Add Roll Paper support

 # Changelog
 
+## 1.3.27
+
+- Add Roll Paper support
+
 ## 1.3.26
 
 - Update Analysis options

@@ -32,7 +32,7 @@ class PdfPage extends PdfObject {
   }
 
   /// This is this page format, ie the size of the page, margins, and rotation
-  final PdfPageFormat pageFormat;
+  PdfPageFormat pageFormat;
 
   /// This holds the contents of the page.
   List<PdfObjectStream> contents = <PdfObjectStream>[];

@@ -23,7 +23,9 @@ class PdfPageFormat {
       double marginLeft = 0.0,
       double marginRight = 0.0,
       double marginAll})
-      : marginTop = marginAll ?? marginTop,
+      : assert(width > 0),
+        assert(height > 0),
+        marginTop = marginAll ?? marginTop,
         marginBottom = marginAll ?? marginBottom,
         marginLeft = marginAll ?? marginLeft,
         marginRight = marginAll ?? marginRight;
@@ -39,6 +41,14 @@ class PdfPageFormat {
   static const PdfPageFormat legal =
       PdfPageFormat(8.5 * inch, 14.0 * inch, marginAll: inch);
 
+  static const PdfPageFormat roll57 =
+      PdfPageFormat(57 * mm, double.infinity, marginAll: 5 * mm);
+  static const PdfPageFormat roll80 =
+      PdfPageFormat(80 * mm, double.infinity, marginAll: 5 * mm);
+
+  static const PdfPageFormat undefined =
+      PdfPageFormat(double.infinity, double.infinity);
+
   static const PdfPageFormat standard = a4;
 
   static const double point = 1.0;

@@ -50,11 +50,15 @@ class PdfStream {
   }
 
   void putNum(double d) {
+    assert(d != double.infinity);
     putString(d.toStringAsFixed(precision));
   }
 
   void putNumList(List<double> d) {
-    putString(d.map((double v) => v.toStringAsFixed(precision)).join(' '));
+    putString(d.map((double v) {
+      assert(v != double.infinity);
+      return v.toStringAsFixed(precision);
+    }).join(' '));
   }
 
   void putIntList(List<int> d) {

@@ -679,6 +679,9 @@ class FullPage extends SingleChildWidget {
   final bool ignoreMargins;
 
   BoxConstraints _getConstraints(Context context) {
+    assert(context.page.pageFormat.width != double.infinity);
+    assert(context.page.pageFormat.height != double.infinity);
+
     return ignoreMargins
         ? BoxConstraints.tightFor(
             width: context.page.pageFormat.width,

@@ -111,6 +111,9 @@ class MultiPage extends Page {
       return;
     }
 
+    assert(pageFormat.width > 0 && pageFormat.width < double.infinity);
+    assert(pageFormat.height > 0 && pageFormat.height < double.infinity);
+
     final EdgeInsets _margin = margin;
     final bool _mustRotate = mustRotate;
     final double pageHeight =

@@ -52,7 +52,7 @@ class Page {
 
   final PageTheme pageTheme;
 
-  PdfPageFormat get pageFormat => pageTheme.pageFormat;
+  PdfPageFormat get pageFormat => _pdfPage?.pageFormat ?? pageTheme.pageFormat;
 
   PageOrientation get orientation => pageTheme.orientation;
 
@@ -92,7 +92,7 @@ class Page {
   void postProcess(Document document) {
     final PdfGraphics canvas = _pdfPage.getGraphics();
     final EdgeInsets _margin = margin;
-    final BoxConstraints constraints = mustRotate
+    BoxConstraints constraints = mustRotate
         ? BoxConstraints(
             maxWidth: pageFormat.height - _margin.vertical,
             maxHeight: pageFormat.width - _margin.horizontal)
@@ -107,6 +107,43 @@ class Page {
       canvas: canvas,
     ).inheritFrom(calculatedTheme);
 
+    Widget background;
+    Widget content;
+    Widget foreground;
+
+    if (_build != null) {
+      content = _build(context);
+      if (content != null) {
+        final PdfPoint size = layout(content, context, constraints);
+
+        if (_pdfPage.pageFormat.height == double.infinity) {
+          _pdfPage.pageFormat =
+              _pdfPage.pageFormat.copyWith(width: size.x, height: size.y);
+          constraints = mustRotate
+              ? BoxConstraints(
+                  maxWidth: _pdfPage.pageFormat.height - _margin.vertical,
+                  maxHeight: _pdfPage.pageFormat.width - _margin.horizontal)
+              : BoxConstraints(
+                  maxWidth: _pdfPage.pageFormat.width - _margin.horizontal,
+                  maxHeight: _pdfPage.pageFormat.height - _margin.vertical);
+        }
+      }
+    }
+
+    if (pageTheme.buildBackground != null) {
+      background = pageTheme.buildBackground(context);
+      if (background != null) {
+        layout(background, context, constraints);
+      }
+    }
+
+    if (pageTheme.buildForeground != null) {
+      foreground = pageTheme.buildForeground(context);
+      if (foreground != null) {
+        layout(foreground, context, constraints);
+      }
+    }
+
     assert(() {
       if (Document.debug) {
         debugPaint(context);
@@ -114,44 +151,42 @@ class Page {
       return true;
     }());
 
