QQuickRectangle: Use parenting on QQuickPen to speed up pen changes

We know that signal connections are slow, so let's not use them. QObject
has a parent pointer sitting there that looks nice and ripe, so:
let's set the parent pointer ourselves, and call update() via QQuickPen.

This improves delegates_rect_border.qml on my mbp by ~5%:
    Before: 394.6  frames; using  samples; MedianAll=395; StdDev=2.30217, CoV=0.00583419
    After:  417.4  frames; using  samples; MedianAll=417; StdDev=1.67332, CoV=0.00400891

... and should additionally decrease memory (no more signal connection).
Hopefully, the decrease in allocation and increase in performance might also
help with stability, since some systems seem a little flappy with this one.

Change-Id: I885654d606bc77d2949b9db81217426cf367b081
Reviewed-by: Gunnar Sletta <gunnar@crimson.no>
Reviewed-by: Michael Brasser <michael.brasser@live.com>

2 files changed, 4 insertions, 7 deletions

diff --git a/src/quick/items/qquickrectangle.cpp b/src/quick/items/qquickrectangle.cpp
index cbf0cdad64..7d8e4de1c0 100644
--- a/src/quick/items/qquickrectangle.cpp
+++ b/src/quick/items/qquickrectangle.cpp
@@ -90,6 +90,7 @@ void QQuickPen::setWidth(qreal w)
 
     m_width = w;
     m_valid = m_color.alpha() && (qRound(m_width) >= 1 || (!m_aligned && m_width > 0));
+    static_cast<QQuickItem*>(parent())->update();
     emit penChanged();
 }
 
@@ -102,6 +103,7 @@ void QQuickPen::setColor(const QColor &c)
 {
     m_color = c;
     m_valid = m_color.alpha() && (qRound(m_width) >= 1 || (!m_aligned && m_width > 0));
+    static_cast<QQuickItem*>(parent())->update();
     emit penChanged();
 }
 
@@ -116,6 +118,7 @@ void QQuickPen::setPixelAligned(bool aligned)
         return;
     m_aligned = aligned;
     m_valid = m_color.alpha() && (qRound(m_width) >= 1 || (!m_aligned && m_width > 0));
+    static_cast<QQuickItem*>(parent())->update();
     emit penChanged();
 }
 
@@ -358,12 +361,7 @@ QQuickPen *QQuickRectangle::border()
     Q_D(QQuickRectangle);
     if (!d->pen) {
         d->pen = new QQuickPen;
-        static int penChangedSignalIdx = -1;
-        if (penChangedSignalIdx < 0)
-            penChangedSignalIdx = QMetaMethod::fromSignal(&QQuickPen::penChanged).methodIndex();
-        if (d->doUpdateSlotIdx < 0)
-            d->doUpdateSlotIdx = QQuickRectangle::staticMetaObject.indexOfSlot("doUpdate()");
-        QMetaObject::connect(d->pen, penChangedSignalIdx, this, d->doUpdateSlotIdx);
+        QQml_setParent_noEvent(d->pen, this);
     }
     return d->pen;
 }
diff --git a/src/quick/items/qquickrectangle_p_p.h b/src/quick/items/qquickrectangle_p_p.h
index b7cd91bd73..3c1aaf7661 100644
--- a/src/quick/items/qquickrectangle_p_p.h
+++ b/src/quick/items/qquickrectangle_p_p.h
@@ -70,7 +70,6 @@ public:
 
     ~QQuickRectanglePrivate()
     {
-        delete pen;
     }
 
     QColor color;