Use PdfDataTypes for internal structures

@@ -4,6 +4,7 @@
 
 - Improve Annotations
 - Implement table row vertical alignment
+- Improve Internal data structure
 
 ## 1.5.0
 

@@ -38,6 +38,7 @@ part 'src/catalog.dart';
 part 'src/color.dart';
 part 'src/colors.dart';
 part 'src/compatibility.dart';
+part 'src/data_types.dart';
 part 'src/document.dart';
 part 'src/encryption.dart';
 part 'src/exif.dart';

@@ -86,7 +86,7 @@ class PdfAnnot extends PdfObject {
   @override
   void _prepare() {
     super._prepare();
-    annot.build(pdfPage, params);
+    annot.build(pdfPage, this, params);
   }
 }
 
@@ -145,44 +145,44 @@ abstract class PdfAnnotBase {
 
   @protected
   @mustCallSuper
-  void build(PdfPage page, Map<String, PdfStream> params) {
-    params['/Subtype'] = PdfStream.string(subtype);
-    params['/Rect'] = PdfStream()
-      ..putNumArray(<double>[rect.left, rect.bottom, rect.right, rect.top]);
+  void build(PdfPage page, PdfObject object, PdfDict params) {
+    params['/Subtype'] = PdfName(subtype);
+    params['/Rect'] = PdfArray.fromNum(
+        <double>[rect.left, rect.bottom, rect.right, rect.top]);
 
     params['/P'] = page.ref();
 
     // handle the border
     if (border == null) {
-      params['/Border'] = PdfStream.string('[0 0 0]');
+      params['/Border'] = PdfArray.fromNum(const <int>[0, 0, 0]);
     } else {
       params['/BS'] = border.ref();
     }
 
     if (content != null) {
-      params['/Contents'] = PdfStream()..putLiteral(content);
+      params['/Contents'] = PdfSecString.fromString(object, content);
     }
 
     if (name != null) {
-      params['/NM'] = PdfStream()..putLiteral(name);
+      params['/NM'] = PdfSecString.fromString(object, name);
     }
 
     if (flags != null) {
-      params['/F'] = PdfStream.intNum(flagValue);
+      params['/F'] = PdfNum(flagValue);
     }
 
     if (date != null) {
-      params['/M'] = PdfStream()..putDate(date);
+      params['/M'] = PdfSecString.fromDate(object, date);
     }
 
     if (color != null) {
       if (color is PdfColorCmyk) {
         final PdfColorCmyk k = color;
-        params['/C'] = PdfStream()
-          ..putNumList(<double>[k.cyan, k.magenta, k.yellow, k.black]);
+        params['/C'] =
+            PdfArray.fromNum(<double>[k.cyan, k.magenta, k.yellow, k.black]);
       } else {
-        params['/C'] = PdfStream()
-          ..putNumList(<double>[color.red, color.green, color.blue]);
+        params['/C'] =
+            PdfArray.fromNum(<double>[color.red, color.green, color.blue]);
       }
     }
   }
@@ -231,13 +231,12 @@ class PdfAnnotNamedLink extends PdfAnnotBase {
   final String dest;
 
   @override
-  void build(PdfPage page, Map<String, PdfStream> params) {
-    super.build(page, params);
-    params['/A'] = PdfStream()
-      ..putDictionary(
-        <String, PdfStream>{
-          '/S': PdfStream()..putString('/GoTo'),
-          '/D': PdfStream()..putText(dest),
+  void build(PdfPage page, PdfObject object, PdfDict params) {
+    super.build(page, object, params);
+    params['/A'] = PdfDict(
+      <String, PdfDataType>{
+        '/S': const PdfName('/GoTo'),
+        '/D': PdfSecString.fromString(object, dest),
       },
     );
   }
@@ -264,13 +263,12 @@ class PdfAnnotUrlLink extends PdfAnnotBase {
   final String url;
 
   @override
-  void build(PdfPage page, Map<String, PdfStream> params) {
-    super.build(page, params);
-    params['/A'] = PdfStream()
-      ..putDictionary(
-        <String, PdfStream>{
-          '/S': PdfStream()..putString('/URI'),
-          '/URI': PdfStream()..putText(url),
+  void build(PdfPage page, PdfObject object, PdfDict params) {
+    super.build(page, object, params);
+    params['/A'] = PdfDict(
+      <String, PdfDataType>{
+        '/S': const PdfName('/URI'),
+        '/URI': PdfSecString.fromString(object, url),
       },
     );
   }
@@ -289,7 +287,6 @@ abstract class PdfAnnotWidget extends PdfAnnotBase {
     DateTime date,
     PdfColor color,
     this.highlighting,
-    this.value,
   }) : super(
           subtype: '/Widget',
           rect: rect,
@@ -305,20 +302,14 @@ abstract class PdfAnnotWidget extends PdfAnnotBase {
 
   final PdfAnnotHighlighting highlighting;
 
-  final PdfStream value;
-
   @override
-  void build(PdfPage page, Map<String, PdfStream> params) {
-    super.build(page, params);
+  void build(PdfPage page, PdfObject object, PdfDict params) {
+    super.build(page, object, params);
 
-    params['/FT'] = PdfStream.string(fieldType);
+    params['/FT'] = PdfName(fieldType);
 
     if (fieldName != null) {
-      params['/T'] = PdfStream()..putLiteral(fieldName);
-    }
-
-    if (value != null) {
-      params['/V'] = value;
+      params['/T'] = PdfSecString.fromString(object, fieldName);
     }
   }
 }
@@ -344,8 +335,8 @@ class PdfAnnotSign extends PdfAnnotWidget {
         );
 
   @override
-  void build(PdfPage page, Map<String, PdfStream> params) {
-    super.build(page, params);
+  void build(PdfPage page, PdfObject object, PdfDict params) {
+    super.build(page, object, params);
     assert(page.pdfDocument.sign != null);
     params['/V'] = page.pdfDocument.sign.ref();
   }

@@ -19,17 +19,17 @@ part of pdf;
 class PdfArrayObject extends PdfObject {
   PdfArrayObject(
     PdfDocument pdfDocument,
-    this.values,
-  )   : assert(values != null),
+    this.array,
+  )   : assert(array != null),
         super(pdfDocument);
 
-  final List<String> values;
+  final PdfArray array;
 
   @override
   void _writeContent(PdfStream os) {
     super._writeContent(os);
 
-    os.putStringArray(values);
+    array.output(os);
     os.putBytes(<int>[0x0a]);
   }
 }

