Rename ScrollDirection to Axis

We use the ScrollDirection for more than just scrolling.

Fixes #151

examples/widgets/horizontal_scrolling.dart

@@ -41,7 +41,7 @@ class HorizontalScrollingApp extends StatelessComponent {
     return new Center(
       child: new Container(
         height: 50.0,
-        child: new Block(circles, scrollDirection: ScrollDirection.horizontal)
+        child: new Block(circles, scrollDirection: Axis.horizontal)
       )
     );
   }

examples/widgets/pageable_list.dart

@@ -38,7 +38,7 @@ class PageableListAppState extends State<PageableListApp> {
 
   List<CardModel> cardModels;
   Size pageSize = new Size(200.0, 200.0);
-  ScrollDirection scrollDirection = ScrollDirection.horizontal;
+  Axis scrollDirection = Axis.horizontal;
   bool itemsWrap = false;
 
   Widget buildCard(CardModel cardModel) {
@@ -52,7 +52,7 @@ class PageableListAppState extends State<PageableListApp> {
       )
     );
 
-    BoxConstraints constraints = (scrollDirection == ScrollDirection.vertical)
+    BoxConstraints constraints = (scrollDirection == Axis.vertical)
       ? new BoxConstraints.tightFor(height: pageSize.height)
       : new BoxConstraints.tightFor(width: pageSize.width);
 
@@ -65,9 +65,9 @@ class PageableListAppState extends State<PageableListApp> {
 
   void switchScrollDirection() {
     setState(() {
-      scrollDirection = (scrollDirection == ScrollDirection.vertical)
-        ? ScrollDirection.horizontal
-        : ScrollDirection.vertical;
+      scrollDirection = (scrollDirection == Axis.vertical)
+        ? Axis.horizontal
+        : Axis.vertical;
     });
   }
 
@@ -83,13 +83,13 @@ class PageableListAppState extends State<PageableListApp> {
         new DrawerHeader(child: new Text('Options')),
         new DrawerItem(
           icon: 'navigation/more_horiz',
-          selected: scrollDirection == ScrollDirection.horizontal,
+          selected: scrollDirection == Axis.horizontal,
           child: new Text('Horizontal Layout'),
           onPressed: switchScrollDirection
         ),
         new DrawerItem(
           icon: 'navigation/more_vert',
-          selected: scrollDirection == ScrollDirection.vertical,
+          selected: scrollDirection == Axis.vertical,
           child: new Text('Vertical Layout'),
           onPressed: switchScrollDirection
         ),
@@ -108,7 +108,7 @@ class PageableListAppState extends State<PageableListApp> {
     return new ToolBar(
       center: new Text('PageableList'),
       right: <Widget>[
-        new Text(scrollDirection == ScrollDirection.horizontal ? "horizontal" : "vertical")
+        new Text(scrollDirection == Axis.horizontal ? "horizontal" : "vertical")
       ]
     );
   }

packages/flutter/lib/src/material/input.dart

@@ -26,7 +26,7 @@ class Input extends Scrollable {
   }) : super(
     key: key,
     initialScrollOffset: 0.0,
-    scrollDirection: ScrollDirection.horizontal
+    scrollDirection: Axis.horizontal
   ) {
     assert(key != null);
   }

packages/flutter/lib/src/material/material_list.dart

@@ -44,7 +44,7 @@ class _MaterialListState extends State<MaterialList> {
   Widget build(BuildContext context) {
     return new ScrollableList(
       initialScrollOffset: config.initialScrollOffset,
-      scrollDirection: ScrollDirection.vertical,
+      scrollDirection: Axis.vertical,
       onScroll: config.onScroll,
       itemExtent: _kItemExtent[config.type],
       padding: const EdgeDims.symmetric(vertical: 8.0),

packages/flutter/lib/src/material/scrollbar_painter.dart

@@ -31,7 +31,7 @@ class ScrollbarPainter extends ScrollableListPainter {
     Size thumbSize;
 
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         double thumbHeight = viewportBounds.height * viewportBounds.height / contentExtent;
         thumbHeight = thumbHeight.clamp(_kMinScrollbarThumbLength, viewportBounds.height);
         final double maxThumbTop = viewportBounds.height - thumbHeight;
@@ -40,7 +40,7 @@ class ScrollbarPainter extends ScrollableListPainter {
         thumbOrigin = new Point(viewportBounds.right - _kScrollbarThumbGirth, thumbTop);
         thumbSize = new Size(_kScrollbarThumbGirth, thumbHeight);
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         double thumbWidth = viewportBounds.width * viewportBounds.width / contentExtent;
         thumbWidth = thumbWidth.clamp(_kMinScrollbarThumbLength, viewportBounds.width);
         final double maxThumbLeft = viewportBounds.width - thumbWidth;

packages/flutter/lib/src/material/tabs.dart

@@ -544,7 +544,7 @@ class TabBar<T> extends Scrollable {
     Key key,
     this.labels,
     this.isScrollable: false
-  }) : super(key: key, scrollDirection: ScrollDirection.horizontal);
+  }) : super(key: key, scrollDirection: Axis.horizontal);
 
