Document the buildTransitions() method (#9182)

examples/flutter_gallery/lib/demo/shrine_demo.dart

@@ -29,8 +29,8 @@ class ShrinePageRoute<T> extends MaterialPageRoute<T> {
   }) : super(builder: builder, settings: settings);
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
-    return buildShrine(context, super.buildPage(context, animation, forwardAnimation));
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
+    return buildShrine(context, super.buildPage(context, animation, secondaryAnimation));
   }
 }
 

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

@@ -231,7 +231,7 @@ class _ModalBottomSheetRoute<T> extends PopupRoute<T> {
   }
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     Widget bottomSheet = new _ModalBottomSheet<T>(route: this);
     if (theme != null)
       bottomSheet = new Theme(data: theme, child: bottomSheet);

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

@@ -337,12 +337,12 @@ class _DialogRoute<T> extends PopupRoute<T> {
   Color get barrierColor => Colors.black54;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     return theme != null ? new Theme(data: theme, child: child) : child;
   }
 
   @override
-  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
     return new FadeTransition(
       opacity: new CurvedAnimation(
         parent: animation,

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

@@ -313,7 +313,7 @@ class _DropdownRoute<T> extends PopupRoute<_DropdownRouteResult<T>> {
   Color get barrierColor => null;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     Widget menu = new _DropdownMenu<T>(route: this);
     if (theme != null)
       menu = new Theme(data: theme, child: menu);

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

@@ -149,7 +149,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
   }
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     final Widget result = builder(context);
     assert(() {
       if (result == null) {
@@ -164,7 +164,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
   }
 
   @override
-  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
     if (Theme.of(context).platform == TargetPlatform.iOS) {
       if (fullscreenDialog)
         return new CupertinoFullscreenDialogTransition(
@@ -174,7 +174,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
       else
         return new CupertinoPageTransition(
           incomingRouteAnimation: animation,
-          outgoingRouteAnimation: forwardAnimation,
+          outgoingRouteAnimation: secondaryAnimation,
           child: child,
           // In the middle of a back gesture drag, let the transition be linear to match finger
           // motions.

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

@@ -402,7 +402,7 @@ class _PopupMenuRoute<T> extends PopupRoute<T> {
   Color get barrierColor => null;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     double selectedItemOffset;
     if (initialValue != null) {
       selectedItemOffset = 0.0;

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

@@ -46,15 +46,15 @@ abstract class PageRoute<T> extends ModalRoute<T> {
 /// primary contents.
 ///
 /// See [ModalRoute.buildPage] for complete definition of the parameters.
-typedef Widget RoutePageBuilder(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation);
+typedef Widget RoutePageBuilder(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation);
 
 /// Signature for the [PageRouteBuilder] function that builds the route's
 /// transitions.
 ///
 /// See [ModalRoute.buildTransitions] for complete definition of the parameters.
-typedef Widget RouteTransitionsBuilder(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child);
+typedef Widget RouteTransitionsBuilder(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child);
 
-Widget _defaultTransitionsBuilder(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
+Widget _defaultTransitionsBuilder(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
   return child;
 }
 
@@ -110,13 +110,13 @@ class PageRouteBuilder<T> extends PageRoute<T> {
   final bool maintainState;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
-    return pageBuilder(context, animation, forwardAnimation);
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
+    return pageBuilder(context, animation, secondaryAnimation);
   }
 
   @override
-  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
-    return transitionsBuilder(context, animation, forwardAnimation, child);
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
+    return transitionsBuilder(context, animation, secondaryAnimation, child);
   }
 
 }

packages/flutter/test/widgets/app_overrides_test.dart

@@ -20,7 +20,7 @@ class TestRoute<T> extends PageRoute<T> {
   bool get maintainState => false;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     return child;
   }
 }

packages/flutter/test/widgets/page_forward_transitions_test.dart

@@ -41,7 +41,7 @@ class TestRoute<T> extends PageRoute<T> {
   bool get maintainState => false;
 
   @override
-  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     return child;
   }
 }
@@ -94,7 +94,7 @@ void main() {
                         new TestTransition(
                           childFirstHalf: new Text('C'),
                           childSecondHalf: new Text('D'),
-                          animation: route.forwardAnimation
+                          animation: route.secondaryAnimation
                         ),
                       ]
                     );