Fix affected signal and docs

Signal wasn't being called in its primary usecase, which was to interact
without altering the particles. Docs have been updated to clarify the
usecase as well.

This also updates the position properties of custom affector to more
accurately specify if they caused changes.

Change-Id: Ia411d9e81002443a56ed8bab9232f1aad49a4c5e
Reviewed-by: Yunqiao Yin <charles.yin@nokia.com>

src/particles/qquickcustomaffector.cpp

@@ -108,7 +108,12 @@ bool QQuickCustomAffector::isAffectConnected()
 
 void QQuickCustomAffector::affectSystem(qreal dt)
 {
-    if (!isAffectConnected()) {
+    //Acts a bit differently, just emits affected for everyone it might affect, when the only thing is connecting to affected(x,y)
+    bool justAffected = (m_acceleration == &m_nullVector
+        && m_speed == &m_nullVector
+        && m_position == &m_nullVector
+        && isAffectedConnected());
+    if (!isAffectConnected() && !justAffected) {
         QQuickParticleAffector::affectSystem(dt);
         return;
     }
@@ -126,6 +131,15 @@ void QQuickCustomAffector::affectSystem(qreal dt)
     if (toAffect.isEmpty())
         return;
 
+    if (justAffected) {
+        foreach (QQuickParticleData* d, toAffect) {//Not postAffect to avoid saying the particle changed
+            if (m_onceOff)
+                m_onceOffed << qMakePair(d->group, d->index);
+            emit affected(d->curX(), d->curY());
+        }
+        return;
+    }
+
     if (m_onceOff)
         dt = 1.0;
 
@@ -167,24 +181,30 @@ bool QQuickCustomAffector::affectParticle(QQuickParticleData *d, qreal dt)
 
     if (m_acceleration != &m_nullVector){
         QPointF pos = m_acceleration->sample(curPos);
+        QPointF curAcc = QPointF(d->curAX(), d->curAY());
         if (m_relative) {
             pos *= dt;
-            pos += QPointF(d->curAX(), d->curAY());
+            pos += curAcc;
+        }
+        if (pos != curAcc) {
+            d->setInstantaneousAX(pos.x());
+            d->setInstantaneousAY(pos.y());
+            changed = true;
         }
-        d->setInstantaneousAX(pos.x());
-        d->setInstantaneousAY(pos.y());
-        changed = true;
     }
 
     if (m_speed != &m_nullVector){
         QPointF pos = m_speed->sample(curPos);
+        QPointF curVel = QPointF(d->curVX(), d->curVY());
         if (m_relative) {
             pos *= dt;
-            pos += QPointF(d->curVX(), d->curVY());
+            pos += curVel;
+        }
+        if (pos != curVel) {
+            d->setInstantaneousVX(pos.x());
+            d->setInstantaneousVY(pos.y());
+            changed = true;
         }
-        d->setInstantaneousVX(pos.x());
-        d->setInstantaneousVY(pos.y());
-        changed = true;
     }
 
     if (m_position != &m_nullVector){
@@ -193,9 +213,11 @@ bool QQuickCustomAffector::affectParticle(QQuickParticleData *d, qreal dt)
             pos *= dt;
             pos += curPos;
         }
-        d->setInstantaneousX(pos.x());
-        d->setInstantaneousY(pos.y());
-        changed = true;
+        if (pos != curPos) {
+            d->setInstantaneousX(pos.x());
+            d->setInstantaneousY(pos.y());
+            changed = true;
+        }
     }
 
     return changed;

src/particles/qquickparticleaffector.cpp

@@ -113,31 +113,17 @@ QT_BEGIN_NAMESPACE
     If a size has been defined, the shape property can be used to affect a
     non-rectangular area.
 */
-/*!
-    \qmlsignal QtQuick.Particles2::Affector::onAffected(x, y)
-
-    This signal is emitted each time the affector actually affects a particle.
-
-    x,y are the coordinates of the affected particle, relative to the ParticleSystem.
-
-*/
-
-/*!
-    \qmlsignal QtQuick.Particles2::Affector::affectParticle(particle particle, real dt)
-
-    This handler is called when particles are selected to be affected.
-
-    dt is the time since the last time it was affected. Use dt to normalize
-    trajectory manipulations to real time.
-
-    Note that JS is slower to execute, so it is not recommended to use this in
-    high-volume particle systems.
-*/
 /*!
     \qmlsignal QtQuick.Particles2::Affector::affected(real x, real y)
 
