[opentype/metadata] properly use the OS/2 table to fetch aspect

opentype/api/metadata/descriptor.go

@@ -30,14 +30,12 @@ type fontDescriptor struct {
 	head  tables.Head
 }
 
-// Describe provides access to family and aspect.
-// 'buffer' may be provided to reduce allocations.
-func Describe(ld *loader.Loader, buffer []byte) (family string, aspect Aspect, _ []byte) {
+func newFontDescriptor(ld *loader.Loader, buffer []byte) (fontDescriptor, []byte) {
 	var desc fontDescriptor
 
 	// load tables, all considered optional
 	buffer, _ = ld.RawTableTo(loader.MustNewTag("OS/2"), buffer)
-	if os2, _, err := tables.ParseOs2(buffer); err != nil {
+	if os2, _, err := tables.ParseOs2(buffer); err == nil {
 		desc.os2 = &os2Table{
 			USWeightClass: os2.USWeightClass,
 			USWidthClass:  os2.USWidthClass,
@@ -50,6 +48,13 @@ func Describe(ld *loader.Loader, buffer []byte) (family string, aspect Aspect, _
 	buffer, _ = ld.RawTableTo(loader.MustNewTag("name"), buffer)
 	desc.names, _, _ = tables.ParseName(buffer)
 
+	return desc, buffer
+}
+
+// Describe provides access to family and aspect.
+// 'buffer' may be provided to reduce allocations.
+func Describe(ld *loader.Loader, buffer []byte) (family string, aspect Aspect, _ []byte) {
+	desc, buffer := newFontDescriptor(ld, buffer)
 	return desc.Family(), desc.Aspect(), buffer
 }
 

opentype/api/metadata/descriptor_test.go

@@ -26,6 +26,11 @@ func TestMetadata(t *testing.T) {
 			Aspect{StyleNormal, WeightNormal, StretchNormal},
 			"Noto Sans Arabic",
 		},
+		{
+			"common/DejaVuSans.ttf",
+			Aspect{StyleNormal, WeightNormal, StretchNormal},
+			"DejaVu Sans",
+		},
 	}
 
 	for _, test := range tests {
@@ -88,3 +93,22 @@ func TestAspect_inferFromStyle(t *testing.T) {
 		tu.AssertC(t, as == tt.want, tt.args)
 	}
 }
+
+func TestAspectFromOS2(t *testing.T) {
+	// This font has two different weight values :
+	// 400, in the OS/2 table and 380, in the style description
+	f, err := td.Files.ReadFile("common/DejaVuSans.ttf")
+	tu.AssertNoErr(t, err)
+
+	ld, err := loader.NewLoader(bytes.NewReader(f))
+	tu.AssertNoErr(t, err)
+
+	fd, _ := newFontDescriptor(ld, nil)
+
+	raw := fd.rawAspect()
+	tu.Assert(t, raw.Weight == WeightNormal)
+
+	var inferred Aspect
+	inferred.inferFromStyle(fd.additionalStyle())
+	tu.Assert(t, inferred.Weight == 380)
+}