Make switch widget accept 3 other colors. (#12118)

* Make switch widget accept 3 other colors: inactiveThumbColor, inactiveTrackColor, activeTrackColor.

* Make switch widget accept 3 other colors.

* Make switch widget accept 3 other colors.

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

diff --git a/packages/flutter/lib/src/material/switch.dart b/packages/flutter/lib/src/material/switch.dart
index bc4953d..d685ae2 100644
--- a/packages/flutter/lib/src/material/switch.dart
+++ b/packages/flutter/lib/src/material/switch.dart
@@ -51,6 +51,9 @@
     @required this.value,
     @required this.onChanged,
     this.activeColor,
+    this.activeTrackColor,
+    this.inactiveThumbColor,
+    this.inactiveTrackColor,
     this.activeThumbImage,
     this.inactiveThumbImage
   }) : super(key: key);
@@ -89,6 +92,21 @@
   /// Defaults to accent color of the current [Theme].
   final Color activeColor;
 
+  /// The color to use on the track when this switch is on.
+  ///
+  /// Defaults to accent color of the current [Theme] with the opacity set at 50%.
+  final Color activeTrackColor;
+
+  /// The color to use on the thumb when this switch is off.
+  ///
+  /// Defaults to the colors described in the Material design specification.
+  final Color inactiveThumbColor;
+
+  /// The color to use on the track when this switch is off.
+  ///
+  /// Defaults to the colors described in the Material design specification.
+  final Color inactiveTrackColor;
+
   /// An image to use on the thumb of this switch when the switch is on.
   final ImageProvider activeThumbImage;
 
@@ -114,16 +132,16 @@
     final bool isDark = themeData.brightness == Brightness.dark;
 
     final Color activeThumbColor = widget.activeColor ?? themeData.accentColor;
-    final Color activeTrackColor = activeThumbColor.withAlpha(0x80);
+    final Color activeTrackColor = widget.activeTrackColor ?? activeThumbColor.withAlpha(0x80);
 
     Color inactiveThumbColor;
     Color inactiveTrackColor;
     if (widget.onChanged != null) {
-      inactiveThumbColor = isDark ? Colors.grey.shade400 : Colors.grey.shade50;
-      inactiveTrackColor = isDark ? Colors.white30 : Colors.black26;
+      inactiveThumbColor = widget.inactiveThumbColor ?? (isDark ? Colors.grey.shade400 : Colors.grey.shade50);
+      inactiveTrackColor = widget.inactiveTrackColor ?? (isDark ? Colors.white30 : Colors.black26);
     } else {
-      inactiveThumbColor = isDark ? Colors.grey.shade800 : Colors.grey.shade400;
-      inactiveTrackColor = isDark ? Colors.white10 : Colors.black12;
+      inactiveThumbColor = widget.inactiveThumbColor ?? (isDark ? Colors.grey.shade800 : Colors.grey.shade400);
+      inactiveTrackColor = widget.inactiveTrackColor ?? (isDark ? Colors.white10 : Colors.black12);
     }
 
     return new _SwitchRenderObjectWidget(

packages/flutter/test/material/switch_test.dart

diff --git a/packages/flutter/test/material/switch_test.dart b/packages/flutter/test/material/switch_test.dart
index c05e0df..78c41bf 100644
--- a/packages/flutter/test/material/switch_test.dart
+++ b/packages/flutter/test/material/switch_test.dart
@@ -6,6 +6,8 @@
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
 
+import '../rendering/mock_canvas.dart';
+
 void main() {
   testWidgets('Switch can toggle on tap', (WidgetTester tester) async {
     final Key switchKey = new UniqueKey();
@@ -110,8 +112,6 @@
       ),
     );
 
-    expect(value, isFalse);
-
     await tester.drag(find.byType(Switch), const Offset(30.0, 0.0));
 
     expect(value, isFalse);
@@ -130,4 +130,59 @@
 
     expect(value, isFalse);
   });
+
+  testWidgets('Switch can be set color', (WidgetTester tester) async {
+    bool value = false;
+    await tester.pumpWidget(
+      new Directionality(
+        textDirection: TextDirection.rtl,
+        child: new StatefulBuilder(
+          builder: (BuildContext context, StateSetter setState) {
+            return new Material(
+              child: new Center(
+                child: new Switch(
+                  value: value,
+                  onChanged: (bool newValue) {
+                    setState(() {
+                      value = newValue;
+                    });
+                  },
+                  activeColor: Colors.red[500],
+                  activeTrackColor: Colors.green[500],
+                  inactiveThumbColor: Colors.yellow[500],
+                  inactiveTrackColor: Colors.blue[500],
+                ),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+
+    expect(
+        Material.of(tester.element(find.byType(Switch))),
+        paints
+          ..rrect(
+              color: Colors.blue[500],
+              rrect: new RRect.fromLTRBR(
+                  383.5, 293.0, 416.5, 307.0, const Radius.circular(7.0)))
+          ..circle(color: const Color(0x33000000))
+          ..circle(color: const Color(0x24000000))
+          ..circle(color: const Color(0x1f000000))
+          ..circle(color: Colors.yellow[500]));
+    await tester.drag(find.byType(Switch), const Offset(-30.0, 0.0));
+    await tester.pump();
+
+    expect(
+        Material.of(tester.element(find.byType(Switch))),
+        paints
+          ..rrect(
+              color: Colors.green[500],
+              rrect: new RRect.fromLTRBR(
+                  383.5, 293.0, 416.5, 307.0, const Radius.circular(7.0)))
+          ..circle(color: const Color(0x33000000))
+          ..circle(color: const Color(0x24000000))
+          ..circle(color: const Color(0x1f000000))
+          ..circle(color: Colors.red[500]));
+  });
 }