Add Page.orientation to force landscape or portrait

 # 1.3.4
 * Add available dimensions for PdfPageFormat
 * Add Document properties
+* Add Page.orientation to force landscape or portrait
 
 # 1.3.3
 * Fix a bug with the RichText Widget

@@ -16,15 +16,6 @@
 
 part of widget;
 
-abstract class BasePage {
-  BasePage({@required this.pageFormat}) : assert(pageFormat != null);
-
-  final PdfPageFormat pageFormat;
-
-  @protected
-  void generate(Document document);
-}
-
 class Document {
   Document(
       {PdfPageMode pageMode = PdfPageMode.none,
@@ -52,7 +43,7 @@ class Document {
 
   final Theme theme;
 
-  void addPage(BasePage page) {
+  void addPage(Page page) {
     page.generate(this);
   }
 
@@ -62,44 +53,83 @@ class Document {
 typedef BuildCallback = Widget Function(Context context);
 typedef BuildListCallback = List<Widget> Function(Context context);
 
-class Page extends BasePage {
-  Page(
-      {PdfPageFormat pageFormat = PdfPageFormat.standard,
+enum PageOrientation { natural, landscape, portrait }
+
+class Page {
+  const Page(
+      {this.pageFormat = PdfPageFormat.standard,
       BuildCallback build,
       this.theme,
+      this.orientation = PageOrientation.natural,
       EdgeInsets margin})
-      : margin = margin ??
-            EdgeInsets.fromLTRB(pageFormat.marginLeft, pageFormat.marginTop,
-                pageFormat.marginRight, pageFormat.marginBottom),
-        _build = build,
-        super(pageFormat: pageFormat);
+      : assert(pageFormat != null),
+        _margin = margin,
+        _build = build;
+
+  final PdfPageFormat pageFormat;
+
+  final PageOrientation orientation;
 
-  final EdgeInsets margin;
+  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);
+
+  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(PdfColor.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)
+      ..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();
   }
 
-  @override
+  @protected
   void generate(Document document) {
     final PdfPage pdfPage = PdfPage(document.document, pageFormat: pageFormat);
     final PdfGraphics canvas = pdfPage.getGraphics();
-    final BoxConstraints constraints = BoxConstraints(
-        maxWidth: pageFormat.width, maxHeight: pageFormat.height);
+    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 Map<Type, Inherited> inherited = <Type, Inherited>{};
@@ -120,19 +150,11 @@ class Page extends BasePage {
   void layout(Widget child, Context context, BoxConstraints constraints,
       {bool parentUsesSize = false}) {
     if (child != null) {
-      final BoxConstraints childConstraints = BoxConstraints(
-          minWidth: constraints.minWidth,
-          minHeight: constraints.minHeight,
-          maxWidth: constraints.hasBoundedWidth
-              ? constraints.maxWidth - margin.horizontal
-              : margin.horizontal,
-          maxHeight: constraints.hasBoundedHeight
-              ? constraints.maxHeight - margin.vertical
-              : margin.vertical);
-      child.layout(context, childConstraints, parentUsesSize: parentUsesSize);
+      final EdgeInsets _margin = margin;
+      child.layout(context, constraints, parentUsesSize: parentUsesSize);
       child.box = PdfRect(
-          margin.left,
-          pageFormat.height - child.box.height - margin.top,
+          _margin.left,
+          pageFormat.height - child.box.height - _margin.top,
           child.box.width,
           child.box.height);
     }
@@ -147,23 +169,44 @@ class Page extends BasePage {
       return true;
     }());
 
-    if (child != null) {
+    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);
     }
   }
 }
 
 class MultiPage extends Page {
-  MultiPage(
+  const MultiPage(
       {PdfPageFormat pageFormat = PdfPageFormat.a4,
       BuildListCallback build,
       this.crossAxisAlignment = CrossAxisAlignment.start,
       this.header,
       this.footer,
       Theme theme,
+      PageOrientation orientation = PageOrientation.natural,
       EdgeInsets margin})
       : _buildList = build,
-        super(pageFormat: pageFormat, margin: margin, theme: theme);
+        super(
+            pageFormat: pageFormat,
+            margin: margin,
+            theme: theme,
+            orientation: orientation);
 
   final BuildListCallback _buildList;
 
@@ -173,16 +216,40 @@ class MultiPage extends Page {
 
   final BuildCallback footer;
 
+  void paintChild(
+      Context context, Widget child, double x, double y, double pageHeight) {
+    if (mustRotate) {
+      final EdgeInsets _margin = margin;
+      context.canvas
+        ..saveContext()
+        ..setTransform(Matrix4.identity()
+          ..rotateZ(-math.pi / 2)
+          ..translate(x - pageHeight + _margin.top - _margin.left,
+              y + _margin.left - _margin.bottom));
+      child.paint(context);
+      context.canvas.restoreContext();
+    } else {
+      child.box = PdfRect(x, y, child.box.width, child.box.height);
+      child.paint(context);
+    }
+  }
+
   @override
   void generate(Document document) {
     if (_buildList == null) {
       return;
     }
 