@@ -66,18 +66,15 @@ class PdfBorder extends PdfObject {
 
   /// @param os OutputStream to send the object to
   @override
-  void _writeContent(PdfStream os) {
-    super._writeContent(os);
+  void _prepare() {
+    super._prepare();
+
+    params['/S'] =
+        PdfName('/' + 'SDBIU'.substring(style.index, style.index + 1));
+    params['/W'] = PdfNum(width);
 
-    final List<PdfStream> data = <PdfStream>[];
-    data.add(PdfStream.string('/S'));
-    data.add(PdfStream.string(
-        '/' + 'SDBIU'.substring(style.index, style.index + 1)));
-    data.add(PdfStream.string('/W $width'));
     if (dash != null) {
-      data.add(PdfStream.string('/D'));
-      data.add(PdfStream.array(dash.map((double d) => PdfStream.num(d))));
+      params['/D'] = PdfArray.fromNum(dash);
     }
-    os.putArray(data);
   }
 }

@@ -52,7 +52,7 @@ class PdfCatalog extends PdfObject {
     super._prepare();
 
     /// the PDF specification version, overrides the header version starting from 1.4
-    params['/Version'] = PdfStream.string('/${pdfDocument.version}');
+    params['/Version'] = PdfName('/${pdfDocument.version}');
 
     params['/Pages'] = pdfPageList.ref();
 
@@ -65,11 +65,10 @@ class PdfCatalog extends PdfObject {
     params['/Names'] = names.ref();
 
     // the /PageMode setting
-    params['/PageMode'] =
-        PdfStream.string(PdfDocument._PdfPageModes[pageMode.index]);
+    params['/PageMode'] = PdfName(PdfDocument._PdfPageModes[pageMode.index]);
 
     if (pdfDocument.sign != null) {
-      params['/Perms'] = PdfStream.dictionary(<String, PdfStream>{
+      params['/Perms'] = PdfDict(<String, PdfDataType>{
         '/DocMDP': pdfDocument.sign.ref(),
       });
     }
@@ -84,9 +83,9 @@ class PdfCatalog extends PdfObject {
     }
 
     if (widgets.isNotEmpty) {
-      params['/AcroForm'] = PdfStream.dictionary(<String, PdfStream>{
-        '/SigFlags': PdfStream.intNum(pdfDocument.sign?.flagsValue ?? 0),
-        '/Fields': PdfStream()..putObjectArray(widgets),
+      params['/AcroForm'] = PdfDict(<String, PdfDataType>{
+        '/SigFlags': PdfNum(pdfDocument.sign?.flagsValue ?? 0),
+        '/Fields': PdfArray.fromObjects(widgets),
       });
     }
   }

@@ -73,7 +73,7 @@ class PDFAnnot extends PdfAnnot {
 @deprecated
 class PDFArrayObject extends PdfArrayObject {
   PDFArrayObject(PdfDocument pdfDocument, List<String> values)
-      : super(pdfDocument, values);
+      : super(pdfDocument, null);
 }
 
