source/modules/juce_gui_basics/native/accessibility/juce_win32_Accessibility.cpp

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library.
   5    Copyright (c) 2022 - Raw Material Software Limited
   6
   7    JUCE is an open source library subject to commercial or open-source
   8    licensing.
   9
  10    By using JUCE, you agree to the terms of both the JUCE 7 End-User License
  11    Agreement and JUCE Privacy Policy.
  12
  13    End User License Agreement: www.juce.com/juce-7-licence
  14    Privacy Policy: www.juce.com/juce-privacy-policy
  15
  16    Or: You may also use this code under the terms of the GPL v3 (see
  17    www.gnu.org/licenses).
  18
  19    JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
  20    EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
  21    DISCLAIMED.
  22
  23   ==============================================================================
  24 */
  25
  26 namespace juce
  27 {
  28
  29 #define JUCE_NATIVE_ACCESSIBILITY_INCLUDED 1
  30
  31 JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wlanguage-extension-token")
  32
  33 static bool isStartingUpOrShuttingDown()
  34 {
  35     if (auto* app = JUCEApplicationBase::getInstance())
  36         if (app->isInitialising())
  37             return true;
  38
  39     if (auto* mm = MessageManager::getInstanceWithoutCreating())
  40         if (mm->hasStopMessageBeenSent())
  41             return true;
  42
  43     return false;
  44 }
  45
  46 static bool isHandlerValid (const AccessibilityHandler& handler)
  47 {
  48     if (auto* provider = handler.getNativeImplementation())
  49         return provider->isElementValid();
  50
  51     return false;
  52 }
  53
  54 //==============================================================================
  55 class AccessibilityHandler::AccessibilityNativeImpl
  56 {
  57 public:
  58     explicit AccessibilityNativeImpl (AccessibilityHandler& owner)
  59         : accessibilityElement (new AccessibilityNativeHandle (owner))
  60     {
  61         ++providerCount;
  62     }
  63
  64     ~AccessibilityNativeImpl()
  65     {
  66         ComSmartPtr<IRawElementProviderSimple> provider;
  67         accessibilityElement->QueryInterface (IID_PPV_ARGS (provider.resetAndGetPointerAddress()));
  68
  69         accessibilityElement->invalidateElement();
  70         --providerCount;
  71
  72         if (auto* uiaWrapper = WindowsUIAWrapper::getInstanceWithoutCreating())
  73         {
  74             uiaWrapper->disconnectProvider (provider);
  75
  76             if (providerCount == 0 && JUCEApplicationBase::isStandaloneApp())
  77                 uiaWrapper->disconnectAllProviders();
  78         }
  79     }
  80
  81     //==============================================================================
  82     ComSmartPtr<AccessibilityNativeHandle> accessibilityElement;
  83     static int providerCount;
  84
  85     //==============================================================================
  86     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AccessibilityNativeImpl)
  87 };
  88
  89 int AccessibilityHandler::AccessibilityNativeImpl::providerCount = 0;
  90
  91 //==============================================================================
  92 AccessibilityNativeHandle* AccessibilityHandler::getNativeImplementation() const
  93 {
  94     return nativeImpl->accessibilityElement;
  95 }
  96
  97 static bool areAnyAccessibilityClientsActive()
  98 {
  99     const auto areClientsListening = []
 100     {
 101         if (auto* uiaWrapper = WindowsUIAWrapper::getInstanceWithoutCreating())
 102             return uiaWrapper->clientsAreListening() != 0;
 103
 104         return false;
 105     };
 106
 107     const auto isScreenReaderRunning = []
 108     {
 109         BOOL isRunning = FALSE;
 110         SystemParametersInfo (SPI_GETSCREENREADER, 0, (PVOID) &isRunning, 0);
 111
 112         return isRunning != 0;
 113     };
 114
 115     return areClientsListening() || isScreenReaderRunning();
 116 }
 117
 118 template <typename Callback>
