Autoscroll when keyboard open on purchase screen

lib/base/base_state.dart

@@ -318,84 +318,3 @@ abstract class BaseState<T extends StatefulWidget> extends State<T> {
     return new Container(margin: margin, height: buttonHeight, child: new Row(children: <Widget>[new Expanded(child: widget)]));
   }
 }
-
-class EnsureVisibleWhenFocused extends StatefulWidget {
-  const EnsureVisibleWhenFocused({
-    Key key,
-    @required this.child,
-    @required this.focusNode,
-    this.curve: Curves.ease,
-    this.duration: const Duration(milliseconds: 100),
-  }) : super(key: key);
-
-  /// The node we will monitor to determine if the child is focused
-  final FocusNode focusNode;
-
-  /// The child widget that we are wrapping
-  final Widget child;
-
-  /// The curve we will use to scroll ourselves into view.
-  ///
-  /// Defaults to Curves.ease.
-  final Curve curve;
-
-  /// The duration we will use to scroll ourselves into view
-  ///
-  /// Defaults to 100 milliseconds.
-  final Duration duration;
-
-  EnsureVisibleWhenFocusedState createState() => new EnsureVisibleWhenFocusedState();
-}
-
-class EnsureVisibleWhenFocusedState extends State<EnsureVisibleWhenFocused> {
-  @override
-  void initState() {
-    super.initState();
-    widget.focusNode.addListener(_ensureVisible);
-  }
-
-  @override
-  void dispose() {
-    super.dispose();
-    widget.focusNode.removeListener(_ensureVisible);
-  }
-
-  Future<Null> _ensureVisible() async {
-    // Wait for the keyboard to come into view
-    // TODO: position doesn't seem to notify listeners when metrics change,
-    // perhaps a NotificationListener around the scrollable could avoid
-    // the need insert a delay here.
-    await new Future.delayed(const Duration(milliseconds: 100));
-
-    if (!widget.focusNode.hasFocus)
-      return;
-
-    final RenderObject object = context.findRenderObject();
-    final RenderAbstractViewport viewport = RenderAbstractViewport.of(object);
-    assert(viewport != null);
-
-    ScrollableState scrollableState = Scrollable.of(context);
-    assert(scrollableState != null);
-
-    ScrollPosition position = scrollableState.position;
-    double alignment;
-    if (position.pixels > viewport.getOffsetToReveal(object, 0.0)) {
-      // Move down to the top of the viewport
-      alignment = 0.0;
-    } else if (position.pixels < viewport.getOffsetToReveal(object, 1.0)) {
-      // Move up to the bottom of the viewport
-      alignment = 1.0;
-    } else {
-      // No scrolling is necessary to reveal the child
-      return;
-    }
-    position.ensureVisible(
-      object,
-      alignment: alignment,
-      duration: widget.duration,
-      curve: widget.curve,
-    );
-  }
-
-  Widget build(BuildContext context) => widget.child;
-}

lib/screens/purchase.dart

@@ -45,6 +45,8 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
   void initState() {
     loading = true;
     requestAsyncData(user);
+    buildFocusNode();
+    scrollController = new ScrollController();
     super.initState();
   }
 
@@ -54,12 +56,14 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
   }
 
   bool purchaseInProgress = false;
+  ScrollController scrollController;
   Map user;
   String card = '';
   String loyalityType = '';
   String loyalty = '';
   String bonus = '';
   List<Map> coupons = [];
+  ListView listView;
 
   @override
   Widget getScreenContent() {
@@ -119,8 +123,8 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
         )
     ));
 
-    return new Container(child: new ListView(reverse: true,
-      children: <Widget>[new Column(children: widgetList)].reversed.toList()));
+    listView = new ListView(children: widgetList, controller: scrollController);
+    return listView;
   }
 
   getBonusInputField() {
@@ -130,6 +134,7 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
         hintText: (app != 'crypto') ? StringsLocalization.bonusHint() : StringsLocalization.joysHint(),
         hintStyle: new TextStyle(color: greyTextColor, fontSize: 16.0)
       ),
+      focusNode: bonusFocusNode,
       controller: bonusController,
       onSubmitted: (String text) {
         setState(() {
@@ -206,13 +211,13 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
           hintText: getHintString(),
           hintStyle: new TextStyle(color: greyTextColor, fontSize: 16.0)),
       controller: controller,
+      focusNode: sumFocusNode,
       onSubmitted: (String text) {
         setState(() {
           controller.text = _parseSum(text);
         });
       },
-      textAlign: TextAlign.center,
-      autofocus: true);
+      textAlign: TextAlign.center);
   }
 
   requestAsyncData(Map user) async {
@@ -436,4 +441,39 @@ class PurchaseScreenState<T> extends BaseState<PurchaseScreen> {
       Navigator.of(context).pop(token);
     });
   }
+
+  FocusNode bonusFocusNode = new FocusNode();
+  FocusNode sumFocusNode = new FocusNode();
+
+  // TODO: Удалить дублирующийся код.
+  void buildFocusNode() {
+
+    sumFocusNode.addListener(() {
+      setState(() {
+
+        if (sumFocusNode.hasFocus && bonusFocusNode.hasFocus) {
+          bonusFocusNode.unfocus();
+        }
+
+        if (sumFocusNode.hasFocus) {
+          scrollController.animateTo(100.0, duration: new Duration(seconds: 1), curve: Curves.ease);
+        }
+
+      });
+    });
+
+    bonusFocusNode.addListener(() {
+      setState(() {
+
+        if (bonusFocusNode.hasFocus && sumFocusNode.hasFocus) {
+          sumFocusNode.unfocus();
+        }
+
+        if (bonusFocusNode.hasFocus) {
+          scrollController.animateTo(120.0, duration: new Duration(seconds: 1), curve: Curves.ease);
+        }
+
+      });
+    });
+  }
 }

lib/screens/registration.dart

@@ -57,15 +57,13 @@ class RegistrationScreenState extends BaseState<RegistrationScreen> {
 
   @override
   getTextWidget() {
-    return new EnsureVisibleWhenFocused(
-      focusNode: _focusNode,
-      child: new TextField(
+    return new TextField(
         focusNode: _focusNode,
         keyboardType: TextInputType.number,
         decoration: new InputDecoration.collapsed(
             hintText: getHintString(),
             hintStyle: new TextStyle(color: greyTextColor, fontSize: 16.0)),
-        onChanged: (text) => handleUserInput(text)));
+        onChanged: (text) => handleUserInput(text));
   }
 
   /// Возвращает кнопку регистрации.