Commit 4b6f92e6b3d0d99a839448bc897673b849981997
2022-06-01T13:24:09
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.
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diff --git a/include/freetype/ftdriver.h b/include/freetype/ftdriver.h
index 0dc91e8..3de6c6b 100644
--- a/include/freetype/ftdriver.h
+++ b/include/freetype/ftdriver.h
@@ -214,9 +214,9 @@ FT_BEGIN_HEADER
* itself, it is possible to control its behaviour with @FT_Property_Set
* and @FT_Property_Get.
*
- * The TrueType driver's module name is 'truetype'; a single property
- * @interpreter-version is available, as documented in the @properties
- * section.
+ * The TrueType driver's module name is 'truetype'; two properties are
+ * available, @interpreter-version and @TEMPORARY-enable-variable-colrv1, as
+ * documented in the @properties section.
*
* To help understand the differences between interpreter versions, we
* introduce a list of definitions, kindly provided by Greg Hitchcock.
@@ -820,6 +820,48 @@ FT_BEGIN_HEADER
* 2.5
*/
+ /**************************************************************************
+ *
+ * @property:
+ * TEMPORARY-enable-variable-colrv1
+ *
+ * @description:
+ * Controls experimental support of variable COLRv1 and whether the COLRv1
+ * implementation should take into account variation deltas. This tells the
+ * COLRv1 API methods whether they should read from the font and apply
+ * variable deltas to COLRv1 properties. The feature is default off. When
+ * on, variable COLRv1 deltas are applied for COLRv1 features for which they
+ * are already implemented. When off, variable deltas are ignored even if
+ * the respective PaintVar* table may already be understood.
+ *
+ * WARNING: Temporary flag during development of variable COLRv1. This flag
+ * will be removed, do not rely on it. Full variable COLRv1 support will be
+ * announced separately.
+ *
+ * @note:
+ * This property cannot be set via the `FREETYPE_PROPERTIES` environment
+ * variable.
+ *
+ * @example:
+ * The following example code demonstrates how to enable variable
+ * COLRv1.
+ *
+ * ```
+ * FT_Library library;
+ * FT_Face face;
+ * FT_Bool variable_colrv1 = TRUE;
+ *
+ *
+ * FT_Init_FreeType( &library );
+ *
+ * FT_Property_Set( library, "truetype",
+ * "TEMPORARY-enable-variable-colrv1",
+ * &variable_colr_v1 );
+ * ```
+ *
+ * @since:
+ * 2.12.2
+ */
/**************************************************************************
*
diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c
index 31dcb3c..dc063bb 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 5fa239d..b1366fc 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;