Mac: Add new accessibility attributes for textfields (and some for all views).

ui/accessibility/platform/ax_platform_node_mac.mm

 // Copyright 2014 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/accessibility/platform/ax_platform_node_mac.h"
 
 #import <Cocoa/Cocoa.h>
 #include <stddef.h>
 
 #include "base/macros.h"
 #include "base/strings/sys_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 
 namespace {
 
-struct MapEntry {
+struct RoleMapEntry {
   ui::AXRole value;
   NSString* nativeValue;
 };
 
+struct EventMapEntry {
+  ui::AXEvent value;
+  NSString* nativeValue;
+};
+
 typedef std::map<ui::AXRole, NSString*> RoleMap;
+typedef std::map<ui::AXEvent, NSString*> EventMap;
 
 RoleMap BuildRoleMap() {
-  const MapEntry roles[] = {
+  const RoleMapEntry roles[] = {
       {ui::AX_ROLE_ABBR, NSAccessibilityGroupRole},
       {ui::AX_ROLE_ALERT, NSAccessibilityGroupRole},
       {ui::AX_ROLE_ALERT_DIALOG, NSAccessibilityGroupRole},
       {ui::AX_ROLE_ANNOTATION, NSAccessibilityUnknownRole},
       {ui::AX_ROLE_APPLICATION, NSAccessibilityGroupRole},
       {ui::AX_ROLE_ARTICLE, NSAccessibilityGroupRole},
       {ui::AX_ROLE_BANNER, NSAccessibilityGroupRole},
       {ui::AX_ROLE_BLOCKQUOTE, NSAccessibilityGroupRole},
       {ui::AX_ROLE_BUSY_INDICATOR, NSAccessibilityBusyIndicatorRole},
       {ui::AX_ROLE_BUTTON, NSAccessibilityButtonRole},
@@ skipping 105 matching lines @@
       // { ui::AX_ROLE_SCROLL_AREA, NSAccessibilityScrollAreaRole },
   };
 
   RoleMap role_map;
   for (size_t i = 0; i < arraysize(roles); ++i)
     role_map[roles[i].value] = roles[i].nativeValue;
   return role_map;
 }
 
 RoleMap BuildSubroleMap() {
-  const MapEntry subroles[] = {
+  const RoleMapEntry subroles[] = {
       {ui::AX_ROLE_ALERT, @"AXApplicationAlert"},
       {ui::AX_ROLE_ALERT_DIALOG, @"AXApplicationAlertDialog"},
       {ui::AX_ROLE_APPLICATION, @"AXLandmarkApplication"},
       {ui::AX_ROLE_ARTICLE, @"AXDocumentArticle"},
       {ui::AX_ROLE_BANNER, @"AXLandmarkBanner"},
       {ui::AX_ROLE_COMPLEMENTARY, @"AXLandmarkComplementary"},
       {ui::AX_ROLE_CONTENT_INFO, @"AXLandmarkContentInfo"},
       {ui::AX_ROLE_DEFINITION, @"AXDefinition"},
       {ui::AX_ROLE_DESCRIPTION_LIST_DETAIL, @"AXDefinition"},
       {ui::AX_ROLE_DESCRIPTION_LIST_TERM, @"AXTerm"},
@@ skipping 18 matching lines @@
       {ui::AX_ROLE_TOOLTIP, @"AXUserInterfaceTooltip"},
       {ui::AX_ROLE_TREE_ITEM, NSAccessibilityOutlineRowSubrole},
   };
 
   RoleMap subrole_map;
   for (size_t i = 0; i < arraysize(subroles); ++i)
     subrole_map[subroles[i].value] = subroles[i].nativeValue;
   return subrole_map;
 }
 
+EventMap BuildEventMap() {
+  const EventMapEntry events[] = {
+      {ui::AX_EVENT_TEXT_CHANGED, NSAccessibilityTitleChangedNotification},
+      {ui::AX_EVENT_VALUE_CHANGED, NSAccessibilityValueChangedNotification},
+      {ui::AX_EVENT_TEXT_SELECTION_CHANGED,
+       NSAccessibilitySelectedTextChangedNotification},
+      // TODO(patricialor): Add more events.
+  };
+
+  EventMap event_map;
+  for (size_t i = 0; i < arraysize(events); ++i) {
+    event_map[events[i].value] = events[i].nativeValue;
+  }
+  return event_map;
+}
+
+void NotifyMacEvent(ui::AXEvent event_type, gfx::AcceleratedWidget target) {
+  NSAccessibilityPostNotification(
+      target, [AXPlatformNodeCocoa nativeNotificationFromAXEvent:event_type]);
+}
+
 }  // namespace
 
