Adds MSAA/IAccessible exposure of web content.

chrome/browser/browser_accessibility.cc

+// Copyright (c) 2006-2008 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.
+
+#include "chrome/browser/browser_accessibility.h"
+
+#include "chrome/browser/browser_accessibility_manager.h"
+#include "chrome/browser/iaccessible_function_ids.h"
+
+BrowserAccessibility::BrowserAccessibility()
+    : iaccessible_id_(-1),
+      instance_active_(true) {
+}
+
+HRESULT BrowserAccessibility::accDoDefaultAction(VARIANT var_id) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    // TODO(klink): Once we have MSAA events, change these fails for having
+    // BrowserAccessibilityManager firing the right event.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_ACCDODEFAULTACTION, var_id,
+                                NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code)
+    return S_FALSE;
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::accHitTest(LONG x_left, LONG y_top,
+                                              VARIANT* child) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (!child)
+    return E_INVALIDARG;
+
+  if (!parent_hwnd()) {
+    // Parent HWND needed for coordinate conversion.
+    return E_FAIL;
+  }
+
+  // Convert coordinates to test from screen into client window coordinates, to
+  // maintain sandbox functionality on renderer side.
+  POINT p = {x_left, y_top};
+  ::ScreenToClient(parent_hwnd(), &p);
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_ACCHITTEST, EmptyVariant(),
+                                p.x, p.y)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // The point is outside of the object's boundaries.
+    child->vt = VT_EMPTY;
+    return S_FALSE;
+  }
+
+  if (response().output_long1 == -1) {
+    if (CreateInstance(IID_IAccessible, response().iaccessible_id,
+                       reinterpret_cast<void**>(&child->pdispVal)) == S_OK) {
+      child->vt = VT_DISPATCH;
+      // Increment the reference count for the retrieved interface.
+      child->pdispVal->AddRef();
+    } else {
+      return E_NOINTERFACE;
+    }
+  } else {
+    child->vt = VT_I4;
+    child->lVal = response().output_long1;
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::accLocation(LONG* x_left, LONG* y_top,
+                                               LONG* width, LONG* height,
+                                               VARIANT var_id) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !x_left || !y_top || !width || !height ||
+      !parent_hwnd()) {
+    return E_INVALIDARG;
+  }
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_ACCLOCATION, var_id, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  POINT top_left = {0, 0};
+
+  // Find the top left corner of the containing window in screen coords, and
+  // adjust the output position by this amount.
+  ::ClientToScreen(parent_hwnd(), &top_left);
+
+  *x_left = response().output_long1 + top_left.x;
+  *y_top  = response().output_long2 + top_left.y;
+
+  *width  = response().output_long3;
+  *height = response().output_long4;
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::accNavigate(LONG nav_dir, VARIANT start,
+                                               VARIANT* end) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (start.vt != VT_I4 || !end)
+    return E_INVALIDARG;
+
+  if ((nav_dir == NAVDIR_LASTCHILD || nav_dir == NAVDIR_FIRSTCHILD) &&
+      start.lVal != CHILDID_SELF) {
+    // MSAA states that navigating to first/last child can only be from self.
+    return E_INVALIDARG;
+  }
+
+  if (nav_dir == NAVDIR_DOWN || nav_dir == NAVDIR_UP ||
+      nav_dir == NAVDIR_LEFT || nav_dir == NAVDIR_RIGHT) {
+    // Directions not implemented, matching Mozilla and IE.
+    return E_INVALIDARG;
+  }
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_ACCNAVIGATE, start, nav_dir,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No screen element was found in the specified direction.
+    end->vt = VT_EMPTY;
+    return S_FALSE;
+  }
+
+  if (response().output_long1 == -1) {
+    if (CreateInstance(IID_IAccessible, response().iaccessible_id,
+                       reinterpret_cast<void**>(&end->pdispVal)) == S_OK) {
+      end->vt = VT_DISPATCH;
+      // Increment the reference count for the retrieved interface.
+      end->pdispVal->AddRef();
+    } else {
+      return E_NOINTERFACE;
+    }
+  } else {
+    end->vt = VT_I4;
+    end->lVal = response().output_long1;
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accChild(VARIANT var_child,
+                                                IDispatch** disp_child) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_child.vt != VT_I4 || !disp_child)
+    return E_INVALIDARG;
+
+  // If var_child is the parent, remain with the same IDispatch.
+  if (var_child.lVal == CHILDID_SELF && iaccessible_id_ != 0)
+    return S_OK;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCCHILD, var_child, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // When at a leaf, children are handled by the parent object.
+    *disp_child = NULL;
+    return S_FALSE;
+  }
+
+  // Retrieve the IUnknown interface for the parent view, and assign the
+  // IDispatch returned.
+  if (CreateInstance(IID_IAccessible, response().iaccessible_id,
+                     reinterpret_cast<void**>(disp_child)) == S_OK) {
+    // Increment the reference count for the retrieved interface.
+    (*disp_child)->AddRef();
+    return S_OK;
+  } else {
+    return E_NOINTERFACE;
+  }
+}
+
+STDMETHODIMP BrowserAccessibility::get_accChildCount(LONG* child_count) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (!child_count)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCCHILDCOUNT,
+                                EmptyVariant(), NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  *child_count = response().output_long1;
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accDefaultAction(VARIANT var_id,
+                                                        BSTR* def_action) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !def_action)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCDEFAULTACTION, var_id,
+                                NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *def_action = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*def_action);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accDescription(VARIANT var_id,
+                                                      BSTR* desc) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !desc)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCDESCRIPTION, var_id,
+                                NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *desc = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*desc);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accFocus(VARIANT* focus_child) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (!focus_child)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCFOCUS, EmptyVariant(),
+                                NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // The window that contains this object is not the active window.
