Special attribute for macOS accessibility

atom/browser/api/atom_api_app.cc

@@ -869,6 +869,18 @@ bool App::IsAccessibilitySupportEnabled() {
   return ax_state->IsAccessibleBrowser();
 }
 
+void App::SetAccessibilitySupportEnabled(bool enabled) {
+  auto ax_state = content::BrowserAccessibilityState::GetInstance();
+
+  if (enabled) {
+    ax_state->OnScreenReaderDetected();
+  } else {
+    ax_state->DisableAccessibility();
+  }
+
+  Browser::Get()->OnAccessibilitySupportChanged();
+}
+
 Browser::LoginItemSettings App::GetLoginItemSettings(mate::Arguments* args) {
   Browser::LoginItemSettings options;
   args->GetNext(&options);
@@ -1141,6 +1153,8 @@ void App::BuildPrototype(
       .SetMethod("relaunch", &App::Relaunch)
       .SetMethod("isAccessibilitySupportEnabled",
                  &App::IsAccessibilitySupportEnabled)
+      .SetMethod("setAccessibilitySupportEnabled",
+                 &App::SetAccessibilitySupportEnabled)
       .SetMethod("disableHardwareAcceleration",
                  &App::DisableHardwareAcceleration)
       .SetMethod("disableDomainBlockingFor3DAPIs",

atom/browser/api/atom_api_app.h

@@ -171,6 +171,7 @@ class App : public AtomBrowserClient::Delegate,
   void DisableHardwareAcceleration(mate::Arguments* args);
   void DisableDomainBlockingFor3DAPIs(mate::Arguments* args);
   bool IsAccessibilitySupportEnabled();
+  void SetAccessibilitySupportEnabled(bool enabled);
   Browser::LoginItemSettings GetLoginItemSettings(mate::Arguments* args);
 #if defined(USE_NSS_CERTS)
   void ImportCertificate(const base::DictionaryValue& options,

atom/browser/mac/atom_application.mm

@@ -72,6 +72,9 @@ - (void)accessibilitySetValue:(id)value forAttribute:(NSString *)attribute {
     bool enableAccessibility = ([self voiceOverEnabled] && [value boolValue]);
     [self updateAccessibilityEnabled:enableAccessibility];
   }
+  else if ([attribute isEqualToString:@"AXManualAccessibility"]) {
+    [self updateAccessibilityEnabled:[value boolValue]];
+  }
   return [super accessibilitySetValue:value forAttribute:attribute];
 }
 

docs/api/app.md

@@ -890,6 +890,15 @@ technologies, such as screen readers, has been detected. See
 https://www.chromium.org/developers/design-documents/accessibility for more
 details.
 
+### `app.setAccessibilitySupportEnabled(enabled)` _macOS_ _Windows_
+
+* `enabled` Boolean - Enable or disable accessibility tree rendering
+
+Manually enables Chrome's accessibility support, allowing to expose accessibility switch to users in application settings. https://www.chromium.org/developers/design-documents/accessibility for more
+details.
+
+**Note:** Rendering accessibility tree can significantly affect the performance of your app. It should not be enabled by default.
+
 ### `app.setAboutPanelOptions(options)` _macOS_
 
 * `options` Object

docs/tutorial/accessibility.md

@@ -8,7 +8,7 @@ Accessibility concerns in Electron applications are similar to those of websites
 
 These new features bring those auditing tools to your Electron app. You can choose to add audits to your tests with Spectron or use them within DevTools with Devtron. Read on for a summary of the tools or checkout our [accessibility documentation](https://electron.atom.io/docs/tutorial/accessibility) for more information.
 
-### Spectron
+## Spectron
 
 In the testing framework Spectron, you can now audit each window and `<webview>` tag in your application. For example:
 
@@ -22,7 +22,7 @@ app.client.auditAccessibility().then(function (audit) {
 
 You can read more about this feature in [Spectron's documentation](https://github.com/electron/spectron#accessibility-testing).
 
-### Devtron
+## Devtron
 
 In Devtron, there is a new accessibility tab which will allow you to audit a page in your app, sort and filter the results.
 
@@ -31,3 +31,32 @@ In Devtron, there is a new accessibility tab which will allow you to audit a pag
 Both of these tools are using the [Accessibility Developer Tools](https://github.com/GoogleChrome/accessibility-developer-tools) library built by Google for Chrome. You can learn more about the accessibility audit rules this library uses on that [repository's wiki](https://github.com/GoogleChrome/accessibility-developer-tools/wiki/Audit-Rules).
 
 If you know of other great accessibility tools for Electron, add them to the [accessibility documentation](https://electron.atom.io/docs/tutorial/accessibility) with a pull request.
+
+## Enabling Accessibility
+
+Electron applications keep accessibility disabled by default for performance reasons but there are multiple ways to enable it.
+
+### Inside Application
+
+By using [`app.setAccessibilitySupportEnabled(enabled)`](https://electron.atom.io/docs/api/app.md#appsetaccessibilitysupportenabledenabled-macos-windows), you can expose accessibility switch to users in the application preferences.
+
+### Assistive Technology
+
+Electron application will enable accessibility automatically when it detects assistive technology (Windows) or VoiceOver (macOS). See Chrome's [accessibility documentation](https://www.chromium.org/developers/design-documents/accessibility#TOC-How-Chrome-detects-the-presence-of-Assistive-Technology) for more details.
+
+On macOS 3rd party assistive technology can switch accessibility inside Electron applications by setting the attribute `AXManualAccessibility` programmatically:
+
+```objc
+CFStringRef kAXManualAccessibility = CFSTR("AXManualAccessibility");
+
++ (void)enableAccessibility:(BOOL)enable inElectronApplication:(NSRunningApplication *)app
+{
+    AXUIElementRef appRef = AXUIElementCreateApplication(app.processIdentifier);
+    if (appRef == nil)
+        return;
+
+    CFBooleanRef value = enable ? kCFBooleanTrue : kCFBooleanFalse;
+    AXUIElementSetAttributeValue(appRef, kAXManualAccessibility, value);
+    CFRelease(appRef);
+}
+```