Replace usage of FractionalOffset with Alignment (#12348)

Alignment will eventually replace FractionalOffset.

dev/integration_tests/ui/lib/keyboard_resize.dart

@@ -44,7 +44,7 @@ class _MyHomePageState extends State<MyHomePage> {
     return new Scaffold(
       body: new Stack(
         fit: StackFit.expand,
-        alignment: FractionalOffset.bottomCenter,
+        alignment: Alignment.bottomCenter,
         children: <Widget>[
           new LayoutBuilder(
             builder: (BuildContext context, BoxConstraints constraints) {

dev/manual_tests/lib/card_collection.dart

@@ -224,7 +224,7 @@ class CardCollectionState extends State<CardCollection> {
       flexibleSpace: new Container(
         padding: const EdgeInsets.only(left: 72.0),
         height: 128.0,
-        alignment: const FractionalOffset(0.0, 0.75),
+        alignment: const Alignment(-1.0, 0.5),
         child: new Text('Swipe Away: ${_cardModels.length}', style: Theme.of(context).primaryTextTheme.title),
       ),
     );
@@ -330,8 +330,8 @@ class CardCollectionState extends State<CardCollection> {
 
   Shader _createShader(Rect bounds) {
     return new LinearGradient(
-        begin: FractionalOffset.topLeft,
-        end: FractionalOffset.bottomLeft,
+        begin: Alignment.topCenter,
+        end: Alignment.bottomCenter,
         colors: <Color>[const Color(0x00FFFFFF), const Color(0xFFFFFFFF)],
         stops: <double>[0.1, 0.35],
     )

dev/manual_tests/lib/color_testing_demo.dart

@@ -64,8 +64,8 @@ class GradientRow extends StatelessWidget {
       height: 100.0,
       decoration: new BoxDecoration(
         gradient: new LinearGradient(
-          begin: FractionalOffset.topLeft,
-          end: FractionalOffset.bottomRight,
+          begin: Alignment.topLeft,
+          end: Alignment.bottomRight,
           colors: <Color>[ leftColor, rightColor ],
         ),
       ),

examples/catalog/lib/app_bar_bottom.dart

@@ -55,7 +55,7 @@ class _AppBarBottomSampleState extends State<AppBarBottomSample> with SingleTick
               data: Theme.of(context).copyWith(accentColor: Colors.white),
               child: new Container(
                 height: 48.0,
-                alignment: FractionalOffset.center,
+                alignment: Alignment.center,
                 child: new TabPageSelector(controller: _tabController),
               ),
             ),

examples/flutter_gallery/lib/demo/animation/home.dart

@@ -169,7 +169,7 @@ class _AllSectionsLayout extends MultiChildLayoutDelegate {
     this.selectedIndex,
   });
 
-  final FractionalOffset translation;
+  final Alignment translation;
   final double tColumnToRow;
   final double tCollapsed;
   final int cardCount;
@@ -349,7 +349,7 @@ class _AllSectionsView extends AnimatedWidget {
 
     return new CustomMultiChildLayout(
       delegate: new _AllSectionsLayout(
-        translation: new FractionalOffset(selectedIndex.value - sectionIndex, 0.0),
+        translation: new Alignment((selectedIndex.value - sectionIndex) * 2.0 - 1.0, -1.0),
         tColumnToRow: tColumnToRow,
         tCollapsed: tCollapsed,
         cardCount: sections.length,

examples/flutter_gallery/lib/demo/animation/widgets.dart

@@ -25,8 +25,8 @@ class SectionCard extends StatelessWidget {
         decoration: new BoxDecoration(
           borderRadius: new BorderRadius.circular(4.0),
           gradient: new LinearGradient(
-            begin: FractionalOffset.topLeft,
-            end: FractionalOffset.topRight,
+            begin: Alignment.centerLeft,
+            end: Alignment.centerRight,
             colors: <Color>[
               section.leftColor,
               section.rightColor,
@@ -82,7 +82,7 @@ class SectionTitle extends StatelessWidget {
         opacity: opacity,
         child: new Transform(
           transform: new Matrix4.identity()..scale(scale),
-          alignment: FractionalOffset.center,
+          alignment: Alignment.center,
           child: new Stack(
             children: <Widget>[
               new Positioned(
@@ -136,7 +136,7 @@ class SectionDetailView extends StatelessWidget {
             package: detail.imageAssetPackage,
           ),
           fit: BoxFit.cover,
-          alignment: FractionalOffset.center,
+          alignment: Alignment.center,
         ),
       ),
     );