 @deprecated

+/*
+ * Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// ignore_for_file: omit_local_variable_types
+// ignore_for_file: avoid_unused_constructor_parameters
+
+part of pdf;
+
+abstract class PdfDataType {
+  const PdfDataType();
+
+  void output(PdfStream s);
+
+  PdfStream toStream() {
+    final PdfStream s = PdfStream();
+    output(s);
+    return s;
+  }
+
+  @override
+  String toString() {
+    return String.fromCharCodes(toStream().output());
+  }
+
+  List<int> toList() {
+    return toStream().output();
+  }
+}
+
+class PdfBool extends PdfDataType {
+  const PdfBool(this.value);
+
+  final bool value;
+
+  @override
+  void output(PdfStream s) {
+    s.putString(value ? 'true' : 'false');
+  }
+}
+
+class PdfNum extends PdfDataType {
+  const PdfNum(this.value);
+
+  final num value;
+
+  @override
+  void output(PdfStream s) {
+    if (value is int) {
+      s.putString(value.toInt().toString());
+    } else {
+      s.putNum(value);
+    }
+  }
+}
+
+enum PdfStringFormat { binary, litteral }
+
+class PdfString extends PdfDataType {
+  const PdfString(this.value, [this.format = PdfStringFormat.litteral]);
+
+  factory PdfString.fromString(String value) {
+    try {
+      return PdfString(latin1.encode(value), PdfStringFormat.litteral);
+    } catch (e) {
+      return PdfString(
+        Uint8List.fromList(<int>[0xfe, 0xff] + encodeUtf16be(value)),
+        PdfStringFormat.litteral,
+      );
+    }
+  }
+
+  factory PdfString.fromDate(DateTime date) {
+    final DateTime utcDate = date.toUtc();
+    final String year = utcDate.year.toString().padLeft(4, '0');
+    final String month = utcDate.month.toString().padLeft(2, '0');
+    final String day = utcDate.day.toString().padLeft(2, '0');
+    final String hour = utcDate.hour.toString().padLeft(2, '0');
+    final String minute = utcDate.minute.toString().padLeft(2, '0');
+    final String second = utcDate.second.toString().padLeft(2, '0');
+    return PdfString.fromString('D:$year$month$day$hour$minute${second}Z');
+  }
+
+  final Uint8List value;
+
+  final PdfStringFormat format;
+
+  /// Returns the ASCII/Unicode code unit corresponding to the hexadecimal digit
+  /// [digit].
+  int _codeUnitForDigit(int digit) =>
+      digit < 10 ? digit + 0x30 : digit + 0x61 - 10;
+
+  @override
+  void output(PdfStream s) {
+    switch (format) {
+      case PdfStringFormat.binary:
+        s.putByte(0x3c);
+        for (int byte in value) {
+          s.putByte(_codeUnitForDigit((byte & 0xF0) >> 4));
+          s.putByte(_codeUnitForDigit(byte & 0x0F));
+        }
+        s.putByte(0x3e);
+
+        break;
+      case PdfStringFormat.litteral:
+        s.putByte(40);
+        s.putTextBytes(value);
+        s.putByte(41);
+        break;
+    }
+  }
+}
+
+class PdfSecString extends PdfString {
+  const PdfSecString(this.object, Uint8List value,
+      [PdfStringFormat format = PdfStringFormat.binary])
+      : super(value, format);
+
+  factory PdfSecString.fromString(PdfObject object, String value) {
+    try {
+      return PdfSecString(
+          object, latin1.encode(value), PdfStringFormat.litteral);
+    } catch (e) {
+      return PdfSecString(
+        object,
+        Uint8List.fromList(<int>[0xfe, 0xff] + encodeUtf16be(value)),
+        PdfStringFormat.litteral,
+      );
+    }
+  }
+
+  factory PdfSecString.fromDate(PdfObject object, DateTime date) {
+    final DateTime utcDate = date.toUtc();
+    final String year = utcDate.year.toString().padLeft(4, '0');
+    final String month = utcDate.month.toString().padLeft(2, '0');
+    final String day = utcDate.day.toString().padLeft(2, '0');
+    final String hour = utcDate.hour.toString().padLeft(2, '0');
+    final String minute = utcDate.minute.toString().padLeft(2, '0');
+    final String second = utcDate.second.toString().padLeft(2, '0');
+    return PdfSecString.fromString(
+        object, 'D:$year$month$day$hour$minute${second}Z');
+  }
+
+  final PdfObject object;
+
+  @override
+  void output(PdfStream s) {
+    if (object.pdfDocument.encryption == null) {
+      return super.output(s);
+    }
+
+    final List<int> enc = object.pdfDocument.encryption.encrypt(value, object);
+    switch (format) {
+      case PdfStringFormat.binary:
+        s.putByte(0x3c);
+        for (int byte in enc) {
+          s.putByte(_codeUnitForDigit((byte & 0xF0) >> 4));
+          s.putByte(_codeUnitForDigit(byte & 0x0F));
+        }
+        s.putByte(0x3e);
+
+        break;
+      case PdfStringFormat.litteral:
+        s.putByte(40);
+        s.putTextBytes(enc);
+        s.putByte(41);
+        break;
+    }
+  }
+}
+
+class PdfName extends PdfDataType {
+  const PdfName(this.value);
+
+  final String value;
+
+  @override
+  void output(PdfStream s) {
+    assert(value[0] == '/');
+    s.putString(value);
+  }
+}
+
+class PdfNull extends PdfDataType {
+  const PdfNull();
+
+  @override
+  void output(PdfStream s) {
+    s.putString('null');
+  }
+}
+
+class PdfIndirect extends PdfDataType {
+  const PdfIndirect(this.ser, this.gen);
+
+  final int ser;
+
+  final int gen;
+
+  @override
+  void output(PdfStream s) {
+    s.putString('$ser $gen R');
+  }
+}
+
+class PdfArray extends PdfDataType {
+  PdfArray([Iterable<PdfDataType> values]) {
+    if (values != null) {
+      this.values.addAll(values);
+    }
+  }
+
+  factory PdfArray.fromObjects(List<PdfObject> objects) {
+    return PdfArray(
+        objects.map<PdfIndirect>((PdfObject e) => e.ref()).toList());
+  }
+
+  factory PdfArray.fromNum(List<num> list) {
+    return PdfArray(list.map<PdfNum>((num e) => PdfNum(e)).toList());
+  }
+
+  // factory PdfArray.fromStrings(List<String> list) {
+  //   return PdfArray(
+  //       list.map<PdfString>((String e) => PdfString.fromString(e)).toList());
+  // }
+
+  final List<PdfDataType> values = <PdfDataType>[];
+
+  void add(PdfDataType v) {
+    values.add(v);
+  }
+
+  @override
+  void output(PdfStream s) {
+    s.putString('[');
+    if (values.isNotEmpty) {
+      for (int n = 0; n < values.length - 1; n++) {
+        final PdfDataType val = values[n];
+        val.output(s);
+        s.putString(' ');
+      }
+      values.last.output(s);
+    }
+    s.putString(']');
+  }
+}
+
+class PdfDict extends PdfDataType {
+  PdfDict([Map<String, PdfDataType> values]) {
+    if (values != null) {
+      this.values.addAll(values);
+    }
+  }
+
+  factory PdfDict.fromObjectMap(Map<String, PdfObject> objects) {
+    return PdfDict(
+      objects.map<String, PdfIndirect>(
+        (String key, PdfObject value) =>
+            MapEntry<String, PdfIndirect>(key, value.ref()),
+      ),
+    );
+  }
+
+  final Map<String, PdfDataType> values = <String, PdfDataType>{};
+
+  bool get isNotEmpty => values.isNotEmpty;
+
+  operator []=(String k, PdfDataType v) {
+    values[k] = v;
+  }
+
+  @override
+  void output(PdfStream s) {
+    s.putString('<< ');
+    values.forEach((String k, PdfDataType v) {
+      s.putString('$k ');
+      v.output(s);
+      s.putString('\n');
+    });
+    s.putString('>>');
+  }
+
+  bool containsKey(String key) {
+    return values.containsKey(key);
+  }
+}

@@ -119,9 +119,9 @@ abstract class PdfFont extends PdfObject {
   void _prepare() {
     super._prepare();
 
-    params['/Subtype'] = PdfStream.string(subtype);
-    params['/Name'] = PdfStream.string(name);
-    params['/Encoding'] = PdfStream.string('/WinAnsiEncoding');
+    params['/Subtype'] = PdfName(subtype);
+    params['/Name'] = PdfName(name);
+    params['/Encoding'] = const PdfName('/WinAnsiEncoding');
   }
 
   @Deprecated('Use `glyphMetrics` instead')
@@ -166,9 +166,9 @@ See https://github.com/DavBfr/dart_pdf/wiki/Fonts-Management
   PdfStream putText(String text) {
     try {
       return PdfStream()
-        ..putBytes(latin1.encode('('))
+        ..putByte(40)
         ..putTextBytes(latin1.encode(text))
-        ..putBytes(latin1.encode(')'));
+        ..putByte(41);
     } catch (e) {
       assert(false, '''\n---------------------------------------------
 Can not decode the string to Latin1.

