Turn off accessibility access to notification images.

ui/message_center/cocoa/notification_controller.mm

 // Copyright (c) 2013 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 "ui/message_center/cocoa/notification_controller.h"
 
 #include <algorithm>
 
 #include "base/mac/foundation_util.h"
 #include "base/strings/string_util.h"
@@ skipping 185 matching lines @@
   }
   [super accessibilityPerformAction:action];
 }
 @end
 
 ////////////////////////////////////////////////////////////////////////////////
 
 @interface AccessibilityIgnoredBox : NSBox
 @end
 
+// Ignore this element, but expose its children to accessibility.
 @implementation AccessibilityIgnoredBox
 - (BOOL)accessibilityIsIgnored {
   return YES;
 }
+
+// Pretend this element has no children.
+// TODO(petewil): Until we have alt text available, we will hide the children of
+//  the box also.  Remove this override once alt text is set (by using
+// NSAccessibilityDescriptionAttribute).
+-(id) accessibilityAttributeValue:(NSString*) attribute {

[Robert Sesek, 2014/06/11 21:37:04]

nit: space after - but not after )

[Robert Sesek, 2014/06/11 21:37:04]

nit: no space after ) in arguments

[Pete Williamson, 2014/06/11 22:12:54]

Done.

[Pete Williamson, 2014/06/11 22:12:54]

Done.

+  // If we get a request for NSAccessibilityChildrenAttribute, return an empty
+  // array to pretend we have no children.
+  if ([attribute isEqualToString:NSAccessibilityChildrenAttribute])
+    return [[[NSMutableArray alloc] init] autorelease];

[Robert Sesek, 2014/06/11 21:37:04]

nit: use [NSMutableArray array], or if it does not have to be mutable, just @[]

[Pete Williamson, 2014/06/11 22:12:54]

Done.

+  else
+    return [super accessibilityAttributeValue:attribute];
+}
 @end
 
 ////////////////////////////////////////////////////////////////////////////////
 
 @interface MCNotificationController (Private)
 // Configures a NSBox to be borderless, titleless, and otherwise appearance-
 // free.
 - (void)configureCustomBox:(NSBox*)box;
 
 // Initializes the icon_ ivar and returns the view to insert into the hierarchy.
@@ skipping 70 matching lines @@
       message_center::kNotificationBackgroundColor)];
   [self setView:rootView];
 
   [rootView addSubview:[self createIconView]];
 
   // Create the close button.
   [self configureCloseButtonInFrame:rootFrame];
   [rootView addSubview:closeButton_];
 
   // Create the small image.
-  [self configureSmallImageInFrame:rootFrame];
-  [[self view] addSubview:smallImage_];
+  [rootView addSubview:[self createSmallImageInFrame:rootFrame]];
 
   NSRect contentFrame = [self currentContentRect];
 
   // Create the title.
   [self configureTitleInFrame:contentFrame];
   [rootView addSubview:title_];
 
   // Create the message body.
   [self configureBodyInFrame:contentFrame];
   [rootView addSubview:message_];
@@ skipping 413 matching lines @@
   [closeButton_ setAction:@selector(close:)];
   [[closeButton_ cell]
       accessibilitySetOverrideValue:NSAccessibilityCloseButtonSubrole
                        forAttribute:NSAccessibilitySubroleAttribute];
   [[closeButton_ cell]
       accessibilitySetOverrideValue:
           l10n_util::GetNSString(IDS_APP_ACCNAME_CLOSE)
                        forAttribute:NSAccessibilityTitleAttribute];
 }
 
-- (void)configureSmallImageInFrame:(NSRect)rootFrame {
+- (NSView*)createSmallImageInFrame:(NSRect)rootFrame {
   int smallImageXOffset =
       message_center::kSmallImagePadding + message_center::kSmallImageSize;
   NSRect smallImageFrame =
       NSMakeRect(NSMaxX(rootFrame) - smallImageXOffset,
                  NSMinY(rootFrame) + message_center::kSmallImagePadding,
                  message_center::kSmallImageSize,
                  message_center::kSmallImageSize);
+
+  // Put the smallImage inside another box which can hide it from accessibility
+  // until we have some alt text to go with it.  Once we have alt text, remove
+  // the box, and set NSAccessibilityDescriptionAttribute with it.
+  base::scoped_nsobject<NSBox> imageBox(
+      [[AccessibilityIgnoredBox alloc] initWithFrame:smallImageFrame]);
+  [self configureCustomBox:imageBox];
+  [imageBox setAutoresizingMask:NSViewMinYMargin];
   smallImage_.reset([[NSImageView alloc] initWithFrame:smallImageFrame]);

[Robert Sesek, 2014/06/11 21:37:04]

Is this frame still correct? Since it's no longer a subview of |rootView|, its
positioning may be off.

[Pete Williamson, 2014/06/11 22:12:54]

The imageBox is supposed to be the same size and position as the smallImage_. 
This implementation is copied from the createIconView method, which does the
same thing.  As long as both boxes are the same size, I would expect this to
still be valid (I'm by no means an expert in this code, though, so I could have
missed something.) 

[Robert Sesek, 2014/06/12 13:31:10]

Unless I'm misreading the code, it's not quite the same. (Have you tested this
visually, does it look right?) The frame is the position and size of a view in
relation to its superview. In -createIconView, the view placed inside the box
has an origin of (0,0), not the origin relative to the rootView, because it's
not inside the rootView. Here the image is being placed inside the box at an
origin relative to rootView, even though rootView is not its parent: the box is.

https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CocoaV...

[Pete Williamson, 2014/06/12 17:29:04]

Ah, I see.  The code I cut and pasted worked since it was at the origin.  Fixed
to use a separate box
starting at 0,0 for the inner image.  I had not tested the image positioning
before (most of our test messages leave the field blank), but I have now with
the change, and it is working properly.

   [smallImage_ setImageScaling:NSImageScaleProportionallyUpOrDown];
-  [smallImage_ setAutoresizingMask:NSViewMinYMargin];
+  [imageBox setContentView:smallImage_];
+
+  return imageBox.autorelease();
 }
 
 - (void)configureTitleInFrame:(NSRect)contentFrame {
   contentFrame.size.height = 0;
   title_.reset([self newLabelWithFrame:contentFrame]);
   [title_ setAutoresizingMask:NSViewMinYMargin];
   [title_ setTextColor:gfx::SkColorToCalibratedNSColor(
       message_center::kRegularTextColor)];
   [title_ setFont:[NSFont messageFontOfSize:message_center::kTitleFontSize]];
 }
@@ skipping 90 matching lines @@
                    forFont:(NSFont*)nsfont
           maxNumberOfLines:(size_t)lines {
   size_t unused;
   return [self wrapText:text
                 forFont:nsfont
        maxNumberOfLines:lines
             actualLines:&unused];
 }
 
 @end