Add Age example

Also added advancePosition property to Age, as it was needed for even this
simple example.

Change-Id: I614a719280efc1bc5140d07ab91ec0f1bc345788
Reviewed-on: http://codereview.qt-project.org/4871
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Martin Jones <martin.jones@nokia.com>

2 files changed, 51 insertions, 5 deletions

diff --git a/src/declarative/particles/qsgage.cpp b/src/declarative/particles/qsgage.cpp
index 2c0678fd0e..0caa8be99c 100644
--- a/src/declarative/particles/qsgage.cpp
+++ b/src/declarative/particles/qsgage.cpp
@@ -57,12 +57,27 @@ QT_BEGIN_NAMESPACE
     \qmlproperty int QtQuick.Particles2::Age::lifeLeft
 
     The amount of life to set the particle to have. Affected particles
-    will jump to a point in their life where they will have this many
+    will advance to a point in their life where they will have this many
     milliseconds left to live.
 */
 
+/*!
+    \qmlproperty bool QtQuick.Particles2::Age::advancePosition
+
+    advancePosition determines whether position, veclocity and acceleration are included in
+    the simulated aging done by the affector. If advancePosition is false,
+    then the position, velocity and acceleration will remain the same and only
+    other attributes (such as opacity) will advance in the simulation to where
+    it would normally be for that point in the particle's life. With advancePosition set to
+    true the position, velocity and acceleration will also advance to where it would
+    normally be by that point in the particle's life, making it advance its position
+    on screen.
+
+    Default value is true.
+*/
+
 QSGAgeAffector::QSGAgeAffector(QSGItem *parent) :
-    QSGParticleAffector(parent), m_lifeLeft(0)
+    QSGParticleAffector(parent), m_lifeLeft(0), m_advancePosition(true)
 {
 }
 
@@ -73,7 +88,23 @@ bool QSGAgeAffector::affectParticle(QSGParticleData *d, qreal dt)
     if (d->stillAlive()){
         qreal curT = (qreal)m_system->m_timeInt/1000.0;
         qreal ttl = (qreal)m_lifeLeft/1000.0;
-        d->t = curT - (d->lifeSpan - ttl) + 1;
+        if (!m_advancePosition && ttl > 0){
+            qreal x = d->curX();
+            qreal vx = d->curVX();
+            qreal ax = d->curAX();
+            qreal y = d->curY();
+            qreal vy = d->curVY();
+            qreal ay = d->curAY();
+            d->t = curT - (d->lifeSpan - ttl);
+            d->setInstantaneousX(x);
+            d->setInstantaneousVX(vx);
+            d->setInstantaneousAX(ax);
+            d->setInstantaneousY(y);
+            d->setInstantaneousVY(vy);
+            d->setInstantaneousAY(ay);
+        } else {
+            d->t = curT - (d->lifeSpan - ttl);
+        }
         return true;
     }
     return false;
diff --git a/src/declarative/particles/qsgage_p.h b/src/declarative/particles/qsgage_p.h
index c4c9929ad8..676122086c 100644
--- a/src/declarative/particles/qsgage_p.h
+++ b/src/declarative/particles/qsgage_p.h
@@ -54,6 +54,7 @@ class QSGAgeAffector : public QSGParticleAffector
 {
     Q_OBJECT
     Q_PROPERTY(int lifeLeft READ lifeLeft WRITE setLifeLeft NOTIFY lifeLeftChanged)
+    Q_PROPERTY(bool advancePosition READ advancePosition WRITE setAdvancePosition NOTIFY advancePositionChanged)
 
 public:
     explicit QSGAgeAffector(QSGItem *parent = 0);
@@ -63,10 +64,16 @@ public:
         return m_lifeLeft;
     }
 
+    bool advancePosition() const
+    {
+        return m_advancePosition;
+    }
+
 protected:
     virtual bool affectParticle(QSGParticleData *d, qreal dt);
 signals:
     void lifeLeftChanged(int arg);
+    void advancePositionChanged(bool arg);
 
 public slots:
     void setLifeLeft(int arg)
@@ -77,9 +84,17 @@ public slots:
         }
     }
 
-private:
+    void setAdvancePosition(bool arg)
+    {
+        if (m_advancePosition != arg) {
+            m_advancePosition = arg;
+            emit advancePositionChanged(arg);
+        }
+    }
 
-int m_lifeLeft;
+private:
+    int m_lifeLeft;
+    bool m_advancePosition;
 };
 
 QT_END_NAMESPACE