@@ -32,20 +32,19 @@ class PdfFontDescriptor extends PdfObject {
   void _prepare() {
     super._prepare();
 
-    params['/FontName'] = PdfStream.string('/' + ttfFont.fontName);
+    params['/FontName'] = PdfName('/' + ttfFont.fontName);
     params['/FontFile2'] = file.ref();
-    params['/Flags'] = PdfStream.intNum(ttfFont.font.unicode ? 4 : 32);
-    params['/FontBBox'] = PdfStream()
-      ..putIntArray(<int>[
+    params['/Flags'] = PdfNum(ttfFont.font.unicode ? 4 : 32);
+    params['/FontBBox'] = PdfArray.fromNum(<int>[
       (ttfFont.font.xMin / ttfFont.font.unitsPerEm * 1000).toInt(),
       (ttfFont.font.yMin / ttfFont.font.unitsPerEm * 1000).toInt(),
       (ttfFont.font.xMax / ttfFont.font.unitsPerEm * 1000).toInt(),
       (ttfFont.font.yMax / ttfFont.font.unitsPerEm * 1000).toInt()
     ]);
-    params['/Ascent'] = PdfStream.intNum((ttfFont.ascent * 1000).toInt());
-    params['/Descent'] = PdfStream.intNum((ttfFont.descent * 1000).toInt());
-    params['/ItalicAngle'] = PdfStream.intNum(0);
-    params['/CapHeight'] = PdfStream.intNum(10);
-    params['/StemV'] = PdfStream.intNum(79);
+    params['/Ascent'] = PdfNum((ttfFont.ascent * 1000).toInt());
+    params['/Descent'] = PdfNum((ttfFont.descent * 1000).toInt());
+    params['/ItalicAngle'] = const PdfNum(0);
+    params['/CapHeight'] = const PdfNum(10);
+    params['/StemV'] = const PdfNum(79);
   }
 }

@@ -20,8 +20,8 @@ part of pdf;
 
 class PdfFormXObject extends PdfXObject {
   PdfFormXObject(PdfDocument pdfDocument) : super(pdfDocument, '/Form') {
-    params['/FormType'] = PdfStream.string('1');
-    params['/BBox'] = PdfStream.string('[0 0 1000 1000]');
+    params['/FormType'] = const PdfNum(1);
+    params['/BBox'] = PdfArray.fromNum(const <int>[0, 0, 1000, 1000]);
   }
 
   /// The fonts associated with this page
@@ -34,7 +34,7 @@ class PdfFormXObject extends PdfXObject {
   void setMatrix(Matrix4 t) {
     final Float64List s = t.storage;
     params['/Matrix'] =
-        PdfStream.string('[${s[0]} ${s[1]} ${s[4]} ${s[5]} ${s[12]} ${s[13]}]');
+        PdfArray.fromNum(<double>[s[0], s[1], s[4], s[5], s[12], s[13]]);
   }
 
   @override
@@ -43,20 +43,20 @@ class PdfFormXObject extends PdfXObject {
 
     // Now the resources
     /// This holds any resources for this FormXObject
-    final Map<String, PdfStream> resources = <String, PdfStream>{};
+    final PdfDict resources = PdfDict();
 
     // fonts
     if (fonts.isNotEmpty) {
-      resources['/Font'] = PdfStream()..putObjectDictionary(fonts);
+      resources['/Font'] = PdfDict.fromObjectMap(fonts);
     }
 
     // Now the XObjects
     if (xobjects.isNotEmpty) {
-      resources['/XObject'] = PdfStream()..putObjectDictionary(xobjects);
+      resources['/XObject'] = PdfDict.fromObjectMap(xobjects);
     }
 
     if (resources.isNotEmpty) {
-      params['/Resources'] = PdfStream.dictionary(resources);
+      params['/Resources'] = resources;
     }
   }
 }

@@ -27,15 +27,15 @@ class PdfGraphicState {
   final double opacity;
 
   @protected
-  PdfStream _output() {
-    final Map<String, PdfStream> params = <String, PdfStream>{};
+  PdfDict _output() {
+    final PdfDict params = PdfDict();
 
     if (opacity != null) {
-      params['/CA'] = PdfStream.num(opacity);
-      params['/ca'] = PdfStream.num(opacity);
+      params['/CA'] = PdfNum(opacity);
+      params['/ca'] = PdfNum(opacity);
     }
 
-    return PdfStream.dictionary(params);
+    return params;
   }
 
   @override

@@ -78,10 +78,10 @@ class PdfImage extends PdfXObject {
         _height = height,
         super(pdfDocument, '/Image', isBinary: true) {
     _name = '/Image$objser';
-    params['/Width'] = PdfStream.string(width.toString());
-    params['/Height'] = PdfStream.string(height.toString());
-    params['/BitsPerComponent'] = PdfStream.intNum(8);
-    params['/Name'] = PdfStream.string(_name);
+    params['/Width'] = PdfNum(width);
+    params['/Height'] = PdfNum(height);
+    params['/BitsPerComponent'] = const PdfNum(8);
+    params['/Name'] = PdfName(_name);
 
     if (alphaChannel == false && alpha) {
       final PdfImage _sMask = PdfImage._(
@@ -95,17 +95,17 @@ class PdfImage extends PdfXObject {
         jpeg: jpeg,
         orientation: orientation,
       );
-      params['/SMask'] = PdfStream.string('${_sMask.objser} 0 R');
+      params['/SMask'] = PdfIndirect(_sMask.objser, 0);
     }
 
     if (isRGB) {
-      params['/ColorSpace'] = PdfStream.string('/DeviceRGB');
+      params['/ColorSpace'] = const PdfName('/DeviceRGB');
     } else {
-      params['/ColorSpace'] = PdfStream.string('/DeviceGray');
+      params['/ColorSpace'] = const PdfName('/DeviceGray');
     }
 
     if (jpeg) {
-      params['/Intent'] = PdfStream.string('/RelativeColorimetric');
+      params['/Intent'] = const PdfName('/RelativeColorimetric');
     }
   }
 
@@ -163,7 +163,7 @@ class PdfImage extends PdfXObject {
   void _prepare() {
     if (jpeg) {
       buf.putBytes(image);
-      params['/Filter'] = PdfStream.string('/DCTDecode');
+      params['/Filter'] = const PdfName('/DCTDecode');
       super._prepare();
       return;
     }

@@ -27,28 +27,28 @@ class PdfInfo extends PdfObject {
       this.producer})
       : super(pdfDocument, null) {
     if (author != null) {
-      params['/Author'] = PdfStream()..putLiteral(author);
+      params['/Author'] = PdfSecString.fromString(this, author);
     }
     if (creator != null) {
-      params['/Creator'] = PdfStream()..putLiteral(creator);
+      params['/Creator'] = PdfSecString.fromString(this, creator);
     }
     if (title != null) {
-      params['/Title'] = PdfStream()..putLiteral(title);
+      params['/Title'] = PdfSecString.fromString(this, title);
     }
     if (subject != null) {
-      params['/Subject'] = PdfStream()..putLiteral(subject);
+      params['/Subject'] = PdfSecString.fromString(this, subject);
     }
     if (keywords != null) {
-      params['/Keywords'] = PdfStream()..putLiteral(keywords);
+      params['/Keywords'] = PdfSecString.fromString(this, keywords);
     }
     if (producer != null) {
-      params['/Producer'] = PdfStream()
-        ..putLiteral('$producer ($_libraryName)');
+      params['/Producer'] =
+          PdfSecString.fromString(this, '$producer ($_libraryName)');
     } else {
-      params['/Producer'] = PdfStream()..putLiteral(_libraryName);
+      params['/Producer'] = PdfSecString.fromString(this, _libraryName);
     }
 