   final Map<T, TabLabel> labels;
   final bool isScrollable;
@@ -687,7 +687,7 @@ class _TabBarState<T> extends ScrollableState<TabBar<T>> implements TabBarSelect
 
   void _updateScrollBehavior() {
     scrollBehavior.updateExtents(
-      containerExtent: config.scrollDirection == ScrollDirection.vertical ? _viewportSize.height : _viewportSize.width,
+      containerExtent: config.scrollDirection == Axis.vertical ? _viewportSize.height : _viewportSize.width,
       contentExtent: _tabWidths.reduce((double sum, double width) => sum + width)
     );
   }
@@ -753,7 +753,7 @@ class _TabBarState<T> extends ScrollableState<TabBar<T>> implements TabBarSelect
       contents = new SizeObserver(
         onSizeChanged: _handleViewportSizeChanged,
         child: new Viewport(
-          scrollDirection: ScrollDirection.horizontal,
+          scrollDirection: Axis.horizontal,
           scrollOffset: new Offset(scrollOffset, 0.0),
           child: contents
         )
@@ -770,7 +770,7 @@ class TabBarView extends PageableList {
     List<Widget> children
   }) : super(
     key: key,
-    scrollDirection: ScrollDirection.horizontal,
+    scrollDirection: Axis.horizontal,
     children: children
   ) {
     assert(children != null);

packages/flutter/lib/src/rendering/block.dart

@@ -32,7 +32,7 @@ abstract class RenderBlockBase extends RenderBox
 
   RenderBlockBase({
     List<RenderBox> children,
-    ScrollDirection direction: ScrollDirection.vertical,
+    Axis direction: Axis.vertical,
     double itemExtent,
     double minExtent: 0.0
   }) : _direction = direction, _itemExtent = itemExtent, _minExtent = minExtent {
@@ -45,9 +45,9 @@ abstract class RenderBlockBase extends RenderBox
   }
 
   /// The direction to use as the main axis.
-  ScrollDirection get direction => _direction;
-  ScrollDirection _direction;
-  void set direction (ScrollDirection value) {
+  Axis get direction => _direction;
+  Axis _direction;
+  void set direction (Axis value) {
     if (_direction != value) {
       _direction = value;
       markNeedsLayout();
@@ -75,9 +75,9 @@ abstract class RenderBlockBase extends RenderBox
   }
 
   /// Whether the main axis is vertical.
-  bool get isVertical => _direction == ScrollDirection.vertical;
+  bool get isVertical => _direction == Axis.vertical;
 
-  ScrollDirection get scrollDirection => _direction;
+  Axis get scrollDirection => _direction;
 
   BoxConstraints _getInnerConstraints(BoxConstraints constraints) {
     if (isVertical)
@@ -126,7 +126,7 @@ class RenderBlock extends RenderBlockBase {
 
   RenderBlock({
     List<RenderBox> children,
-    ScrollDirection direction: ScrollDirection.vertical,
+    Axis direction: Axis.vertical,
     double itemExtent,
     double minExtent: 0.0
   }) : super(children: children, direction: direction, itemExtent: itemExtent, minExtent: minExtent);
@@ -242,7 +242,7 @@ class RenderBlockViewport extends RenderBlockBase {
     ExtentCallback maxCrossAxisDimensionCallback,
     ExtentCallback minCrossAxisDimensionCallback,
     Painter overlayPainter,
-    ScrollDirection direction: ScrollDirection.vertical,
+    Axis direction: Axis.vertical,
     double itemExtent,
     double minExtent: 0.0,
     double startOffset: 0.0,

packages/flutter/lib/src/rendering/box.dart

@@ -23,6 +23,15 @@ class _DebugSize extends Size {
   final bool _canBeUsedByParent;
 }
 
+/// The two cardinal directions in two dimensions.
+enum Axis {
+  /// Left and right
+  horizontal,
+
+  /// Up and down
+  vertical,
+}
+
 /// Immutable layout constraints for box layout.
 ///
 /// A size respects a BoxConstraints if, and only if, all of the following

packages/flutter/lib/src/rendering/list.dart

@@ -18,7 +18,7 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
     EdgeDims padding,
     int virtualChildCount,
     Offset paintOffset: Offset.zero,
-    ScrollDirection scrollDirection: ScrollDirection.vertical,
+    Axis scrollDirection: Axis.vertical,
     LayoutCallback callback
   }) : _itemExtent = itemExtent,
        _padding = padding,
@@ -50,9 +50,9 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
     markNeedsLayout();
   }
 
