views/accessibility/native_view_accessibility_win.h

   1 // Copyright (c) 2011 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 VIEWS_ACCESSIBILITY_NATIVE_VIEW_ACCESSIBILITY_WIN_H_
   6 #define VIEWS_ACCESSIBILITY_NATIVE_VIEW_ACCESSIBILITY_WIN_H_
   7 #pragma once
   8
   9 #include <atlbase.h>
  10 #include <atlcom.h>
  11
  12 #include <oleacc.h>
  13
  14 #include "base/memory/scoped_ptr.h"
  15 #include "ui/base/accessibility/accessible_view_state.h"
  16 #include "views/controls/native/native_view_host.h"
  17 #include "views/view.h"
  18
  19 // Note: do not put NativeViewAccessibilityWin in the namespace "views";
  20 // Visual Studio 2005 does not allow an ATL::CComObject symbol in a namespace.
  21
  22 ////////////////////////////////////////////////////////////////////////////////
  23 //
  24 // NativeViewAccessibilityWin
  25 //
  26 // Class implementing the MSAA IAccessible COM interface for a generic View,
  27 // providing accessibility to be used by screen readers and other assistive
  28 // technology (AT).
  29 //
  30 ////////////////////////////////////////////////////////////////////////////////
  31 class ATL_NO_VTABLE NativeViewAccessibilityWin
  32   : public CComObjectRootEx<CComMultiThreadModel>,
  33     public IDispatchImpl<IAccessible, &IID_IAccessible, &LIBID_Accessibility> {
  34  public:
  35   BEGIN_COM_MAP(NativeViewAccessibilityWin)
  36     COM_INTERFACE_ENTRY2(IDispatch, IAccessible)
  37     COM_INTERFACE_ENTRY(IAccessible)
  38   END_COM_MAP()
  39
  40   // Create method for view accessibility.
  41   static scoped_refptr<NativeViewAccessibilityWin> Create(views::View* view);
  42
  43   virtual ~NativeViewAccessibilityWin();
  44
  45   void set_view(views::View* view) { view_ = view; }
  46
  47   // Supported IAccessible methods.
  48
  49   // Retrieves the child element or child object at a given point on the screen.
  50   STDMETHODIMP accHitTest(LONG x_left, LONG y_top, VARIANT* child);
  51
  52   // Performs the object's default action.
  53   STDMETHODIMP accDoDefaultAction(VARIANT var_id);
  54
  55   // Retrieves the specified object's current screen location.
  56   STDMETHODIMP accLocation(LONG* x_left,
  57                            LONG* y_top,
  58                            LONG* width,
  59                            LONG* height,
  60                            VARIANT var_id);
  61
  62   // Traverses to another UI element and retrieves the object.
  63   STDMETHODIMP accNavigate(LONG nav_dir, VARIANT start, VARIANT* end);
  64
  65   // Retrieves an IDispatch interface pointer for the specified child.
  66   STDMETHODIMP get_accChild(VARIANT var_child, IDispatch** disp_child);
  67
  68   // Retrieves the number of accessible children.
  69   STDMETHODIMP get_accChildCount(LONG* child_count);
  70
  71   // Retrieves a string that describes the object's default action.
  72   STDMETHODIMP get_accDefaultAction(VARIANT var_id, BSTR* default_action);
  73
  74   // Retrieves the tooltip description.
  75   STDMETHODIMP get_accDescription(VARIANT var_id, BSTR* desc);
  76
  77   // Retrieves the object that has the keyboard focus.
  78   STDMETHODIMP get_accFocus(VARIANT* focus_child);
  79
  80   // Retrieves the specified object's shortcut.
  81   STDMETHODIMP get_accKeyboardShortcut(VARIANT var_id, BSTR* access_key);
  82
  83   // Retrieves the name of the specified object.
  84   STDMETHODIMP get_accName(VARIANT var_id, BSTR* name);
  85
  86   // Retrieves the IDispatch interface of the object's parent.
  87   STDMETHODIMP get_accParent(IDispatch** disp_parent);
  88
  89   // Retrieves information describing the role of the specified object.
  90   STDMETHODIMP get_accRole(VARIANT var_id, VARIANT* role);
  91
  92   // Retrieves the current state of the specified object.
  93   STDMETHODIMP get_accState(VARIANT var_id, VARIANT* state);
  94
  95   // Retrieves the current value associated with the specified object.
  96   STDMETHODIMP get_accValue(VARIANT var_id, BSTR* value);
  97
  98   // Non-supported IAccessible methods.
  99
 100   // Selections not applicable to views.
 101   STDMETHODIMP get_accSelection(VARIANT* selected);
 102   STDMETHODIMP accSelect(LONG flags_sel, VARIANT var_id);
 103
 104   // Help functions not supported.
 105   STDMETHODIMP get_accHelp(VARIANT var_id, BSTR* help);
 106   STDMETHODIMP get_accHelpTopic(BSTR* help_file,
 107                                 VARIANT var_id,
 108                                 LONG* topic_id);
 109
 110   // Deprecated functions, not implemented here.
 111   STDMETHODIMP put_accName(VARIANT var_id, BSTR put_name);
 112   STDMETHODIMP put_accValue(VARIANT var_id, BSTR put_val);
 113
 114   // Returns a conversion from the event (as defined in accessibility_types.h)
 115   // to an MSAA event.
 116   static int32 MSAAEvent(ui::AccessibilityTypes::Event event);
 117
 118   // Returns a conversion from the Role (as defined in accessibility_types.h)
 119   // to an MSAA role.
 120   static int32 MSAARole(ui::AccessibilityTypes::Role role);
 121
 122   // Returns a conversion from the State (as defined in accessibility_types.h)
 123   // to MSAA states set.
 124   static int32 MSAAState(ui::AccessibilityTypes::State state);
 125
 126  private:
 127   NativeViewAccessibilityWin();
 128
 129   // Determines navigation direction for accNavigate, based on left, up and
 130   // previous being mapped all to previous and right, down, next being mapped
 131   // to next. Returns true if navigation direction is next, false otherwise.
 132   bool IsNavDirNext(int nav_dir) const;
 133
 134   // Determines if the navigation target is within the allowed bounds. Returns
 135   // true if it is, false otherwise.
 136   bool IsValidNav(int nav_dir,
 137                   int start_id,
 138                   int lower_bound,
 139                   int upper_bound) const;
 140
 141   // Determines if the child id variant is valid.
 142   bool IsValidId(const VARIANT& child) const;
 143
 144   // Helper function which sets applicable states of view.
 145   void SetState(VARIANT* msaa_state, views::View* view);
 146
 147   // Give CComObject access to the class constructor.
 148   template <class Base> friend class CComObject;
 149
 150   // Member View needed for view-specific calls.
 151   views::View* view_;
 152
 153   DISALLOW_COPY_AND_ASSIGN(NativeViewAccessibilityWin);
 154 };
 155
 156 #endif  // VIEWS_ACCESSIBILITY_NATIVE_VIEW_ACCESSIBILITY_WIN_H_