Bug 1322532: Platform a11y changes to enable handler-based live regions; r=tbsaunde

MozReview-Commit-ID: nNPvBy3ZGO

--HG--
extra : rebase_source : d8a797c9ddfb3d8ab4f13c9f2f261fba04320beb
extra : histedit_source : cc4f0bd8ba26cc88bcf9907f684e5d6c240d354f

accessible/ipc/DocAccessibleParent.cpp

@@ -338,6 +338,21 @@ DocAccessibleParent::RecvTextChangeEvent(const uint64_t& aID,
   return IPC_OK();
 }
 
+#if defined(XP_WIN)
+
+mozilla::ipc::IPCResult
+DocAccessibleParent::RecvSyncTextChangeEvent(const uint64_t& aID,
+                                             const nsString& aStr,
+                                             const int32_t& aStart,
+                                             const uint32_t& aLen,
+                                             const bool& aIsInsert,
+                                             const bool& aFromUser)
+{
+  return RecvTextChangeEvent(aID, aStr, aStart, aLen, aIsInsert, aFromUser);
+}
+
+#endif // defined(XP_WIN)
+
 mozilla::ipc::IPCResult
 DocAccessibleParent::RecvSelectionEvent(const uint64_t& aID,
                                         const uint64_t& aWidgetID,

accessible/ipc/DocAccessibleParent.h

@@ -88,6 +88,13 @@ public:
                                                       const bool& aIsInsert,
                                                       const bool& aFromUser) override;
 
+#if defined(XP_WIN)
+  virtual mozilla::ipc::IPCResult RecvSyncTextChangeEvent(const uint64_t& aID, const nsString& aStr,
+                                                          const int32_t& aStart, const uint32_t& aLen,
+                                                          const bool& aIsInsert,
+                                                          const bool& aFromUser) override;
+#endif // defined(XP_WIN)
+
   virtual mozilla::ipc::IPCResult RecvSelectionEvent(const uint64_t& aID,
                                                      const uint64_t& aWidgetID,
                                                      const uint32_t& aType) override;

accessible/ipc/win/DocAccessibleChild.cpp

@@ -190,6 +190,13 @@ DocAccessibleChild::SendTextChangeEvent(const uint64_t& aID,
                                         const bool& aFromUser)
 {
   if (IsConstructedInParentProcess()) {
+    if (aStr.Contains(L'\xfffc')) {
+      // The AT is going to need to reenter content while the event is being
+      // dispatched synchronously.
+      return PDocAccessibleChild::SendSyncTextChangeEvent(aID, aStr, aStart,
+                                                          aLen, aIsInsert,
+                                                          aFromUser);
+    }
     return PDocAccessibleChild::SendTextChangeEvent(aID, aStr, aStart,
                                                     aLen, aIsInsert, aFromUser);
   }

accessible/windows/msaa/AccessibleWrap.cpp

@@ -43,6 +43,7 @@
 #include "nsArrayUtils.h"
 #include "mozilla/Preferences.h"
 #include "nsIXULRuntime.h"
+#include "mozilla/mscom/AsyncInvoker.h"
 
 #include "oleacc.h"
 
@@ -1627,3 +1628,60 @@ AccessibleWrap::SetHandlerControl(DWORD aPid, RefPtr<IHandlerControl> aCtrl)
   sHandlerControllers->AppendElement(Move(ctrlData));
 }
 
+
+bool
+AccessibleWrap::DispatchTextChangeToHandler(bool aIsInsert,
+                                            const nsString& aText,
+                                            int32_t aStart, uint32_t aLen)
+{
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!sHandlerControllers || sHandlerControllers->IsEmpty()) {
+    return false;
+  }
+
+  HWND hwnd = GetHWNDFor(this);
+  MOZ_ASSERT(hwnd);
+  if (!hwnd) {
+    return false;
+  }
+
+  long msaaId = GetChildIDFor(this);
+
+  DWORD ourPid = ::GetCurrentProcessId();
+
+  // The handler ends up calling NotifyWinEvent, which should only be done once
+  // since it broadcasts the same event to every process who is subscribed.
+  // OTOH, if our chrome process contains a handler, we should prefer to
+  // broadcast the event from that process, as we want any DLLs injected by ATs
+  // to receive the event synchronously. Otherwise we simply choose the first
+  // handler in the list, for the lack of a better heuristic.
+
+  nsTArray<HandlerControllerData>::index_type ctrlIndex =
+    sHandlerControllers->IndexOf(ourPid);
+
+  if (ctrlIndex == nsTArray<HandlerControllerData>::NoIndex) {
+    ctrlIndex = 0;
+  }
+
+  HandlerControllerData& controller = sHandlerControllers->ElementAt(ctrlIndex);
+  MOZ_ASSERT(controller.mPid);
+  MOZ_ASSERT(controller.mCtrl);
+
+  VARIANT_BOOL isInsert = aIsInsert ? VARIANT_TRUE : VARIANT_FALSE;
+
+  IA2TextSegment textSegment{::SysAllocStringLen(aText.get(), aText.Length()),
+                             aStart, static_cast<long>(aLen)};
+
+  ASYNC_INVOKER_FOR(IHandlerControl) invoker(controller.mCtrl,
+                                             Some(controller.mIsProxy));
+
+  HRESULT hr = ASYNC_INVOKE(invoker, OnTextChange, PtrToLong(hwnd), msaaId,
+                            isInsert, &textSegment);
+
+  ::SysFreeString(textSegment.text);
+
+  return SUCCEEDED(hr);
+}
+

accessible/windows/msaa/AccessibleWrap.h

@@ -192,6 +192,8 @@ public: // construction, destruction
 
   static void SetHandlerControl(DWORD aPid, RefPtr<IHandlerControl> aCtrl);
 
+  bool DispatchTextChangeToHandler(bool aIsInsert, const nsString& aText,
+                                   int32_t aStart, uint32_t aLen);
 protected:
   virtual ~AccessibleWrap();
 

accessible/windows/msaa/Platform.cpp

@@ -132,6 +132,14 @@ a11y::ProxyTextChangeEvent(ProxyAccessible* aText, const nsString& aStr,
     return;
   }
 
+  static const bool useHandler =
+    Preferences::GetBool("accessibility.handler.enabled", false);
+
+  if (useHandler) {
+    wrapper->DispatchTextChangeToHandler(aInsert, aStr, aStart, aLen);
+    return;
+  }
+
   auto text = static_cast<HyperTextAccessibleWrap*>(wrapper->AsHyperText());
   if (text) {
     ia2AccessibleText::UpdateTextChangeData(text, aInsert, aStr, aStart, aLen);