content/browser/accessibility/browser_accessibility_manager.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
   6 #define CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_
   7
   8 #include <vector>
   9
  10 #include "base/containers/hash_tables.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "build/build_config.h"
  13 #include "content/common/content_export.h"
  14 #include "third_party/WebKit/public/web/WebAXEnums.h"
  15 #include "ui/accessibility/ax_node_data.h"
  16 #include "ui/accessibility/ax_serializable_tree.h"
  17 #include "ui/accessibility/ax_tree_update.h"
  18 #include "ui/gfx/native_widget_types.h"
  19
  20 struct AccessibilityHostMsg_EventParams;
  21 struct AccessibilityHostMsg_LocationChangeParams;
  22
  23 namespace content {
  24 class BrowserAccessibility;
  25 class BrowserAccessibilityManager;
  26 #if defined(OS_ANDROID)
  27 class BrowserAccessibilityManagerAndroid;
  28 #elif defined(OS_WIN)
  29 class BrowserAccessibilityManagerWin;
  30 #elif defined(OS_LINUX) && !defined(OS_CHROMEOS) && defined(USE_X11)
  31 class BrowserAccessibilityManagerAuraLinux;
  32 #endif
  33
  34 // For testing.
  35 CONTENT_EXPORT ui::AXTreeUpdate MakeAXTreeUpdate(
  36     const ui::AXNodeData& node,
  37     const ui::AXNodeData& node2 = ui::AXNodeData(),
  38     const ui::AXNodeData& node3 = ui::AXNodeData(),
  39     const ui::AXNodeData& node4 = ui::AXNodeData(),
  40     const ui::AXNodeData& node5 = ui::AXNodeData(),
  41     const ui::AXNodeData& node6 = ui::AXNodeData(),
  42     const ui::AXNodeData& node7 = ui::AXNodeData(),
  43     const ui::AXNodeData& node8 = ui::AXNodeData(),
  44     const ui::AXNodeData& node9 = ui::AXNodeData());
  45
  46 // Class that can perform actions on behalf of the BrowserAccessibilityManager.
  47 // Note: BrowserAccessibilityManager should never cache any of the return
  48 // values from any of these interfaces, especially those that return pointers.
  49 // They may only be valid within this call stack. That policy eliminates any
  50 // concerns about ownership and lifecycle issues; none of these interfaces
  51 // transfer ownership and no return values are guaranteed to be valid outside
  52 // of the current call stack.
  53 class CONTENT_EXPORT BrowserAccessibilityDelegate {
  54  public:
  55   virtual ~BrowserAccessibilityDelegate() {}
  56   virtual void AccessibilitySetFocus(int acc_obj_id) = 0;
  57   virtual void AccessibilityDoDefaultAction(int acc_obj_id) = 0;
  58   virtual void AccessibilityShowContextMenu(int acc_obj_id) = 0;
  59   virtual void AccessibilityScrollToMakeVisible(
  60       int acc_obj_id, const gfx::Rect& subfocus) = 0;
  61   virtual void AccessibilityScrollToPoint(
  62       int acc_obj_id, const gfx::Point& point) = 0;
  63   virtual void AccessibilitySetScrollOffset(
  64       int acc_obj_id, const gfx::Point& offset) = 0;
  65   virtual void AccessibilitySetTextSelection(
  66       int acc_obj_id, int start_offset, int end_offset) = 0;
  67   virtual void AccessibilitySetValue(
  68       int acc_obj_id, const base::string16& value) = 0;
  69   virtual bool AccessibilityViewHasFocus() const = 0;
  70   virtual gfx::Rect AccessibilityGetViewBounds() const = 0;
  71   virtual gfx::Point AccessibilityOriginInScreen(
  72       const gfx::Rect& bounds) const = 0;
  73   virtual void AccessibilityHitTest(
  74       const gfx::Point& point) = 0;
  75   virtual void AccessibilitySetAccessibilityFocus(int acc_obj_id) = 0;
  76   virtual void AccessibilityFatalError() = 0;
  77   virtual gfx::AcceleratedWidget AccessibilityGetAcceleratedWidget() = 0;
  78   virtual gfx::NativeViewAccessible AccessibilityGetNativeViewAccessible() = 0;
  79   virtual BrowserAccessibilityManager* AccessibilityGetChildFrame(
  80       int accessibility_node_id) = 0;
  81   virtual void AccessibilityGetAllChildFrames(
  82       std::vector<BrowserAccessibilityManager*>* child_frames) = 0;
  83   virtual BrowserAccessibility* AccessibilityGetParentFrame() = 0;
  84 };
  85
  86 class CONTENT_EXPORT BrowserAccessibilityFactory {
  87  public:
  88   virtual ~BrowserAccessibilityFactory() {}
  89
  90   // Create an instance of BrowserAccessibility and return a new
  91   // reference to it.