-  ScrollDirection get scrollDirection => _scrollDirection;
-  ScrollDirection _scrollDirection;
-  void set scrollDirection (ScrollDirection newValue) {
+  Axis get scrollDirection => _scrollDirection;
+  Axis _scrollDirection;
+  void set scrollDirection (Axis newValue) {
     if (_scrollDirection == newValue)
       return;
     _scrollDirection = newValue;
@@ -66,9 +66,9 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
 
   double get _scrollAxisPadding {
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return padding.vertical;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return padding.horizontal;
     }
   }
@@ -85,9 +85,9 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
   double _getIntrinsicWidth(BoxConstraints constraints) {
     assert(constraints.isNormalized);
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return constraints.constrainWidth(0.0);
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return constraints.constrainWidth(_preferredExtent);
     }
   }
@@ -103,9 +103,9 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
   double _getIntrinsicHeight(BoxConstraints constraints) {
     assert(constraints.isNormalized);
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return constraints.constrainHeight(_preferredExtent);
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return constraints.constrainHeight(0.0);
     }
   }
@@ -120,11 +120,11 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
 
   void performLayout() {
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         size = new Size(constraints.maxWidth,
                         constraints.constrainHeight(_preferredExtent));
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         size = new Size(constraints.constrainWidth(_preferredExtent),
                         constraints.maxHeight);
         break;
@@ -143,13 +143,13 @@ class RenderList extends RenderVirtualViewport<ListParentData> implements HasScr
     double dy = 0.0;
 
     switch (scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         itemWidth = math.max(0, size.width - (padding == null ? 0.0 : padding.horizontal));
         itemHeight = itemExtent ?? size.height;
         y = padding != null ? padding.top : 0.0;
         dy = itemHeight;
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         itemWidth = itemExtent ?? size.width;
         itemHeight = math.max(0, size.height - (padding == null ? 0.0 : padding.vertical));
         x = padding != null ? padding.left : 0.0;

packages/flutter/lib/src/rendering/viewport.dart

@@ -9,17 +9,8 @@ import 'package:vector_math/vector_math_64.dart';
 import 'box.dart';
 import 'object.dart';
 
-/// The direction in which to scroll
-enum ScrollDirection {
-  /// Scroll left and right
-  horizontal,
-
-  /// Scroll up and down
-  vertical,
-}
-
 abstract class HasScrollDirection {
-  ScrollDirection get scrollDirection;
+  Axis get scrollDirection;
 }
 
 /// A render object that's bigger on the inside.
@@ -37,18 +28,18 @@ class RenderViewport extends RenderBox with RenderObjectWithChildMixin<RenderBox
   RenderViewport({
     RenderBox child,
     Offset scrollOffset: Offset.zero,
-    ScrollDirection scrollDirection: ScrollDirection.vertical
+    Axis scrollDirection: Axis.vertical
   }) : _scrollOffset = scrollOffset,
        _scrollDirection = scrollDirection {
     assert(_offsetIsSane(scrollOffset, scrollDirection));
     this.child = child;
   }
 
-  bool _offsetIsSane(Offset offset, ScrollDirection direction) {
+  bool _offsetIsSane(Offset offset, Axis direction) {
     switch (direction) {
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return offset.dy == 0.0;
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return offset.dx == 0.0;
     }
   }
@@ -71,9 +62,9 @@ class RenderViewport extends RenderBox with RenderObjectWithChildMixin<RenderBox
   /// If the viewport is scrollable in a particular direction (e.g., vertically),
   /// the child is given layout constraints that are fully unconstrainted in
   /// that direction (e.g., the child can be as tall as it wants).
-  ScrollDirection get scrollDirection => _scrollDirection;
-  ScrollDirection _scrollDirection;
-  void set scrollDirection(ScrollDirection value) {
+  Axis get scrollDirection => _scrollDirection;
+  Axis _scrollDirection;
+  void set scrollDirection(Axis value) {
     if (value == _scrollDirection)
       return;
     assert(_offsetIsSane(scrollOffset, value));
@@ -84,10 +75,10 @@ class RenderViewport extends RenderBox with RenderObjectWithChildMixin<RenderBox
   BoxConstraints _getInnerConstraints(BoxConstraints constraints) {
     BoxConstraints innerConstraints;
     switch (scrollDirection) {
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         innerConstraints = constraints.heightConstraints();
         break;
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         innerConstraints = constraints.widthConstraints();
         break;
     }

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

@@ -54,7 +54,7 @@ export 'package:flutter/rendering.dart' show
     PointerUpEvent,
     RadialGradient,
     Rect,
-    ScrollDirection,
+    Axis,
     Size,
     StyledTextSpan,
     TextAlign,
@@ -755,7 +755,7 @@ class Baseline extends OneChildRenderObjectWidget {
 class Viewport extends OneChildRenderObjectWidget {
   Viewport({
     Key key,
-    this.scrollDirection: ScrollDirection.vertical,
+    this.scrollDirection: Axis.vertical,
     this.scrollOffset: Offset.zero,
     Widget child
   }) : super(key: key, child: child) {
@@ -768,7 +768,7 @@ class Viewport extends OneChildRenderObjectWidget {
   /// If the viewport is scrollable in a particular direction (e.g., vertically),
   /// the child is given layout constraints that are fully unconstrainted in
   /// that direction (e.g., the child can be as tall as it wants).
-  final ScrollDirection scrollDirection;
+  final Axis scrollDirection;
 