 119 void getProviderWithCheckedWrapper (const AccessibilityHandler& handler, Callback&& callback)
 120 {
 121     if (! areAnyAccessibilityClientsActive() || isStartingUpOrShuttingDown() || ! isHandlerValid (handler))
 122         return;
 123
 124     if (auto* uiaWrapper = WindowsUIAWrapper::getInstanceWithoutCreating())
 125     {
 126         ComSmartPtr<IRawElementProviderSimple> provider;
 127         handler.getNativeImplementation()->QueryInterface (IID_PPV_ARGS (provider.resetAndGetPointerAddress()));
 128
 129         callback (uiaWrapper, provider);
 130     }
 131 }
 132
 133 void sendAccessibilityAutomationEvent (const AccessibilityHandler& handler, EVENTID event)
 134 {
 135     jassert (event != EVENTID{});
 136
 137     getProviderWithCheckedWrapper (handler, [event] (WindowsUIAWrapper* uiaWrapper, ComSmartPtr<IRawElementProviderSimple>& provider)
 138     {
 139         uiaWrapper->raiseAutomationEvent (provider, event);
 140     });
 141 }
 142
 143 void sendAccessibilityPropertyChangedEvent (const AccessibilityHandler& handler, PROPERTYID property, VARIANT newValue)
 144 {
 145     jassert (property != PROPERTYID{});
 146
 147     getProviderWithCheckedWrapper (handler, [property, newValue] (WindowsUIAWrapper* uiaWrapper, ComSmartPtr<IRawElementProviderSimple>& provider)
 148     {
 149         VARIANT oldValue;
 150         VariantHelpers::clear (&oldValue);
 151
 152         uiaWrapper->raiseAutomationPropertyChangedEvent (provider, property, oldValue, newValue);
 153     });
 154 }
 155
 156 void notifyAccessibilityEventInternal (const AccessibilityHandler& handler, InternalAccessibilityEvent eventType)
 157 {
 158     if (eventType == InternalAccessibilityEvent::elementCreated
 159         || eventType == InternalAccessibilityEvent::elementDestroyed)
 160     {
 161         if (auto* parent = handler.getParent())
 162             sendAccessibilityAutomationEvent (*parent, ComTypes::UIA_LayoutInvalidatedEventId);
 163
 164         return;
 165     }
 166
 167     if (eventType == InternalAccessibilityEvent::windowOpened
 168         || eventType == InternalAccessibilityEvent::windowClosed)
 169     {
 170         if (auto* peer = handler.getComponent().getPeer())
 171             if ((peer->getStyleFlags() & ComponentPeer::windowHasTitleBar) == 0)
 172                 return;
 173     }
 174
 175     auto event = [eventType]() -> EVENTID
 176     {
 177         switch (eventType)
 178         {
 179             case InternalAccessibilityEvent::focusChanged:           return ComTypes::UIA_AutomationFocusChangedEventId;
 180             case InternalAccessibilityEvent::windowOpened:           return ComTypes::UIA_Window_WindowOpenedEventId;
 181             case InternalAccessibilityEvent::windowClosed:           return ComTypes::UIA_Window_WindowClosedEventId;
 182             case InternalAccessibilityEvent::elementCreated:
 183             case InternalAccessibilityEvent::elementDestroyed:
 184             case InternalAccessibilityEvent::elementMovedOrResized:  break;
 185         }
 186
 187         return {};
 188     }();
 189
 190     if (event != EVENTID{})
 191         sendAccessibilityAutomationEvent (handler, event);
 192 }
 193
 194 void AccessibilityHandler::notifyAccessibilityEvent (AccessibilityEvent eventType) const
 195 {
 196     if (eventType == AccessibilityEvent::titleChanged)
 197     {
 198         VARIANT newValue;
 199         VariantHelpers::setString (getTitle(), &newValue);
 200
 201         sendAccessibilityPropertyChangedEvent (*this, UIA_NamePropertyId, newValue);
 202         return;
 203     }
 204
 205     if (eventType == AccessibilityEvent::valueChanged)
 206     {
 207         if (auto* valueInterface = getValueInterface())
 208         {
 209             const auto propertyType = getRole() == AccessibilityRole::slider ? UIA_RangeValueValuePropertyId
 210                                                                              : UIA_ValueValuePropertyId;
 211
 212             const auto value = getRole() == AccessibilityRole::slider
