Remove dependency to the deprecated utf library

@@ -16,6 +16,7 @@
 - Improve gradient functions
 - Add blend mode
 - Add soft mask
+- Remove dependency to the deprecated utf library
 
 ## 1.12.0
 

@@ -18,7 +18,6 @@ import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:meta/meta.dart';
-import 'package:utf/utf.dart';
 
 import 'color.dart';
 import 'object.dart';
@@ -120,7 +119,7 @@ class PdfString extends PdfDataType {
     try {
       return latin1.encode(value);
     } catch (e) {
-      return Uint8List.fromList(<int>[0xfe, 0xff] + encodeUtf16be(value));
+      return Uint8List.fromList(<int>[0xfe, 0xff] + _encodeUtf16be(value));
     }
   }
 
@@ -135,6 +134,46 @@ class PdfString extends PdfDataType {
     return _string('D:$year$month$day$hour$minute${second}Z');
   }
 
+  /// Produce a list of UTF-16BE encoded bytes.
+  static List<int> _encodeUtf16be(String str) {
+    const UNICODE_REPLACEMENT_CHARACTER_CODEPOINT = 0xfffd;
+    const UNICODE_BYTE_ZERO_MASK = 0xff;
+    const UNICODE_BYTE_ONE_MASK = 0xff00;
+    const UNICODE_VALID_RANGE_MAX = 0x10ffff;
+    const UNICODE_PLANE_ONE_MAX = 0xffff;
+    const UNICODE_UTF16_RESERVED_LO = 0xd800;
+    const UNICODE_UTF16_RESERVED_HI = 0xdfff;
+    const UNICODE_UTF16_OFFSET = 0x10000;
+    const UNICODE_UTF16_SURROGATE_UNIT_0_BASE = 0xd800;
+    const UNICODE_UTF16_SURROGATE_UNIT_1_BASE = 0xdc00;
+    const UNICODE_UTF16_HI_MASK = 0xffc00;
+    const UNICODE_UTF16_LO_MASK = 0x3ff;
+
+    final encoding = <int>[];
+
+    final add = (int unit) {
+      encoding.add((unit & UNICODE_BYTE_ONE_MASK) >> 8);
+      encoding.add(unit & UNICODE_BYTE_ZERO_MASK);
+    };
+
+    for (var unit in str.codeUnits) {
+      if ((unit >= 0 && unit < UNICODE_UTF16_RESERVED_LO) ||
+          (unit > UNICODE_UTF16_RESERVED_HI && unit <= UNICODE_PLANE_ONE_MAX)) {
+        add(unit);
+      } else if (unit > UNICODE_PLANE_ONE_MAX &&
+          unit <= UNICODE_VALID_RANGE_MAX) {
+        final base = unit - UNICODE_UTF16_OFFSET;
+        add(UNICODE_UTF16_SURROGATE_UNIT_0_BASE +
+            ((base & UNICODE_UTF16_HI_MASK) >> 10));
+        add(UNICODE_UTF16_SURROGATE_UNIT_1_BASE +
+            (base & UNICODE_UTF16_LO_MASK));
+      } else {
+        add(UNICODE_REPLACEMENT_CHARACTER_CODEPOINT);
+      }
+    }
+    return encoding;
+  }
+
   /// Escape special characters
   /// \ddd Character code ddd (octal)
   void _putTextBytes(PdfStream s, List<int> b) {

@@ -19,7 +19,6 @@ import 'dart:math' as math;
 import 'dart:typed_data';
 
 import 'package:meta/meta.dart';
-import 'package:utf/utf.dart';
 
 import 'font_metrics.dart';
 
@@ -125,7 +124,7 @@ class TtfParser {
       }
       if (platformID == 3 && nameID == 6) {
         try {
-          _fontName = decodeUtf16(bytes.buffer
+          _fontName = _decodeUtf16(bytes.buffer
               .asUint8List(basePosition + stringOffset + offset, length));
           return;
         } catch (a) {
@@ -403,4 +402,12 @@ class TtfParser {
       components,
     );
   }
+
+  String _decodeUtf16(Uint8List bytes) {
+    final charCodes = <int>[];
+    for (var i = 0; i < bytes.length; i += 2) {
+      charCodes.add((bytes[i] << 8) | bytes[i + 1]);
+    }
+    return String.fromCharCodes(charCodes);
+  }
 }

@@ -16,7 +16,6 @@ dependencies:
   image: ^2.1.10
   meta: ^1.1.5
   path_parsing: ^0.1.4
-  utf: ^0.9.0
   vector_math: ^2.0.0
 
 dev_dependencies: