source/modules/juce_gui_basics/native/accessibility/juce_win32_WindowsUIAWrapper.h

   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 class WindowsUIAWrapper  : public DeletedAtShutdown
  30 {
  31 public:
  32     bool isLoaded() const noexcept
  33     {
  34         return uiaReturnRawElementProvider            != nullptr
  35             && uiaHostProviderFromHwnd                != nullptr
  36             && uiaRaiseAutomationPropertyChangedEvent != nullptr
  37             && uiaRaiseAutomationEvent                != nullptr
  38             && uiaClientsAreListening                 != nullptr
  39             && uiaDisconnectProvider                  != nullptr
  40             && uiaDisconnectAllProviders              != nullptr;
  41     }
  42
  43     //==============================================================================
  44     LRESULT returnRawElementProvider (HWND hwnd, WPARAM wParam, LPARAM lParam, IRawElementProviderSimple* provider)
  45     {
  46         return uiaReturnRawElementProvider != nullptr ? uiaReturnRawElementProvider (hwnd, wParam, lParam, provider)
  47                                                       : (LRESULT) nullptr;
  48     }
  49
  50     JUCE_COMRESULT hostProviderFromHwnd (HWND hwnd, IRawElementProviderSimple** provider)
  51     {
  52         return uiaHostProviderFromHwnd != nullptr ? uiaHostProviderFromHwnd (hwnd, provider)
  53                                                   : (HRESULT) UIA_E_NOTSUPPORTED;
  54     }
  55
  56     JUCE_COMRESULT raiseAutomationPropertyChangedEvent (IRawElementProviderSimple* provider, PROPERTYID propID, VARIANT oldValue, VARIANT newValue)
  57     {
  58         return uiaRaiseAutomationPropertyChangedEvent != nullptr ? uiaRaiseAutomationPropertyChangedEvent (provider, propID, oldValue, newValue)
  59                                                                  : (HRESULT) UIA_E_NOTSUPPORTED;
  60     }
  61
  62     JUCE_COMRESULT raiseAutomationEvent (IRawElementProviderSimple* provider, EVENTID eventID)
  63     {
  64         return uiaRaiseAutomationEvent != nullptr ? uiaRaiseAutomationEvent (provider, eventID)
  65                                                   : (HRESULT) UIA_E_NOTSUPPORTED;
  66     }
  67
  68     BOOL clientsAreListening()
  69     {
  70         return uiaClientsAreListening != nullptr ? uiaClientsAreListening()
  71                                                  : false;
  72     }
  73
  74     JUCE_COMRESULT disconnectProvider (IRawElementProviderSimple* provider)
  75     {
  76         if (uiaDisconnectProvider != nullptr)
  77         {
  78             const ScopedValueSetter<IRawElementProviderSimple*> disconnectingProviderSetter (disconnectingProvider, provider);
  79             return uiaDisconnectProvider (provider);
  80         }
  81
  82         return (HRESULT) UIA_E_NOTSUPPORTED;
  83     }
  84
  85     JUCE_COMRESULT disconnectAllProviders()
  86     {
  87         if (uiaDisconnectAllProviders != nullptr)
  88         {
  89             const ScopedValueSetter<bool> disconnectingAllProvidersSetter (disconnectingAllProviders, true);
  90             return uiaDisconnectAllProviders();
  91         }
  92
  93         return (HRESULT) UIA_E_NOTSUPPORTED;
  94     }
  95
  96     //==============================================================================
  97     bool isProviderDisconnecting (IRawElementProviderSimple* provider)
  98     {
  99         return disconnectingProvider == provider || disconnectingAllProviders;
 100     }
 101
 102     //==============================================================================
 103     JUCE_DECLARE_SINGLETON_SINGLETHREADED_MINIMAL (WindowsUIAWrapper)
 104
 105 private:
 106     //==============================================================================
 107     WindowsUIAWrapper()
 108     {
 109         // force UIA COM library initialisation here to prevent an exception when calling methods from SendMessage()
 110         if (isLoaded())
 111             returnRawElementProvider (nullptr, 0, 0, nullptr);
 112         else
 113             jassertfalse; // UIAutomationCore could not be loaded!
 114     }
 115
 116     ~WindowsUIAWrapper()
 117     {
 118         disconnectAllProviders();
 119
 120         if (uiaHandle != nullptr)
 121             ::FreeLibrary (uiaHandle);
 122
 123         clearSingletonInstance();
 124     }
 125
 126     //==============================================================================
 127     template <typename FuncType>
 128     static FuncType getUiaFunction (HMODULE module, LPCSTR funcName)
 129     {
 130         JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wcast-function-type")
 131         return (FuncType) GetProcAddress (module, funcName);
 132         JUCE_END_IGNORE_WARNINGS_GCC_LIKE
 133     }
 134
 135     //==============================================================================
 136     using UiaReturnRawElementProviderFunc            = LRESULT (WINAPI*) (HWND, WPARAM, LPARAM, IRawElementProviderSimple*);
 137     using UiaHostProviderFromHwndFunc                = HRESULT (WINAPI*) (HWND, IRawElementProviderSimple**);
 138     using UiaRaiseAutomationPropertyChangedEventFunc = HRESULT (WINAPI*) (IRawElementProviderSimple*, PROPERTYID, VARIANT, VARIANT);
 139     using UiaRaiseAutomationEventFunc                = HRESULT (WINAPI*) (IRawElementProviderSimple*, EVENTID);
 140     using UiaClientsAreListeningFunc                 = BOOL    (WINAPI*) ();
 141     using UiaDisconnectProviderFunc                  = HRESULT (WINAPI*) (IRawElementProviderSimple*);
 142     using UiaDisconnectAllProvidersFunc              = HRESULT (WINAPI*) ();
 143
 144     HMODULE uiaHandle = ::LoadLibraryA ("UIAutomationCore.dll");
 145     UiaReturnRawElementProviderFunc            uiaReturnRawElementProvider            = getUiaFunction<UiaReturnRawElementProviderFunc>            (uiaHandle, "UiaReturnRawElementProvider");
 146     UiaHostProviderFromHwndFunc                uiaHostProviderFromHwnd                = getUiaFunction<UiaHostProviderFromHwndFunc>                (uiaHandle, "UiaHostProviderFromHwnd");
 147     UiaRaiseAutomationPropertyChangedEventFunc uiaRaiseAutomationPropertyChangedEvent = getUiaFunction<UiaRaiseAutomationPropertyChangedEventFunc> (uiaHandle, "UiaRaiseAutomationPropertyChangedEvent");
 148     UiaRaiseAutomationEventFunc                uiaRaiseAutomationEvent                = getUiaFunction<UiaRaiseAutomationEventFunc>                (uiaHandle, "UiaRaiseAutomationEvent");
 149     UiaClientsAreListeningFunc                 uiaClientsAreListening                 = getUiaFunction<UiaClientsAreListeningFunc>                 (uiaHandle, "UiaClientsAreListening");
 150     UiaDisconnectProviderFunc                  uiaDisconnectProvider                  = getUiaFunction<UiaDisconnectProviderFunc>                  (uiaHandle, "UiaDisconnectProvider");
 151     UiaDisconnectAllProvidersFunc              uiaDisconnectAllProviders              = getUiaFunction<UiaDisconnectAllProvidersFunc>              (uiaHandle, "UiaDisconnectAllProviders");
 152
 153     IRawElementProviderSimple* disconnectingProvider = nullptr;
 154     bool disconnectingAllProviders = false;
 155
 156     //==============================================================================
 157     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (WindowsUIAWrapper)
 158 };
 159
 160 } // namespace juce