Bug 1195722 - Add a new pref to enable the accessible carets if touch events are supported, and enable the pref on nightly. r=tylin

MozReview-Commit-ID: 2eaVJ4fLqjt

layout/base/nsPresShell.cpp

@@ -92,6 +92,7 @@
 #include "PLDHashTable.h"
 #include "mozilla/dom/BeforeAfterKeyboardEventBinding.h"
 #include "mozilla/dom/Touch.h"
+#include "mozilla/dom/TouchEvent.h"
 #include "mozilla/dom/PointerEventBinding.h"
 #include "nsIObserverService.h"
 #include "nsDocShell.h"        // for reflow observation
@@ -734,17 +735,29 @@ static bool sSynthMouseMove = true;
 static uint32_t sNextPresShellId;
 static bool sPointerEventEnabled = true;
 static bool sAccessibleCaretEnabled = false;
+static bool sAccessibleCaretOnTouch = false;
 static bool sBeforeAfterKeyboardEventEnabled = false;
 
 /* static */ bool
-PresShell::AccessibleCaretEnabled()
+PresShell::AccessibleCaretEnabled(nsIDocShell* aDocShell)
 {
   static bool initialized = false;
   if (!initialized) {
     Preferences::AddBoolVarCache(&sAccessibleCaretEnabled, "layout.accessiblecaret.enabled");
+    Preferences::AddBoolVarCache(&sAccessibleCaretOnTouch, "layout.accessiblecaret.enabled_on_touch");
     initialized = true;
   }
-  return sAccessibleCaretEnabled;
+  // If the pref forces it on, then enable it.
+  if (sAccessibleCaretEnabled) {
+    return true;
+  }
+  // If the touch pref is on, and touch events are enabled (this depends
+  // on the specific device running), then enable it.
+  if (sAccessibleCaretOnTouch && dom::TouchEvent::PrefEnabled(aDocShell)) {
+    return true;
+  }
+  // Otherwise, disabled.
+  return false;
 }
 
 /* static */ bool
@@ -898,7 +911,7 @@ PresShell::Init(nsIDocument* aDocument,
   // Add the preference style sheet.
   UpdatePreferenceStyles();
 
-  if (AccessibleCaretEnabled()) {
+  if (AccessibleCaretEnabled(mDocument->GetDocShell())) {
     // Need to happen before nsFrameSelection has been set up.
     mAccessibleCaretEventHub = new AccessibleCaretEventHub(this);
   }
@@ -7603,7 +7616,7 @@ PresShell::HandleEvent(nsIFrame* aFrame,
 
   RecordMouseLocation(aEvent);
 
-  if (AccessibleCaretEnabled()) {
+  if (AccessibleCaretEnabled(mDocument->GetDocShell())) {
     // We have to target the focus window because regardless of where the
     // touch goes, we want to access the copy paste manager.
     nsCOMPtr<nsPIDOMWindowOuter> window = GetFocusedDOMWindowInOurWindow();

layout/base/nsPresShell.h

@@ -40,6 +40,7 @@
 #include "MobileViewportManager.h"
 #include "ZoomConstraintsClient.h"
 
+class nsIDocShell;
 class nsRange;
 
 struct RangePaintInfo;
@@ -94,7 +95,7 @@ public:
   // nsISupports
   NS_DECL_ISUPPORTS
 
-  static bool AccessibleCaretEnabled();
+  static bool AccessibleCaretEnabled(nsIDocShell* aDocShell);
 
   // BeforeAfterKeyboardEvent preference
   static bool BeforeAfterKeyboardEventEnabled();

modules/libpref/init/all.js

@@ -5166,6 +5166,16 @@ pref("snav.enabled", false);
 // New implementation to unify touch-caret and selection-carets.
 pref("layout.accessiblecaret.enabled", false);
 
+// On Nightly, enable the accessible caret on platforms/devices
+// that we detect have touch support. Note that this pref is an
+// additional way to enable the accessible carets, rather than
+// overriding the layout.accessiblecaret.enabled pref.
+#ifdef NIGHTLY_BUILD
+pref("layout.accessiblecaret.enabled_on_touch", true);
+#else
+pref("layout.accessiblecaret.enabled_on_touch", false);
+#endif
+
 // CSS attributes of the AccessibleCaret in CSS pixels.
 pref("layout.accessiblecaret.width", "34.0");
 pref("layout.accessiblecaret.height", "36.0");

testing/profiles/prefs_general.js

@@ -48,6 +48,7 @@ user_pref("app.update.url.android", "");
 // Make sure GMPInstallManager won't hit the network.
 user_pref("media.gmp-manager.url.override", "http://%(server)s/dummy-gmp-manager.xml");
 user_pref("dom.w3c_touch_events.enabled", 1);
+user_pref("layout.accessiblecaret.enabled_on_touch", false);
 user_pref("dom.undo_manager.enabled", true);
 user_pref("dom.webcomponents.enabled", true);
 user_pref("dom.webcomponents.customelements.enabled", true);