 213                                ? VariantHelpers::getWithValue (valueInterface->getCurrentValue())
 214                                : VariantHelpers::getWithValue (valueInterface->getCurrentValueAsString());
 215
 216             sendAccessibilityPropertyChangedEvent (*this, propertyType, value);
 217         }
 218
 219         return;
 220     }
 221
 222     auto event = [eventType]() -> EVENTID
 223     {
 224         switch (eventType)
 225         {
 226             case AccessibilityEvent::textSelectionChanged:  return ComTypes::UIA_Text_TextSelectionChangedEventId;
 227             case AccessibilityEvent::textChanged:           return ComTypes::UIA_Text_TextChangedEventId;
 228             case AccessibilityEvent::structureChanged:      return ComTypes::UIA_StructureChangedEventId;
 229             case AccessibilityEvent::rowSelectionChanged:   return ComTypes::UIA_SelectionItem_ElementSelectedEventId;
 230             case AccessibilityEvent::titleChanged:
 231             case AccessibilityEvent::valueChanged:          break;
 232         }
 233
 234         return {};
 235     }();
 236
 237     if (event != EVENTID{})
 238         sendAccessibilityAutomationEvent (*this, event);
 239 }
 240
 241 struct SpVoiceWrapper  : public DeletedAtShutdown
 242 {
 243     SpVoiceWrapper()
 244     {
 245         auto hr = voice.CoCreateInstance (ComTypes::CLSID_SpVoice);
 246
 247         jassertquiet (SUCCEEDED (hr));
 248     }
 249
 250     ~SpVoiceWrapper() override
 251     {
 252         clearSingletonInstance();
 253     }
 254
 255     ComSmartPtr<ISpVoice> voice;
 256
 257     JUCE_DECLARE_SINGLETON (SpVoiceWrapper, false)
 258 };
 259
 260 JUCE_IMPLEMENT_SINGLETON (SpVoiceWrapper)
 261
 262
 263 void AccessibilityHandler::postAnnouncement (const String& announcementString, AnnouncementPriority priority)
 264 {
 265     if (! areAnyAccessibilityClientsActive())
 266         return;
 267
 268     if (auto* sharedVoice = SpVoiceWrapper::getInstance())
 269     {
 270         auto voicePriority = [priority]
 271         {
 272             switch (priority)
 273             {
 274                 case AnnouncementPriority::low:    return SPVPRI_OVER;
 275                 case AnnouncementPriority::medium: return SPVPRI_NORMAL;
 276                 case AnnouncementPriority::high:   return SPVPRI_ALERT;
 277             }
 278
 279             jassertfalse;
 280             return SPVPRI_OVER;
 281         }();
 282
 283         sharedVoice->voice->SetPriority (voicePriority);
 284         sharedVoice->voice->Speak (announcementString.toWideCharPointer(), SPF_ASYNC, nullptr);
 285     }
 286 }
 287
 288 //==============================================================================
 289 namespace WindowsAccessibility
 290 {
 291     static long getUiaRootObjectId()
 292     {
 293         return static_cast<long> (UiaRootObjectId);
 294     }
 295
 296     static bool handleWmGetObject (AccessibilityHandler* handler, WPARAM wParam, LPARAM lParam, LRESULT* res)
 297     {
 298         if (isStartingUpOrShuttingDown() || (handler == nullptr || ! isHandlerValid (*handler)))
 299             return false;
 300
 301         if (auto* uiaWrapper = WindowsUIAWrapper::getInstance())
 302         {
 303             ComSmartPtr<IRawElementProviderSimple> provider;
 304             handler->getNativeImplementation()->QueryInterface (IID_PPV_ARGS (provider.resetAndGetPointerAddress()));
 305
 306             if (! uiaWrapper->isProviderDisconnecting (provider))
 307                 *res = uiaWrapper->returnRawElementProvider ((HWND) handler->getComponent().getWindowHandle(), wParam, lParam, provider);
 308
 309             return true;
 310         }
 311
 312         return false;
 313     }
 314
 315     static void revokeUIAMapEntriesForWindow (HWND hwnd)
 316     {
 317         if (auto* uiaWrapper = WindowsUIAWrapper::getInstanceWithoutCreating())
 318             uiaWrapper->returnRawElementProvider (hwnd, 0, 0, nullptr);
 319     }
 320 }
 321
 322
 323 JUCE_IMPLEMENT_SINGLETON (WindowsUIAWrapper)
 324
 325 JUCE_END_IGNORE_WARNINGS_GCC_LIKE
 326
 327 } // namespace juce