examples/flutter_gallery/lib/demo/contacts_demo.dart

@@ -166,8 +166,8 @@ class ContactsDemoState extends State<ContactsDemo> {
                     const DecoratedBox(
                       decoration: const BoxDecoration(
                         gradient: const LinearGradient(
-                          begin: const FractionalOffset(0.5, 0.0),
-                          end: const FractionalOffset(0.5, 0.30),
+                          begin: const Alignment(0.0, -1.0),
+                          end: const Alignment(0.0, -0.4),
                           colors: const <Color>[const Color(0x60000000), const Color(0x00000000)],
                         ),
                       ),

examples/flutter_gallery/lib/demo/cupertino/cupertino_buttons_demo.dart

@@ -39,7 +39,7 @@ class _CupertinoButtonDemoState extends State<CupertinoButtonsDemo> {
                     : ' '),
                 const Padding(padding: const EdgeInsets.all(12.0)),
                 new Align(
-                  alignment: const FractionalOffset(0.5, 0.4),
+                  alignment: const Alignment(0.0, -0.2),
                   child: new Row(
                     mainAxisSize: MainAxisSize.min,
                     children: <Widget>[

examples/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart

@@ -47,9 +47,9 @@ class NavigationIconView {
     return new FadeTransition(
       opacity: _animation,
       child: new SlideTransition(
-        position: new FractionalOffsetTween(
-          begin: const FractionalOffset(0.0, 0.02), // Small offset from the top.
-          end: FractionalOffset.topLeft,
+        position: new AlignmentTween(
+          begin: const Alignment(0.0, 0.4), // Slightly down.
+          end: Alignment.center,
         ).animate(_animation),
         child: new IconTheme(
           data: new IconThemeData(

examples/flutter_gallery/lib/demo/material/buttons_demo.dart

@@ -90,7 +90,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildRaisedButton() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new ButtonBar(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -111,7 +111,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildFlatButton() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new ButtonBar(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -213,7 +213,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildIconButton() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -237,7 +237,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildActionButton() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new FloatingActionButton(
         child: const Icon(Icons.add),
         onPressed: () {

examples/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -85,7 +85,7 @@ class TravelDestinationItem extends StatelessWidget {
                     right: 16.0,
                     child: new FittedBox(
                       fit: BoxFit.scaleDown,
-                      alignment: FractionalOffset.centerLeft,
+                      alignment: Alignment.centerLeft,
                       child: new Text(destination.title,
                         style: titleStyle,
                       ),

examples/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -25,7 +25,7 @@ class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {
 
   AnimationController _controller;
   Animation<double> _drawerContentsOpacity;
-  Animation<FractionalOffset> _drawerDetailsPosition;
+  Animation<Alignment> _drawerDetailsPosition;
   bool _showDrawerContents = true;
 
   @override
@@ -39,9 +39,9 @@ class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {
       parent: new ReverseAnimation(_controller),
       curve: Curves.fastOutSlowIn,
     );
-    _drawerDetailsPosition = new FractionalOffsetTween(
-      begin: const FractionalOffset(0.0, -1.0),
-      end: const FractionalOffset(0.0, 0.0),
+    _drawerDetailsPosition = new AlignmentTween(
+      begin: const Alignment(0.0, -2.0),
+      end: Alignment.center,
     ).animate(new CurvedAnimation(
       parent: _controller,
       curve: Curves.fastOutSlowIn,
@@ -80,7 +80,7 @@ class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {
       appBar: new AppBar(
         leading: new IconButton(
           icon: new Icon(_backIcon()),
-          alignment: FractionalOffset.centerLeft,
+          alignment: Alignment.centerLeft,
           tooltip: 'Back',
           onPressed: () {
             Navigator.pop(context);

examples/flutter_gallery/lib/demo/material/expansion_panels_demo.dart

@@ -51,7 +51,7 @@ class DualHeaderWithHint extends StatelessWidget {
             margin: const EdgeInsets.only(left: 24.0),
             child: new FittedBox(
               fit: BoxFit.scaleDown,
-              alignment: FractionalOffset.centerLeft,
+              alignment: Alignment.centerLeft,
               child: new Text(
                 name,
                 style: textTheme.body1.copyWith(fontSize: 15.0),

examples/flutter_gallery/lib/demo/material/full_screen_dialog_demo.dart

@@ -165,7 +165,7 @@ class FullScreenDialogDemoState extends State<FullScreenDialogDemo> {
               decoration: new BoxDecoration(
                 border: new Border(bottom: new BorderSide(color: theme.dividerColor))
               ),
-              alignment: FractionalOffset.bottomLeft,
+              alignment: Alignment.bottomLeft,
               child: new Text('Event name', style: theme.textTheme.display2)
             ),
             new Container(
@@ -173,7 +173,7 @@ class FullScreenDialogDemoState extends State<FullScreenDialogDemo> {
               decoration: new BoxDecoration(
                 border: new Border(bottom: new BorderSide(color: theme.dividerColor))
               ),
-              alignment: FractionalOffset.bottomLeft,
+              alignment: Alignment.bottomLeft,
               child: new Text('Location', style: theme.textTheme.title.copyWith(color: Colors.black54))
             ),
             new Column(

