From fdeb68f0b8c7f4ce9bedbb9c97de5f9aafffb5f4 Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Thu, 14 Jan 2021 17:17:28 +0000
Subject: [PATCH] Issue #1689 - Part 3: Add a preference for animation
 composite modes.

This feature should not be shipped until the various definitions of addition for
each additive property are properly specified and then implemented accordingly.

Unlike other patches in this series, compositing is not frequently used
internally so there is no need to enable this by default for chrome callers.
---
 dom/animation/KeyframeEffect.cpp            | 5 +++--
 dom/animation/test/mochitest.ini            | 1 +
 layout/reftests/web-animations/reftest.list | 6 +++---
 modules/libpref/init/all.js                 | 1 +
 4 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/dom/animation/KeyframeEffect.cpp b/dom/animation/KeyframeEffect.cpp
index 90230a5b44..090c7019d7 100644
--- a/dom/animation/KeyframeEffect.cpp
+++ b/dom/animation/KeyframeEffect.cpp
@@ -10,6 +10,7 @@
 #include "mozilla/dom/AnimationEffectTiming.h"
 #include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/KeyframeUtils.h"
+#include "mozilla/Preferences.h"
 #include "nsContentUtils.h"
 #include "nsDOMMutationObserver.h" // For nsAutoAnimationMutationBatch
 #include "nsIScriptError.h"
@@ -135,9 +136,9 @@ void
 KeyframeEffect::SetIterationComposite(
   const IterationCompositeOperation& aIterationComposite)
 {
-  // Ignore iterationComposite if the Web Animations API is not enabled,
+  // Ignore iterationComposite if the API is not enabled,
   // then the default value 'Replace' will be used.
-  if (!AnimationUtils::IsCoreAPIEnabledForCaller()) {
+  if (!Preferences::GetBool("dom.animations-api.compositing.enabled")) {
     return;
   }
 
diff --git a/dom/animation/test/mochitest.ini b/dom/animation/test/mochitest.ini
index b56136d250..fff62ac7c9 100644
--- a/dom/animation/test/mochitest.ini
+++ b/dom/animation/test/mochitest.ini
@@ -1,5 +1,6 @@
 [DEFAULT]
 prefs =
+  dom.animations-api.compositing.enabled=true
   dom.animations-api.core.enabled=true
   dom.animations-api.implicit-keyframes.enabled=true
   dom.animations-api.timelines.enabled=true
diff --git a/layout/reftests/web-animations/reftest.list b/layout/reftests/web-animations/reftest.list
index eefd41f49d..da1d07089c 100644
--- a/layout/reftests/web-animations/reftest.list
+++ b/layout/reftests/web-animations/reftest.list
@@ -15,6 +15,6 @@ test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-ch
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-effect.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-changing-display-property.html stacking-context-animation-ref.html
 test-pref(dom.animations-api.core.enabled,true) == stacking-context-transform-losing-css-animation-in-delay.html stacking-context-animation-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-accumulate-to-replace.html style-updates-for-iteration-composite-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-iteration-composition-changed-from-replace-to-accumulate.html style-updates-for-iteration-composite-ref.html
-test-pref(dom.animations-api.core.enabled,true) == style-updates-on-current-iteration-changed.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-iteration-composition-changed-from-accumulate-to-replace.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-iteration-composition-changed-from-replace-to-accumulate.html style-updates-for-iteration-composite-ref.html
+test-pref(dom.animations-api.core.enabled,true) test-pref(dom.animations-api.compositing.enabled,true) == style-updates-on-current-iteration-changed.html style-updates-for-iteration-composite-ref.html
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 4103a2d220..b8cb114580 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2720,6 +2720,7 @@ pref("dom.animations-api.core.enabled", true);
 #endif
 pref("dom.animations-api.timelines.enabled", false);
 pref("dom.animations-api.implicit-keyframes.enabled", false);
+pref("dom.animations-api.compositing.enabled", false);
 
 // Is support for the Element.animate() function (a subset of the Web Animations
 // API) enabled?