-    if (pageTheme.buildBackground != null) {
-      final Widget child = pageTheme.buildBackground(context);
-      if (child != null) {
-        layout(child, context, constraints);
-        paint(child, context);
-      }
+    if (background != null) {
+      paint(background, context);
     }
 
-    if (_build != null) {
-      final Widget child = _build(context);
-      if (child != null) {
-        layout(child, context, constraints);
-        paint(child, context);
-      }
+    if (content != null) {
+      paint(content, context);
     }
 
-    if (pageTheme.buildForeground != null) {
-      final Widget child = pageTheme.buildForeground(context);
-      if (child != null) {
-        layout(child, context, constraints);
-        paint(child, context);
-      }
+    if (foreground != null) {
+      paint(foreground, context);
     }
   }
 
   @protected
-  void layout(Widget child, Context context, BoxConstraints constraints,
+  PdfPoint layout(Widget child, Context context, BoxConstraints constraints,
       {bool parentUsesSize = false}) {
-    if (child != null) {
-      final EdgeInsets _margin = margin;
-      child.layout(context, constraints, parentUsesSize: parentUsesSize);
-      assert(child.box != null);
-      child.box = PdfRect(
-          _margin.left,
-          pageFormat.height - child.box.height - _margin.top,
-          child.box.width,
-          child.box.height);
+    if (child == null) {
+      return PdfPoint(pageFormat.width, pageFormat.height);
     }
+
+    final EdgeInsets _margin = margin;
+    child.layout(context, constraints, parentUsesSize: parentUsesSize);
+    assert(child.box != null);
+
+    final double width = pageFormat.width == double.infinity
+        ? child.box.width + _margin.left + _margin.right
+        : pageFormat.width;
+
+    final double height = pageFormat.height == double.infinity
+        ? child.box.height + _margin.top + _margin.bottom
+        : pageFormat.height;
+
+    child.box = PdfRect(_margin.left, height - child.box.height - _margin.top,
+        child.box.width, child.box.height);
+
+    return PdfPoint(width, height);
   }
 
   @protected

@@ -4,7 +4,7 @@ description: A pdf producer for Dart. It can create pdf files for both web or fl
 homepage: https://github.com/DavBfr/dart_pdf/tree/master/pdf
 repository: https://github.com/DavBfr/dart_pdf
 issue_tracker: https://github.com/DavBfr/dart_pdf/issues
-version: 1.3.26
+version: 1.3.27
 
 environment:
   sdk: ">=2.3.0 <3.0.0"

@@ -25,6 +25,7 @@ import 'jpeg_test.dart' as jpeg;
 import 'metrics_test.dart' as metrics;
 import 'minimal_test.dart' as minimal;
 import 'orientation_test.dart' as orientation;
+import 'roll_paper_test.dart' as roll;
 import 'ttf_test.dart' as ttf;
 import 'type1_test.dart' as type1;
 import 'widget_basic_test.dart' as widget_basic;
@@ -49,6 +50,7 @@ void main() {
   metrics.main();
   minimal.main();
   orientation.main();
+  roll.main();
   ttf.main();
   type1.main();
   widget_basic.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:io';
+
+import 'package:pdf/pdf.dart';
+import 'package:pdf/widgets.dart';
+import 'package:test/test.dart';
+
+Document pdf;
+
+void main() {
+  setUpAll(() {
+    Document.debug = true;
+    pdf = Document();
+  });
+
+  test('Pdf Roll Paper', () async {
+    pdf.addPage(Page(
+      pageFormat: PdfPageFormat.roll80,
+      build: (Context context) => Padding(
+        padding: const EdgeInsets.all(30),
+        child: Center(
+          child: Text('Hello World!'),
+        ),
+      ),
+    ));
+  });
+
+  test('Pdf Automatic Paper', () async {
+    pdf.addPage(Page(
+        pageFormat: PdfPageFormat.undefined,
+        build: (Context context) => Text('Hello World!')));
+  });
+
+  tearDownAll(() {
+    final File file = File('roll-paper.pdf');
+    file.writeAsBytesSync(pdf.save());
+  });
+}