[CRD iOS] Fix the jarring "Hide Keyboard" UX

Previously when the user taps "Hide Keyboard" from the session menu, the
keyboard will immediately show then hide itself. This CL prevents the
keyboard from showing between (alert is shown, action is executed) and
manually shows it again only when necessary.

This CL also includes some refactoring to reduce redundant common code.

Bug: 750956
Change-Id: I545e1880352e279ebf324676f7680600761b78f3
Reviewed-on: https://chromium-review.googlesource.com/595016Reviewed-by: Scott Nichols <nicholss@chromium.org>
Commit-Queue: Yuwei Huang <yuweih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491154}

remoting/ios/app/host_view_controller.mm

@@ -44,6 +44,10 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
   CGSize _keyboardSize;
   BOOL _surfaceCreated;
   HostSettings* _settings;
+
+  // When set to true, ClientKeyboard will immediately resign first responder
+  // after it becomes first responder.
+  BOOL _blocksKeyboard;
 }
 @end
 
@@ -55,6 +59,7 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
     _client = client;
     _keyboardSize = CGSizeZero;
     _surfaceCreated = NO;
+    _blocksKeyboard = NO;
     _settings =
         [[RemotingPreferences instance] settingsForHost:client.hostInfo.hostId];
   }
@@ -203,6 +208,15 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
 #pragma mark - Keyboard Notifications
 
 - (void)keyboardWillShow:(NSNotification*)notification {
+  if (_blocksKeyboard) {
+    [self hideKeyboard];
+
+    // This is to make sure the keyboard is removed from the responder chain.
+    [_clientKeyboard removeFromSuperview];
+    [self.view addSubview:_clientKeyboard];
+    return;
+  }
+
   CGSize keyboardSize =
       [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey]
           CGRectValue]
@@ -320,41 +334,44 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
   // more options. This is not ideal but it gets us an easy way to make a
   // modal window option selector. Replace this with a real menu later.
 
+  // ClientKeyboard may gain first responder immediately after the alert is
+  // dismissed. This will cause weird show-then-hide animation when hiding
+  // keyboard on iPhone (iPad is unaffected since it shows the alert as popup).
+  // The fix is to remove ClientKeyboard from the responder chain in
+  // keyboardWillShow and manually show the keyboard again only when needed.
+
   UIAlertController* alert = [UIAlertController
       alertControllerWithTitle:nil
                        message:nil
                 preferredStyle:UIAlertControllerStyleActionSheet];
 
+  __weak HostViewController* weakSelf = self;
   if (!_clientKeyboard.hasPhysicalKeyboard) {
     // These are only needed for soft keyboard.
     if ([self isKeyboardActive]) {
-      void (^hideKeyboardHandler)(UIAlertAction*) = ^(UIAlertAction*) {
-        [self hideKeyboard];
-        [_actionImageView setActive:NO animated:YES];
-      };
-      [alert addAction:[UIAlertAction actionWithTitle:l10n_util::GetNSString(
-                                                          IDS_HIDE_KEYBOARD)
-                                                style:UIAlertActionStyleDefault
-                                              handler:hideKeyboardHandler]];
+      [self addActionToAlert:alert
+                       title:IDS_HIDE_KEYBOARD
+                       style:UIAlertActionStyleDefault
+            restoresKeyboard:NO
+                     handler:^() {
+                       [weakSelf hideKeyboard];
+                     }];
     } else {
-      void (^showKeyboardHandler)(UIAlertAction*) = ^(UIAlertAction*) {
-        [self showKeyboard];
-        [_actionImageView setActive:NO animated:YES];
-      };
-      [alert addAction:[UIAlertAction actionWithTitle:l10n_util::GetNSString(
-                                                          IDS_SHOW_KEYBOARD)
-                                                style:UIAlertActionStyleDefault
-                                              handler:showKeyboardHandler]];
+      [self addActionToAlert:alert
+                       title:IDS_SHOW_KEYBOARD
+                     handler:^() {
+                       [weakSelf showKeyboard];
+                     }];
     }
   }
 
   remoting::GestureInterpreter::InputMode currentInputMode =
       _client.gestureInterpreter->GetInputMode();
-  NSString* switchInputModeTitle = l10n_util::GetNSString(
+  int switchInputModeTitle =
       currentInputMode == remoting::GestureInterpreter::DIRECT_INPUT_MODE
           ? IDS_SELECT_TRACKPAD_MODE
-          : IDS_SELECT_TOUCH_MODE);
-  void (^switchInputModeHandler)(UIAlertAction*) = ^(UIAlertAction*) {
+          : IDS_SELECT_TOUCH_MODE;
+  void (^switchInputModeHandler)() = ^() {
     switch (currentInputMode) {
       case remoting::GestureInterpreter::DIRECT_INPUT_MODE:
         [self useTrackpadInputMode];
@@ -364,25 +381,22 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
         [self useDirectInputMode];
         break;
     }
-    [_actionImageView setActive:NO animated:YES];
   };
-  [alert addAction:[UIAlertAction actionWithTitle:switchInputModeTitle
-                                            style:UIAlertActionStyleDefault
-                                          handler:switchInputModeHandler]];
+  [self addActionToAlert:alert
+                   title:switchInputModeTitle
+                 handler:switchInputModeHandler];
 
