Merge pull request #1157 from smoogipoo/stop-clock-update

Expose a way to stop clock updates

osu.Framework/Graphics/Drawable.cs

@@ -320,7 +320,7 @@ public virtual bool UpdateSubTree()
             if (isDisposed)
                 throw new ObjectDisposedException(ToString(), "Disposed Drawables may never be in the scene graph.");
 
-            if (Parent != null) //we don't want to update our clock if we are at the top of the stack. it's handled elsewhere for us.
+            if (ShouldProcessClock)
                 customClock?.ProcessFrame();
 
             if (loadState < LoadState.Ready)
@@ -1152,6 +1152,12 @@ public virtual void UpdateClock(IFrameBasedClock clock)
             scheduler?.UpdateClock(this.clock);
         }
 
+        /// <summary>
+        /// Whether <see cref="IFrameBasedClock.ProcessFrame"/> should be automatically invoked on this <see cref="Drawable"/>'s <see cref="Clock"/>
+        /// in <see cref="UpdateSubTree"/>. This should only be used in scenarios where <see cref="UpdateSubTree"/> is overridden to perform the functionality itself.
+        /// </summary>
+        protected virtual bool ShouldProcessClock => Parent != null; //we don't want to update our clock if we are at the top of the stack. it's handled elsewhere for us.
+
         /// <summary>
         /// The time at which this drawable becomes valid (and is considered for drawing).
         /// </summary>