+    focus_child->vt = VT_EMPTY;
+    return S_FALSE;
+  }
+
+  if (response().output_long1 == -1) {
+    if (CreateInstance(IID_IAccessible, response().iaccessible_id,
+           reinterpret_cast<void**>(&focus_child->pdispVal)) == S_OK) {
+      focus_child->vt = VT_DISPATCH;
+      // Increment the reference count for the retrieved interface.
+      focus_child->pdispVal->AddRef();
+    } else {
+      return E_NOINTERFACE;
+    }
+  } else {
+    focus_child->vt = VT_I4;
+    focus_child->lVal = response().output_long1;
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accHelp(VARIANT var_id, BSTR* help) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !help)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCHELP, var_id, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *help = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*help);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accKeyboardShortcut(VARIANT var_id,
+                                                           BSTR* acc_key) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !acc_key)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCKEYBOARDSHORTCUT,
+                                var_id, NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *acc_key = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*acc_key);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accName(VARIANT var_id, BSTR* name) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !name)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCNAME, var_id, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *name = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*name);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accParent(IDispatch** disp_parent) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (!disp_parent || !parent_hwnd())
+    return E_INVALIDARG;
+
+  // Root node's parent is the containing HWND's IAccessible.
+  if (iaccessible_id() == 0) {
+    // For an object that has no parent (e.g. root), point the accessible parent
+    // to the default implementation.
+    HRESULT hr =
+        ::CreateStdAccessibleObject(parent_hwnd(), OBJID_WINDOW,
+                                    IID_IAccessible,
+                                    reinterpret_cast<void**>(disp_parent));
+
+    if (!SUCCEEDED(hr)) {
+      *disp_parent = NULL;
+      return S_FALSE;
+    }
+    return S_OK;
+  }
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCPARENT, EmptyVariant(),
+                                NULL, NULL)) {
+    return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No parent exists for this object.
+    return S_FALSE;
+  }
+
+  // Retrieve the IUnknown interface for the parent view, and assign the
+  // IDispatch returned.
+  if (CreateInstance(IID_IAccessible, response().iaccessible_id,
+                     reinterpret_cast<void**>(disp_parent)) == S_OK) {
+    // Increment the reference count for the retrieved interface.
+    (*disp_parent)->AddRef();
+    return S_OK;
+  } else {
+    return E_NOINTERFACE;
+  }
+}
+
+STDMETHODIMP BrowserAccessibility::get_accRole(VARIANT var_id, VARIANT* role) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !role)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCROLE, var_id, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  role->vt = VT_I4;
+  role->lVal = response().output_long1;
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accState(VARIANT var_id,
+                                                VARIANT* state) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !state)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCSTATE, var_id, NULL,
+                                NULL)) {
+    return E_FAIL;
+  }
+
+  state->vt = VT_I4;
+  state->lVal = response().output_long1;
+
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accValue(VARIANT var_id, BSTR* value) {
+  if (!instance_active()) {
+    // Instance no longer active, fail gracefully.
+    return E_FAIL;
+  }
+
+  if (var_id.vt != VT_I4 || !value)
+    return E_INVALIDARG;
+
+  if (!RequestAccessibilityInfo(IACCESSIBLE_FUNC_GET_ACCVALUE, var_id, NULL,
+                                NULL)) {
+        return E_FAIL;
+  }
+
+  if (!response().return_code) {
+    // No string found.
+    return S_FALSE;
+  }
+
+  *value = CComBSTR(response().output_string.c_str()).Detach();
+
+  DCHECK(*value);
+  return S_OK;
+}
+
+STDMETHODIMP BrowserAccessibility::accSelect(LONG flags_select,
+                                             VARIANT var_id) {
+  return DISP_E_MEMBERNOTFOUND;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accHelpTopic(BSTR* help_file,
+                                                    VARIANT var_id,
+                                                    LONG* topic_id) {
+  if (help_file) {
+    *help_file = NULL;
+  }
+  if (topic_id) {
+    *topic_id = static_cast<LONG>(-1);
+  }
+  return DISP_E_MEMBERNOTFOUND;
+}
+
+STDMETHODIMP BrowserAccessibility::get_accSelection(VARIANT* selected) {
+  if (selected)
+    selected->vt = VT_EMPTY;
+
+  return DISP_E_MEMBERNOTFOUND;
+}
+
+STDMETHODIMP BrowserAccessibility::put_accName(VARIANT var_id, BSTR put_name) {
+  return DISP_E_MEMBERNOTFOUND;
+}
+
+STDMETHODIMP BrowserAccessibility::put_accValue(VARIANT var_id, BSTR put_val) {
+  return DISP_E_MEMBERNOTFOUND;
+}
+
+STDMETHODIMP BrowserAccessibility::CreateInstance(REFIID iid,
+                                                  int iaccessible_id,
+                                                  void** interface_ptr) {
+  return BrowserAccessibilityManager::Instance()->CreateAccessibilityInstance(
+      iid, iaccessible_id, instance_id(), interface_ptr);
+}
+
+bool BrowserAccessibility::RequestAccessibilityInfo(int iaccessible_func_id,
+                                                    VARIANT var_id, LONG input1,
+                                                    LONG input2) {
+  return BrowserAccessibilityManager::Instance()->RequestAccessibilityInfo(
+      iaccessible_id(), instance_id(), iaccessible_func_id, var_id, input1,
+      input2);
+}
+
+ViewHostMsg_Accessibility_Out_Params BrowserAccessibility::response() {
+  return BrowserAccessibilityManager::Instance()->response();
+}
+
+HWND BrowserAccessibility::parent_hwnd() {
+  return BrowserAccessibilityManager::Instance()->parent_hwnd(instance_id());
+}
+