examples/flutter_gallery/lib/demo/material/grid_list_demo.dart

@@ -54,7 +54,7 @@ class _GridTitleText extends StatelessWidget {
   Widget build(BuildContext context) {
     return new FittedBox(
       fit: BoxFit.scaleDown,
-      alignment: FractionalOffset.centerLeft,
+      alignment: Alignment.centerLeft,
       child: new Text(text),
     );
   }

examples/flutter_gallery/lib/demo/material/selection_controls_demo.dart

@@ -75,7 +75,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildCheckbox() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new Column(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -109,7 +109,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildRadio() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new Column(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -161,7 +161,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildSwitch() {
     return new Align(
-      alignment: const FractionalOffset(0.5, 0.4),
+      alignment: const Alignment(0.0, -0.2),
       child: new Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[

examples/flutter_gallery/lib/demo/material/tabs_demo.dart

@@ -107,8 +107,8 @@ class _CardDataItem extends StatelessWidget {
           children: <Widget>[
             new Align(
               alignment: page.id == 'L'
-                ? FractionalOffset.centerLeft
-                : FractionalOffset.centerRight,
+                ? Alignment.centerLeft
+                : Alignment.centerRight,
               child: new CircleAvatar(child: new Text('${page.id}')),
             ),
             new SizedBox(

examples/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -188,7 +188,7 @@ class TextFormFieldDemoState extends State<TextFormFieldDemo> {
             ),
             new Container(
               padding: const EdgeInsets.all(20.0),
-              alignment: const FractionalOffset(0.5, 0.5),
+              alignment: Alignment.center,
               child: new RaisedButton(
                 child: const Text('SUBMIT'),
                 onPressed: _handleSubmitted,

examples/flutter_gallery/lib/demo/pesto_demo.dart

@@ -211,7 +211,7 @@ class _PestoLogoState extends State<PestoLogo> {
   Widget build(BuildContext context) {
     return new Transform(
       transform: new Matrix4.identity()..scale(widget.height / kLogoHeight),
-      alignment: FractionalOffset.topCenter,
+      alignment: Alignment.topCenter,
       child: new SizedBox(
         width: kLogoWidth,
         child: new Stack(
@@ -362,8 +362,8 @@ class _RecipePageState extends State<RecipePage> {
                   background: new DecoratedBox(
                     decoration: new BoxDecoration(
                       gradient: new LinearGradient(
-                        begin: const FractionalOffset(0.5, 0.0),
-                        end: const FractionalOffset(0.5, 0.40),
+                        begin: const Alignment(0.0, -1.0),
+                        end: const Alignment(0.0, -0.2),
                         colors: <Color>[const Color(0x60000000), const Color(0x00000000)],
                       ),
                     ),
@@ -450,7 +450,7 @@ class RecipeSheet extends StatelessWidget {
                     package: recipe.ingredientsImagePackage,
                     width: 32.0,
                     height: 32.0,
-                    alignment: FractionalOffset.centerLeft,
+                    alignment: Alignment.centerLeft,
                     fit: BoxFit.scaleDown
                   )
                 ),

examples/flutter_gallery/lib/demo/shrine/shrine_home.dart

@@ -320,7 +320,7 @@ class _ProductItem extends StatelessWidget {
             new Column(
               children: <Widget>[
                 new Align(
-                  alignment: FractionalOffset.centerRight,
+                  alignment: Alignment.centerRight,
                   child: new _ProductPriceItem(product: product),
                 ),
                 new Container(

examples/flutter_gallery/lib/demo/shrine/shrine_order.dart

@@ -85,7 +85,7 @@ class _VendorItem extends StatelessWidget {
         new SizedBox(
           height: 24.0,
           child: new Align(
-            alignment: FractionalOffset.bottomLeft,
+            alignment: Alignment.bottomLeft,
             child: new Text(vendor.name, style: theme.vendorTitleStyle),
           ),
         ),
@@ -174,7 +174,7 @@ class _Heading extends StatelessWidget {
                     product.imageAsset,
                     package: product.imageAssetPackage,
                     fit: BoxFit.contain,
-                    alignment: FractionalOffset.center,
+                    alignment: Alignment.center,
                   ),
                 ),
               ),

examples/flutter_gallery/lib/gallery/home.dart

@@ -138,7 +138,7 @@ class GalleryHomeState extends State<GalleryHome> with SingleTickerProviderState
             child: new Container(
               height: 48.0,
               padding: const EdgeInsets.only(left: 16.0),
-              alignment: FractionalOffset.centerLeft,
+              alignment: Alignment.centerLeft,
               child: new Text(galleryItem.category, style: headerStyle)
             ),
           )

