feat: Add support for "UniGB-UCS2-H" encoding.

page.go

@@ -226,6 +226,8 @@ func (f Font) getEncoder() TextEncoding {
 			return &byteEncoder{&macRomanEncoding}
 		case "Identity-H":
 			return f.charmapEncoding()
+		case "UniGB-UCS2-H":
+			return &ucs2Encoder{}
 		default:
 			if DebugOn {
 				println("unknown encoding", enc.Name())
@@ -303,6 +305,12 @@ func (e *nopEncoder) Decode(raw string) (text string) {
 	return raw
 }
 
+type ucs2Encoder struct{}
+
+func (e *ucs2Encoder) Decode(raw string) (text string) {
+	return utf16Decode(raw)
+}
+
 type byteEncoder struct {
 	table *[256]rune
 }

page_test.go

@@ -6,6 +6,36 @@ import (
 	"testing"
 )
 
+func TestUcs2Encoder(t *testing.T) {
+	// raw content in PDF (hexed for pretty)
+	// 6c5f82cf94f6884c005c284ea4661362636b3e56de5355005c29
+
+	// raw bytes in showEncodedText (hexed for pretty)
+	// 6c5f82cf94f6884c00284ea4661362636b3e56de53550029
+	data := []byte{
+		0x6C, 0x5F, // 江
+		0x82, 0xCF, // 苏
+		0x94, 0xF6, // 银
+		0x88, 0x4C, // 行
+		0x00, 0x28, // (
+		0x4E, 0xA4, // 交
+		0x66, 0x13, // 易
+		0x62, 0x63, // 扣
+		0x6B, 0x3E, // 款
+		0x56, 0xDE, // 回
+		0x53, 0x55, // 单
+		0x00, 0x29, // )
+	}
+
+	var e ucs2Encoder
+	text := e.Decode(string(data))
+
+	const want = "江苏银行(交易扣款回单)"
+	if text != want {
+		t.Errorf("got %q, want %q", text, want)
+	}
+}
+
 func TestNopEncoder(t *testing.T) {
 	e := &nopEncoder{}
 	if got := e.Decode("abc"); got != "abc" {