   /// The offset at which to paint the child.
   ///
@@ -824,7 +824,7 @@ class Container extends StatelessComponent {
     this.transform,
     double width,
     double height
-  }) : constraints = 
+  }) : constraints =
         (width != null || height != null)
           ? constraints?.tighten(width: width, height: height)
             ?? new BoxConstraints.tightFor(width: width, height: height)
@@ -929,13 +929,13 @@ class Container extends StatelessComponent {
 class BlockBody extends MultiChildRenderObjectWidget {
   BlockBody(List<Widget> children, {
     Key key,
-    this.direction: ScrollDirection.vertical
+    this.direction: Axis.vertical
   }) : super(key: key, children: children) {
     assert(direction != null);
   }
 
   /// The direction to use as the main axis.
-  final ScrollDirection direction;
+  final Axis direction;
 
   RenderBlock createRenderObject() => new RenderBlock(direction: direction);
 

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

@@ -17,7 +17,7 @@ abstract class _ViewportBase extends RenderObjectWidget {
     this.builder,
     this.itemsWrap: false,
     this.itemCount,
-    this.direction: ScrollDirection.vertical,
+    this.direction: Axis.vertical,
     this.startOffset: 0.0,
     this.overlayPainter
   }) : super(key: key);
@@ -25,7 +25,7 @@ abstract class _ViewportBase extends RenderObjectWidget {
   final ListBuilder builder;
   final bool itemsWrap;
   final int itemCount;
-  final ScrollDirection direction;
+  final Axis direction;
   final double startOffset;
   final Painter overlayPainter;
 
@@ -112,7 +112,7 @@ abstract class _ViewportBaseElement<T extends _ViewportBase> extends RenderObjec
   }
 
   double getMaxCrossAxisExtent(BoxConstraints constraints) {
-    if (widget.direction == ScrollDirection.vertical)
+    if (widget.direction == Axis.vertical)
       return constraints.maxWidth;
     return constraints.maxHeight;
   }
@@ -141,7 +141,7 @@ class HomogeneousViewport extends _ViewportBase {
     ListBuilder builder,
     bool itemsWrap: false,
     int itemCount, // optional, but you cannot shrink-wrap this class or otherwise use its intrinsic dimensions if you don't specify it
-    ScrollDirection direction: ScrollDirection.vertical,
+    Axis direction: Axis.vertical,
     double startOffset: 0.0,
     Painter overlayPainter,
     this.itemExtent // required, must be non-zero
@@ -180,7 +180,7 @@ class _HomogeneousViewportElement extends _ViewportBaseElement<HomogeneousViewpo
     // be ok because we are exempt from that assert since we are still actively
     // doing our own layout.)
     BuildableElement.lockState(() {
-      double mainAxisExtent = widget.direction == ScrollDirection.vertical ? constraints.maxHeight : constraints.maxWidth;
+      double mainAxisExtent = widget.direction == Axis.vertical ? constraints.maxHeight : constraints.maxWidth;
       double offset;
       if (widget.startOffset <= 0.0 && !widget.itemsWrap) {
         _layoutFirstIndex = 0;

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

@@ -18,7 +18,7 @@ class MixedViewport extends RenderObjectWidget {
   MixedViewport({
     Key key,
     this.startOffset: 0.0,
-    this.direction: ScrollDirection.vertical,
+    this.direction: Axis.vertical,
     this.builder,
     this.token,
     this.onExtentsUpdate,
@@ -26,7 +26,7 @@ class MixedViewport extends RenderObjectWidget {
   }) : super(key: key);
 
   final double startOffset;
-  final ScrollDirection direction;
+  final Axis direction;
   final IndexedBuilder builder;
   final Object token; // change this if the list changed (i.e. there are added, removed, or resorted items)
   final ExtentsUpdateCallback onExtentsUpdate;
@@ -315,18 +315,18 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
   double _getElementExtent(Element element, BoxConstraints innerConstraints) {
     final RenderBox childRenderObject = element.renderObject;
     switch (widget.direction) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return childRenderObject.getMaxIntrinsicHeight(innerConstraints);
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return childRenderObject.getMaxIntrinsicWidth(innerConstraints);
     }
   }
 
   BoxConstraints _getInnerConstraints(BoxConstraints constraints) {
     switch (widget.direction) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return new BoxConstraints.tightFor(width: constraints.constrainWidth());
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return new BoxConstraints.tightFor(height: constraints.constrainHeight());
     }
   }
@@ -353,14 +353,14 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
     // Establish the start and end offsets based on our current constraints.
     double extent;
     switch (widget.direction) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         extent = constraints.maxHeight;
         assert(extent < double.INFINITY &&
           'There is no point putting a lazily-built vertical MixedViewport inside a box with infinite internal ' +
           'height (e.g. inside something else that scrolls vertically), because it would then just eagerly build ' +
           'all the children. You probably want to put the MixedViewport inside a Container with a fixed height.' is String);
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         extent = constraints.maxWidth;
         assert(extent < double.INFINITY &&
           'There is no point putting a lazily-built horizontal MixedViewport inside a box with infinite internal ' +

