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// Copyright (c) 2010 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.
#ifndef VIEWS_ACCESSIBILITY_VIEW_ACCESSIBILITY_H_
#define VIEWS_ACCESSIBILITY_VIEW_ACCESSIBILITY_H_
#pragma once
#include <atlbase.h>
#include <atlcom.h>
#include <oleacc.h>
#include "views/controls/native/native_view_host.h"
#include "views/view.h"
////////////////////////////////////////////////////////////////////////////////
//
// ViewAccessibility
//
// Class implementing the MSAA IAccessible COM interface for a generic View,
// providing accessibility to be used by screen readers and other assistive
// technology (AT).
//
////////////////////////////////////////////////////////////////////////////////
class ATL_NO_VTABLE ViewAccessibility
: public CComObjectRootEx<CComMultiThreadModel>,
public IDispatchImpl<IAccessible, &IID_IAccessible, &LIBID_Accessibility> {
public:
BEGIN_COM_MAP(ViewAccessibility)
COM_INTERFACE_ENTRY2(IDispatch, IAccessible)
COM_INTERFACE_ENTRY(IAccessible)
END_COM_MAP()
ViewAccessibility() {}
~ViewAccessibility() {}
HRESULT Initialize(views::View* view);
// Supported IAccessible methods.
// Retrieves the child element or child object at a given point on the screen.
STDMETHODIMP accHitTest(LONG x_left, LONG y_top, VARIANT* child);
// Retrieves the specified object's current screen location.
STDMETHODIMP accLocation(LONG* x_left,
LONG* y_top,
LONG* width,
LONG* height,
VARIANT var_id);
// Traverses to another UI element and retrieves the object.
STDMETHODIMP accNavigate(LONG nav_dir, VARIANT start, VARIANT* end);
// Retrieves an IDispatch interface pointer for the specified child.
STDMETHODIMP get_accChild(VARIANT var_child, IDispatch** disp_child);
// Retrieves the number of accessible children.
STDMETHODIMP get_accChildCount(LONG* child_count);
// Retrieves a string that describes the object's default action.
STDMETHODIMP get_accDefaultAction(VARIANT var_id, BSTR* default_action);
// Retrieves the tooltip description.
STDMETHODIMP get_accDescription(VARIANT var_id, BSTR* desc);
// Retrieves the object that has the keyboard focus.
STDMETHODIMP get_accFocus(VARIANT* focus_child);
// Retrieves the specified object's shortcut.
STDMETHODIMP get_accKeyboardShortcut(VARIANT var_id, BSTR* access_key);
// Retrieves the name of the specified object.
STDMETHODIMP get_accName(VARIANT var_id, BSTR* name);
// Retrieves the IDispatch interface of the object's parent.
STDMETHODIMP get_accParent(IDispatch** disp_parent);
// Retrieves information describing the role of the specified object.
STDMETHODIMP get_accRole(VARIANT var_id, VARIANT* role);
// Retrieves the current state of the specified object.
STDMETHODIMP get_accState(VARIANT var_id, VARIANT* state);
// Retrieves the current value associated with the specified object.
STDMETHODIMP get_accValue(VARIANT var_id, BSTR* value);
// Non-supported IAccessible methods.
// Out-dated and can be safely said to be very rarely used.
STDMETHODIMP accDoDefaultAction(VARIANT var_id);
// Selections not applicable to views.
STDMETHODIMP get_accSelection(VARIANT* selected);
STDMETHODIMP accSelect(LONG flags_sel, VARIANT var_id);
// Help functions not supported.
STDMETHODIMP get_accHelp(VARIANT var_id, BSTR* help);
STDMETHODIMP get_accHelpTopic(BSTR* help_file,
VARIANT var_id,
LONG* topic_id);
// Deprecated functions, not implemented here.
STDMETHODIMP put_accName(VARIANT var_id, BSTR put_name);
STDMETHODIMP put_accValue(VARIANT var_id, BSTR put_val);
// Returns a conversion from the event (as defined in accessibility_types.h)
// to an MSAA event.
static int32 MSAAEvent(AccessibilityTypes::Event event);
// Returns a conversion from the Role (as defined in accessibility_types.h)
// to an MSAA role.
static int32 MSAARole(AccessibilityTypes::Role role);
// Returns a conversion from the State (as defined in accessibility_types.h)
// to MSAA states set.
static int32 MSAAState(AccessibilityTypes::State state);
private:
// Checks to see if child_id is within the child bounds of view. Returns true
// if the child is within the bounds, false otherwise.
bool IsValidChild(int child_id, views::View* view) const;
// Determines navigation direction for accNavigate, based on left, up and
// previous being mapped all to previous and right, down, next being mapped
// to next. Returns true if navigation direction is next, false otherwise.
bool IsNavDirNext(int nav_dir) const;
// Determines if the navigation target is within the allowed bounds. Returns
// true if it is, false otherwise.
bool IsValidNav(int nav_dir,
int start_id,
int lower_bound,
int upper_bound) const;
// Wrapper to retrieve the view's instance of IAccessible.
ViewAccessibilityWrapper* GetViewAccessibilityWrapper(views::View* v) const {
return v->GetViewAccessibilityWrapper();
}
// Helper function which sets applicable states of view.
void SetState(VARIANT* msaa_state, views::View* view);
// Returns the IAccessible interface for a native view if applicable.
// Returns S_OK on success.
HRESULT GetNativeIAccessibleInterface(views::NativeViewHost* native_host,
IDispatch** disp_child);
HRESULT GetNativeIAccessibleInterface(HWND native_view_window,
IDispatch** disp_child);
// Member View needed for view-specific calls.
views::View* view_;
DISALLOW_COPY_AND_ASSIGN(ViewAccessibility);
};
extern const wchar_t kViewsUninitializeAccessibilityInstance[];
extern const wchar_t kViewsNativeHostPropForAccessibility[];
#endif // VIEWS_ACCESSIBILITY_VIEW_ACCESSIBILITY_H_
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