Move Page class to its own file

@@ -36,6 +36,7 @@ part 'widgets/geometry.dart';
 part 'widgets/grid_view.dart';
 part 'widgets/image.dart';
 part 'widgets/multi_page.dart';
+part 'widgets/page.dart';
 part 'widgets/placeholders.dart';
 part 'widgets/progress.dart';
 part 'widgets/stack.dart';

@@ -69,149 +69,3 @@ class Document {
     return document.save();
   }
 }
-
-typedef BuildCallback = Widget Function(Context context);
-typedef BuildListCallback = List<Widget> Function(Context context);
-
-enum PageOrientation { natural, landscape, portrait }
-
-class Page {
-  Page(
-      {this.pageFormat = PdfPageFormat.standard,
-      BuildCallback build,
-      this.theme,
-      this.orientation = PageOrientation.natural,
-      EdgeInsets margin})
-      : assert(pageFormat != null),
-        _margin = margin,
-        _build = build;
-
-  final PdfPageFormat pageFormat;
-
-  final PageOrientation orientation;
-
-  final EdgeInsets _margin;
-
-  final BuildCallback _build;
-
-  final Theme theme;
-
-  bool get mustRotate =>
-      (orientation == PageOrientation.landscape &&
-          pageFormat.height > pageFormat.width) ||
-      (orientation == PageOrientation.portrait &&
-          pageFormat.width > pageFormat.height);
-
-  PdfPage _pdfPage;
-
-  EdgeInsets get margin {
-    if (_margin != null) {
-      if (mustRotate) {
-        return EdgeInsets.fromLTRB(
-            _margin.bottom, _margin.left, _margin.top, _margin.right);
-      } else {
-        return _margin;
-      }
-    }
-
-    if (mustRotate) {
-      return EdgeInsets.fromLTRB(pageFormat.marginBottom, pageFormat.marginLeft,
-          pageFormat.marginTop, pageFormat.marginRight);
-    } else {
-      return EdgeInsets.fromLTRB(pageFormat.marginLeft, pageFormat.marginTop,
-          pageFormat.marginRight, pageFormat.marginBottom);
-    }
-  }
-
-  @protected
-  void debugPaint(Context context) {
-    final EdgeInsets _margin = margin;
-    context.canvas
-      ..setFillColor(PdfColors.lightGreen)
-      ..moveTo(0, 0)
-      ..lineTo(pageFormat.width, 0)
-      ..lineTo(pageFormat.width, pageFormat.height)
-      ..lineTo(0, pageFormat.height)
-      ..moveTo(_margin.left, _margin.bottom)
-      ..lineTo(_margin.left, pageFormat.height - _margin.top)
-      ..lineTo(
-          pageFormat.width - _margin.right, pageFormat.height - _margin.top)
-      ..lineTo(pageFormat.width - _margin.right, _margin.bottom)
-      ..fillPath();
-  }
-
-  @protected
-  void generate(Document document) {
-    _pdfPage = PdfPage(document.document, pageFormat: pageFormat);
-  }
-
-  @protected
-  void postProcess(Document document) {
-    final PdfGraphics canvas = _pdfPage.getGraphics();
-    final EdgeInsets _margin = margin;
-    final BoxConstraints constraints = mustRotate
-        ? BoxConstraints(
-            maxWidth: pageFormat.height - _margin.vertical,
-            maxHeight: pageFormat.width - _margin.horizontal)
-        : BoxConstraints(
-            maxWidth: pageFormat.width - _margin.horizontal,
-            maxHeight: pageFormat.height - _margin.vertical);
-
-    final Theme calculatedTheme = theme ?? document.theme ?? Theme.base();
-    final Context context = Context(
-      document: document.document,
-      page: _pdfPage,
-      canvas: canvas,
-    ).inheritFrom(calculatedTheme);
-    if (_build != null) {
-      final Widget child = _build(context);
-      layout(child, context, constraints);
-      paint(child, context);
-    }
-  }
-
-  @protected
-  void 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);
-    }
-  }
-
-  @protected
-  void paint(Widget child, Context context) {
-    assert(() {
-      if (Document.debug) {
-        debugPaint(context);
-      }
-      return true;
-    }());
-
-    if (child == null) {
-      return;
-    }
-
-    if (mustRotate) {
-      final EdgeInsets _margin = margin;
-      final Matrix4 mat = Matrix4.identity();
-      mat
-        ..rotateZ(-math.pi / 2)
-        ..translate(-pageFormat.height - _margin.left + _margin.top,
-            child.box.height - child.box.width + _margin.left - _margin.bottom);
-      context.canvas
-        ..saveContext()
-        ..setTransform(mat);
-      child.paint(context);
-      context.canvas.restoreContext();
-    } else {
-      child.paint(context);
-    }
-  }
-}

