ui::AXFragmentRootPlatformNodeWin Class Reference

Inheritance diagram for ui::AXFragmentRootPlatformNodeWin:

Public Member Functions
IFACEMETHODIMP	FindItemByProperty (IRawElementProviderSimple *start_after_element, PROPERTYID property_id, VARIANT value, IRawElementProviderSimple **result) override
IFACEMETHODIMP	get_HostRawElementProvider (IRawElementProviderSimple **host_element_provider) override
IFACEMETHODIMP	GetPatternProvider (PATTERNID pattern_id, IUnknown **result) override
IFACEMETHODIMP	GetPropertyValue (PROPERTYID property_id, VARIANT *result) override
IFACEMETHODIMP	get_FragmentRoot (IRawElementProviderFragmentRoot **fragment_root) override
IFACEMETHODIMP	ElementProviderFromPoint (double screen_physical_pixel_x, double screen_physical_pixel_y, IRawElementProviderFragment **element_provider) override
IFACEMETHODIMP	GetFocus (IRawElementProviderFragment **focus) override
IFACEMETHODIMP	AdviseEventAdded (EVENTID event_id, SAFEARRAY *property_ids) override
IFACEMETHODIMP	AdviseEventRemoved (EVENTID event_id, SAFEARRAY *property_ids) override

Static Public Member Functions
static AXFragmentRootPlatformNodeWin *	Create (AXPlatformNodeDelegate *delegate)

Detailed Description

Definition at line 16 of file ax_fragment_root_win.cc.

Member Function Documentation

AdviseEventAdded()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::AdviseEventAdded ( EVENTID  event_id, SAFEARRAY *  property_ids  )

inlineoverride

Definition at line 219 of file ax_fragment_root_win.cc.

                                                                    {
    if (event_id == UIA_LiveRegionChangedEventId) {
      live_region_change_listeners_++;
 
      if (live_region_change_listeners_ == 1) {
        // Fire a LiveRegionChangedEvent for each live-region to tell the
        // newly-attached assistive technology about the regions.
        //
        // Ideally we'd be able to direct these events to only the
        // newly-attached AT, but we don't have that capability, so we only
        // fire events when the *first* AT attaches. (A common scenario will
        // be an attached screen-reader, then a software-keyboard attaches to
        // handle an input field; we don't want the screen-reader to announce
        // that every live-region has changed.) There isn't a perfect solution,
        // but this heuristic seems to work well in practice.
        FireLiveRegionChangeRecursive();
      }
    }
    return S_OK;
  }

AdviseEventRemoved()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::AdviseEventRemoved ( EVENTID  event_id, SAFEARRAY *  property_ids  )

inlineoverride

Definition at line 241 of file ax_fragment_root_win.cc.

                                                                      {
    if (event_id == UIA_LiveRegionChangedEventId) {
      BASE_DCHECK(live_region_change_listeners_ > 0);
      live_region_change_listeners_--;
    }
    return S_OK;
  }

Create()

static AXFragmentRootPlatformNodeWin * ui::AXFragmentRootPlatformNodeWin::Create ( AXPlatformNodeDelegate *  delegate )

inlinestatic

Definition at line 28 of file ax_fragment_root_win.cc.

                                        {
    // Make sure ATL is initialized in this module.
    win::CreateATLModuleIfNeeded();
 
    CComObject<AXFragmentRootPlatformNodeWin>* instance = nullptr;
    HRESULT hr =
        CComObject<AXFragmentRootPlatformNodeWin>::CreateInstance(&instance);
    BASE_DCHECK(SUCCEEDED(hr));
    instance->Init(delegate);
    instance->AddRef();
    return instance;
  }

ElementProviderFromPoint()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::ElementProviderFromPoint ( double  screen_physical_pixel_x, double  screen_physical_pixel_y, IRawElementProviderFragment **  element_provider  )

inlineoverride

Definition at line 157 of file ax_fragment_root_win.cc.

                                                               {
    UIA_VALIDATE_CALL_1_ARG(element_provider);
 
    *element_provider = nullptr;
 
    gfx::NativeViewAccessible hit_element = nullptr;
 
    // Descend the tree until we get a non-hit or can't go any further.
    AXPlatformNode* node_to_test = this;
    do {
      gfx::NativeViewAccessible test_result =
          node_to_test->GetDelegate()->HitTestSync(screen_physical_pixel_x,
                                                   screen_physical_pixel_y);
      if (test_result != nullptr && test_result != hit_element) {
        hit_element = test_result;
        node_to_test = AXPlatformNode::FromNativeViewAccessible(test_result);
      } else {
        node_to_test = nullptr;
      }
    } while (node_to_test);
 
    if (hit_element)
      hit_element->QueryInterface(element_provider);
 
    return S_OK;
  }

FindItemByProperty()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::FindItemByProperty ( IRawElementProviderSimple *  start_after_element, PROPERTYID  property_id, VARIANT  value, IRawElementProviderSimple **  result  )

inlineoverride

Definition at line 45 of file ax_fragment_root_win.cc.

