libdeng2|Clock: Priority audience for time change

In some cases it is necessary for certain time change audience members
to be notified before other members (e.g., ScalarRule must be already
invalidated when the regular time change notifications go out).

Added a "priority" audience to Clock that will always be notified
before the regular audience. Animation-related clock observers are now
put in the priority audience.

doomsday/libdeng2/include/de/core/clock.h

@@ -32,8 +32,19 @@ namespace de {
 class DENG2_PUBLIC Clock
 {
 public:
+    /**
+     * Notified whenever the time of the clock changes. The audience members
+     * will be notified in unspecified order.
+     */
     DENG2_DEFINE_AUDIENCE(TimeChange, void timeChanged(Clock const &))
 
+    /**
+     * Notified whenever the time of the clock changes. The entire priority
+     * audience is notified before the regular TimeChange audience.
+     */
+    typedef Observers<DENG2_AUDIENCE_INTERFACE(TimeChange)> PriorityTimeChangeAudience;
+    PriorityTimeChangeAudience audienceForPriorityTimeChange;
+
 public:
     Clock();
 

doomsday/libdeng2/include/de/widgets/scalarrule.h

@@ -40,6 +40,13 @@ class DENG2_PUBLIC ScalarRule : public Rule, DENG2_OBSERVES(Clock, TimeChange)
 
     void set(Rule const &target, TimeDelta transition = 0);
 
+    /**
+     * Sets the animation style of the rule.
+     *
+     * @param style  Animation style.
+     */
+    void setStyle(Animation::Style style);
+
     /**
      * Read-only access to the scalar animation.
      */

doomsday/libdeng2/src/core/clock.cpp

@@ -36,6 +36,10 @@ void Clock::setTime(Time const &currentTime)
 
     if(changed)
     {
+        DENG2_FOR_EACH_OBSERVER(PriorityTimeChangeAudience, i, audienceForPriorityTimeChange)
+        {
+            i->timeChanged(*this);
+        }
         DENG2_FOR_AUDIENCE(TimeChange, i) i->timeChanged(*this);
     }
 }

doomsday/libdeng2/src/widgets/rulerectangle.cpp

@@ -325,7 +325,7 @@ public DelegateRule::ISource
 
         if(normalizedAnchorPoint.done())
         {
-            clock.audienceForTimeChange -= this;
+            clock.audienceForPriorityTimeChange -= this;
         }
     }
 };
@@ -417,7 +417,7 @@ void RuleRectangle::setAnchorPoint(Vector2f const &normalizedPoint, TimeDelta co
     if(transition > 0.0)
     {
         // Animation started, keep an eye on the clock until it ends.
-        Clock::appClock().audienceForTimeChange += d;
+        Clock::appClock().audienceForPriorityTimeChange += d;
     }
 }
 

doomsday/libdeng2/src/widgets/scalarrule.cpp

@@ -37,7 +37,7 @@ void ScalarRule::set(float target, de::TimeDelta transition)
     independentOf(_targetRule);
     _targetRule = 0;
 
-    _animation.clock().audienceForTimeChange += this;
+    _animation.clock().audienceForPriorityTimeChange += this;
 
     _animation.setValue(target, transition);
     invalidate();
@@ -52,6 +52,11 @@ void ScalarRule::set(Rule const &target, TimeDelta transition)
     dependsOn(_targetRule);
 }
 
+void ScalarRule::setStyle(Animation::Style style)
+{
+    _animation.setStyle(style);
+}
+
 void ScalarRule::shift(float delta)
 {
     _animation.shift(delta);
@@ -75,7 +80,7 @@ void ScalarRule::timeChanged(Clock const &clock)
 
     if(_animation.done())
     {
-        clock.audienceForTimeChange -= this;
+        clock.audienceForPriorityTimeChange -= this;
     }
 }