  92   virtual BrowserAccessibility* Create();
  93 };
  94
  95 // This is all of the information about the current find in page result,
  96 // so we can activate it if requested.
  97 struct BrowserAccessibilityFindInPageInfo {
  98   BrowserAccessibilityFindInPageInfo();
  99
 100   // This data about find in text results is updated as the user types.
 101   int request_id;
 102   int match_index;
 103   int start_id;
 104   int start_offset;
 105   int end_id;
 106   int end_offset;
 107
 108   // The active request id indicates that the user committed to a find query,
 109   // e.g. by pressing enter or pressing the next or previous buttons. If
 110   // |active_request_id| == |request_id|, we fire an accessibility event
 111   // to move screen reader focus to that event.
 112   int active_request_id;
 113 };
 114
 115 // Manages a tree of BrowserAccessibility objects.
 116 class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
 117  public:
 118   // Creates the platform-specific BrowserAccessibilityManager, but
 119   // with no parent window pointer. Only useful for unit tests.
 120   static BrowserAccessibilityManager* Create(
 121       const ui::AXTreeUpdate& initial_tree,
 122       BrowserAccessibilityDelegate* delegate,
 123       BrowserAccessibilityFactory* factory = new BrowserAccessibilityFactory());
 124
 125   ~BrowserAccessibilityManager() override;
 126
 127   void Initialize(const ui::AXTreeUpdate& initial_tree);
 128
 129   static ui::AXTreeUpdate GetEmptyDocument();
 130
 131   virtual void NotifyAccessibilityEvent(
 132       ui::AXEvent event_type, BrowserAccessibility* node) { }
 133
 134   // Return a pointer to the root of the tree, does not make a new reference.
 135   BrowserAccessibility* GetRoot();
 136
 137   // Returns a pointer to the BrowserAccessibility object for a given AXNode.
 138   BrowserAccessibility* GetFromAXNode(ui::AXNode* node);
 139
 140   // Return a pointer to the object corresponding to the given id,
 141   // does not make a new reference.
 142   BrowserAccessibility* GetFromID(int32 id);
 143
 144   // Called to notify the accessibility manager that its associated native
 145   // view got focused.
 146   virtual void OnWindowFocused();
 147
 148   // Called to notify the accessibility manager that its associated native
 149   // view lost focus.
 150   virtual void OnWindowBlurred();
 151
 152   // Notify the accessibility manager about page navigation.
 153   void UserIsNavigatingAway();
 154   virtual void UserIsReloading();
 155   void NavigationSucceeded();
 156   void NavigationFailed();
 157
 158   // Called to notify the accessibility manager that a mouse down event
 159   // occurred in the tab.
 160   void GotMouseDown();
 161
 162   // Update the focused node to |node|, which may be null.
 163   // If |notify| is true, send a message to the renderer to set focus
 164   // to this node.
 165   void SetFocus(ui::AXNode* node, bool notify);
 166   void SetFocus(BrowserAccessibility* node, bool notify);
 167
 168   // Tell the renderer to do the default action for this node.
