Fix SpringAnimation in Behavior when current value is set.

Fixes regression introduced by d489f2f6549a86b3949004d1c8ec68487fc2adb7.
We now only avoid running the animation if the Behavior wasn't already
mid-animation. This ensure correct behavior for SpringAnimation, and
also correct state for 'running'.

Task-number: QTBUG-21549
Change-Id: I0f97813294cca22fb7a273e222fa0549c6de9ca7
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/quick/util/qquickbehavior.cpp b/src/quick/util/qquickbehavior.cpp
index d649f9ff97..407b80915d 100644
--- a/src/quick/util/qquickbehavior.cpp
+++ b/src/quick/util/qquickbehavior.cpp
@@ -185,7 +185,8 @@ void QQuickBehavior::write(const QVariant &value)
         return;
     }
 
-    if (d->animation->isRunning() && value == d->targetValue)
+    bool behaviorActive = d->animation->isRunning();
+    if (behaviorActive && value == d->targetValue)
         return;
 
     d->targetValue = value;
@@ -201,7 +202,10 @@ void QQuickBehavior::write(const QVariant &value)
     // to the item, so we need to read the value after.
     const QVariant &currentValue = d->property.read();
 
-    if (d->targetValue == currentValue) {
+    // Don't unnecessarily wake up the animation system if no real animation
+    // is needed (value has not changed). If the Behavior was already
+    // running, let it continue as normal to ensure correct behavior and state.
+    if (!behaviorActive && d->targetValue == currentValue) {
         QQmlPropertyPrivate::write(d->property, value, QQmlPropertyPrivate::BypassInterceptor | QQmlPropertyPrivate::DontRemoveBinding);
         return;
     }