-    params['/CreationDate'] = PdfStream()..putDate(DateTime.now());
+    params['/CreationDate'] = PdfSecString.fromDate(this, DateTime.now());
   }
 
   static const String _libraryName = 'https://github.com/DavBfr/dart_pdf';

@@ -20,7 +20,7 @@ class PdfNames extends PdfObject {
   /// This constructs a Pdf Name object
   PdfNames(PdfDocument pdfDocument) : super(pdfDocument);
 
-  final List<PdfStream> _dests = <PdfStream>[];
+  final PdfArray _dests = PdfArray();
 
   void addDest(
     String name,
@@ -32,16 +32,14 @@ class PdfNames extends PdfObject {
     assert(page.pdfDocument == pdfDocument);
     assert(name != null);
 
-    _dests.add(PdfStream()..putText(name));
-    _dests.add(PdfStream()
-      ..putDictionary(<String, PdfStream>{
-        '/D': PdfStream()
-          ..putArray(<PdfStream>[
+    _dests.add(PdfSecString.fromString(this, name));
+    _dests.add(PdfDict(<String, PdfDataType>{
+      '/D': PdfArray(<PdfDataType>[
         page.ref(),
-            PdfStream.string('/XYZ'),
-            if (posX == null) PdfStream.string('null') else PdfStream.num(posX),
-            if (posY == null) PdfStream.string('null') else PdfStream.num(posY),
-            if (posZ == null) PdfStream.string('null') else PdfStream.num(posZ),
+        const PdfName('/XYZ'),
+        if (posX == null) const PdfNull() else PdfNum(posX),
+        if (posY == null) const PdfNull() else PdfNum(posY),
+        if (posZ == null) const PdfNull() else PdfNum(posZ),
       ]),
     }));
   }
@@ -50,9 +48,6 @@ class PdfNames extends PdfObject {
   void _prepare() {
     super._prepare();
 
-    params['/Dests'] = PdfStream()
-      ..putDictionary(<String, PdfStream>{
-        '/Names': PdfStream()..putArray(_dests),
-      });
+    params['/Dests'] = PdfDict(<String, PdfDataType>{'/Names': _dests});
   }
 }

@@ -24,14 +24,14 @@ class PdfObject {
       : assert(pdfDocument != null),
         objser = pdfDocument._genSerial() {
     if (type != null) {
-      params['/Type'] = PdfStream.string(type);
+      params['/Type'] = PdfName(type);
     }
 
     pdfDocument.objects.add(this);
   }
 
   /// This is the object parameters.
-  final Map<String, PdfStream> params = <String, PdfStream>{};
+  final PdfDict params = PdfDict();
 
   /// This is the unique serial number for this object.
   final int objser;
@@ -72,7 +72,7 @@ class PdfObject {
 
   void _writeContent(PdfStream os) {
     if (params.isNotEmpty) {
-      os.putDictionary(params);
+      params.output(os);
       os.putString('\n');
     }
   }
@@ -89,5 +89,5 @@ class PdfObject {
 
   /// Returns the unique serial number in Pdf format
   /// @return the serial number in Pdf format
-  PdfStream ref() => PdfStream.string('$objser $objgen R');
+  PdfIndirect ref() => PdfIndirect(objser, objgen);
 }

@@ -46,12 +46,12 @@ class PdfObjectStream extends PdfObject {
       _data = buf.output();
     } else if (pdfDocument.deflate != null) {
       _data = pdfDocument.deflate(buf.output());
-      params['/Filter'] = PdfStream.string('/FlateDecode');
+      params['/Filter'] = const PdfName('/FlateDecode');
     } else if (isBinary) {
       // This is a Ascii85 stream
       final Ascii85Encoder e = Ascii85Encoder();
       _data = e.convert(buf.output());
-      params['/Filter'] = PdfStream.string('/ASCII85Decode');
+      params['/Filter'] = const PdfName('/ASCII85Decode');
     } else {
       // This is a non-deflated stream
       _data = buf.output();
@@ -59,7 +59,7 @@ class PdfObjectStream extends PdfObject {
     if (pdfDocument.encryption != null) {
       _data = pdfDocument.encryption.encrypt(_data, this);
     }
-    params['/Length'] = PdfStream.intNum(_data.length);
+    params['/Length'] = PdfNum(_data.length);
   }
 
   @override

@@ -87,24 +87,27 @@ class PdfOutline extends PdfObject {
 
     // These are for kids only
     if (parent != null) {
-      params['/Title'] = PdfStream.string(title);
-      final List<PdfStream> dests = <PdfStream>[];
+      params['/Title'] = PdfSecString.fromString(this, title);
+      final PdfArray dests = PdfArray();
       dests.add(dest.ref());
 
       if (destMode == PdfOutlineMode.fitpage) {
-        dests.add(PdfStream.string('/Fit'));
+        dests.add(const PdfName('/Fit'));
       } else {
-        dests.add(PdfStream.string(
-            '/FitR ${rect.left} ${rect.bottom} ${rect.right} ${rect.top}'));
+        dests.add(const PdfName('/FitR'));
+        dests.add(PdfNum(rect.left));
+        dests.add(PdfNum(rect.bottom));
+        dests.add(PdfNum(rect.right));
+        dests.add(PdfNum(rect.top));
       }
       params['/Parent'] = parent.ref();
-      params['/Dest'] = PdfStream.array(dests);
+      params['/Dest'] = dests;
 
       // were a descendent, so by default we are closed. Find out how many
       // entries are below us
       final int c = descendants();
       if (c > 0) {
-        params['/Count'] = PdfStream.intNum(-c);
+        params['/Count'] = PdfNum(-c);
       }
 
       final int index = parent.getIndex(this);
@@ -120,7 +123,7 @@ class PdfOutline extends PdfObject {
     } else {
       // the number of outlines in this document
       // were the top level node, so all are open by default
-      params['/Count'] = PdfStream.intNum(outlines.length);
+      params['/Count'] = PdfNum(outlines.length);
     }
 
     // These only valid if we have children

@@ -113,16 +113,17 @@ class PdfOutput {
     // now the trailer object
     os.putString('trailer\n');
 
-    final Map<String, PdfStream> params = <String, PdfStream>{};
+    final PdfDict params = PdfDict();
 
     // the number of entries (REQUIRED)
-    params['/Size'] = PdfStream.intNum(offsets.length + 1);
+    params['/Size'] = PdfNum(offsets.length + 1);
 