                                                   {
    UIA_VALIDATE_CALL_1_ARG(result);
    *result = nullptr;
 
    // We currently only support the custom UIA property ID for unique id.
    if (property_id ==
            UiaRegistrarWin::GetInstance().GetUiaUniqueIdPropertyId() &&
        value.vt == VT_BSTR) {
      int32_t ax_unique_id;
 
      // TODO(gw280): https://github.com/flutter/flutter/issues/78802
      // detect and handle errors
      ax_unique_id = std::stoi(value.bstrVal);
 
      // In the Windows accessibility platform implementation, id 0 represents
      // self; a positive id represents the immediate descendants; and a
      // negative id represents a unique id that can be mapped to any node.
      if (AXPlatformNodeWin* result_platform_node =
              static_cast<AXPlatformNodeWin*>(GetFromUniqueId(-ax_unique_id))) {
        if (start_after_element) {
          Microsoft::WRL::ComPtr<AXPlatformNodeWin> start_after_platform_node;
          if (!SUCCEEDED(start_after_element->QueryInterface(
                  IID_PPV_ARGS(&start_after_platform_node))))
            return E_INVALIDARG;
 
          // We want |result| to be nullptr if it comes before or is equal to
          // |start_after_element|.
          if (start_after_platform_node->CompareTo(*result_platform_node) >= 0)
            return S_OK;
        }
 
        return result_platform_node->QueryInterface(IID_PPV_ARGS(result));
      }
    }
 
    return E_INVALIDARG;
  }

get_FragmentRoot()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::get_FragmentRoot ( IRawElementProviderFragmentRoot **  fragment_root )

inlineoverride

Definition at line 146 of file ax_fragment_root_win.cc.

                                                                {
    UIA_VALIDATE_CALL_1_ARG(fragment_root);
 
    QueryInterface(IID_PPV_ARGS(fragment_root));
    return S_OK;
  }

get_HostRawElementProvider()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::get_HostRawElementProvider ( IRawElementProviderSimple **  host_element_provider )

inlineoverride

Definition at line 91 of file ax_fragment_root_win.cc.

                                                                  {
    UIA_VALIDATE_CALL_1_ARG(host_element_provider);
 
    HWND hwnd = GetDelegate()->GetTargetForNativeAccessibilityEvent();
    return UiaHostProviderFromHwnd(hwnd, host_element_provider);
  }

GetFocus()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::GetFocus ( IRawElementProviderFragment **  focus )

inlineoverride

Definition at line 187 of file ax_fragment_root_win.cc.

                                                                        {
    UIA_VALIDATE_CALL_1_ARG(focus);
 
    *focus = nullptr;
 
    gfx::NativeViewAccessible focused_element = nullptr;
 
    // GetFocus() can return a node at the root of a subtree, for example when
    // transitioning from Views into web content. In such cases we want to
    // continue drilling to retrieve the actual focused element.
    AXPlatformNode* node_to_test = this;
    do {
      gfx::NativeViewAccessible test_result =
          node_to_test->GetDelegate()->GetFocus();
      if (test_result != nullptr && test_result != focused_element) {
        focused_element = test_result;
        node_to_test =
            AXPlatformNode::FromNativeViewAccessible(focused_element);
      } else {
        node_to_test = nullptr;
      }
    } while (node_to_test);
 
    if (focused_element)
      focused_element->QueryInterface(IID_PPV_ARGS(focus));
 
    return S_OK;
  }

GetPatternProvider()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::GetPatternProvider ( PATTERNID  pattern_id, IUnknown **  result  )

inlineoverride

Definition at line 99 of file ax_fragment_root_win.cc.

                                                                {
    UIA_VALIDATE_CALL_1_ARG(result);
    *result = nullptr;
 
    if (pattern_id == UIA_ItemContainerPatternId) {
      AddRef();
      *result = static_cast<IItemContainerProvider*>(this);
      return S_OK;
    }
 
    return AXPlatformNodeWin::GetPatternProviderImpl(pattern_id, result);
  }

GetPropertyValue()

IFACEMETHODIMP ui::AXFragmentRootPlatformNodeWin::GetPropertyValue ( PROPERTYID  property_id, VARIANT *  result  )

inlineoverride

Definition at line 113 of file ax_fragment_root_win.cc.

                                                            {
    UIA_VALIDATE_CALL_1_ARG(result);
 
    switch (property_id) {
      default:
        // UIA has a built-in provider that will expose values for several
        // properties based on the HWND. This information is useful to someone
        // examining the accessibility tree using tools such as Inspect. Return
        // VT_EMPTY for most properties so that we don't override values from
        // the default provider with blank data.
        result->vt = VT_EMPTY;
        break;
 
      case UIA_IsControlElementPropertyId:
      case UIA_IsContentElementPropertyId:
        // Override IsControlElement and IsContentElement to fine tune which
        // fragment roots appear in the control and content views.
        result->vt = VT_BOOL;
        result->boolVal =
            static_cast<AXFragmentRootWin*>(GetDelegate())->IsControlElement()
                ? VARIANT_TRUE
                : VARIANT_FALSE;
        break;
    }
 
    return S_OK;
  }

---

The documentation for this class was generated from the following file:

• third_party/accessibility/ax/platform/ax_fragment_root_win.cc