examples/layers/rendering/hello_world.dart

@@ -13,7 +13,7 @@ void main() {
     // The root of our render tree is a RenderPositionedBox, which centers its
     // child both vertically and horizontally.
     root: new RenderPositionedBox(
-      alignment: FractionalOffset.center,
+      alignment: Alignment.center,
       // We use a RenderParagraph to display the text 'Hello, world.' without
       // any explicit styling.
       child: new RenderParagraph(

examples/layers/rendering/spinning_square.dart

@@ -34,12 +34,12 @@ void main() {
   // spin.
   final RenderTransform spin = new RenderTransform(
     transform: new Matrix4.identity(),
-    alignment: FractionalOffset.center,
+    alignment: Alignment.center,
     child: square
   );
   // Finally, we center the spinning green square...
   final RenderBox root = new RenderPositionedBox(
-    alignment: FractionalOffset.center,
+    alignment: Alignment.center,
     child: spin
   );
   // and attach it to the window.

examples/layers/widgets/spinning_mixed.dart

@@ -100,7 +100,7 @@ void main() {
   flexRoot.add(proxy);
   addFlexChildSolidColor(flexRoot, const Color(0xFF0000FF), flex: 1);
 
-  transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity(), alignment: FractionalOffset.center);
+  transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity(), alignment: Alignment.center);
   final RenderPadding root = new RenderPadding(padding: const EdgeInsets.all(80.0), child: transformBox);
 
   binding.renderView.child = root;

packages/flutter/test/painting/alignment_test.dart

@@ -14,14 +14,14 @@ void approxExpect(Alignment a, Alignment b) {
 
 void main() {
   test('Alignment control test', () {
-    const Alignment offset = const Alignment(0.5, 0.25);
+    const Alignment alignment = const Alignment(0.5, 0.25);
 
-    expect(offset, hasOneLineDescription);
-    expect(offset.hashCode, equals(const Alignment(0.5, 0.25).hashCode));
+    expect(alignment, hasOneLineDescription);
+    expect(alignment.hashCode, equals(const Alignment(0.5, 0.25).hashCode));
 
-    expect(offset / 2.0, const Alignment(0.25, 0.125));
-    expect(offset ~/ 2.0, const Alignment(0.0, 0.0));
-    expect(offset % 5.0, const Alignment(0.5, 0.25));
+    expect(alignment / 2.0, const Alignment(0.25, 0.125));
+    expect(alignment ~/ 2.0, const Alignment(0.0, 0.0));
+    expect(alignment % 5.0, const Alignment(0.5, 0.25));
   });
 
   test('Alignment.lerp()', () {

packages/flutter_test/lib/src/finders.dart

@@ -290,7 +290,7 @@ abstract class Finder {
   ///
   /// The [at] parameter specifies the location relative to the size of the
   /// target element where the hit test is performed.
-  Finder hitTestable({ FractionalOffset at: FractionalOffset.center }) => new _HitTestableFinder(this, at);
+  Finder hitTestable({ Alignment at: Alignment.center }) => new _HitTestableFinder(this, at);
 
   @override
   String toString() {
@@ -336,10 +336,10 @@ class _LastFinder extends Finder {
 }
 
 class _HitTestableFinder extends Finder {
-  _HitTestableFinder(this.parent, this.offset);
+  _HitTestableFinder(this.parent, this.alignment);
 
   final Finder parent;
-  final FractionalOffset offset;
+  final Alignment alignment;
 
   @override
   String get description => '${parent.description} (considering only hit-testable ones)';
@@ -349,7 +349,7 @@ class _HitTestableFinder extends Finder {
     for (final Element candidate in parent.apply(candidates)) {
       final RenderBox box = candidate.renderObject;
       assert(box != null);
-      final Offset absoluteOffset = box.localToGlobal(offset.alongSize(box.size));
+      final Offset absoluteOffset = box.localToGlobal(alignment.alongSize(box.size));
       final HitTestResult hitResult = new HitTestResult();
       WidgetsBinding.instance.hitTest(hitResult, absoluteOffset);
       for (final HitTestEntry entry in hitResult.path) {

packages/flutter_test/test/finders_test.dart

@@ -29,7 +29,7 @@ void main() {
         )),
       );
       expect(find.byType(GestureDetector), findsNWidgets(2));
-      final Finder hitTestable = find.byType(GestureDetector).hitTestable(at: const FractionalOffset(0.5, 0.5));
+      final Finder hitTestable = find.byType(GestureDetector).hitTestable(at: Alignment.center);
       expect(hitTestable, findsOneWidget);
       expect(tester.widget(hitTestable).key, const ValueKey<int>(0));
     });