Bug 1166500 - Part 11: Add a preference for offscreen throttling. r=dbaron

MozReview-Commit-ID: AD34RTVZcxy

dom/animation/AnimationUtils.cpp

@@ -13,6 +13,7 @@
 #include "nsGlobalWindow.h"
 #include "nsString.h"
 #include "xpcpublic.h" // For xpc::NativeGlobal
+#include "mozilla/Preferences.h"
 
 namespace mozilla {
 
@@ -46,4 +47,19 @@ AnimationUtils::GetCurrentRealmDocument(JSContext* aCx)
   return win->GetDoc();
 }
 
+/* static */ bool
+AnimationUtils::IsOffscreenThrottlingEnabled()
+{
+  static bool sOffscreenThrottlingEnabled;
+  static bool sPrefCached = false;
+
+  if (!sPrefCached) {
+    sPrefCached = true;
+    Preferences::AddBoolVarCache(&sOffscreenThrottlingEnabled,
+                                 "dom.animations.offscreen-throttling");
+  }
+
+  return sOffscreenThrottlingEnabled;
+}
+
 } // namespace mozilla

dom/animation/AnimationUtils.h

@@ -54,6 +54,12 @@ public:
    */
   static nsIDocument*
   GetCurrentRealmDocument(JSContext* aCx);
+
+  /**
+   * Checks if offscreen animation throttling is enabled.
+   */
+  static bool
+  IsOffscreenThrottlingEnabled();
 };
 
 } // namespace mozilla

dom/animation/KeyframeEffect.cpp

@@ -1349,6 +1349,10 @@ KeyframeEffectReadOnly::CalculateCumulativeChangeHint()
 bool
 KeyframeEffectReadOnly::CanIgnoreIfNotVisible() const
 {
+  if (!AnimationUtils::IsOffscreenThrottlingEnabled()) {
+    return false;
+  }
+
   // FIXME: For further sophisticated optimization we need to check
   // change hint on the segment corresponding to computedTiming.progress.
   return NS_IsHintSubset(

dom/animation/test/chrome/test_restyles.html

@@ -207,6 +207,10 @@ waitForAllPaints(function() {
   });
 
   add_task_if_omta_enabled(function* no_restyling_compositor_animations_out_of_view_element() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     var div = addDiv(null,
       { style: 'animation: opacity 100s; transform: translateY(-400px);' });
     var animation = div.getAnimations()[0];
@@ -223,6 +227,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* no_restyling_main_thread_animations_out_of_view_element() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     var div = addDiv(null,
       { style: 'animation: background-color 100s; transform: translateY(-400px);' });
     var animation = div.getAnimations()[0];
@@ -237,6 +245,10 @@ waitForAllPaints(function() {
   });
 
   add_task_if_omta_enabled(function* no_restyling_compositor_animations_in_scrolled_out_element() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     /*
      On Android the opacity animation runs on the compositor even if it is
      scrolled out of view.  We will fix this in bug 1247800.
@@ -263,6 +275,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* no_restyling_main_thread_animations_in_scrolled_out_element() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     /*
      On Android throttled animations are left behind on the main thread in some
      frames, We will fix this in bug 1247800.
@@ -289,6 +305,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* no_restyling_main_thread_animations_in_nested_scrolled_out_element() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     /*
      On Android throttled animations are left behind on the main thread in some
      frames, We will fix this in bug 1247800.
@@ -334,6 +354,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* restyling_main_thread_animations_moved_in_view_by_scrolling() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     /*
      On Android throttled animations are left behind on the main thread in some
      frames, We will fix this in bug 1247800.
@@ -372,6 +396,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* restyling_main_thread_animations_moved_in_view_by_scrolling() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     var grandParent = addDiv(null,
       { style: 'overflow-y: scroll; height: 20px;' });
     var parentElement = addDiv(null,
@@ -406,6 +434,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* restyling_main_thread_animations_move_out_of_view_by_scrolling() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     /*
      On Android throttled animations are left behind on the main thread in some
      frames, We will fix this in bug 1247800.
@@ -447,6 +479,10 @@ waitForAllPaints(function() {
   });
 
   add_task(function* restyling_main_thread_animations_moved_in_view_by_resizing() {
+    if (!SpecialPowers.getBoolPref('dom.animations.offscreen-throttling')) {
+      return;
+    }
+
     var parentElement = addDiv(null,
       { style: 'overflow-y: scroll; height: 20px;' });
     var div = addDiv(null,

modules/libpref/init/all.js

@@ -2596,6 +2596,9 @@ pref("dom.animations-api.core.enabled", true);
 // ignored.
 pref("dom.animations-api.element-animate.enabled", true);
 
+// Pref to throttle offsreen animations
+pref("dom.animations.offscreen-throttling", true);
+
 // pref to permit users to make verified SOAP calls by default
 pref("capability.policy.default.SOAPCall.invokeVerifySourceHeader", "allAccess");