Show all mailto: handlers, but dim unavailable ones.

ios/chrome/browser/ui/settings/compose_email_handler_collection_view_controller.mm

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/chrome/browser/ui/settings/compose_email_handler_collection_view_controller.h"
 
 #include "base/mac/foundation_util.h"
 #import "ios/chrome/browser/ui/collection_view/cells/collection_view_text_item.h"
+#import "ios/chrome/browser/ui/colors/MDCPalette+CrAdditions.h"

[rohitrao (ping after 24h), 2017/05/22 12:50:37]

If all you need is greyColor, you should be able to depend directly on the MDC
Palette component.  (The +CrAdditions are there for red/green/blue/yellow
specifically.)

Changes here and in the BUILD.gn file.

[pkl (ping after 24h if needed), 2017/05/22 20:27:09]

Thanks! Makes sense.

 #import "ios/chrome/browser/web/mailto_handler.h"
 #import "ios/chrome/browser/web/mailto_url_rewriter.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
@@ skipping 30 matching lines @@
 
 - (void)loadModel {
   [super loadModel];
   CollectionViewModel* model = self.collectionViewModel;
   [model addSectionWithIdentifier:SectionIdentifierMailtoHandlers];
 
   // Since this is a one-of-several selection UI, there must be more than one
   // choice available to the user. If this UI is being presented when there is
   // only one choice, it is considered a software error.
   NSArray<MailtoHandler*>* handlers = [_rewriter defaultHandlers];
-  DCHECK([handlers count] > 1);
   NSString* currentHandlerID = [_rewriter defaultHandlerID];
   for (MailtoHandler* handler in handlers) {
     CollectionViewTextItem* item =
         [[CollectionViewTextItem alloc] initWithType:ItemTypeMailtoHandlers];
     [item setText:[handler appName]];
-    [item setAccessibilityTraits:UIAccessibilityTraitButton];
+    if ([handler isAvailable]) {
+      [item setTextColor:[[MDCPalette greyPalette] tint900]];
+      [item setAccessibilityTraits:UIAccessibilityTraitButton];
+    } else {
+      [item setTextColor:[[MDCPalette greyPalette] tint500]];
+      [item setAccessibilityTraits:UIAccessibilityTraitNotEnabled];
+    }
     if ([currentHandlerID isEqualToString:[handler appStoreID]])
       [item setAccessoryType:MDCCollectionViewCellAccessoryCheckmark];
     [model addItem:item
         toSectionWithIdentifier:SectionIdentifierMailtoHandlers];
   }
 }
 
 #pragma mark UICollectionViewDelegate
 
 - (void)collectionView:(UICollectionView*)collectionView
     didSelectItemAtIndexPath:(NSIndexPath*)indexPath {
   [super collectionView:collectionView didSelectItemAtIndexPath:indexPath];
   CollectionViewModel* model = self.collectionViewModel;
 
   // The items created in -loadModel are all MailtoHandlers type.
   CollectionViewTextItem* selectedItem =
       base::mac::ObjCCastStrict<CollectionViewTextItem>(
           [model itemAtIndexPath:indexPath]);
   DCHECK_EQ(ItemTypeMailtoHandlers, selectedItem.type);
 
   // Do nothing if the tapped row is already chosen as the default.
   if (selectedItem.accessoryType == MDCCollectionViewCellAccessoryCheckmark)
     return;
 
+  // Do nothing if the handler for the tapped row is not available.

[rohitrao (ping after 24h), 2017/05/22 12:50:37]

Consider handling this in shouldSelectItemAtIndexPath instead.  If you put the
logic is there, it may also disable the "ink" effect for free.  (We probably
don't want the ink ripple to fire for dimmed-out cells.)

[pkl (ping after 24h if needed), 2017/05/22 20:27:09]

Added shouldSelectItemAtIndexPath:, however it does not stop the ink ripple.
To stop ink ripple, I added shouldHighlightItemAtIndexPath: as well.

+  NSUInteger handlerIndex = [model indexInItemTypeForIndexPath:indexPath];
+  MailtoHandler* handler =
+      [[_rewriter defaultHandlers] objectAtIndex:handlerIndex];
+  if (![handler isAvailable])
+    return;
+
   // Iterate through the rows and remove the checkmark from any that has it.
   NSMutableArray* modifiedItems = [NSMutableArray array];
   for (id item in
        [model itemsInSectionWithIdentifier:SectionIdentifierMailtoHandlers]) {
     CollectionViewTextItem* textItem =
         base::mac::ObjCCastStrict<CollectionViewTextItem>(item);
     DCHECK_EQ(ItemTypeMailtoHandlers, textItem.type);
     if (textItem == selectedItem) {
       // Shows the checkmark on the new default mailto: URL handler.
       textItem.accessoryType = MDCCollectionViewCellAccessoryCheckmark;
       [modifiedItems addObject:textItem];
     } else if (textItem.accessoryType ==
                MDCCollectionViewCellAccessoryCheckmark) {
       // Unchecks any currently checked selection.
       textItem.accessoryType = MDCCollectionViewCellAccessoryNone;
       [modifiedItems addObject:textItem];
     }
   }
 
-  NSUInteger handlerIndex = [model indexInItemTypeForIndexPath:indexPath];
-  MailtoHandler* handler =
-      [[_rewriter defaultHandlers] objectAtIndex:handlerIndex];
   [_rewriter setDefaultHandlerID:[handler appStoreID]];
 
   [self reconfigureCellsForItems:modifiedItems];
 }
 
 @end