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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_a11y_LazyInstantiator_h
+#define mozilla_a11y_LazyInstantiator_h
+
+#include "IUnknownImpl.h"
+#include "mozilla/RefPtr.h"
+#include "nsString.h"
+
+#include <oleacc.h>
+
+class nsIFile;
+
+namespace mozilla {
+namespace a11y {
+
+class MsaaRootAccessible;
+
+/**
+ * LazyInstantiator is an IAccessible that initially acts as a placeholder.
+ * The a11y service is not actually started until two conditions are met:
+ *
+ * (1) A method is called on the LazyInstantiator that would require a11y
+ * services in order to fulfill; and
+ * (2) LazyInstantiator::ShouldInstantiate returns true.
+ */
+class LazyInstantiator final : public IAccessible, public IServiceProvider {
+ public:
+ [[nodiscard]] static already_AddRefed<IAccessible> GetRootAccessible(
+ HWND aHwnd);
+ static void EnableBlindAggregation(HWND aHwnd);
+
+ // IUnknown
+ STDMETHODIMP QueryInterface(REFIID aIid, void** aOutInterface) override;
+ STDMETHODIMP_(ULONG) AddRef() override;
+ STDMETHODIMP_(ULONG) Release() override;
+
+ // IDispatch
+ STDMETHODIMP GetTypeInfoCount(UINT* pctinfo) override;
+ STDMETHODIMP GetTypeInfo(UINT iTInfo, LCID lcid,
+ ITypeInfo** ppTInfo) override;
+ STDMETHODIMP GetIDsOfNames(REFIID riid, LPOLESTR* rgszNames, UINT cNames,
+ LCID lcid, DISPID* rgDispId) override;
+ STDMETHODIMP Invoke(DISPID dispIdMember, REFIID riid, LCID lcid, WORD wFlags,
+ DISPPARAMS* pDispParams, VARIANT* pVarResult,
+ EXCEPINFO* pExcepInfo, UINT* puArgErr) override;
+
+ // IAccessible
+ STDMETHODIMP get_accParent(IDispatch** ppdispParent) override;
+ STDMETHODIMP get_accChildCount(long* pcountChildren) override;
+ STDMETHODIMP get_accChild(VARIANT varChild, IDispatch** ppdispChild) override;
+ STDMETHODIMP get_accName(VARIANT varChild, BSTR* pszName) override;
+ STDMETHODIMP get_accValue(VARIANT varChild, BSTR* pszValue) override;
+ STDMETHODIMP get_accDescription(VARIANT varChild,
+ BSTR* pszDescription) override;
+ STDMETHODIMP get_accRole(VARIANT varChild, VARIANT* pvarRole) override;
+ STDMETHODIMP get_accState(VARIANT varChild, VARIANT* pvarState) override;
+ STDMETHODIMP get_accHelp(VARIANT varChild, BSTR* pszHelp) override;
+ STDMETHODIMP get_accHelpTopic(BSTR* pszHelpFile, VARIANT varChild,
+ long* pidTopic) override;
+ STDMETHODIMP get_accKeyboardShortcut(VARIANT varChild,
+ BSTR* pszKeyboardShortcut) override;
+ STDMETHODIMP get_accFocus(VARIANT* pvarChild) override;
+ STDMETHODIMP get_accSelection(VARIANT* pvarChildren) override;
+ STDMETHODIMP get_accDefaultAction(VARIANT varChild,
+ BSTR* pszDefaultAction) override;
+ STDMETHODIMP accSelect(long flagsSelect, VARIANT varChild) override;
+ STDMETHODIMP accLocation(long* pxLeft, long* pyTop, long* pcxWidth,
+ long* pcyHeight, VARIANT varChild) override;
+ STDMETHODIMP accNavigate(long navDir, VARIANT varStart,
+ VARIANT* pvarEndUpAt) override;
+ STDMETHODIMP accHitTest(long xLeft, long yTop, VARIANT* pvarChild) override;
+ STDMETHODIMP accDoDefaultAction(VARIANT varChild) override;
+ STDMETHODIMP put_accName(VARIANT varChild, BSTR szName) override;
+ STDMETHODIMP put_accValue(VARIANT varChild, BSTR szValue) override;
+
+ // IServiceProvider
+ STDMETHODIMP QueryService(REFGUID aServiceId, REFIID aServiceIid,
+ void** aOutInterface) override;
+
+ private:
+ explicit LazyInstantiator(HWND aHwnd);
+ ~LazyInstantiator();
+
+ bool IsBlockedInjection();
+ bool ShouldInstantiate(const DWORD aClientTid);
+
+ DWORD GetClientPid(const DWORD aClientTid);
+
+ /**
+ * @return S_OK if we have a valid mRealRoot to invoke methods on
+ */
+ HRESULT MaybeResolveRoot();
+
+ /**
+ * @return S_OK if we have a valid mWeakDispatch to invoke methods on
+ */
+ HRESULT ResolveDispatch();
+
+ MsaaRootAccessible* ResolveMsaaRoot();
+ void TransplantRefCnt();
+ void ClearProp();
+
+ private:
+ mozilla::a11y::AutoRefCnt mRefCnt;
+ HWND mHwnd;
+ bool mAllowBlindAggregation;
+ RefPtr<IUnknown> mRealRootUnk;
+ RefPtr<IUnknown> mStdDispatch;
+ /**
+ * mWeakRootAccWrap, mWeakAccessible and mWeakDispatch are weak because they
+ * are interfaces that come from objects that we aggregate. Aggregated object
+ * interfaces share refcount methods with ours, so if we were to hold strong
+ * references to them, we would be holding strong references to ourselves,
+ * creating a cycle.
+ */
+ MsaaRootAccessible* mWeakMsaaRoot;
+ IAccessible* mWeakAccessible;
+ IDispatch* mWeakDispatch;
+};
+
+} // namespace a11y
+} // namespace mozilla
+
+#endif // mozilla_a11y_LazyInstantiator_h