More Cupertino dialog UI tweaks (#9960)

* is default

* hit target

* correct test name

* review note

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

@@ -53,11 +53,12 @@ class _CupertinoDialogDemoState extends State<CupertinoDialogDemo> {
                   actions: <Widget>[
                     new CupertinoDialogAction(
                       child: const Text('Discard'),
-                      isDestructive: true,
+                      isDestructiveAction: true,
                       onPressed: () { Navigator.pop(context, 'Discard'); }
                     ),
                     new CupertinoDialogAction(
-                      child: const Text('Cancel', style: const TextStyle(fontWeight: FontWeight.w600)),
+                      child: const Text('Cancel'),
+                      isDefaultAction: true,
                       onPressed: () { Navigator.pop(context, 'Cancel'); }
                     ),
                   ]

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

@@ -191,7 +191,8 @@ class CupertinoDialogAction extends StatelessWidget {
   /// Creates an action for an iOS-style dialog.
   const CupertinoDialogAction({
     this.onPressed,
-    this.isDestructive: false,
+    this.isDefaultAction: false,
+    this.isDestructiveAction: false,
     @required this.child,
   }) : assert(child != null);
 
@@ -200,10 +201,15 @@ class CupertinoDialogAction extends StatelessWidget {
   /// If this is set to null, the button will be disabled.
   final VoidCallback onPressed;
 
+  /// Set to true if button is the default choice in the dialog.
+  ///
+  /// Default buttons are bolded.
+  final bool isDefaultAction;
+
   /// Whether this action destroys an object.
   ///
   /// For example, an action that deletes an email is destructive.
-  final bool isDestructive;
+  final bool isDestructiveAction;
 
   /// The widget below this widget in the tree.
   ///
@@ -218,7 +224,10 @@ class CupertinoDialogAction extends StatelessWidget {
   Widget build(BuildContext context) {
     TextStyle style = _kCupertinoDialogActionStyle;
 
-    if (isDestructive)
+    if (isDefaultAction)
+      style = style.copyWith(fontWeight: FontWeight.w600);
+
+    if (isDestructiveAction)
       style = style.copyWith(color: _kDestructiveActionColor);
 
     if (!enabled)
@@ -226,6 +235,7 @@ class CupertinoDialogAction extends StatelessWidget {
 
     return new GestureDetector(
       onTap: onPressed,
+      behavior: HitTestBehavior.opaque,
       child: new Center(
         child: new DefaultTextStyle(
           style: style,

packages/flutter/test/cupertino/dialog_test.dart

@@ -27,7 +27,7 @@ void main() {
                           child: const Text('Cancel'),
                         ),
                         new CupertinoDialogAction(
-                          isDestructive: true,
+                          isDestructiveAction: true,
                           onPressed: () {
                             didDelete = true;
                             Navigator.pop(context);
@@ -63,9 +63,9 @@ void main() {
     expect(find.text('Delete'), findsNothing);
   });
 
-  testWidgets('Dialog action styles', (WidgetTester tester) async {
+  testWidgets('Dialog destructive action styles', (WidgetTester tester) async {
     await tester.pumpWidget(const CupertinoDialogAction(
-      isDestructive: true,
+      isDestructiveAction: true,
       child: const Text('Ok'),
     ));
 
@@ -74,4 +74,28 @@ void main() {
     expect(widget.style.color.red, greaterThan(widget.style.color.blue));
     expect(widget.style.color.alpha, lessThan(255));
   });
+
+  testWidgets('Dialog default action styles', (WidgetTester tester) async {
+    await tester.pumpWidget(const CupertinoDialogAction(
+      isDefaultAction: true,
+      child: const Text('Ok'),
+    ));
+
+    final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
+
+    expect(widget.style.fontWeight, equals(FontWeight.w600));
+  });
+
+  testWidgets('Default and destructive style', (WidgetTester tester) async {
+    await tester.pumpWidget(const CupertinoDialogAction(
+      isDefaultAction: true,
+      isDestructiveAction: true,
+      child: const Text('Ok'),
+    ));
+
+    final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
+
+    expect(widget.style.fontWeight, equals(FontWeight.w600));
+    expect(widget.style.color.red, greaterThan(widget.style.color.blue));
+  });
 }