Web Animations: Don't mark players as outdated upon currentTime access

Source/core/animation/Player.cpp

Index: Source/core/animation/Player.cpp
diff --git a/Source/core/animation/Player.cpp b/Source/core/animation/Player.cpp
index 79e796d4d653cd810d9f12eaaca62afd0ae948b6..1e0a5aedbba992c430c8bb593be89633c9da587f 100644
--- a/Source/core/animation/Player.cpp
+++ b/Source/core/animation/Player.cpp
@@ -92,7 +92,7 @@ double Player::currentTimeWithLag() const
     return std::isinf(time) ? time : time - m_storedTimeLag;
 }
 
-void Player::updateTimingState(double newCurrentTime)
+void Player::updateTimingState(double newCurrentTime, bool shouldSetOutdated)
 {
     ASSERT(!isNull(newCurrentTime));
     m_held = m_paused || !m_playbackRate || limited(newCurrentTime);
@@ -103,15 +103,16 @@ void Player::updateTimingState(double newCurrentTime)
         m_holdTime = nullValue();
         m_storedTimeLag = currentTimeWithoutLag() - newCurrentTime;
     }
-    setOutdated();
+    if (shouldSetOutdated)

[dstockwell, 2014/02/24 07:44:07]

Shouldn't we be able to derive this from above? Changes in the values of
m_holdTime/m_storedTimeLag indicate shouldSetOutdated?

[Timothy Loh, 2014/03/04 03:13:07]

Ok this ends up being a little more complicated because the calculation for
storedTimeLag currently is something like (currentTimeWithoutLag -
(currentTimeWithoutLag - storedTimeLag)) when we aren't held. This probably
introduces both floating point issues and timing issues (if we aren't in an
animation frame the timeline's time could advance between calls).

I've tweaked things around to hopefully avoid these issues in patch set 2. I
don't bother checking for changes in m_storedTimeLag since if we're not held
then currentTime() calls shouldn't come through here and for the reasons above.

+        setOutdated();
 }
 
-void Player::updateCurrentTimingState()
+void Player::updateCurrentTimingState(bool shouldSetOutdated)
 {
     if (m_held) {
-        updateTimingState(m_holdTime);
+        updateTimingState(m_holdTime, shouldSetOutdated);
     } else {
-        updateTimingState(currentTimeWithLag());
+        updateTimingState(currentTimeWithLag(), shouldSetOutdated);
         if (m_held && limited(m_holdTime))
             m_holdTime = m_playbackRate < 0 ? 0 : sourceEnd();
     }
@@ -119,7 +120,7 @@ void Player::updateCurrentTimingState()
 
 double Player::currentTime()
 {
-    updateCurrentTimingState();
+    updateCurrentTimingState(false);
     if (m_held)
         return m_holdTime;
     return currentTimeWithLag();
@@ -261,15 +262,12 @@ void Player::cancelAnimationOnCompositor()
 
 bool Player::update()
 {
-    if (!m_timeline)
-        return false;
-
-    double inheritedTime = isNull(m_timeline->currentTime()) ? nullValue() : currentTime();
     m_outdated = false;
 
-    if (!m_content)
+    if (!m_timeline || !m_content)
         return false;
 
+    double inheritedTime = isNull(m_timeline->currentTime()) ? nullValue() : currentTime();
     m_content->updateInheritedTime(inheritedTime);
 
     ASSERT(!m_outdated);