-  void (^disconnectHandler)(UIAlertAction*) = ^(UIAlertAction*) {
+  void (^disconnectHandler)() = ^() {
     [_client disconnectFromHost];
     [self.navigationController popToRootViewControllerAnimated:YES];
-    [_actionImageView setActive:NO animated:YES];
   };
-  [alert
-      addAction:[UIAlertAction actionWithTitle:l10n_util::GetNSString(
-                                                   IDS_DISCONNECT_MYSELF_BUTTON)
-                                         style:UIAlertActionStyleDefault
-                                       handler:disconnectHandler]];
+  [self addActionToAlert:alert
+                   title:IDS_DISCONNECT_MYSELF_BUTTON
+                   style:UIAlertActionStyleDefault
+        restoresKeyboard:NO
+                 handler:disconnectHandler];
 
-  __weak HostViewController* weakSelf = self;
-  void (^settingsHandler)(UIAlertAction*) = ^(UIAlertAction*) {
+  void (^settingsHandler)() = ^() {
     RemotingSettingsViewController* settingsViewController =
         [[RemotingSettingsViewController alloc] init];
     settingsViewController.delegate = weakSelf;
@@ -392,22 +406,23 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
     UINavigationController* navController = [[UINavigationController alloc]
         initWithRootViewController:settingsViewController];
     [weakSelf presentViewController:navController animated:YES completion:nil];
-    [_actionImageView setActive:NO animated:YES];
   };
-  [alert addAction:[UIAlertAction actionWithTitle:l10n_util::GetNSString(
-                                                      IDS_SETTINGS_BUTTON)
-                                            style:UIAlertActionStyleDefault
-                                          handler:settingsHandler]];
+  // Don't restore keyboard since the settings view will be show immediately.
+  [self addActionToAlert:alert
+                   title:IDS_SETTINGS_BUTTON
+                   style:UIAlertActionStyleDefault
+        restoresKeyboard:NO
+                 handler:settingsHandler];
 
   __weak UIAlertController* weakAlert = alert;
-  void (^cancelHandler)(UIAlertAction*) = ^(UIAlertAction*) {
+  void (^cancelHandler)() = ^() {
     [weakAlert dismissViewControllerAnimated:YES completion:nil];
-    [_actionImageView setActive:NO animated:YES];
   };
-  [alert addAction:[UIAlertAction
-                       actionWithTitle:l10n_util::GetNSString(IDS_CANCEL)
-                                 style:UIAlertActionStyleCancel
-                               handler:cancelHandler]];
+  [self addActionToAlert:alert
+                   title:IDS_CANCEL
+                   style:UIAlertActionStyleCancel
+        restoresKeyboard:YES
+                 handler:cancelHandler];
 
   alert.popoverPresentationController.sourceView = self.view;
   // Target the alert menu at the top middle of the FAB.
@@ -417,7 +432,48 @@ static const CGFloat kKeyboardAnimationTime = 0.3;
   alert.popoverPresentationController.permittedArrowDirections =
       UIPopoverArrowDirectionDown;
   [self presentViewController:alert animated:YES completion:nil];
+
+  // Prevent keyboard from showing between (alert is shown, action is executed).
+  _blocksKeyboard = YES;
+
   [_actionImageView setActive:YES animated:YES];
 }
 
+// Adds an action to the alert. And restores the states for you.
+// restoresKeyboard:
+//   Set to YES to show the keyboard if it was previously shown. Do not assume
+//   the keyboard will always be hidden when the alert view is shown.
+- (void)addActionToAlert:(UIAlertController*)alert
+                   title:(int)titleMessageId
+                   style:(UIAlertActionStyle)style
+        restoresKeyboard:(BOOL)restoresKeyboard
+                 handler:(void (^)())handler {
+  BOOL isKeyboardActive = [self isKeyboardActive];
+  [alert addAction:[UIAlertAction
+                       actionWithTitle:l10n_util::GetNSString(titleMessageId)
+                                 style:style
+                               handler:^(UIAlertAction*) {
+                                 _blocksKeyboard = NO;
+                                 if (isKeyboardActive && restoresKeyboard) {
+                                   [self showKeyboard];
+                                 }
+                                 if (handler) {
+                                   handler();
+                                 }
+                                 [_actionImageView setActive:NO animated:YES];
+                               }]];
+}
+
+// Shorter version of addActionToAlert with default action style and
+// restoresKeyboard == YES.
+- (void)addActionToAlert:(UIAlertController*)alert
+                   title:(int)titleMessageId
+                 handler:(void (^)())handler {
+  [self addActionToAlert:alert
+                   title:titleMessageId
+                   style:UIAlertActionStyleDefault
+        restoresKeyboard:YES
+                 handler:handler];
+}
+
 @end