+/*
+ * 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.
+ */
+
+part of widget;
+
+typedef BuildCallback = Widget Function(Context context);
+typedef BuildListCallback = List<Widget> Function(Context context);
+
+enum PageOrientation { natural, landscape, portrait }
+
+class Page {
+  Page(
+      {this.pageFormat = PdfPageFormat.standard,
+      BuildCallback build,
+      this.theme,
+      this.orientation = PageOrientation.natural,
+      EdgeInsets margin})
+      : assert(pageFormat != null),
+        _margin = margin,
+        _build = build;
+
+  final PdfPageFormat pageFormat;
+
+  final PageOrientation orientation;
+
+  final EdgeInsets _margin;
+
+  final BuildCallback _build;
+
+  final Theme theme;
+
+  bool get mustRotate =>
+      (orientation == PageOrientation.landscape &&
+          pageFormat.height > pageFormat.width) ||
+      (orientation == PageOrientation.portrait &&
+          pageFormat.width > pageFormat.height);
+
+  PdfPage _pdfPage;
+
+  EdgeInsets get margin {
+    if (_margin != null) {
+      if (mustRotate) {
+        return EdgeInsets.fromLTRB(
+            _margin.bottom, _margin.left, _margin.top, _margin.right);
+      } else {
+        return _margin;
+      }
+    }
+
+    if (mustRotate) {
+      return EdgeInsets.fromLTRB(pageFormat.marginBottom, pageFormat.marginLeft,
+          pageFormat.marginTop, pageFormat.marginRight);
+    } else {
+      return EdgeInsets.fromLTRB(pageFormat.marginLeft, pageFormat.marginTop,
+          pageFormat.marginRight, pageFormat.marginBottom);
+    }
+  }
+
+  @protected
+  void debugPaint(Context context) {
+    final EdgeInsets _margin = margin;
+    context.canvas
+      ..setFillColor(PdfColors.lightGreen)
+      ..moveTo(0, 0)
+      ..lineTo(pageFormat.width, 0)
+      ..lineTo(pageFormat.width, pageFormat.height)
+      ..lineTo(0, pageFormat.height)
+      ..moveTo(_margin.left, _margin.bottom)
+      ..lineTo(_margin.left, pageFormat.height - _margin.top)
+      ..lineTo(
+          pageFormat.width - _margin.right, pageFormat.height - _margin.top)
+      ..lineTo(pageFormat.width - _margin.right, _margin.bottom)
+      ..fillPath();
+  }
+
+  @protected
+  void generate(Document document) {
+    _pdfPage = PdfPage(document.document, pageFormat: pageFormat);
+  }
+
+  @protected
+  void postProcess(Document document) {
+    final PdfGraphics canvas = _pdfPage.getGraphics();
+    final EdgeInsets _margin = margin;
+    final BoxConstraints constraints = mustRotate
+        ? BoxConstraints(
+            maxWidth: pageFormat.height - _margin.vertical,
+            maxHeight: pageFormat.width - _margin.horizontal)
+        : BoxConstraints(
+            maxWidth: pageFormat.width - _margin.horizontal,
+            maxHeight: pageFormat.height - _margin.vertical);
+
+    final Theme calculatedTheme = theme ?? document.theme ?? Theme.base();
+    final Context context = Context(
+      document: document.document,
+      page: _pdfPage,
+      canvas: canvas,
+    ).inheritFrom(calculatedTheme);
+    if (_build != null) {
+      final Widget child = _build(context);
+      layout(child, context, constraints);
+      paint(child, context);
+    }
+  }
+
+  @protected
+  void 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);
+    }
+  }
+
+  @protected
+  void paint(Widget child, Context context) {
+    assert(() {
+      if (Document.debug) {
+        debugPaint(context);
+      }
+      return true;
+    }());
+
+    if (child == null) {
+      return;
+    }
+
+    if (mustRotate) {
+      final EdgeInsets _margin = margin;
+      final Matrix4 mat = Matrix4.identity();
+      mat
+        ..rotateZ(-math.pi / 2)
+        ..translate(-pageFormat.height - _margin.left + _margin.top,
+            child.box.height - child.box.width + _margin.left - _margin.bottom);
+      context.canvas
+        ..saveContext()
+        ..setTransform(mat);
+      child.paint(context);
+      context.canvas.restoreContext();
+    } else {
+      child.paint(context);
+    }
+  }
+}