Added InputDecorationTheme (#14177)

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

@@ -28,6 +28,13 @@ import 'package:flutter/widgets.dart';
 ///    rounded rectangle around the input decorator's container.
 ///  * [InputDecoration], which is used to configure an [InputDecorator].
 abstract class InputBorder extends ShapeBorder {
+  /// No input border.
+  ///
+  /// Use this value with [InputDecoration.border] to specify that no border
+  /// should be drawn. The [InputDecoration.collapsed] constructor sets
+  /// its border to this value.
+  static const InputBorder none = const _NoInputBorder();
+
   /// Creates a border for an [InputDecorator].
   ///
   /// The [borderSide] parameter must not be null. Applications typically do
@@ -72,6 +79,43 @@ abstract class InputBorder extends ShapeBorder {
   });
 }
 
+// Used to create the InputBorder.none singleton.
+class _NoInputBorder extends InputBorder {
+  const _NoInputBorder() : super(borderSide: BorderSide.none);
+
+  @override
+  _NoInputBorder copyWith({ BorderSide borderSide }) => const _NoInputBorder();
+
+  @override
+  bool get isOutline => false;
+
+  @override
+  EdgeInsetsGeometry get dimensions => EdgeInsets.zero;
+
+  @override
+  _NoInputBorder scale(double t) => const _NoInputBorder();
+
+  @override
+  Path getInnerPath(Rect rect, { TextDirection textDirection }) {
+    return new Path()..addRect(rect);
+  }
+
+  @override
+  Path getOuterPath(Rect rect, { TextDirection textDirection }) {
+    return new Path()..addRect(rect);
+  }
+
+  @override
+  void paint(Canvas canvas, Rect rect, {
+      double gapStart,
+      double gapExtent: 0.0,
+      double gapPercentage: 0.0,
+      TextDirection textDirection,
+  }) {
+    // Do not paint.
+  }
+}
+
 /// Draws a horizontal line at the bottom of an [InputDecorator]'s container.
 ///
 /// The input decorator's "container" is the optionally filled area above the

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

@@ -296,10 +296,12 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
     && widget.decoration.counterText == null;
 
   InputDecoration _getEffectiveDecoration() {
+    final InputDecoration effectiveDecoration = (widget.decoration ?? const InputDecoration())
+      .applyDefaults(Theme.of(context).inputDecorationTheme);
+
     if (!needsCounter)
-      return widget.decoration;
+      return effectiveDecoration;
 
-    final InputDecoration effectiveDecoration = widget?.decoration ?? const InputDecoration();
     final String counterText = '${_effectiveController.value.text.runes.length} / ${widget.maxLength}';
     if (_effectiveController.value.text.runes.length > widget.maxLength) {
       final ThemeData themeData = Theme.of(context);

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

@@ -7,6 +7,7 @@ import 'package:flutter/widgets.dart';
 
 import 'input_decorator.dart';
 import 'text_field.dart';
+import 'theme.dart';
 
 /// A [FormField] that contains a [TextField].
 ///
@@ -71,10 +72,12 @@ class TextFormField extends FormField<String> {
     validator: validator,
     builder: (FormFieldState<String> field) {
       final _TextFormFieldState state = field;
+      final InputDecoration effectiveDecoration = (decoration ?? const InputDecoration())
+        .applyDefaults(Theme.of(field.context).inputDecorationTheme);
       return new TextField(
         controller: state._effectiveController,
         focusNode: focusNode,
-        decoration: decoration.copyWith(errorText: field.errorText),
+        decoration: effectiveDecoration.copyWith(errorText: field.errorText),
         keyboardType: keyboardType,
         style: style,
         textAlign: textAlign,

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

@@ -10,6 +10,7 @@ import 'package:flutter/widgets.dart';
 import 'colors.dart';
 import 'ink_splash.dart';
 import 'ink_well.dart' show InteractiveInkFeatureFactory;
+import 'input_decorator.dart';
 import 'typography.dart';
 