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

@@ -25,7 +25,7 @@ class PageableList extends Scrollable {
   PageableList({
     Key key,
     initialScrollOffset,
-    ScrollDirection scrollDirection: ScrollDirection.vertical,
+    Axis scrollDirection: Axis.vertical,
     ScrollListener onScrollStart,
     ScrollListener onScroll,
     ScrollListener onScrollEnd,
@@ -68,7 +68,7 @@ class PageableListState<T extends PageableList> extends ScrollableState<T> {
     final RenderBox box = context.findRenderObject();
     if (box == null || !box.hasSize)
       return 0.0;
-    final double pixelScrollExtent = config.scrollDirection == ScrollDirection.vertical ? box.size.height : box.size.width;
+    final double pixelScrollExtent = config.scrollDirection == Axis.vertical ? box.size.height : box.size.width;
     return pixelScrollExtent == 0.0 ? 0.0 : value / pixelScrollExtent;
   }
 
@@ -183,7 +183,7 @@ class PageViewport extends VirtualViewport {
   PageViewport({
     Key key,
     this.startOffset: 0.0,
-    this.scrollDirection: ScrollDirection.vertical,
+    this.scrollDirection: Axis.vertical,
     this.itemsWrap: false,
     this.overlayPainter,
     this.children
@@ -192,7 +192,7 @@ class PageViewport extends VirtualViewport {
   }
 
   final double startOffset;
-  final ScrollDirection scrollDirection;
+  final Axis scrollDirection;
   final bool itemsWrap;
   final Painter overlayPainter;
   final Iterable<Widget> children;
@@ -235,9 +235,9 @@ class _PageViewportElement extends VirtualViewportElement<PageViewport> {
 
   double _getContainerExtentFromRenderObject() {
     switch (widget.scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return renderObject.size.height;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return renderObject.size.width;
     }
   }

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

@@ -38,19 +38,19 @@ abstract class Scrollable extends StatefulComponent {
   Scrollable({
     Key key,
     this.initialScrollOffset,
-    this.scrollDirection: ScrollDirection.vertical,
+    this.scrollDirection: Axis.vertical,
     this.onScrollStart,
     this.onScroll,
     this.onScrollEnd,
     this.snapOffsetCallback,
     this.snapAlignmentOffset: 0.0
   }) : super(key: key) {
-    assert(scrollDirection == ScrollDirection.vertical ||
-           scrollDirection == ScrollDirection.horizontal);
+    assert(scrollDirection == Axis.vertical ||
+           scrollDirection == Axis.horizontal);
   }
 
   final double initialScrollOffset;
-  final ScrollDirection scrollDirection;
+  final Axis scrollDirection;
   final ScrollListener onScrollStart;
   final ScrollListener onScroll;
   final ScrollListener onScrollEnd;
@@ -81,12 +81,12 @@ abstract class Scrollable extends StatefulComponent {
 
     double scrollOffsetDelta;
     switch (scrollable.config.scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         Point targetCenter = targetBox.localToGlobal(new Point(0.0, targetSize.height / 2.0));
         Point scrollableCenter = scrollableBox.localToGlobal(new Point(0.0, scrollableSize.height / 2.0));
         scrollOffsetDelta = targetCenter.y - scrollableCenter.y;
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         Point targetCenter = targetBox.localToGlobal(new Point(targetSize.width / 2.0, 0.0));
         Point scrollableCenter = scrollableBox.localToGlobal(new Point(scrollableSize.width / 2.0, 0.0));
         scrollOffsetDelta = targetCenter.x - scrollableCenter.x;
@@ -119,7 +119,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   double _scrollOffset;
 
   Offset get scrollOffsetVector {
-    if (config.scrollDirection == ScrollDirection.horizontal)
+    if (config.scrollDirection == Axis.horizontal)
       return new Offset(scrollOffset, 0.0);
     return new Offset(0.0, scrollOffset);
   }
@@ -131,7 +131,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   double pixelToScrollOffset(double pixelValue) => pixelValue;
 
   double scrollDirectionVelocity(Offset scrollVelocity) {
-    return config.scrollDirection == ScrollDirection.horizontal
+    return config.scrollDirection == Axis.horizontal
       ? -scrollVelocity.dx
       : -scrollVelocity.dy;
   }
@@ -144,19 +144,19 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
     return _scrollBehavior;
   }
 
-  GestureDragStartCallback _getDragStartHandler(ScrollDirection direction) {
+  GestureDragStartCallback _getDragStartHandler(Axis direction) {
     if (config.scrollDirection != direction || !scrollBehavior.isScrollable)
       return null;
     return _handleDragStart;
   }
 
-  GestureDragUpdateCallback _getDragUpdateHandler(ScrollDirection direction) {
+  GestureDragUpdateCallback _getDragUpdateHandler(Axis direction) {
     if (config.scrollDirection != direction || !scrollBehavior.isScrollable)
       return null;
     return _handleDragUpdate;
   }
 