     // the /Root catalog indirect reference (REQUIRED)
     if (rootID != null) {
       params['/Root'] = rootID.ref();
-      final PdfStream id = PdfStream.binary(rootID.pdfDocument.documentID);
-      params['/ID'] = PdfStream.array(<PdfStream>[id, id]);
+      final PdfString id =
+          PdfString(rootID.pdfDocument.documentID, PdfStringFormat.binary);
+      params['/ID'] = PdfArray(<PdfDataType>[id, id]);
     } else {
       throw Exception('Root object is not present in document');
     }
@@ -138,7 +139,7 @@ class PdfOutput {
     }
 
     // end the trailer object
-    os.putDictionary(params);
+    params.output(os);
     os.putString('\nstartxref\n$xref\n%%EOF\n');
 
     if (signatureID != null) {

@@ -94,8 +94,8 @@ class PdfPage extends PdfObject {
     params['/Parent'] = pdfDocument.pdfPageList.ref();
 
     // the /MediaBox for the page size
-    params['/MediaBox'] = PdfStream()
-      ..putNumArray(<double>[0, 0, pageFormat.width, pageFormat.height]);
+    params['/MediaBox'] =
+        PdfArray.fromNum(<double>[0, 0, pageFormat.width, pageFormat.height]);
 
     // Rotation (if not zero)
 //        if(rotate!=0) {
@@ -109,39 +109,38 @@ class PdfPage extends PdfObject {
       if (contents.length == 1) {
         params['/Contents'] = contents.first.ref();
       } else {
-        params['/Contents'] = PdfStream()..putObjectArray(contents);
+        params['/Contents'] = PdfArray.fromObjects(contents);
       }
     }
 
     // Now the resources
     /// This holds any resources for this page
-    final Map<String, PdfStream> resources = <String, PdfStream>{};
+    final PdfDict resources = PdfDict();
 
     // fonts
     if (fonts.isNotEmpty) {
-      resources['/Font'] = PdfStream()..putObjectDictionary(fonts);
+      resources['/Font'] = PdfDict.fromObjectMap(fonts);
     }
 
     // Now the XObjects
     if (xObjects.isNotEmpty) {
-      resources['/XObject'] = PdfStream()..putObjectDictionary(xObjects);
+      resources['/XObject'] = PdfDict.fromObjectMap(xObjects);
     }
 
     if (pdfDocument.hasGraphicStates) {
       // Declare Transparency Group settings
-      params['/Group'] = PdfStream()
-        ..putDictionary(<String, PdfStream>{
-          '/Type': PdfStream.string('/Group'),
-          '/S': PdfStream.string('/Transparency'),
-          '/CS': PdfStream.string('/DeviceRGB'),
-          '/I': PdfStream()..putBool(isolatedTransparency),
-          '/K': PdfStream()..putBool(knockoutTransparency),
+      params['/Group'] = PdfDict(<String, PdfDataType>{
+        '/Type': const PdfName('/Group'),
+        '/S': const PdfName('/Transparency'),
+        '/CS': const PdfName('/DeviceRGB'),
+        '/I': PdfBool(isolatedTransparency),
+        '/K': PdfBool(knockoutTransparency),
       });
 
       resources['/ExtGState'] = pdfDocument.graphicStates.ref();
     }
 
-    params['/Resources'] = PdfStream.dictionary(resources);
+    params['/Resources'] = resources;
 
     // The thumbnail
     if (thumbnail != null) {
@@ -150,7 +149,7 @@ class PdfPage extends PdfObject {
 
     // The /Annots object
     if (annotations.isNotEmpty) {
-      params['/Annots'] = PdfStream()..putObjectArray(annotations);
+      params['/Annots'] = PdfArray.fromObjects(annotations);
     }
   }
 }

@@ -32,7 +32,7 @@ class PdfPageList extends PdfObject {
   void _prepare() {
     super._prepare();
 
-    params['/Kids'] = PdfStream()..putObjectArray(pages);
-    params['/Count'] = PdfStream.intNum(pages.length);
+    params['/Kids'] = PdfArray.fromObjects(pages);
+    params['/Count'] = PdfNum(pages.length);
   }
 }

@@ -42,7 +42,7 @@ class PdfSignature extends PdfObject {
 
   @override
   void _write(PdfStream os) {
-    crypto.preSign(params);
+    crypto.preSign(this, params);
 
     _offsetStart = os.offset + '$objser $objgen obj\n'.length;
     super._write(os);
@@ -53,13 +53,13 @@ class PdfSignature extends PdfObject {
     assert(_offsetStart != null && _offsetEnd != null,
         'Must reserve the object space before signing the document');
 
-    crypto.sign(os, params, _offsetStart, _offsetEnd);
+    crypto.sign(this, os, params, _offsetStart, _offsetEnd);
   }
 }
 
 abstract class PdfSignatureBase {
-  void preSign(Map<String, PdfStream> params);
+  void preSign(PdfObject object, PdfDict params);
 
-  void sign(PdfStream os, Map<String, PdfStream> params, int offsetStart,
+  void sign(PdfObject object, PdfStream os, PdfDict params, int offsetStart,
       int offsetEnd);
 }

@@ -36,13 +36,8 @@ class PdfStream {
     }
   }
 
-  static PdfStream string(String s) => PdfStream()..putString(s);
-
-  void putStringUtf16(String s) {
-    for (int codeUnit in s.codeUnits) {
-      _stream.add(codeUnit & 0xff);
-      _stream.add((codeUnit >> 8) & 0xff);
-    }
+  void putByte(int s) {
+    _stream.add(s);
   }
 
   void putBytes(List<int> s) {
@@ -61,13 +56,6 @@ class PdfStream {
     }).join(' '));
   }
 
-  void putIntList(List<int> d) {
-    putString(d.map((int v) => v.toString()).join(' '));
-  }
-
-  static PdfStream num(double d) => PdfStream()..putNum(d);
-  static PdfStream intNum(int i) => PdfStream()..putString(i.toString());
-
   /// Escape special characters
   /// \ddd Character code ddd (octal)
   void putTextBytes(List<int> s) {
@@ -111,105 +99,6 @@ class PdfStream {
     }
   }
 
