Remove BlockDirection in favor of ScrollDirection

We'll probably renaming ScrollDirection to Axis in a future patch.

Fixes #151

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

@@ -13,14 +13,6 @@ import 'viewport.dart';
 /// Parent data for use with [RenderBlockBase].
 class BlockParentData extends ContainerBoxParentDataMixin<RenderBox> { }
 
-/// The direction in which the block should lay out.
-enum BlockDirection {
-  /// Children are arranged horizontally, from left to right.
-  horizontal,
-  /// Children are arranged vertically, from top to bottom.
-  vertical
-}
-
 typedef double _ChildSizingFunction(RenderBox child, BoxConstraints constraints);
 typedef double _Constrainer(double value);
 
@@ -40,7 +32,7 @@ abstract class RenderBlockBase extends RenderBox
 
   RenderBlockBase({
     List<RenderBox> children,
-    BlockDirection direction: BlockDirection.vertical,
+    ScrollDirection direction: ScrollDirection.vertical,
     double itemExtent,
     double minExtent: 0.0
   }) : _direction = direction, _itemExtent = itemExtent, _minExtent = minExtent {
@@ -53,9 +45,9 @@ abstract class RenderBlockBase extends RenderBox
   }
 
   /// The direction to use as the main axis.
-  BlockDirection get direction => _direction;
-  BlockDirection _direction;
-  void set direction (BlockDirection value) {
+  ScrollDirection get direction => _direction;
+  ScrollDirection _direction;
+  void set direction (ScrollDirection value) {
     if (_direction != value) {
       _direction = value;
       markNeedsLayout();
@@ -83,10 +75,9 @@ abstract class RenderBlockBase extends RenderBox
   }
 
   /// Whether the main axis is vertical.
-  bool get isVertical => _direction == BlockDirection.vertical;
+  bool get isVertical => _direction == ScrollDirection.vertical;
 
-  // TODO(abarth): Remove BlockDirection in favor of ScrollDirection.
-  ScrollDirection get scrollDirection => isVertical ? ScrollDirection.vertical : ScrollDirection.horizontal;
+  ScrollDirection get scrollDirection => _direction;
 
   BoxConstraints _getInnerConstraints(BoxConstraints constraints) {
     if (isVertical)
@@ -135,7 +126,7 @@ class RenderBlock extends RenderBlockBase {
 
   RenderBlock({
     List<RenderBox> children,
-    BlockDirection direction: BlockDirection.vertical,
+    ScrollDirection direction: ScrollDirection.vertical,
     double itemExtent,
     double minExtent: 0.0
   }) : super(children: children, direction: direction, itemExtent: itemExtent, minExtent: minExtent);
@@ -251,7 +242,7 @@ class RenderBlockViewport extends RenderBlockBase {
     ExtentCallback maxCrossAxisDimensionCallback,
     ExtentCallback minCrossAxisDimensionCallback,
     Painter overlayPainter,
-    BlockDirection direction: BlockDirection.vertical,
+    ScrollDirection direction: ScrollDirection.vertical,
     double itemExtent,
     double minExtent: 0.0,
     double startOffset: 0.0,

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

@@ -11,7 +11,6 @@ import 'framework.dart';
 
 export 'package:flutter/rendering.dart' show
     BackgroundImage,
-    BlockDirection,
     Border,
     BorderSide,
     BoxConstraints,
@@ -948,13 +947,13 @@ class Container extends StatelessComponent {
 class BlockBody extends MultiChildRenderObjectWidget {
   BlockBody(List<Widget> children, {
     Key key,
-    this.direction: BlockDirection.vertical
+    this.direction: ScrollDirection.vertical
   }) : super(key: key, children: children) {
     assert(direction != null);
   }
 
   /// The direction to use as the main axis.
-  final BlockDirection direction;
+  final ScrollDirection direction;
 
   RenderBlock createRenderObject() => new RenderBlock(direction: direction);
 

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

@@ -207,7 +207,7 @@ class _HomogeneousViewportElement extends _ViewportBaseElement<HomogeneousViewpo
       _layoutItemCount = math.max(0, _layoutItemCount);
       _updateChildren();
       // Update the renderObject configuration
-      renderObject.direction = widget.direction == ScrollDirection.vertical ? BlockDirection.vertical : BlockDirection.horizontal;
+      renderObject.direction = widget.direction;
       renderObject.itemExtent = widget.itemExtent;
       renderObject.minExtent = getTotalExtent(null);
       renderObject.startOffset = offset;

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

@@ -509,14 +509,7 @@ class _MixedViewportElement extends RenderObjectElement<MixedViewport> {
     int index = startIndex;
     if (haveChildren) {
       // Update the renderObject configuration
-      switch (widget.direction) {
-        case ScrollDirection.vertical:
-          renderObject.direction = BlockDirection.vertical;
-          break;
-        case ScrollDirection.horizontal:
-          renderObject.direction = BlockDirection.horizontal;
-          break;
-      }
+      renderObject.direction = renderObject.direction;
       renderObject.startOffset = _childOffsets[index] - widget.startOffset;
       // Build all the widgets we still need.
       while (_childOffsets[index] < endOffset) {

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

@@ -424,14 +424,8 @@ class Block extends StatelessComponent {
   final ScrollDirection scrollDirection;
   final ScrollListener onScroll;
 
-  BlockDirection get _direction {
-    if (scrollDirection == ScrollDirection.vertical)
-      return BlockDirection.vertical;
-    return BlockDirection.horizontal;
-  }
-
   Widget build(BuildContext context) {
-    Widget contents = new BlockBody(children, direction: _direction);
+    Widget contents = new BlockBody(children, direction: scrollDirection);
     if (padding != null)
       contents = new Padding(padding: padding, child: contents);
     return new ScrollableViewport(