-  GestureDragEndCallback _getDragEndHandler(ScrollDirection direction) {
+  GestureDragEndCallback _getDragEndHandler(Axis direction) {
     if (config.scrollDirection != direction || !scrollBehavior.isScrollable)
       return null;
     return _handleDragEnd;
@@ -164,12 +164,12 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
 
   Widget build(BuildContext context) {
     return new GestureDetector(
-      onVerticalDragStart: _getDragStartHandler(ScrollDirection.vertical),
-      onVerticalDragUpdate: _getDragUpdateHandler(ScrollDirection.vertical),
-      onVerticalDragEnd: _getDragEndHandler(ScrollDirection.vertical),
-      onHorizontalDragStart: _getDragStartHandler(ScrollDirection.horizontal),
-      onHorizontalDragUpdate: _getDragUpdateHandler(ScrollDirection.horizontal),
-      onHorizontalDragEnd: _getDragEndHandler(ScrollDirection.horizontal),
+      onVerticalDragStart: _getDragStartHandler(Axis.vertical),
+      onVerticalDragUpdate: _getDragUpdateHandler(Axis.vertical),
+      onVerticalDragEnd: _getDragEndHandler(Axis.vertical),
+      onHorizontalDragStart: _getDragStartHandler(Axis.horizontal),
+      onHorizontalDragUpdate: _getDragUpdateHandler(Axis.horizontal),
+      onHorizontalDragEnd: _getDragEndHandler(Axis.horizontal),
       behavior: HitTestBehavior.opaque,
       child: new Listener(
         child: buildContent(context),
@@ -348,7 +348,7 @@ class ScrollableViewport extends Scrollable {
     Key key,
     this.child,
     double initialScrollOffset,
-    ScrollDirection scrollDirection: ScrollDirection.vertical,
+    Axis scrollDirection: Axis.vertical,
     ScrollListener onScroll
   }) : super(
     key: key,
@@ -369,13 +369,13 @@ class ScrollableViewportState extends ScrollableState<ScrollableViewport> {
   double _viewportSize = 0.0;
   double _childSize = 0.0;
   void _handleViewportSizeChanged(Size newSize) {
-    _viewportSize = config.scrollDirection == ScrollDirection.vertical ? newSize.height : newSize.width;
+    _viewportSize = config.scrollDirection == Axis.vertical ? newSize.height : newSize.width;
     setState(() {
       _updateScrollBehavior();
     });
   }
   void _handleChildSizeChanged(Size newSize) {
-    _childSize = config.scrollDirection == ScrollDirection.vertical ? newSize.height : newSize.width;
+    _childSize = config.scrollDirection == Axis.vertical ? newSize.height : newSize.width;
     setState(() {
       _updateScrollBehavior();
     });
@@ -412,7 +412,7 @@ class Block extends StatelessComponent {
     Key key,
     this.padding,
     this.initialScrollOffset,
-    this.scrollDirection: ScrollDirection.vertical,
+    this.scrollDirection: Axis.vertical,
     this.onScroll
   }) : super(key: key) {
     assert(!children.any((Widget child) => child == null));
@@ -421,7 +421,7 @@ class Block extends StatelessComponent {
   final List<Widget> children;
   final EdgeDims padding;
   final double initialScrollOffset;
-  final ScrollDirection scrollDirection;
+  final Axis scrollDirection;
   final ScrollListener onScroll;
 
   Widget build(BuildContext context) {
@@ -446,7 +446,7 @@ abstract class ScrollableListPainter extends Painter {
 
   RenderBox get renderObject => super.renderObject;
 
-  ScrollDirection get scrollDirection {
+  Axis get scrollDirection {
     HasScrollDirection scrollable = renderObject as dynamic;
     return scrollable?.scrollDirection;
   }
@@ -495,7 +495,7 @@ abstract class ScrollableWidgetList extends Scrollable {
   ScrollableWidgetList({
     Key key,
     double initialScrollOffset,
-    ScrollDirection scrollDirection: ScrollDirection.vertical,
+    Axis scrollDirection: Axis.vertical,
     ScrollListener onScroll,
     SnapOffsetCallback snapOffsetCallback,
     double snapAlignmentOffset: 0.0,
@@ -554,7 +554,7 @@ abstract class ScrollableWidgetListState<T extends ScrollableWidgetList> extends
   ExtentScrollBehavior get scrollBehavior => super.scrollBehavior;
 
   double get _containerExtent {
-    return config.scrollDirection == ScrollDirection.vertical
+    return config.scrollDirection == Axis.vertical
       ? _containerSize.height
       : _containerSize.width;
   }
@@ -568,14 +568,14 @@ abstract class ScrollableWidgetListState<T extends ScrollableWidgetList> extends
 
   double get _leadingPadding {
     EdgeDims padding = config.padding;
-    if (config.scrollDirection == ScrollDirection.vertical)
+    if (config.scrollDirection == Axis.vertical)
       return padding != null ? padding.top : 0.0;
     return padding != null ? padding.left : -.0;
   }
 
