feat: add screen reader support to Win32 toast notifications

brightray/BUILD.gn

@@ -109,6 +109,8 @@ static_library("brightray") {
     "browser/win/win32_desktop_notifications/common.h",
     "browser/win/win32_desktop_notifications/desktop_notification_controller.cc",
     "browser/win/win32_desktop_notifications/desktop_notification_controller.h",
+    "browser/win/win32_desktop_notifications/toast_uia.cc",
+    "browser/win/win32_desktop_notifications/toast_uia.h",
     "browser/win/win32_desktop_notifications/toast.cc",
     "browser/win/win32_desktop_notifications/toast.h",
     "browser/win/win32_notification.cc",

brightray/browser/win/win32_desktop_notifications/toast.cc

@@ -2,11 +2,17 @@
 #define NOMINMAX
 #endif
 #include "brightray/browser/win/win32_desktop_notifications/toast.h"
+
+#include <combaseapi.h>
+
+#include <UIAutomation.h>
 #include <uxtheme.h>
 #include <windowsx.h>
 #include <algorithm>
+
 #include "base/logging.h"
 #include "brightray/browser/win/win32_desktop_notifications/common.h"
+#include "brightray/browser/win/win32_desktop_notifications/toast_uia.h"
 
 #pragma comment(lib, "msimg32.lib")
 #pragma comment(lib, "uxtheme.lib")
@@ -196,6 +202,22 @@ DesktopNotificationController::Toast::Toast(HWND hwnd,
 }
 
 DesktopNotificationController::Toast::~Toast() {
+  if (uia_) {
+    auto* UiaDisconnectProvider =
+        reinterpret_cast<decltype(&::UiaDisconnectProvider)>(GetProcAddress(
+            GetModuleHandle(L"uiautomationcore.dll"), "UiaDisconnectProvider"));
+    // first detach from the toast, then call UiaDisconnectProvider;
+    // UiaDisconnectProvider may call WM_GETOBJECT and we don't want
+    // it to return the object that we're disconnecting
+    uia_->DetachToast();
+
+    if (UiaDisconnectProvider)
+      UiaDisconnectProvider(uia_);
+
+    uia_->Release();
+    uia_ = nullptr;
+  }
+
   DeleteDC(hdc_);
   if (bitmap_)
     DeleteBitmap(bitmap_);
@@ -232,6 +254,13 @@ LRESULT DesktopNotificationController::Toast::WndProc(HWND hwnd,
       SetWindowLongPtr(hwnd, 0, 0);
       return 0;
 
+    case WM_DESTROY:
+      if (Get(hwnd)->uia_) {
+        // free UI Automation resources associated with this window
+        UiaReturnRawElementProvider(hwnd, 0, 0, nullptr);
+      }
+      break;
+
     case WM_MOUSEACTIVATE:
       return MA_NOACTIVATE;
 
@@ -295,6 +324,20 @@ LRESULT DesktopNotificationController::Toast::WndProc(HWND hwnd,
           Get(hwnd)->is_highlighted_ = false;
       }
     } break;
+
+    case WM_GETOBJECT:
+      if (lparam == UiaRootObjectId) {
+        auto* inst = Get(hwnd);
+        if (!inst->uia_) {
+          inst->uia_ = new UIAutomationInterface(inst);
+          inst->uia_->AddRef();
+        }
+        // don't return the interface if it's being disconnected
+        if (!inst->uia_->IsDetached()) {
+          return UiaReturnRawElementProvider(hwnd, wparam, lparam, inst->uia_);
+        }
+      }
+      break;
   }
 
   return DefWindowProc(hwnd, message, wparam, lparam);

brightray/browser/win/win32_desktop_notifications/toast.h

@@ -70,6 +70,9 @@ class DesktopNotificationController::Toast {
   HDC hdc_;
   HBITMAP bitmap_ = NULL;
 
+  class UIAutomationInterface;
+  UIAutomationInterface* uia_ = nullptr;
+
   const std::shared_ptr<NotificationData> data_;  // never null
 
   SIZE toast_size_ = {};