 @interface AXPlatformNodeCocoa ()
 // Helper function for string attributes that don't require extra processing.
 - (NSString*)getStringAttribute:(ui::AXStringAttribute)attribute;
 @end
 
 @implementation AXPlatformNodeCocoa
 
 // A mapping of AX roles to native roles.
 + (NSString*)nativeRoleFromAXRole:(ui::AXRole)role {
   CR_DEFINE_STATIC_LOCAL(RoleMap, role_map, (BuildRoleMap()));
   RoleMap::iterator it = role_map.find(role);
   return it != role_map.end() ? it->second : NSAccessibilityUnknownRole;
 }
 
 // A mapping of AX roles to native subroles.
 + (NSString*)nativeSubroleFromAXRole:(ui::AXRole)role {
   CR_DEFINE_STATIC_LOCAL(RoleMap, subrole_map, (BuildSubroleMap()));
   RoleMap::iterator it = subrole_map.find(role);
   return it != subrole_map.end() ? it->second : nil;
 }
 
+// A mapping of AX events to native notifications.
++ (NSString*)nativeNotificationFromAXEvent:(ui::AXEvent)event {
+  CR_DEFINE_STATIC_LOCAL(EventMap, event_map, (BuildEventMap()));
+  EventMap::iterator it = event_map.find(event);
+  return it != event_map.end() ? it->second : nil;
+}
+
 - (instancetype)initWithNode:(ui::AXPlatformNodeBase*)node {
   if ((self = [super init])) {
     node_ = node;
   }
   return self;
 }
 
 - (void)detach {
   node_ = nil;
 }
@@ skipping 38 matching lines @@
     NSAccessibilityRoleAttribute,
     NSAccessibilitySizeAttribute,
     NSAccessibilitySubroleAttribute,
 
     // Title is required for most elements. Cocoa asks for the value even if it
     // is omitted here, but won't present it to accessibility APIs without this.
     NSAccessibilityTitleAttribute,
 
     // Attributes which are not required, but are general to all roles.
     NSAccessibilityRoleDescriptionAttribute,
+    NSAccessibilityEnabledAttribute,
+    NSAccessibilityFocusedAttribute,
   ];
 
   // Attributes required for user-editable controls.
   NSArray* const kValueAttributes = @[ NSAccessibilityValueAttribute ];
 
+  // Attributes required for textfields.
+  NSArray* const kTextfieldAttributes = @[
+    NSAccessibilityInsertionPointLineNumberAttribute,
+    NSAccessibilityNumberOfCharactersAttribute,
+    NSAccessibilityPlaceholderValueAttribute,
+    NSAccessibilitySelectedTextAttribute,
+    NSAccessibilitySelectedTextRangeAttribute,
+    NSAccessibilityVisibleCharacterRangeAttribute,
+  ];
+
   base::scoped_nsobject<NSMutableArray> axAttributes(
       [[NSMutableArray alloc] init]);
 
   [axAttributes addObjectsFromArray:kAllRoleAttributes];
   switch (node_->GetData().role) {
+    case ui::AX_ROLE_TEXT_FIELD:
+      [axAttributes addObjectsFromArray:kTextfieldAttributes];

[dmazzoni, 2016/06/29 16:24:11]

Please add a comment like "fallthrough" so that it's clear you meant for this to
keep going with the switch and you're not accidentally missing a "break".

[Patti Lor, 2016/06/30 05:29:54]

Done.

     case ui::AX_ROLE_CHECK_BOX:
     case ui::AX_ROLE_COMBO_BOX:
     case ui::AX_ROLE_MENU_ITEM_CHECK_BOX:
     case ui::AX_ROLE_MENU_ITEM_RADIO:
     case ui::AX_ROLE_RADIO_BUTTON:
     case ui::AX_ROLE_SEARCH_BOX:
     case ui::AX_ROLE_SLIDER:
     case ui::AX_ROLE_SLIDER_THUMB:
     case ui::AX_ROLE_TOGGLE_BUTTON:
-    case ui::AX_ROLE_TEXT_FIELD:
       [axAttributes addObjectsFromArray:kValueAttributes];
       break;
     // TODO(tapted): Add additional attributes based on role.
     default:
       break;
   }
   return axAttributes.autorelease();
 }
 
 - (BOOL)accessibilityIsAttributeSettable:(NSString*)attribute {
@@ skipping 61 matching lines @@
 }
 
 - (NSString*)AXTitle {
   return [self getStringAttribute:ui::AX_ATTR_NAME];
 }
 
 - (NSString*)AXValue {
   return [self getStringAttribute:ui::AX_ATTR_VALUE];
 }
 
+- (NSValue*)AXEnabled {
+  // TODO(patricialor): Check with dmazzoni@ to see if AX_STATE_ENABLED is still

[dmazzoni, 2016/06/29 16:24:11]

This is correct for now, no TODO needed. My plan is to get rid of ENABLED at
some point, so this code will be unaffected.