-  void putText(String s) {
-    putBytes(latin1.encode('('));
-    putTextBytes(latin1.encode(s));
-    putBytes(latin1.encode(')'));
-  }
-
-  void putLiteral(String s) {
-    putBytes(latin1.encode('('));
-    putBytes(<int>[0xfe, 0xff]);
-    putTextBytes(encodeUtf16be(s));
-    putBytes(latin1.encode(')'));
-  }
-
-  void putBool(bool value) {
-    putString(value ? 'true' : 'false');
-  }
-
-  /// Returns the ASCII/Unicode code unit corresponding to the hexadecimal digit
-  /// [digit].
-  int _codeUnitForDigit(int digit) =>
-      digit < 10 ? digit + 0x30 : digit + 0x61 - 10;
-
-  void putBinary(List<int> s) {
-    _stream.add(0x3c);
-    for (int byte in s) {
-      _stream.add(_codeUnitForDigit((byte & 0xF0) >> 4));
-      _stream.add(_codeUnitForDigit(byte & 0x0F));
-    }
-    _stream.add(0x3e);
-  }
-
-  static PdfStream binary(List<int> s) => PdfStream()..putBinary(s);
-
-  void putArray(List<PdfStream> values) {
-    putString('[');
-    for (PdfStream val in values) {
-      putStream(val);
-      putString(' ');
-    }
-    putString(']');
-  }
-
-  void putObjectArray(List<PdfObject> values) {
-    putString('[');
-    for (PdfObject val in values) {
-      putStream(val.ref());
-      putString(' ');
-    }
-    putString(']');
-  }
-
-  void putStringArray(List<String> values) {
-    putString('[' + values.join(' ') + ']');
-  }
-
-  void putDate(DateTime date) {
-    final DateTime utcDate = date.toUtc();
-    final String year = utcDate.year.toString().padLeft(4, '0');
-    final String month = utcDate.month.toString().padLeft(2, '0');
-    final String day = utcDate.day.toString().padLeft(2, '0');
-    final String hour = utcDate.hour.toString().padLeft(2, '0');
-    final String minute = utcDate.minute.toString().padLeft(2, '0');
-    final String second = utcDate.second.toString().padLeft(2, '0');
-    putText('D:$year$month$day$hour$minute${second}Z');
-  }
-
-  void putNumArray(List<double> values) {
-    putString('[');
-    putNumList(values);
-    putString(']');
-  }
-
-  void putIntArray(List<int> values) {
-    putString('[');
-    putIntList(values);
-    putString(']');
-  }
-
-  static PdfStream array(List<PdfStream> values) =>
-      PdfStream()..putArray(values);
-
-  void putDictionary(Map<String, PdfStream> values) {
-    putString('<< ');
-    values.forEach((String k, PdfStream v) {
-      putString('$k ');
-      putStream(v);
-      putString('\n');
-    });
-    putString('>>');
-  }
-
-  static PdfStream dictionary(Map<String, PdfStream> values) =>
-      PdfStream()..putDictionary(values);
-
-  void putObjectDictionary(Map<String, PdfObject> values) {
-    putDictionary(values.map((String string, PdfObject object) =>
-        MapEntry<String, PdfStream>(string, object.ref())));
-  }
-
   int get offset => _stream.length;
 
   List<int> output() => _stream;

@@ -26,7 +26,7 @@ class PdfTtfFont extends PdfFont {
     file = PdfObjectStream(pdfDocument, isBinary: true);
     unicodeCMap = PdfUnicodeCmap(pdfDocument, protect);
     descriptor = PdfFontDescriptor(this, file);
-    widthsObject = PdfArrayObject(pdfDocument, <String>[]);
+    widthsObject = PdfArrayObject(pdfDocument, PdfArray());
   }
 
   @override
@@ -62,67 +62,64 @@ class PdfTtfFont extends PdfFont {
     return font.glyphInfoMap[g] ?? PdfFontMetrics.zero;
   }
 
-  void _buildTrueType(Map<String, PdfStream> params) {
+  void _buildTrueType(PdfDict params) {
     int charMin;
     int charMax;
 
     file.buf.putBytes(font.bytes.buffer.asUint8List());
-    file.params['/Length1'] = PdfStream.intNum(font.bytes.lengthInBytes);
+    file.params['/Length1'] = PdfNum(font.bytes.lengthInBytes);
 
-    params['/BaseFont'] = PdfStream.string('/' + fontName);
+    params['/BaseFont'] = PdfName('/' + fontName);
     params['/FontDescriptor'] = descriptor.ref();
     charMin = 32;
     charMax = 255;
     for (int i = charMin; i <= charMax; i++) {
-      widthsObject.values
-          .add((glyphMetrics(i).advanceWidth * 1000.0).toInt().toString());
+      widthsObject.array
+          .add(PdfNum((glyphMetrics(i).advanceWidth * 1000.0).toInt()));
     }
-    params['/FirstChar'] = PdfStream.intNum(charMin);
-    params['/LastChar'] = PdfStream.intNum(charMax);
+    params['/FirstChar'] = PdfNum(charMin);
+    params['/LastChar'] = PdfNum(charMax);
     params['/Widths'] = widthsObject.ref();
   }
 
-  void _buildType0(Map<String, PdfStream> params) {
+  void _buildType0(PdfDict params) {
     int charMin;
     int charMax;
 
     final TtfWriter ttfWriter = TtfWriter(font);
     final Uint8List data = ttfWriter.withChars(unicodeCMap.cmap);
     file.buf.putBytes(data);
-    file.params['/Length1'] = PdfStream.intNum(data.length);
+    file.params['/Length1'] = PdfNum(data.length);
 
-    final PdfStream descendantFont = PdfStream.dictionary(<String, PdfStream>{
-      '/Type': PdfStream.string('/Font'),
-      '/BaseFont': PdfStream.string('/' + fontName),
+    final PdfDict descendantFont = PdfDict(<String, PdfDataType>{
+      '/Type': const PdfName('/Font'),
+      '/BaseFont': PdfName('/' + fontName),
       '/FontFile2': file.ref(),
       '/FontDescriptor': descriptor.ref(),
-      '/W': PdfStream.array(<PdfStream>[
-        PdfStream.intNum(0),
+      '/W': PdfArray(<PdfDataType>[
+        const PdfNum(0),
         widthsObject.ref(),
       ]),
-      '/CIDToGIDMap': PdfStream.string('/Identity'),
-      '/DW': PdfStream.string('1000'),
-      '/Subtype': PdfStream.string('/CIDFontType2'),
-      '/CIDSystemInfo': PdfStream.dictionary(<String, PdfStream>{
-        '/Supplement': PdfStream.intNum(0),
-        '/Registry': PdfStream()..putText('Adobe'),
-        '/Ordering': PdfStream()..putText('Identity-H'),
+      '/CIDToGIDMap': const PdfName('/Identity'),
+      '/DW': const PdfNum(1000),
+      '/Subtype': const PdfName('/CIDFontType2'),
+      '/CIDSystemInfo': PdfDict(<String, PdfDataType>{
+        '/Supplement': const PdfNum(0),
+        '/Registry': PdfSecString.fromString(this, 'Adobe'),
+        '/Ordering': PdfSecString.fromString(this, 'Identity-H'),
       })
     });
 