 /// Describes the contrast needs of a color.
@@ -101,6 +102,7 @@ class ThemeData {
     TextTheme textTheme,
     TextTheme primaryTextTheme,
     TextTheme accentTextTheme,
+    InputDecorationTheme inputDecorationTheme,
     IconThemeData iconTheme,
     IconThemeData primaryIconTheme,
     IconThemeData accentIconTheme,
@@ -135,6 +137,7 @@ class ThemeData {
     indicatorColor ??= accentColor == primaryColor ? Colors.white : accentColor;
     hintColor ??= isDark ? const Color(0x42FFFFFF) : const Color(0x4C000000);
     errorColor ??= Colors.red[700];
+    inputDecorationTheme ??= const InputDecorationTheme();
     iconTheme ??= isDark ? const IconThemeData(color: Colors.white) : const IconThemeData(color: Colors.black);
     primaryIconTheme ??= primaryIsDark ? const IconThemeData(color: Colors.white) : const IconThemeData(color: Colors.black);
     accentIconTheme ??= accentIsDark ? const IconThemeData(color: Colors.white) : const IconThemeData(color: Colors.black);
@@ -176,6 +179,7 @@ class ThemeData {
       textTheme: textTheme,
       primaryTextTheme: primaryTextTheme,
       accentTextTheme: accentTextTheme,
+      inputDecorationTheme: inputDecorationTheme,
       iconTheme: iconTheme,
       primaryIconTheme: primaryIconTheme,
       accentIconTheme: accentIconTheme,
@@ -217,6 +221,7 @@ class ThemeData {
     @required this.textTheme,
     @required this.primaryTextTheme,
     @required this.accentTextTheme,
+    @required this.inputDecorationTheme,
     @required this.iconTheme,
     @required this.primaryIconTheme,
     @required this.accentIconTheme,
@@ -248,6 +253,7 @@ class ThemeData {
        assert(textTheme != null),
        assert(primaryTextTheme != null),
        assert(accentTextTheme != null),
+       assert(inputDecorationTheme != null),
        assert(iconTheme != null),
        assert(primaryIconTheme != null),
        assert(accentIconTheme != null),
@@ -388,6 +394,12 @@ class ThemeData {
   /// A text theme that contrasts with the accent color.
   final TextTheme accentTextTheme;
 
+  /// The default [InputDecoration] values for [InputDecorator], [TextField],
+  /// and [TextFormField] are based on this theme.
+  ///
+  /// See [InputDecoration.applyDefaults].
+  final InputDecorationTheme inputDecorationTheme;
+
   /// An icon theme that contrasts with the card and canvas colors.
   final IconThemeData iconTheme;
 
@@ -431,6 +443,7 @@ class ThemeData {
     TextTheme textTheme,
     TextTheme primaryTextTheme,
     TextTheme accentTextTheme,
+    InputDecorationTheme inputDecorationTheme,
     IconThemeData iconTheme,
     IconThemeData primaryIconTheme,
     IconThemeData accentIconTheme,
@@ -464,6 +477,7 @@ class ThemeData {
       textTheme: textTheme ?? this.textTheme,
       primaryTextTheme: primaryTextTheme ?? this.primaryTextTheme,
       accentTextTheme: accentTextTheme ?? this.accentTextTheme,
+      inputDecorationTheme: inputDecorationTheme ?? this.inputDecorationTheme,
       iconTheme: iconTheme ?? this.iconTheme,
       primaryIconTheme: primaryIconTheme ?? this.primaryIconTheme,
       accentIconTheme: accentIconTheme ?? this.accentIconTheme,
@@ -582,6 +596,7 @@ class ThemeData {
       textTheme: TextTheme.lerp(a.textTheme, b.textTheme, t),
       primaryTextTheme: TextTheme.lerp(a.primaryTextTheme, b.primaryTextTheme, t),
       accentTextTheme: TextTheme.lerp(a.accentTextTheme, b.accentTextTheme, t),
+      inputDecorationTheme: t < 0.5 ? a.inputDecorationTheme : b.inputDecorationTheme,
       iconTheme: IconThemeData.lerp(a.iconTheme, b.iconTheme, t),
       primaryIconTheme: IconThemeData.lerp(a.primaryIconTheme, b.primaryIconTheme, t),
       accentIconTheme: IconThemeData.lerp(a.accentIconTheme, b.accentIconTheme, t),
@@ -621,6 +636,7 @@ class ThemeData {
            (otherData.textTheme == textTheme) &&
            (otherData.primaryTextTheme == primaryTextTheme) &&
            (otherData.accentTextTheme == accentTextTheme) &&
+           (otherData.inputDecorationTheme == inputDecorationTheme) &&
            (otherData.iconTheme == iconTheme) &&
            (otherData.primaryIconTheme == primaryIconTheme) &&
            (otherData.accentIconTheme == accentIconTheme) &&
@@ -659,6 +675,7 @@ class ThemeData {
         primaryTextTheme,
         accentTextTheme,
         iconTheme,
+        inputDecorationTheme,
         primaryIconTheme,
         accentIconTheme,
         platform,