(Having both is redundant, so given the choice, I prefer all of our boolean
flags are set to false as the default, most common case - so that suggests
calling it "disabled" internally and mapping it to AXEnabled on Mac only)

[Patti Lor, 2016/06/30 05:29:54]

Removed, thanks for clarifying!

+  // relevant.
+  return [NSNumber
+      numberWithBool:!ui::AXViewState::IsFlagSet(node_->GetData().state,
+                                                 ui::AX_STATE_DISABLED)];
+}
+
+- (NSValue*)AXFocused {
+  if (ui::AXViewState::IsFlagSet(node_->GetData().state,
+                                 ui::AX_STATE_FOCUSABLE) &&
+      ui::AXViewState::IsFlagSet(node_->GetData().state, ui::AX_STATE_FOCUSED))
+    return [NSNumber numberWithBool:YES];
+  return [NSNumber numberWithBool:NO];
+}
+
+// Textfield-specific NSAccessibility attributes.
+
+- (NSNumber*)AXInsertionPointLineNumber {
+  // Multiline is not supported on views.
+  return [NSNumber numberWithInteger:0];
+}
+
+- (NSNumber*)AXNumberOfCharacters {
+  return [NSNumber numberWithInteger:[[self AXValue] length]];
+}
+
+- (NSString*)AXPlaceholderValue {
+  return [self getStringAttribute:ui::AX_ATTR_PLACEHOLDER];
+}
+
+- (NSString*)AXSelectedText {
+  NSRange selectedTextRange;
+  [[self AXSelectedTextRange] getValue:&selectedTextRange];
+  return [[self AXValue] substringWithRange:selectedTextRange];
+}
+
+- (NSValue*)AXSelectedTextRange {
+  int textDir, start, end;
+  node_->GetIntAttribute(ui::AX_ATTR_TEXT_DIRECTION, &textDir);
+  node_->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_START, &start);
+  node_->GetIntAttribute(ui::AX_ATTR_TEXT_SEL_END, &end);
+  // NSRange cannot represent the direction the text was selected in, so make
+  // sure the correct selection index is used when creating a new range, taking
+  // into account the textfield text direction as well.
+  bool isReversed = (textDir == ui::AX_TEXT_DIRECTION_RTL) ||
+                    (textDir == ui::AX_TEXT_DIRECTION_BTT);
+  int beginSelectionIndex = (end > start && !isReversed) ? start : end;
+  return [NSValue
+      valueWithRange:NSMakeRange(beginSelectionIndex, abs(end - start))];
+}
+
+- (NSValue*)AXVisibleCharacterRange {
+  return [NSValue
+      valueWithRange:NSMakeRange(0, [[self AXNumberOfCharacters] intValue])];
+}
+
 @end
 
 namespace ui {
 
 // static
 AXPlatformNode* AXPlatformNode::Create(AXPlatformNodeDelegate* delegate) {
   AXPlatformNodeBase* node = new AXPlatformNodeMac();
   node->Init(delegate);
   return node;
 }
@@ skipping 10 matching lines @@
   AXPlatformNodeBase::Destroy();
 }
 
 gfx::NativeViewAccessible AXPlatformNodeMac::GetNativeViewAccessible() {
   if (!native_node_)
     native_node_.reset([[AXPlatformNodeCocoa alloc] initWithNode:this]);
   return native_node_.get();
 }
 
 void AXPlatformNodeMac::NotifyAccessibilityEvent(ui::AXEvent event_type) {
-  // TODO(dmazzoni): implement this.  http://crbug.com/396137
+  gfx::AcceleratedWidget target =
+      GetDelegate()->GetTargetForNativeAccessibilityEvent();
+
+  // Add mappings between ui::AXEvent and NSAccessibility notifications using
+  // the EventMap above. This switch contains exceptions to those mappings.
+  switch (event_type) {
+    case ui::AX_EVENT_TEXT_CHANGED:
+      // If the view is a user-editable textfield, this should change the value.
+      if (GetData().role == ui::AX_ROLE_TEXT_FIELD) {
+        NSAccessibilityPostNotification(
+            target, NSAccessibilityValueChangedNotification);
+        return;
+      }
+      break;
+    default:
+      break;
+  }
+  NotifyMacEvent(event_type, target);
 }
 
 int AXPlatformNodeMac::GetIndexInParent() {
   // TODO(dmazzoni): implement this.  http://crbug.com/396137
   return -1;
 }
 
 }  // namespace ui