-    This handler is called when a particle is selected to be affected. It will
-    only be called if signal is set to true.
+    This handler is called when a particle is selected to be affected. It will not be called
+    if a particle is considered by the Affector but not actually altered in any way.
+
+    In the special case where an Affector has no possible effect (e.g. Affector {}), affected
+    will be emitted for all particles being considered if you connect to it. This allows you to
+    execute arbitrary code in response to particles (see \l affectParticles if you want to execute
+    code which affects the particles themselves) . As this executes JS scritps per particle, it is
+    not recommended to use this signal with a high-volume particle system.
 
     x,y is the particles current position.
 */

src/particles/qquickparticleaffector_p.h

@@ -178,13 +178,14 @@ protected:
     bool shouldAffect(QQuickParticleData* datum);//Call to do the logic on whether it is affecting that datum
     void postAffect(QQuickParticleData* datum);//Call to do the post-affect logic on particles which WERE affected(once off, needs reset, affected signal)
     virtual void componentComplete();
-    QPointF m_offset;
     bool isAffectedConnected();
     static const qreal simulationDelta;
     static const qreal simulationCutoff;
+
+    QPointF m_offset;
+    QSet<QPair<int, int> > m_onceOffed;
 private:
     QSet<int> m_groupIds;
-    QSet<QPair<int, int> > m_onceOffed;
     bool m_updateIntSet;
 
     QQuickParticleExtruder* m_shape;

tests/auto/particles/qquickcustomaffector/data/affectedSignal.qml

@@ -0,0 +1,90 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.0
+import QtQuick.Particles 2.0
+
+Rectangle {
+    color: "black"
+    width: 320
+    height: 320
+
+    ParticleSystem {
+        id: sys
+        objectName: "system"
+        anchors.fill: parent
+        property real resultX1: 1234
+        property real resultY1: 1234
+        property real resultX2: 1234
+        property real resultY2: 1234
+
+        ImageParticle {
+            source: "../../shared/star.png"
+            rotation: 90
+        }
+
+        Emitter{
+            //0,100 position
+            y: 100
+            size: 32
+            emitRate: 1000
+            lifeSpan: 500
+        }
+
+        Affector {
+            once: true
+            onAffected: {//Does nothing else, so should be called for all particles
+                sys.resultX1 = x;
+                sys.resultY1 = y;
+            }
+        }
+
+        Affector {
+            once: true
+            relative: false
+            position: PointDirection { x: 0; y: 100; }
+            onAffected: {//Does something, so should only be called when it causes a change (it won't)
+                sys.resultX2 = x;
+                sys.resultY2 = y;
+            }
+        }
+    }
+}

tests/auto/particles/qquickcustomaffector/tst_qquickcustomaffector.cpp

@@ -56,6 +56,7 @@ private slots:
     void initTestCase();
     void test_basic();
     void test_move();
+    void test_affectedSignal();
 };
 
 void tst_qquickcustomaffector::initTestCase()
@@ -124,6 +125,19 @@ void tst_qquickcustomaffector::test_move()
     delete view;
 }
 
+void tst_qquickcustomaffector::test_affectedSignal()
+{
+    QQuickView* view = createView(testFileUrl("affectedSignal.qml"), 600);
+    QQuickParticleSystem* system = view->rootObject()->findChild<QQuickParticleSystem*>("system");
+    ensureAnimTime(600, system->m_animation);
+
+    QCOMPARE(system->property("resultX1").toInt(), 0);
+    QCOMPARE(system->property("resultY1").toInt(), 100);
+    QCOMPARE(system->property("resultX2").toInt(), 1234);
+    QCOMPARE(system->property("resultY2").toInt(), 1234);
+    delete view;
+}
+
 QTEST_MAIN(tst_qquickcustomaffector);
 
 #include "tst_qquickcustomaffector.moc"