QQuickItem: Make x/y/width/height bindable

This ports the four properties properties to Q_OBJECT_COMPAT_PROPERTY.
It is not possible to use Q_OBJECT_BINDABLE_PROPERTY, not even for the
simpler x and y properties, as QQuickItem calls the virtual
geometryChange method in the setters, making them non-trivial.

For width/height, we use the new property system to improve the
width/heightValid check: We return not only valid if the property has
explictily been set (either via a direct setter call, or because the
setter has been called when a binding evaluated), but also when a
binding is set. This matches the fact that implicitWidth/Height should
only be used when width/height is not specified. In theory, this could
help in cases where one sets both implicit and explicit properties for
Text, skipping one initial layout calculation.

As the setters now remove the binding (this aligns with the behavior of
writing through the meta-object system), a few test cases had to be
adjusted, which relied on the setter not removing it.
Further test changes were necessary because the location of a few
warnings changed, due to differences in binding order evaluation and
error reporting.


[ChangeLog][QtQuick][QQuickItem] The x, y, width and height properties
of QQuickItem are now bindable. This enables modifying their bindings
from C++. One could for instance swap the width of two items,
preserving the bindings:
// QML
Item {
  Rectangle { id: a; width: parent.width / 2 }
  Rectangle { id: b; width: parent.width / 3; anchors.right: a.left }
}
// C++
auto rootCtxt = engine.rootContext();
auto a = qobject_cast<QQuickItem*>(rootCtxt->objectForName(u"a"_qs));
auto b = qobject_cast<QQuickItem*>(rootCtxt->objectForName(u"b"_qs));
auto aBinding = a->bindableWidth().takeBinding();
auto bBinding = b->bindableWidth().takeBinding();
a->bindableWidth()->setBinding(bBinding);
b->bindableWidth()->setBinding(aBinding);
Afterwards, if the root item gets resized, the width of the rectangles
will still be adjusted.



[ChangeLog][QtQuick][QQuickItem][Important Behavior Changes] Calling
the setWidth, setHeight, setX and setY properties now removes any
existing binding from the corresponding property.

Change-Id: I5e1553611cb92b033247ada715cea48c962395bc
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

2 files changed, 32 insertions, 3 deletions

diff --git a/tests/auto/quick/qquickitem2/CMakeLists.txt b/tests/auto/quick/qquickitem2/CMakeLists.txt
index f60d1b2d55..6ecd164787 100644
--- a/tests/auto/quick/qquickitem2/CMakeLists.txt
+++ b/tests/auto/quick/qquickitem2/CMakeLists.txt
@@ -22,6 +22,8 @@ qt_internal_add_test(tst_qquickitem2
         Qt::GuiPrivate
         Qt::QmlPrivate
         Qt::QuickPrivate
+    LIBRARIES
+        Qt::TestPrivate
     TESTDATA ${test_data}
 )
 
diff --git a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
index 94f71af394..b5e2f5e141 100644
--- a/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem2/tst_qquickitem.cpp
@@ -42,6 +42,7 @@
 #include "../../shared/util.h"
 #include "../shared/visualtestutil.h"
 #include "../../shared/platforminputcontext.h"
+#include <QtTest/private/qpropertytesthelper_p.h>
 
 using namespace QQuickVisualTestUtil;
 
@@ -117,6 +118,8 @@ private slots:
 
     void childrenProperty();
     void resourcesProperty();
+    void bindableProperties_data();
+    void bindableProperties();
 
     void changeListener();
     void transformCrash();
@@ -2843,6 +2846,30 @@ void tst_QQuickItem::resourcesProperty()
     delete object;
 }
 
+void tst_QQuickItem::bindableProperties_data()
+{
+    QTest::addColumn<qreal>("initialValue");
+    QTest::addColumn<qreal>("newValue");
+    QTest::addColumn<QString>("property");
+
+    // can't simply use 3. or 3.0 for the numbers as qreal might
+    // be float instead of double...
+    QTest::addRow("x") << qreal(3) << qreal(14) << "x";
+    QTest::addRow("y") << qreal(10) << qreal(20) << "y";
+    QTest::addRow("width") << qreal(100) << qreal(200) << "width";
+    QTest::addRow("height") << qreal(50) << qreal(40) << "height";
+}
+
+void tst_QQuickItem::bindableProperties()
+{
+    QQuickItem item;
+    QFETCH(qreal, initialValue);
+    QFETCH(qreal, newValue);
+    QFETCH(QString, property);
+
+    QTestPrivate::testReadWritePropertyBasics(item, initialValue, newValue, property.toUtf8().constData());
+}
+
 void tst_QQuickItem::propertyChanges()
 {
     QQuickView *window = new QQuickView(nullptr);
@@ -2967,7 +2994,7 @@ void tst_QQuickItem::childrenRectBug()
 {
     QQuickView *window = new QQuickView(nullptr);
 
-    QString warning = testFileUrl("childrenRectBug.qml").toString() + ":7:5: QML Item: Binding loop detected for property \"height\"";
+    QString warning = testFileUrl("childrenRectBug.qml").toString() + ":11:9: QML Item: Binding loop detected for property \"height\"";
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning));
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning));
 
@@ -2988,11 +3015,11 @@ void tst_QQuickItem::childrenRectBug2()
 {
     QQuickView *window = new QQuickView(nullptr);
 
-    QString warning1 = testFileUrl("childrenRectBug2.qml").toString() + ":7:5: QML Item: Binding loop detected for property \"width\"";
+    QString warning1 = testFileUrl("childrenRectBug2.qml").toString() + ":10:9: QML Item: Binding loop detected for property \"width\"";
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning1));
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning1));
 
-    QString warning2 = testFileUrl("childrenRectBug2.qml").toString() + ":7:5: QML Item: Binding loop detected for property \"height\"";
+    QString warning2 = testFileUrl("childrenRectBug2.qml").toString() + ":11:9: QML Item: Binding loop detected for property \"height\"";
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning2));
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning2));
     QTest::ignoreMessage(QtWarningMsg, qPrintable(warning2));