 169   void DoDefaultAction(const BrowserAccessibility& node);
 170
 171   // Tell the renderer to scroll to make |node| visible.
 172   // In addition, if it's not possible to make the entire object visible,
 173   // scroll so that the |subfocus| rect is visible at least. The subfocus
 174   // rect is in local coordinates of the object itself.
 175   void ScrollToMakeVisible(
 176       const BrowserAccessibility& node, gfx::Rect subfocus);
 177
 178   // Tell the renderer to scroll such that |node| is at |point|,
 179   // where |point| is in global coordinates of the WebContents.
 180   void ScrollToPoint(
 181       const BrowserAccessibility& node, gfx::Point point);
 182
 183   // If |node| is itself a scrollable container, set its scroll
 184   // offset to |offset|.
 185   void SetScrollOffset(const BrowserAccessibility& node, gfx::Point offset);
 186
 187   // Tell the renderer to set the value of an editable text node.
 188   void SetValue(
 189       const BrowserAccessibility& node, const base::string16& value);
 190
 191   // Tell the renderer to set the text selection on a node.
 192   void SetTextSelection(
 193       const BrowserAccessibility& node, int start_offset, int end_offset);
 194
 195   // Retrieve the bounds of the parent View in screen coordinates.
 196   gfx::Rect GetViewBounds();
 197
 198   // Fire an event telling native assistive technology to move focus to the
 199   // given find in page result.
 200   void ActivateFindInPageResult(int request_id, int match_index);
 201
 202   // Called when the renderer process has notified us of about tree changes.
 203   void OnAccessibilityEvents(
 204       const std::vector<AccessibilityHostMsg_EventParams>& params);
 205
 206   // Called when the renderer process updates the location of accessibility
 207   // objects.
 208   void OnLocationChanges(
 209       const std::vector<AccessibilityHostMsg_LocationChangeParams>& params);
 210
 211   // Called when a new find in page result is received. We hold on to this
 212   // information and don't activate it until the user requests it.
 213   void OnFindInPageResult(
 214       int request_id, int match_index, int start_id, int start_offset,
 215       int end_id, int end_offset);
 216
 217   // This is called when the user has committed to a find in page query,
 218   // e.g. by pressing enter or tapping on the next / previous result buttons.
 219   // If a match has already been received for this request id,
 220   // activate the result now by firing an accessibility event. If a match
 221   // has not been received, we hold onto this request id and update it
 222   // when OnFindInPageResult is called.
 223   void ActivateFindInPageResult(int request_id);
 224
 225 #if defined(OS_WIN)
 226   BrowserAccessibilityManagerWin* ToBrowserAccessibilityManagerWin();
 227 #endif
 228
 229 #if defined(OS_ANDROID)
 230   BrowserAccessibilityManagerAndroid* ToBrowserAccessibilityManagerAndroid();
 231 #endif
 232
 233 #if defined(OS_LINUX) && !defined(OS_CHROMEOS) && defined(USE_X11)
 234   BrowserAccessibilityManagerAuraLinux*
 235       ToBrowserAccessibilityManagerAuraLinux();
 236 #endif
 237
 238   // Return the object that has focus, if it's a descandant of the
 239   // given root (inclusive). Does not make a new reference.
 240   virtual BrowserAccessibility* GetFocus(BrowserAccessibility* root);
 241
 242   // Return the descentant of the given root that has focus, or that object's
 243   // active descendant if it has one.
 244   BrowserAccessibility* GetActiveDescendantFocus(BrowserAccessibility* root);
 245
 246   // True by default, but some platforms want to treat the root
 247   // scroll offsets separately.
 248   virtual bool UseRootScrollOffsetsWhenComputingBounds();
 249
 250   // Walk the tree.
 251   BrowserAccessibility* NextInTreeOrder(BrowserAccessibility* node);
 252   BrowserAccessibility* PreviousInTreeOrder(BrowserAccessibility* node);
 253
 254   // AXTreeDelegate implementation.