   double get _trailingPadding {
     EdgeDims padding = config.padding;
-    if (config.scrollDirection == ScrollDirection.vertical)
+    if (config.scrollDirection == Axis.vertical)
       return padding != null ? padding.bottom : 0.0;
     return padding != null ? padding.right : 0.0;
   }
@@ -584,7 +584,7 @@ abstract class ScrollableWidgetListState<T extends ScrollableWidgetList> extends
     EdgeDims padding = config.padding;
     if (padding == null)
       return null;
-    if (config.scrollDirection == ScrollDirection.vertical)
+    if (config.scrollDirection == Axis.vertical)
       return new EdgeDims.only(left: padding.left, right: padding.right);
     return new EdgeDims.only(top: padding.top, bottom: padding.bottom);
   }

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

@@ -29,7 +29,7 @@ class ScrollableGrid extends Scrollable {
     // TODO(abarth): Support horizontal offsets. For horizontally scrolling
     // grids. For horizontally scrolling grids, we'll probably need to use a
     // delegate that places children in column-major order.
-    scrollDirection: ScrollDirection.vertical,
+    scrollDirection: Axis.vertical,
     onScroll: onScroll,
     snapOffsetCallback: snapOffsetCallback,
     snapAlignmentOffset: snapAlignmentOffset
@@ -80,7 +80,7 @@ class GridViewport extends VirtualViewport {
   final Iterable<Widget> children;
 
   // TODO(abarth): Support horizontal scrolling;
-  ScrollDirection get scrollDirection => ScrollDirection.vertical;
+  Axis get scrollDirection => Axis.vertical;
 
   RenderGrid createRenderObject() => new RenderGrid(delegate: delegate);
 

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

@@ -15,7 +15,7 @@ class ScrollableList extends Scrollable {
   ScrollableList({
     Key key,
     double initialScrollOffset,
-    ScrollDirection scrollDirection: ScrollDirection.vertical,
+    Axis scrollDirection: Axis.vertical,
     ScrollListener onScroll,
     SnapOffsetCallback snapOffsetCallback,
     double snapAlignmentOffset: 0.0,
@@ -93,7 +93,7 @@ class ListViewport extends VirtualViewport {
     Key key,
     this.onExtentsChanged,
     this.startOffset: 0.0,
-    this.scrollDirection: ScrollDirection.vertical,
+    this.scrollDirection: Axis.vertical,
     this.itemExtent,
     this.itemsWrap: false,
     this.padding,
@@ -106,7 +106,7 @@ class ListViewport extends VirtualViewport {
 
   final ExtentsChangedCallback onExtentsChanged;
   final double startOffset;
-  final ScrollDirection scrollDirection;
+  final Axis scrollDirection;
   final double itemExtent;
   final bool itemsWrap;
   final EdgeDims padding;
@@ -148,9 +148,9 @@ class _ListViewportElement extends VirtualViewportElement<ListViewport> {
 
   double _getContainerExtentFromRenderObject() {
     switch (widget.scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         return renderObject.size.height;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         return renderObject.size.width;
     }
   }

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

@@ -13,7 +13,7 @@ typedef void ExtentsChangedCallback(double contentExtent, double containerExtent
 
 abstract class VirtualViewport extends RenderObjectWidget {
   double get startOffset;
-  ScrollDirection get scrollDirection;
+  Axis get scrollDirection;
   Iterable<Widget> get children;
 }
 
@@ -64,10 +64,10 @@ abstract class VirtualViewportElement<T extends VirtualViewport> extends RenderO
 
   void _updatePaintOffset() {
     switch (widget.scrollDirection) {
-      case ScrollDirection.vertical:
+      case Axis.vertical:
         renderObject.paintOffset = new Offset(0.0, paintOffset);
         break;
-      case ScrollDirection.horizontal:
+      case Axis.horizontal:
         renderObject.paintOffset = new Offset(paintOffset, 0.0);
         break;
     }

packages/flutter/test/widget/dismissable_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter/widgets.dart';
 import 'package:test/test.dart';
 
 const double itemExtent = 100.0;
-ScrollDirection scrollDirection = ScrollDirection.vertical;
+Axis scrollDirection = Axis.vertical;
 DismissDirection dismissDirection = DismissDirection.horizontal;
 List<int> dismissedItems = <int>[];
 
@@ -120,7 +120,7 @@ class Test1215DismissableComponent extends StatelessComponent {
 void main() {
   test('Horizontal drag triggers dismiss scrollDirection=vertical', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.vertical;
+      scrollDirection = Axis.vertical;
       dismissDirection = DismissDirection.horizontal;
       dismissedItems = <int>[];
 
@@ -139,7 +139,7 @@ void main() {
 
   test('Vertical drag triggers dismiss scrollDirection=horizontal', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.horizontal;
+      scrollDirection = Axis.horizontal;
       dismissDirection = DismissDirection.vertical;
       dismissedItems = <int>[];
 