+    final EdgeInsets _margin = margin;
+    final bool _mustRotate = mustRotate;
+    final double pageHeight =
+        _mustRotate ? pageFormat.width : pageFormat.height;
+    final double pageHeightMargin =
+        _mustRotate ? _margin.horizontal : _margin.vertical;
     final BoxConstraints constraints = BoxConstraints(
-        maxWidth: pageFormat.width, maxHeight: pageFormat.height);
-    final BoxConstraints childConstraints =
-        BoxConstraints(maxWidth: constraints.maxWidth - margin.horizontal);
+        maxWidth: _mustRotate
+            ? (pageFormat.height - _margin.vertical)
+            : (pageFormat.width - _margin.horizontal));
     final Theme calculatedTheme = theme ?? document.theme ?? Theme.base();
     final Map<Type, Inherited> inherited = <Type, Inherited>{};
     inherited[calculatedTheme.runtimeType] = calculatedTheme;
@@ -209,19 +276,16 @@ class MultiPage extends Page {
           }
           return true;
         }());
-        offsetStart = pageFormat.height - margin.top;
-        offsetEnd = margin.bottom;
+        offsetStart = pageHeight -
+            (_mustRotate ? pageHeightMargin - margin.bottom : _margin.top);
+        offsetEnd =
+            _mustRotate ? pageHeightMargin - _margin.left : _margin.bottom;
         if (header != null) {
           final Widget headerWidget = header(context);
           if (headerWidget != null) {
-            headerWidget.layout(context, childConstraints,
-                parentUsesSize: false);
-            headerWidget.box = PdfRect(
-                margin.left,
-                offsetStart - headerWidget.box.height,
-                headerWidget.box.width,
-                headerWidget.box.height);
-            headerWidget.paint(context);
+            headerWidget.layout(context, constraints, parentUsesSize: false);
+            paintChild(context, headerWidget, _margin.left,
+                offsetStart - headerWidget.box.height, pageFormat.height);
             offsetStart -= headerWidget.box.height;
           }
         }
@@ -229,11 +293,9 @@ class MultiPage extends Page {
         if (footer != null) {
           final Widget footerWidget = footer(context);
           if (footerWidget != null) {
-            footerWidget.layout(context, childConstraints,
-                parentUsesSize: false);
-            footerWidget.box = PdfRect(margin.left, margin.bottom,
-                footerWidget.box.width, footerWidget.box.height);
-            footerWidget.paint(context);
+            footerWidget.layout(context, constraints, parentUsesSize: false);
+            paintChild(context, footerWidget, _margin.left, _margin.bottom,
+                pageFormat.height);
             offsetEnd += footerWidget.box.height;
           }
         }
@@ -244,10 +306,11 @@ class MultiPage extends Page {
         widgetContext = null;
       }
 
-      child.layout(context, childConstraints, parentUsesSize: false);
+      child.layout(context, constraints, parentUsesSize: false);
 
       if (offsetStart - child.box.height < offsetEnd) {
-        if (child.box.height <= pageFormat.height - margin.vertical) {
+        if (child.box.height <= pageHeight - pageHeightMargin &&
+            !(child is SpanningWidget)) {
           context = null;
           continue;
         }
@@ -255,18 +318,17 @@ class MultiPage extends Page {
         if (!(child is SpanningWidget)) {
           throw Exception(
               'Widget won\'t fit into the page as its height (${child.box.height}) '
-              'exceed a page height (${pageFormat.height - margin.vertical}). '
+              'exceed a page height (${pageHeight - pageHeightMargin}). '
               'You probably need a SpanningWidget or use a single page layout');
         }
 
         final SpanningWidget span = child;
 
-        child.layout(context,
-            childConstraints.copyWith(maxHeight: offsetStart - offsetEnd),
+        child.layout(
+            context, constraints.copyWith(maxHeight: offsetStart - offsetEnd),
             parentUsesSize: false);
-        child.box = PdfRect(margin.left, offsetStart - child.box.height,
-            child.box.width, child.box.height);
-        child.paint(context);
+        paintChild(context, child, _margin.left, offsetStart - child.box.height,
+            pageFormat.height);
 
         if (span.canSpan) {
           widgetContext = span.saveContext();
@@ -278,9 +340,8 @@ class MultiPage extends Page {
         continue;
       }
 
-      child.box = PdfRect(margin.left, offsetStart - child.box.height,
-          child.box.width, child.box.height);
-      child.paint(context);
+      paintChild(context, child, _margin.left, offsetStart - child.box.height,
+          pageFormat.height);
       offsetStart -= child.box.height;
       index++;
     }

@@ -266,6 +266,9 @@ class EdgeInsets {
       bottom + other.bottom,
     );
   }
+
+  @override
+  String toString() => 'EdgeInsets $left, $top, $right, $bottom';
 }
 
 class Alignment {