From 0df21afcdfe1a92f9f56b1fa3b5b226402b0e5bd Mon Sep 17 00:00:00 2001
From: Paul Betts <paul@paulbetts.org>
Date: Thu, 13 Oct 2016 11:46:55 -0700
Subject: [PATCH] Check harder before enabling Accessibility support

---
 atom/browser/native_window_views.h      |  5 +++++
 atom/browser/native_window_views_win.cc | 26 +++++++++++++++++--------
 electron.gyp                            |  1 +
 3 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/atom/browser/native_window_views.h b/atom/browser/native_window_views.h
index 0b4a9245db10..e81f61ca0a93 100644
--- a/atom/browser/native_window_views.h
+++ b/atom/browser/native_window_views.h
@@ -18,6 +18,8 @@
 #include "atom/browser/ui/win/message_handler_delegate.h"
 #include "atom/browser/ui/win/taskbar_host.h"
 #include "base/win/scoped_gdi_object.h"
+#include "ui/base/win/accessibility_misc_utils.h"
+#include <UIAutomationCoreApi.h>
 #endif
 
 namespace views {
@@ -228,6 +230,9 @@ class NativeWindowViews : public NativeWindow,
   // In charge of running taskbar related APIs.
   TaskbarHost taskbar_host_;
 
+  // Memoized version of a11y check
+  bool checked_for_a11y_support_;
+
   // If true we have enabled a11y
   bool enabled_a11y_support_;
 
diff --git a/atom/browser/native_window_views_win.cc b/atom/browser/native_window_views_win.cc
index bb6d9858f045..b8fc690a30c6 100644
--- a/atom/browser/native_window_views_win.cc
+++ b/atom/browser/native_window_views_win.cc
@@ -92,15 +92,25 @@ bool NativeWindowViews::PreHandleMSG(
     // accessibility object.
     case WM_GETOBJECT: {
       const DWORD obj_id = static_cast<DWORD>(l_param);
-      if (enabled_a11y_support_) return false;
+      if (checked_for_a11y_support_) return false;
 
-      if (obj_id == OBJID_CLIENT) {
-        const auto axState = content::BrowserAccessibilityState::GetInstance();
-        if (axState && !axState->IsAccessibleBrowser()) {
-          axState->OnScreenReaderDetected();
-          enabled_a11y_support_ = true;
-          Browser::Get()->OnAccessibilitySupportChanged();
-        }
+      checked_for_a11y_support_ = true;
+
+      if (obj_id != OBJID_CLIENT) {
+        return false;
+      }
+
+      UINT screenReader = 0;
+      SystemParametersInfo(SPI_GETSCREENREADER, 0, &screenReader, 0);
+      if (!screenReader || !UiaClientsAreListening()) {
+        return false;
+      }
+
+      const auto axState = content::BrowserAccessibilityState::GetInstance();
+      if (axState && !axState->IsAccessibleBrowser()) {
+        axState->OnScreenReaderDetected();
+        enabled_a11y_support_ = true;
+        Browser::Get()->OnAccessibilitySupportChanged();
       }
 
       return false;
diff --git a/electron.gyp b/electron.gyp
index 821ec27707a4..a186197f4743 100644
--- a/electron.gyp
+++ b/electron.gyp
@@ -281,6 +281,7 @@
               '-lwininet.lib',
               '-lwinmm.lib',
               '-lcrypt32.lib',
+              '-luiautomationcore.lib',
             ],
           },
           'dependencies': [