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