QPropertyAnimation reevaluates the default start value after each run

When the start value is not explicitly defined, the property animation
will set the default start to be the current property value when updating
the animation's state to Running.

Reviewed-by: Jan-Arve

3 files changed, 41 insertions, 7 deletions

diff --git a/src/corelib/animation/qpropertyanimation.cpp b/src/corelib/animation/qpropertyanimation.cpp
index adf3527c72..edcabaab1f 100644
--- a/src/corelib/animation/qpropertyanimation.cpp
+++ b/src/corelib/animation/qpropertyanimation.cpp
@@ -233,14 +233,16 @@ void QPropertyAnimation::updateState(QAbstractAnimation::State oldState,
         d->updateMetaProperty();
         QPropertyAnimation *oldAnim = hash->value(key, 0);
         if (oldAnim) {
-            //we try to stop the top level group
+            // try to stop the top level group
             QAbstractAnimation *current = oldAnim;
             while(current->group() && current->state() != Stopped) current = current->group();
             current->stop();
         }
         hash->insert(key, this);
         // Initialize start value
-        if (d->target && !d->defaultStartValue.isValid() && (d->atBeginning() || d->atEnd())) {
+        // ### review this line below, d->atEnd() ?
+        // ### avoid entering a state where start value is not set
+        if (d->target && (d->atBeginning() || d->atEnd())) {
             d->setDefaultStartValue(d->target->property(d->propertyName.constData()));
         }
     } else if (hash->value(key) == this) {
diff --git a/tests/auto/qanimationgroup/tst_qanimationgroup.cpp b/tests/auto/qanimationgroup/tst_qanimationgroup.cpp
index 3cf56312ea..2952a391ef 100644
--- a/tests/auto/qanimationgroup/tst_qanimationgroup.cpp
+++ b/tests/auto/qanimationgroup/tst_qanimationgroup.cpp
@@ -69,6 +69,7 @@ private slots:
     void setParentAutoAdd();
     void beginNestedGroup();
     void addChildTwice();
+    void loopWithoutStartValue();
 };
 
 tst_QAnimationGroup::tst_QAnimationGroup()
@@ -377,5 +378,36 @@ void tst_QAnimationGroup::addChildTwice()
     delete parent;
 }
 
+void tst_QAnimationGroup::loopWithoutStartValue()
+{
+    QAnimationGroup *parent = new QSequentialAnimationGroup();
+    QObject o;
+    o.setProperty("ole", 0);
+    QCOMPARE(o.property("ole").toInt(), 0);
+
+    QPropertyAnimation anim1(&o, "ole");
+    anim1.setEndValue(-50);
+    anim1.setDuration(100);
+
+    QPropertyAnimation anim2(&o, "ole");
+    anim2.setEndValue(50);
+    anim2.setDuration(100);
+
+    parent->addAnimation(&anim1);
+    parent->addAnimation(&anim2);
+
+    parent->setLoopCount(-1);
+    parent->start();
+
+    QVERIFY(anim1.startValue().isNull());
+    QCOMPARE(anim1.currentValue().toInt(), 0);
+    QCOMPARE(parent->currentLoop(), 0);
+
+    parent->setCurrentTime(200);
+    QCOMPARE(parent->currentLoop(), 1);
+    QCOMPARE(anim1.currentValue().toInt(), 50);
+    parent->stop();
+}
+
 QTEST_MAIN(tst_QAnimationGroup)
 #include "tst_qanimationgroup.moc"
diff --git a/tests/auto/qpropertyanimation/tst_qpropertyanimation.cpp b/tests/auto/qpropertyanimation/tst_qpropertyanimation.cpp
index 2ab0605d09..437c86213e 100644
--- a/tests/auto/qpropertyanimation/tst_qpropertyanimation.cpp
+++ b/tests/auto/qpropertyanimation/tst_qpropertyanimation.cpp
@@ -42,7 +42,6 @@
 #include <QtTest/QtTest>
 
 #include <QtCore/qpropertyanimation.h>
-#include <QtGui/qitemanimation.h>
 #include <QtGui/qwidget.h>
 
 //TESTED_CLASS=QPropertyAnimation
@@ -526,13 +525,14 @@ void tst_QPropertyAnimation::startWithoutStartValue()
     anim.setEndValue(110);
     anim.start();
     current = anim.currentValue().toInt();
-    QCOMPARE(current, 42); // the initial default start value
-
+    // the default start value will reevaluate the current property
+    // and set it to the end value of the last iteration
+    QCOMPARE(current, 100);
     QTest::qWait(100);
     current = anim.currentValue().toInt();
     //it is somewhere in the animation
-    QVERIFY(current > 42);
-    QVERIFY(current < 110);
+    QVERIFY(current >= 100);
+    QVERIFY(current <= 110);
 }
 
 void tst_QPropertyAnimation::playForwardBackward()