR( Unimplemented_Feature );
+      } else
+        error = FT_ERR( Invalid_Argument );
+
+      return error;
+    }
+
     FT_TRACE2(( "tt_property_set: missing property `%s'\n",
                 property_name ));
     return FT_THROW( Missing_Property );
diff --git a/src/truetype/ttobjs.h b/src/truetype/ttobjs.h
index 5fa239d43..b1366fc63 100644
--- a/src/truetype/ttobjs.h
+++ b/src/truetype/ttobjs.h
@@ -337,6 +337,8 @@ FT_BEGIN_HEADER
 
     FT_UInt  interpreter_version;
 
+    FT_Bool  enable_variable_colrv1;
+
   } TT_DriverRec;