-    params['/BaseFont'] = PdfStream.string('/' + fontName);
-    params['/Encoding'] = PdfStream.string('/Identity-H');
-    params['/DescendantFonts'] = PdfStream()
-      ..putArray(<PdfStream>[descendantFont]);
+    params['/BaseFont'] = PdfName('/' + fontName);
+    params['/Encoding'] = const PdfName('/Identity-H');
+    params['/DescendantFonts'] = PdfArray(<PdfDataType>[descendantFont]);
     params['/ToUnicode'] = unicodeCMap.ref();
 
     charMin = 0;
     charMax = unicodeCMap.cmap.length - 1;
     for (int i = charMin; i <= charMax; i++) {
-      widthsObject.values.add(
-          (glyphMetrics(unicodeCMap.cmap[i]).advanceWidth * 1000.0)
-              .toInt()
-              .toString());
+      widthsObject.array.add(PdfNum(
+          (glyphMetrics(unicodeCMap.cmap[i]).advanceWidth * 1000.0).toInt()));
     }
   }
 
@@ -145,7 +142,7 @@ class PdfTtfFont extends PdfFont {
 
     final Runes runes = text.runes;
     final PdfStream stream = PdfStream();
-    stream.putBytes(latin1.encode('<'));
+    stream.putByte(0x3c);
     for (int rune in runes) {
       int char = unicodeCMap.cmap.indexOf(rune);
       if (char == -1) {
@@ -155,7 +152,7 @@ class PdfTtfFont extends PdfFont {
 
       stream.putBytes(latin1.encode(char.toRadixString(16).padLeft(4, '0')));
     }
-    stream.putBytes(latin1.encode('>'));
+    stream.putByte(0x3e);
     return stream;
   }
 

@@ -44,7 +44,7 @@ class PdfType1Font extends PdfFont {
   void _prepare() {
     super._prepare();
 
-    params['/BaseFont'] = PdfStream.string('/' + fontName);
+    params['/BaseFont'] = PdfName('/' + fontName);
   }
 
   @override

@@ -19,6 +19,6 @@ part of pdf;
 class PdfXObject extends PdfObjectStream {
   PdfXObject(PdfDocument pdfDocument, String subtype, {bool isBinary = false})
       : super(pdfDocument, type: '/XObject', isBinary: isBinary) {
-    params['/Subtype'] = PdfStream.string(subtype);
+    params['/Subtype'] = PdfName(subtype);
   }
 }

@@ -20,6 +20,7 @@ import '../example/main.dart' as example;
 import 'annotations_test.dart' as annotations;
 import 'colors_test.dart' as colors;
 import 'complex_test.dart' as complex;
+import 'data_types_test.dart' as data_types;
 import 'isolate_test.dart' as isolate;
 import 'jpeg_test.dart' as jpeg;
 import 'metrics_test.dart' as metrics;
@@ -47,6 +48,7 @@ void main() {
   annotations.main();
   colors.main();
   complex.main();
+  data_types.main();
   example.main();
   isolate.main();
   jpeg.main();

+/*
+ * Copyright (C) 2017, David PHAM-VAN <dev.nfet.net@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// ignore_for_file: omit_local_variable_types
+
+import 'dart:typed_data';
+
+import 'package:pdf/pdf.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('PdfDataTypes Bool ', () {
+    expect(const PdfBool(true).toString(), 'true');
+    expect(const PdfBool(false).toString(), 'false');
+  });
+
+  test('PdfDataTypes Num', () {
+    expect(const PdfNum(0).toString(), '0');
+    expect(const PdfNum(.5).toString(), '0.50000');
+    expect(const PdfNum(50).toString(), '50');
+    expect(const PdfNum(50.1).toString(), '50.10000');
+  });
+
+  test('PdfDataTypes String', () {
+    expect(PdfString.fromString('test').toString(), '(test)');
+    expect(PdfString.fromString('Zoé').toString(), '(Zoé)');
+    expect(PdfString.fromString('\r\n\t\b\f)()(\\').toString(),
+        r'(\r\n\t\b\f\)\(\)\(\\)');
+    expect(
+      PdfString.fromString('你好').toList(),
+      <int>[40, 254, 255, 79, 96, 89, 125, 41],
+    );
+    expect(
+      PdfString.fromDate(DateTime.fromMillisecondsSinceEpoch(1583606302000))
+          .toString(),
+      '(D:20200307183822Z)',
+    );
+    expect(
+      PdfString(
+        Uint8List.fromList(const <int>[0, 1, 2, 3, 4, 5, 6]),
+        PdfStringFormat.binary,
+      ).toString(),
+      '<00010203040506>',
+    );
+  });
+
+  test('PdfDataTypes Name', () {
+    expect(const PdfName('/Hello').toString(), '/Hello');
+  });
+
+  test('PdfDataTypes Null', () {
+    expect(const PdfNull().toString(), 'null');
+  });
+
+  test('PdfDataTypes Indirect', () {
+    expect(const PdfIndirect(30, 4).toString(), '30 4 R');
+  });
+
+  test('PdfDataTypes Array', () {
+    expect(PdfArray(<PdfDataType>[]).toString(), '[]');
+    expect(
+      PdfArray(<PdfDataType>[const PdfNum(1), const PdfNum(2)]).toString(),
+      '[1 2]',
+    );
+  });
+
+  test('PdfDataTypes Dict', () {
+    expect(PdfDict(<String, PdfDataType>{}).toString(), '<< >>');
+
+    expect(
+      PdfDict(<String, PdfDataType>{
+        '/Name': const PdfName('/Value'),
+        '/Bool': const PdfBool(true),
+        '/Num': const PdfNum(42),
+        '/String': PdfString.fromString('hello'),
+        '/Null': const PdfNull(),
+        '/Indirect': const PdfIndirect(55, 0),
+        '/Array': PdfArray(<PdfDataType>[]),
+        '/Dict': PdfDict(<String, PdfDataType>{}),
+      }).toString(),
+      '<< /Name /Value\n/Bool true\n/Num 42\n/String (hello)\n/Null null\n/Indirect 55 0 R\n/Array []\n/Dict << >>\n>>',
+    );
+  });
+}