brightray/browser/win/win32_desktop_notifications/toast_uia.cc

@@ -0,0 +1,250 @@
+#include "brightray/browser/win/win32_desktop_notifications/toast_uia.h"
+#include <UIAutomation.h>
+#include "brightray/browser/win/win32_desktop_notifications/common.h"
+
+#pragma comment(lib, "uiautomationcore.lib")
+
+namespace brightray {
+
+DesktopNotificationController::Toast::UIAutomationInterface::
+    UIAutomationInterface(Toast* toast)
+    : hwnd_(toast->hwnd_) {
+  text_ = toast->data_->caption;
+  if (!toast->data_->body_text.empty()) {
+    if (!text_.empty())
+      text_.append(L", ");
+    text_.append(toast->data_->body_text);
+  }
+}
+
+ULONG DesktopNotificationController::Toast::UIAutomationInterface::AddRef() {
+  return InterlockedIncrement(&cref_);
+}
+
+ULONG DesktopNotificationController::Toast::UIAutomationInterface::Release() {
+  LONG ret = InterlockedDecrement(&cref_);
+  if (ret == 0) {
+    delete this;
+    return 0;
+  }
+  _ASSERT(ret > 0);
+  return ret;
+}
+
+STDMETHODIMP
+DesktopNotificationController::Toast::UIAutomationInterface::QueryInterface(
+    REFIID riid,
+    LPVOID* ppv) {
+  if (!ppv)
+    return E_INVALIDARG;
+
+  if (riid == IID_IUnknown) {
+    *ppv =
+        static_cast<IUnknown*>(static_cast<IRawElementProviderSimple*>(this));
+  } else if (riid == __uuidof(IRawElementProviderSimple)) {
+    *ppv = static_cast<IRawElementProviderSimple*>(this);
+  } else if (riid == __uuidof(IWindowProvider)) {
+    *ppv = static_cast<IWindowProvider*>(this);
+  } else if (riid == __uuidof(IInvokeProvider)) {
+    *ppv = static_cast<IInvokeProvider*>(this);
+  } else if (riid == __uuidof(ITextProvider)) {
+    *ppv = static_cast<ITextProvider*>(this);
+  } else {
+    *ppv = nullptr;
+    return E_NOINTERFACE;
+  }
+
+  this->AddRef();
+  return S_OK;
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::
+    get_ProviderOptions(ProviderOptions* retval) {
+  *retval = ProviderOptions_ServerSideProvider;
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::GetPatternProvider(
+    PATTERNID pattern_id,
+    IUnknown** retval) {
+  switch (pattern_id) {
+    case UIA_WindowPatternId:
+      *retval = static_cast<IWindowProvider*>(this);
+      break;
+    case UIA_InvokePatternId:
+      *retval = static_cast<IInvokeProvider*>(this);
+      break;
+    case UIA_TextPatternId:
+      *retval = static_cast<ITextProvider*>(this);
+      break;
+    default:
+      *retval = nullptr;
+      return S_OK;
+  }
+  this->AddRef();
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::GetPropertyValue(
+    PROPERTYID property_id,
+    VARIANT* retval) {
+  // Note: In order to have the toast read by the NVDA screen reader, we
+  // pretend that we're a Windows 8 native toast notification by reporting
+  // these property values:
+  //    ClassName: ToastContentHost
+  //    ControlType: UIA_ToolTipControlTypeId
+
+  retval->vt = VT_EMPTY;
+  switch (property_id) {
+    case UIA_NamePropertyId:
+      retval->vt = VT_BSTR;
+      retval->bstrVal = SysAllocString(text_.c_str());
+      break;
+
+    case UIA_ClassNamePropertyId:
+      retval->vt = VT_BSTR;
+      retval->bstrVal = SysAllocString(L"ToastContentHost");
+      break;
+
+    case UIA_ControlTypePropertyId:
+      retval->vt = VT_I4;
+      retval->lVal = UIA_ToolTipControlTypeId;
+      break;
+
+    case UIA_LiveSettingPropertyId:
+      retval->vt = VT_I4;
+      retval->lVal = Assertive;
+      break;
+
+    case UIA_IsContentElementPropertyId:
+    case UIA_IsControlElementPropertyId:
+    case UIA_IsPeripheralPropertyId:
+      retval->vt = VT_BOOL;
+      retval->lVal = VARIANT_TRUE;
+      break;
+
+    case UIA_HasKeyboardFocusPropertyId:
+    case UIA_IsKeyboardFocusablePropertyId:
+    case UIA_IsOffscreenPropertyId:
+      retval->vt = VT_BOOL;
+      retval->lVal = VARIANT_FALSE;
+      break;
+  }
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::
+    get_HostRawElementProvider(IRawElementProviderSimple** retval) {
+  if (!hwnd_)
+    return E_FAIL;
+  return UiaHostProviderFromHwnd(hwnd_, retval);
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::Invoke() {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::SetVisualState(
+    WindowVisualState state) {
+  // setting the visual state is not supported
+  return E_FAIL;
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::Close() {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::WaitForInputIdle(
+    int milliseconds,
+    BOOL* retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::get_CanMaximize(
+    BOOL* retval) {
+  *retval = FALSE;
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::get_CanMinimize(
+    BOOL* retval) {
+  *retval = FALSE;
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::get_IsModal(
+    BOOL* retval) {
+  *retval = FALSE;
+  return S_OK;
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::
+    get_WindowVisualState(WindowVisualState* retval) {
+  *retval = WindowVisualState_Normal;
+  return S_OK;
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::
+    get_WindowInteractionState(WindowInteractionState* retval) {
+  if (!hwnd_)
+    *retval = WindowInteractionState_Closing;
+  else
+    *retval = WindowInteractionState_ReadyForUserInteraction;
+
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::get_IsTopmost(
+    BOOL* retval) {
+  *retval = TRUE;
+  return S_OK;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::GetSelection(
+    SAFEARRAY** retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::GetVisibleRanges(
+    SAFEARRAY** retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::RangeFromChild(
+    IRawElementProviderSimple* child_element,
+    ITextRangeProvider** retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::RangeFromPoint(
+    UiaPoint point,
+    ITextRangeProvider** retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT
+DesktopNotificationController::Toast::UIAutomationInterface::get_DocumentRange(
+    ITextRangeProvider** retval) {
+  return E_NOTIMPL;
+}
+
+HRESULT DesktopNotificationController::Toast::UIAutomationInterface::
+    get_SupportedTextSelection(SupportedTextSelection* retval) {
+  *retval = SupportedTextSelection_None;
+  return S_OK;
+}
+
+}  // namespace brightray