Particles: reduce excessive hash accesses to a more passable level.

By caching the group id in the particle emitter, and groups in the
painter.

Test case: samegame, 1 player, click 1 set of 3 stones, quit.
QQuickParticleSystem::emittersChanged(), before patch:
 - 64M instr. inclusive
 - 145,880 calls to findNode (29M instr.)
after:
 - 21M instr. inclusive
 - 0 calls to findNode
 - 25 calls to QQuickParticlePainter::recalculateGroupIds (9800 instr.
   inclusive).

Change-Id: I4aba9d50100513c6b7cdd230e30b3aecaf84485a
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

1 files changed, 38 insertions, 8 deletions

diff --git a/src/particles/qquickparticlepainter.cpp b/src/particles/qquickparticlepainter.cpp
index 134689713d..556d137fd4 100644
--- a/src/particles/qquickparticlepainter.cpp
+++ b/src/particles/qquickparticlepainter.cpp
@@ -64,9 +64,13 @@ QT_BEGIN_NAMESPACE
 
     If empty, it will paint the default particle group ("").
 */
-QQuickParticlePainter::QQuickParticlePainter(QQuickItem *parent) :
-    QQuickItem(parent),
-    m_system(0), m_count(0), m_pleaseReset(true), m_window(0)
+QQuickParticlePainter::QQuickParticlePainter(QQuickItem *parent)
+    : QQuickItem(parent)
+    , m_system(0)
+    , m_count(0)
+    , m_pleaseReset(true)
+    , m_window(0)
+    , m_groupIdsNeedRecalculation(false)
 {
 }
 
@@ -89,11 +93,32 @@ void QQuickParticlePainter::componentComplete()
     QQuickItem::componentComplete();
 }
 
+void QQuickParticlePainter::recalculateGroupIds() const
+{
+    if (!m_system) {
+        m_groupIds.clear();
+        return;
+    }
+
+    m_groupIdsNeedRecalculation = false;
+    m_groupIds.clear();
+
+    for (const QString &str : groups()) {
+        QQuickParticleGroupData::ID groupId = m_system->groupIds.value(str, QQuickParticleGroupData::InvalidID);
+        if (groupId == QQuickParticleGroupData::InvalidID) {
+            // invalid data, not finished setting up, or whatever. Fallback: do not cache.
+            m_groupIdsNeedRecalculation = true;
+        } else {
+            m_groupIds.append(groupId);
+        }
+    }
+}
 
 void QQuickParticlePainter::setSystem(QQuickParticleSystem *arg)
 {
     if (m_system != arg) {
         m_system = arg;
+        m_groupIdsNeedRecalculation = true;
         if (m_system){
             m_system->registerParticlePainter(this);
             reset();
@@ -102,6 +127,16 @@ void QQuickParticlePainter::setSystem(QQuickParticleSystem *arg)
     }
 }
 
+void QQuickParticlePainter::setGroups(const QStringList &arg)
+{
+    if (m_groups != arg) {
+        m_groups = arg;
+        m_groupIdsNeedRecalculation = true;
+        //Note: The system watches this as it has to recalc things when groups change. It will request a reset if necessary
+        Q_EMIT groupsChanged(arg);
+    }
+}
+
 void QQuickParticlePainter::load(QQuickParticleData* d)
 {
     initialize(d->group, d->index);
@@ -133,11 +168,6 @@ void QQuickParticlePainter::setCount(int c)//### TODO: some resizeing so that pa
     reset();
 }
 
-int QQuickParticlePainter::count()
-{
-    return m_count;
-}
-
 void QQuickParticlePainter::calcSystemOffset(bool resetPending)
 {
     if (!m_system || !parentItem())