applied golang/freetype golang#88

Author: Randall C. O'Reilly

truetype/truetype.go

@@ -137,7 +137,7 @@ func parseSubtables(table []byte, name string, offset, size int, pred func([]byt
 	if len(table) < size*nSubtables+offset {
 		return 0, 0, FormatError(name + " too short")
 	}
-	ok := false
+	bestScore := -1
 	for i := 0; i < nSubtables; i, offset = i+1, offset+size {
 		if pred != nil && !pred(table[offset:]) {
 			continue
@@ -147,19 +147,24 @@ func parseSubtables(table []byte, name string, offset, size int, pred func([]byt
 		pidPsid := u32(table, offset)
 		// We prefer the Unicode cmap encoding. Failing to find that, we fall
 		// back onto the Microsoft cmap encoding.
+		// And we prefer full/UCS4 encoding over BMP/UCS2. So the priority goes:
+		//    unicodeEncodingFull > microsoftUCS4Encoding > unicodeEncodingBMPOnly > microsoftUCS2Encoding > microsoftSymbolEncoding
+		// It is in accord with the Psid part.
+		score := int(pidPsid & 0xFFFF)
+		if score <= bestScore {
+			continue
+		}
 		if pidPsid == unicodeEncodingBMPOnly || pidPsid == unicodeEncodingFull {
-			bestOffset, bestPID, ok = offset, pidPsid>>16, true
+			bestOffset, bestPID, bestScore = offset, pidPsid>>16, score
 			break
 
 		} else if pidPsid == microsoftSymbolEncoding ||
 			pidPsid == microsoftUCS2Encoding ||
 			pidPsid == microsoftUCS4Encoding {
-
-			bestOffset, bestPID, ok = offset, pidPsid>>16, true
-			// We don't break out of the for loop, so that Unicode can override Microsoft.
+			bestOffset, bestPID, bestScore = offset, pidPsid>>16, score
 		}
 	}
-	if !ok {
+	if bestScore < 0 {
 		return 0, 0, UnsupportedError(name + " encoding")
 	}
 	return bestOffset, bestPID, nil