@@ -158,7 +158,7 @@ void main() {
 
   test('drag-left with DismissDirection.left triggers dismiss', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.vertical;
+      scrollDirection = Axis.vertical;
       dismissDirection = DismissDirection.left;
       dismissedItems = <int>[];
 
@@ -177,7 +177,7 @@ void main() {
 
   test('drag-right with DismissDirection.right triggers dismiss', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.vertical;
+      scrollDirection = Axis.vertical;
       dismissDirection = DismissDirection.right;
       dismissedItems = <int>[];
 
@@ -196,7 +196,7 @@ void main() {
 
   test('drag-up with DismissDirection.up triggers dismiss', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.horizontal;
+      scrollDirection = Axis.horizontal;
       dismissDirection = DismissDirection.up;
       dismissedItems = <int>[];
 
@@ -215,7 +215,7 @@ void main() {
 
   test('drag-down with DismissDirection.down triggers dismiss', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.horizontal;
+      scrollDirection = Axis.horizontal;
       dismissDirection = DismissDirection.down;
       dismissedItems = <int>[];
 
@@ -240,7 +240,7 @@ void main() {
   // irrelevant by fn3, but just in case...
   test('Verify that drag-move events do not assert', () {
     testWidgets((WidgetTester tester) {
-      scrollDirection = ScrollDirection.horizontal;
+      scrollDirection = Axis.horizontal;
       dismissDirection = DismissDirection.down;
       dismissedItems = <int>[];
 

packages/flutter/test/widget/homogeneous_viewport_test.dart

@@ -143,7 +143,7 @@ void main() {
             builder: itemBuilder,
             startOffset: offset,
             itemExtent: 200.0,
-            direction: ScrollDirection.horizontal
+            direction: Axis.horizontal
           ),
           right: new Text('Not Today')
         );

packages/flutter/test/widget/mixed_viewport_test.dart

@@ -127,7 +127,7 @@ void main() {
           left: new MixedViewport(
             builder: itemBuilder,
             startOffset: offset,
-            direction: ScrollDirection.horizontal
+            direction: Axis.horizontal
           ),
           right: new Text('Not Today')
         );

packages/flutter/test/widget/pageable_list_test.dart

@@ -26,7 +26,7 @@ Widget buildFrame({ List<int> pages: defaultPages }) {
   final list = new PageableList(
     children: pages.map(buildPage),
     itemsWrap: itemsWrap,
-    scrollDirection: ScrollDirection.horizontal,
+    scrollDirection: Axis.horizontal,
     onPageChanged: (int page) { currentPage = page; }
   );
 

packages/flutter/test/widget/scrollable_list_hit_testing_test.dart

@@ -20,7 +20,7 @@ void main() {
           child: new ScrollableList(
             key: new GlobalKey(),
             itemExtent: 290.0,
-            scrollDirection: ScrollDirection.horizontal,
+            scrollDirection: Axis.horizontal,
             children: items.map((int item) {
               return new Container(
                 child: new GestureDetector(
@@ -60,7 +60,7 @@ void main() {
           child: new ScrollableList(
             key: new GlobalKey(),
             itemExtent: 290.0,
-            scrollDirection: ScrollDirection.vertical,
+            scrollDirection: Axis.vertical,
             children: items.map((int item) {
               return new Container(
                 child: new GestureDetector(

packages/flutter/test/widget/scrollable_list_horizontal_test.dart

@@ -15,7 +15,7 @@ Widget buildFrame() {
       height: 50.0,
       child: new ScrollableList(
         itemExtent: 290.0,
-        scrollDirection: ScrollDirection.horizontal,
+        scrollDirection: Axis.horizontal,
         children: items.map((int item) {
           return new Container(
             child: new Text('$item')

packages/flutter/test/widget/scrollable_list_vertical_test.dart

@@ -11,7 +11,7 @@ const List<int> items = const <int>[0, 1, 2, 3, 4, 5];
 Widget buildFrame() {
   return new ScrollableList(
     itemExtent: 290.0,
-    scrollDirection: ScrollDirection.vertical,
+    scrollDirection: Axis.vertical,
     children: items.map((int item) {
       return new Container(
         child: new Text('$item')

packages/flutter/test/widget/snap_scrolling_test.dart

@@ -9,7 +9,7 @@ import 'package:flutter/widgets.dart';
 import 'package:test/test.dart';
 
 const double itemExtent = 200.0;
-ScrollDirection scrollDirection = ScrollDirection.vertical;
+Axis scrollDirection = Axis.vertical;
 GlobalKey scrollableListKey;
 
 Widget buildItem(int item) {
@@ -48,7 +48,7 @@ void set scrollOffset(double value) {
 }
 
 Future fling(double velocity) {
-  Offset velocityOffset = scrollDirection == ScrollDirection.vertical
+  Offset velocityOffset = scrollDirection == Axis.vertical
     ? new Offset(0.0, velocity)
     : new Offset(velocity, 0.0);
   return scrollableState.fling(velocityOffset);