Add an inSync property that holds whether the target has "caught up"

Useful for determining when the target has finished animating.

4 files changed, 47 insertions, 11 deletions

diff --git a/examples/declarative/follow/follow.qml b/examples/declarative/follow/follow.qml
index 21a0309..37a953c 100644
--- a/examples/declarative/follow/follow.qml
+++ b/examples/declarative/follow/follow.qml
@@ -40,11 +40,24 @@ Rect {
         id: Mouse
         anchors.fill: parent
         Rect {
+            id: "Ball"
             width: 20; height: 20
             radius: 10
             color: "#0000ff"
-            x: Follow { source: Mouse.mouseX-10; spring: 1.0; damping: 0.05 }
-            y: Follow { source: Mouse.mouseY-10; spring: 1.0; damping: 0.05 }
+            x: Follow { id: "F1"; source: Mouse.mouseX-10; spring: 1.0; damping: 0.05; epsilon: 0.25 }
+            y: Follow { id: "F2"; source: Mouse.mouseY-10; spring: 1.0; damping: 0.05; epsilon: 0.25 }
+            states: [
+                State {
+                    name: "following"
+                    when: !F1.inSync || !F2.inSync
+                    SetProperties { target: Ball; color: "#ff0000" }
+                }
+            ]
+            transitions: [
+                Transition {
+                    ColorAnimation { duration: 200 }
+                }
+            ]
         }
     }
 }
diff --git a/examples/declarative/snow/snow.qml b/examples/declarative/snow/snow.qml
index 2b413bb..f65e0ac 100644
--- a/examples/declarative/snow/snow.qml
+++ b/examples/declarative/snow/snow.qml
@@ -27,11 +27,12 @@ Rect {
             property real targetDeform: 0
             property bool slowDeform: true
 
-            property real deform
-            deform: Follow { source: MyLayout.targetDeform; velocity: MyLayout.slowDeform?0.1:2 }
+            property real deform: 0
+            deform: Follow {
+                id: "DeformFollow"; source: MyLayout.targetDeform; velocity: MyLayout.slowDeform?0.1:2
+                onSyncChanged: if(inSync) { MyLayout.slowDeform = true; MyLayout.targetDeform = 0; }
+            }
                 
-            onDeformChanged: if(deform == targetDeform) { slowDeform = true; targetDeform = 0; }
-
             ImageBatch { offset: 0; ref: ImagePanel }
 
             x: Follow { source: MyLayout.targetX; velocity: 1000 }
diff --git a/src/declarative/util/qmlfollow.cpp b/src/declarative/util/qmlfollow.cpp
index b8e6685..851d4c2 100644
--- a/src/declarative/util/qmlfollow.cpp
+++ b/src/declarative/util/qmlfollow.cpp
@@ -56,7 +56,7 @@ class QmlFollowPrivate : public QObjectPrivate
 public:
     QmlFollowPrivate()
         : sourceValue(0), maxVelocity(0), lastTime(0)
-        , mass(1.0), spring(0.), damping(0.), velocity(0), epsilon(0.005), modulus(0.0), enabled(true), mode(Track), clock(this) {}
+        , mass(1.0), spring(0.), damping(0.), velocity(0), epsilon(0.01), modulus(0.0), enabled(true), mode(Track), clock(this) {}
 
     QmlMetaProperty property;
     qreal currentValue;
@@ -164,8 +164,10 @@ void QmlFollowPrivate::tick(int time)
         }
         lastTime = time;
     }
-    emit q->valueChanged(currentValue);
     property.write(currentValue);
+    emit q->valueChanged(currentValue);
+    if (clock.state() != QAbstractAnimation::Running)
+        emit q->syncChanged();
 }
 
 void QmlFollowPrivate::updateMode()
@@ -183,12 +185,14 @@ void QmlFollowPrivate::start()
     if (!enabled)
         return;
 
+    Q_Q(QmlFollow);
     if (mode == QmlFollowPrivate::Track) {
         currentValue = sourceValue;
         property.write(currentValue);
     } else if (sourceValue != currentValue && clock.state() != QAbstractAnimation::Running) {
         lastTime = 0;
         clock.start(); // infinity??
+        emit q->syncChanged();
     }
 }
 
@@ -261,8 +265,10 @@ qreal QmlFollow::sourceValue() const
 void QmlFollow::setSourceValue(qreal value)
 {
     Q_D(QmlFollow);
-    d->sourceValue = value;
-    d->start();
+    if (d->sourceValue != value) {
+        d->sourceValue = value;
+        d->start();
+    }
 }
 
 /*!
@@ -338,7 +344,7 @@ void QmlFollow::setDamping(qreal damping)
     to 0 to be considered equal to zero. This will depend on the usage of the value.
     For pixel positions, 0.25 would suffice. For scale, 0.005 will suffice.
 
-    The default is 0.005. Small performance improvements can result in tuning this
+    The default is 0.01. Small performance improvements can result in tuning this
     value.
 */
 qreal QmlFollow::epsilon() const
@@ -397,6 +403,19 @@ void QmlFollow::setEnabled(bool enabled)
         d->stop();
 }
 
+/*!
+    \qmlproperty bool Follow::inSync
+    This property is true when target is equal to the source; otherwise
+    false.  If inSync is true the target is not being animated.
+
+    If \l enabled is false then inSync will also be false.
+*/
+bool QmlFollow::inSync() const
+{
+    Q_D(const QmlFollow);
+    return d->enabled && d->clock.state() != QAbstractAnimation::Running;
+}
+
 qreal QmlFollow::value() const
 {
     Q_D(const QmlFollow);
diff --git a/src/declarative/util/qmlfollow.h b/src/declarative/util/qmlfollow.h
index 07e15e9..e0a588b 100644
--- a/src/declarative/util/qmlfollow.h
+++ b/src/declarative/util/qmlfollow.h
@@ -68,6 +68,7 @@ class Q_DECLARATIVE_EXPORT QmlFollow : public QmlPropertyValueSource,
     Q_PROPERTY(bool enabled READ enabled WRITE setEnabled)
     Q_PROPERTY(qreal followValue READ value NOTIFY valueChanged)
     Q_PROPERTY(qreal modulus READ modulus WRITE setModulus NOTIFY modulusChanged)
+    Q_PROPERTY(bool inSync READ inSync NOTIFY syncChanged)
 
 public:
     QmlFollow(QObject *parent=0);
@@ -89,11 +90,13 @@ public:
     void setModulus(qreal modulus);
     bool enabled() const;
     void setEnabled(bool enabled);
+    bool inSync() const;
 
     qreal value() const;
 
 Q_SIGNALS:
     void valueChanged(qreal);
+    void syncChanged();
 };
 
 QT_END_NAMESPACE