Revert "QQuickRectangle: Optimize setGradient"

This reverts commit 9709d04ba7787c853a1ddbeed0347eab27c0924f.

We changed this from using a signal for notification to using parenting. But
this cannot be done for two related reasons: the first:

    QtObject {
        property Gradient someGradient: Gradient {
            id: someGradient
        }
    }
    ...
    Rectangle {
        gradient: someGradient
    }

... should work, and no longer did, because the Gradient's parent was
the QtObject, not the Rectangle it was tied to. And secondly:

    Rectangle {
        id: rectOne
        gradient: Gradient {
            id: someGradient
        }
    }
    Rectangle {
        id: rectTwo
        gradient: someGradient
    }

... also didn't work anymore, as the Gradient was only notifying a
single Item about changes to it.

The easiest way to fix this is to just revert back to using a signal
connection.

This also caused problems in qtquickcontrols autotests.

Change-Id: Ic07dd02e9920596d0c047bfc23995b3be8c96c49
Task-number: QTBUG-60268
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 17 insertions, 2 deletions

diff --git a/src/quick/items/qquickrectangle.cpp b/src/quick/items/qquickrectangle.cpp
index 0c532bcd4c..65284eb532 100644
--- a/src/quick/items/qquickrectangle.cpp
+++ b/src/quick/items/qquickrectangle.cpp
@@ -1,6 +1,5 @@
 /****************************************************************************
 **
-** Copyright (C) 2017 Crimson AS <info@crimson.no>
 ** Copyright (C) 2016 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
@@ -270,9 +269,11 @@ QGradientStops QQuickGradient::gradientStops() const
 
 void QQuickGradient::doUpdate()
 {
-    static_cast<QQuickItem*>(parent())->update();
+    emit updated();
 }
 
+int QQuickRectanglePrivate::doUpdateSlotIdx = -1;
+
 /*!
     \qmltype Rectangle
     \instantiates QQuickRectangle
@@ -326,6 +327,11 @@ QQuickRectangle::QQuickRectangle(QQuickItem *parent)
     setFlag(ItemHasContents);
 }
 
+void QQuickRectangle::doUpdate()
+{
+    update();
+}
+
 /*!
     \qmlproperty bool QtQuick::Rectangle::antialiasing
 
@@ -390,7 +396,16 @@ void QQuickRectangle::setGradient(QQuickGradient *gradient)
     Q_D(QQuickRectangle);
     if (d->gradient == gradient)
         return;
+    static int updatedSignalIdx = -1;
+    if (updatedSignalIdx < 0)
+        updatedSignalIdx = QMetaMethod::fromSignal(&QQuickGradient::updated).methodIndex();
+    if (d->doUpdateSlotIdx < 0)
+        d->doUpdateSlotIdx = QQuickRectangle::staticMetaObject.indexOfSlot("doUpdate()");
+    if (d->gradient)
+        QMetaObject::disconnect(d->gradient, updatedSignalIdx, this, d->doUpdateSlotIdx);
     d->gradient = gradient;
+    if (d->gradient)
+        QMetaObject::connect(d->gradient, updatedSignalIdx, this, d->doUpdateSlotIdx);
     update();
 }