 255   void OnNodeWillBeDeleted(ui::AXTree* tree, ui::AXNode* node) override;
 256   void OnSubtreeWillBeDeleted(ui::AXTree* tree, ui::AXNode* node) override;
 257   void OnNodeCreated(ui::AXTree* tree, ui::AXNode* node) override;
 258   void OnNodeChanged(ui::AXTree* tree, ui::AXNode* node) override;
 259   void OnAtomicUpdateFinished(
 260       ui::AXTree* tree,
 261       bool root_changed,
 262       const std::vector<ui::AXTreeDelegate::Change>& changes) override;
 263
 264   BrowserAccessibilityDelegate* delegate() const { return delegate_; }
 265   void set_delegate(BrowserAccessibilityDelegate* delegate) {
 266     delegate_ = delegate;
 267   }
 268
 269   // If this BrowserAccessibilityManager is a child frame or guest frame,
 270   // return the BrowserAccessibilityDelegate from the highest ancestor frame
 271   // in the frame tree.
 272   BrowserAccessibilityDelegate* GetDelegateFromRootManager();
 273
 274   // Get a snapshot of the current tree as an AXTreeUpdate.
 275   ui::AXTreeUpdate SnapshotAXTreeForTesting();
 276
 277  protected:
 278   BrowserAccessibilityManager(
 279       BrowserAccessibilityDelegate* delegate,
 280       BrowserAccessibilityFactory* factory);
 281
 282   BrowserAccessibilityManager(
 283       const ui::AXTreeUpdate& initial_tree,
 284       BrowserAccessibilityDelegate* delegate,
 285       BrowserAccessibilityFactory* factory);
 286
 287  private:
 288   // The following states keep track of whether or not the
 289   // on-screen keyboard is allowed to be shown.
 290   enum OnScreenKeyboardState {
 291     // Never show the on-screen keyboard because this tab is hidden.
 292     OSK_DISALLOWED_BECAUSE_TAB_HIDDEN,
 293
 294     // This tab was just shown, so don't pop-up the on-screen keyboard if a
 295     // text field gets focus that wasn't the result of an explicit touch.
 296     OSK_DISALLOWED_BECAUSE_TAB_JUST_APPEARED,
 297
 298     // A touch event has occurred within the window, but focus has not
 299     // explicitly changed. Allow the on-screen keyboard to be shown if the
 300     // touch event was within the bounds of the currently focused object.
 301     // Otherwise we'll just wait to see if focus changes.
 302     OSK_ALLOWED_WITHIN_FOCUSED_OBJECT,
 303
 304     // Focus has changed within a tab that's already visible. Allow the
 305     // on-screen keyboard to show anytime that a touch event leads to an
 306     // editable text control getting focus.
 307     OSK_ALLOWED
 308   };
 309
 310  protected:
 311   // The object that can perform actions on our behalf.
 312   BrowserAccessibilityDelegate* delegate_;
 313
 314   // Factory to create BrowserAccessibility objects (for dependency injection).
 315   scoped_ptr<BrowserAccessibilityFactory> factory_;
 316
 317   // The underlying tree of accessibility objects.
 318   scoped_ptr<ui::AXSerializableTree> tree_;
 319
 320   // The node that currently has focus.
 321   ui::AXNode* focus_;
 322
 323   // A mapping from a node id to its wrapper of type BrowserAccessibility.
 324   base::hash_map<int32, BrowserAccessibility*> id_wrapper_map_;
 325
 326   // True if the user has initiated a navigation to another page.
 327   bool user_is_navigating_away_;
 328
 329   // The on-screen keyboard state.
 330   OnScreenKeyboardState osk_state_;
 331
 332   BrowserAccessibilityFindInPageInfo find_in_page_info_;
 333
 334   DISALLOW_COPY_AND_ASSIGN(BrowserAccessibilityManager);
 335 };
 336
 337 }  // namespace content
 338
 339 #endif  // CONTENT_BROWSER_ACCESSIBILITY_BROWSER_ACCESSIBILITY_MANAGER_H_