Enable dynamic changes to itemsWrap in PageableList

examples/widgets/pageable_list.dart

@@ -23,6 +23,7 @@ class PageableListApp extends App {
   List<CardModel> cardModels;
   Size pageSize = new Size(200.0, 200.0);
   ScrollDirection scrollDirection = ScrollDirection.horizontal;
+  bool itemsWrap = false;
 
   void initState() {
     List<Size> cardSizes = [
@@ -67,13 +68,18 @@ class PageableListApp extends App {
     );
   }
 
-  EventDisposition switchScrollDirection() {
+  void switchScrollDirection() {
     setState(() {
       scrollDirection = (scrollDirection == ScrollDirection.vertical)
         ? ScrollDirection.horizontal
         : ScrollDirection.vertical;
     });
-    return EventDisposition.processed;
+  }
+
+  void toggleItemsWrap() {
+    setState(() {
+      itemsWrap = !itemsWrap;
+    });
   }
 
   bool _drawerShowing = false;
@@ -113,6 +119,13 @@ class PageableListApp extends App {
           selected: scrollDirection == ScrollDirection.vertical,
           child: new Text('Vertical Layout'),
           onPressed: switchScrollDirection
+        ),
+        new DrawerItem(
+          onPressed: toggleItemsWrap,
+          child: new Row([
+            new Flexible(child: new Text('Scrolling wraps around')),
+            new Checkbox(value: itemsWrap)
+          ])
         )
       ]
     );
@@ -132,7 +145,7 @@ class PageableListApp extends App {
   Widget buildBody() {
     Widget list = new PageableList<CardModel>(
       items: cardModels,
-      itemsWrap: true,
+      itemsWrap: itemsWrap,
       itemBuilder: buildCard,
       scrollDirection: scrollDirection,
       itemExtent: (scrollDirection == ScrollDirection.vertical)

packages/flutter/lib/src/widgets/homogeneous_viewport.dart

@@ -83,6 +83,10 @@ class HomogeneousViewport extends RenderObjectWrapper {
       _layoutDirty = true;
       itemCount = newNode.itemCount;
     }
+    if (itemsWrap != newNode.itemsWrap) {
+      _layoutDirty = true;
+      itemsWrap = newNode.itemsWrap;
+    }
     if (itemExtent != newNode.itemExtent) {
       _layoutDirty = true;
       itemExtent = newNode.itemExtent;

packages/flutter/lib/src/widgets/scrollable.dart

@@ -371,7 +371,13 @@ abstract class ScrollableWidgetList extends Scrollable {
       itemExtent != source.itemExtent ||
       scrollDirection != source.scrollDirection;
 
+    if (itemsWrap != source.itemsWrap) {
+      _scrollBehavior = null;
+      scrollBehaviorUpdateNeeded = true;
+    }
+
     padding = source.padding;
+    itemsWrap = source.itemsWrap;
     itemExtent = source.itemExtent;
     super.syncConstructorArguments(source); // update scrollDirection
 
@@ -492,7 +498,6 @@ class ScrollableList<T> extends ScrollableWidgetList {
   void syncConstructorArguments(ScrollableList<T> source) {
     items = source.items;
     itemBuilder = source.itemBuilder;
-    itemsWrap = source.itemsWrap;
     super.syncConstructorArguments(source);
   }
 

packages/unit/test/widget/pageable_list_test.dart

@@ -7,6 +7,7 @@ import 'widget_tester.dart';
 const Size pageSize = const Size(800.0, 600.0);
 const List<int> pages = const <int>[0, 1, 2, 3, 4, 5];
 int currentPage = null;
+bool itemsWrap = false;
 
 Widget buildPage(int page) {
   return new Container(
@@ -17,7 +18,7 @@ Widget buildPage(int page) {
   );
 }
 
-Widget buildFrame({ bool itemsWrap: false }) {
+Widget buildFrame() {
   // The test framework forces the frame (and so the PageableList)
   // to be 800x600. The pageSize constant reflects as much.
   return new PageableList<int>(
@@ -55,6 +56,7 @@ void main() {
   test('Scroll left from page 0 to page 1', () {
     WidgetTester tester = new WidgetTester();
     currentPage = null;
+    itemsWrap = false;
     tester.pumpFrame(buildFrame);
     expect(currentPage, isNull);
     pageLeft(tester);
@@ -64,6 +66,7 @@ void main() {
   test('Underscroll (scroll right), return to page 0', () {
     WidgetTester tester = new WidgetTester();
     currentPage = null;
+    itemsWrap = false;
     tester.pumpFrame(buildFrame);
     expect(currentPage, isNull);
     pageRight(tester);
@@ -72,10 +75,13 @@ void main() {
 
   // PageableList with itemsWrap: true
 
+  itemsWrap = true;
+
   test('Scroll left page 0 to page 1, itemsWrap: true', () {
     WidgetTester tester = new WidgetTester();
     currentPage = null;
-    tester.pumpFrame(() { return buildFrame(itemsWrap: true); });
+    itemsWrap = true;
+    tester.pumpFrame(buildFrame);
     expect(currentPage, isNull);
     pageLeft(tester);
     expect(currentPage, equals(1));
@@ -84,7 +90,8 @@ void main() {
   test('Scroll right from page 0 to page 5, itemsWrap: true', () {
     WidgetTester tester = new WidgetTester();
     currentPage = null;
-    tester.pumpFrame(() { return buildFrame(itemsWrap: true); });
+    itemsWrap = true;
+    tester.pumpFrame(buildFrame);
     expect(currentPage, isNull);
     pageRight(tester);
     expect(currentPage, equals(5));