Fix style inheritance

When unable to find a parent item style on window change, use
the window style as a fallback to avoid a parentless style.

Task-number: QTBUG-52631
Change-Id: I5d31dc72075f06f865f01c3ee2411de6a1485677
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

2 files changed, 21 insertions, 5 deletions

diff --git a/src/quickcontrols2/qquickstyleattached.cpp b/src/quickcontrols2/qquickstyleattached.cpp
index cdfa902e..e72abde0 100644
--- a/src/quickcontrols2/qquickstyleattached.cpp
+++ b/src/quickcontrols2/qquickstyleattached.cpp
@@ -241,10 +241,13 @@ void QQuickStyleAttached::parentStyleChange(QQuickStyleAttached *newParent, QQui
 
 void QQuickStyleAttached::itemWindowChanged(QQuickWindow *window)
 {
-    Q_UNUSED(window);
+    QQuickStyleAttached *parentStyle = nullptr;
     QQuickItem *item = qobject_cast<QQuickItem *>(sender());
     if (item)
-        setParentStyle(findParentStyle(metaObject(), item));
+        parentStyle = findParentStyle(metaObject(), item);
+    if (!parentStyle)
+        parentStyle = attachedStyle(metaObject(), window);
+    setParentStyle(parentStyle);
 }
 
 void QQuickStyleAttached::itemParentChanged(QQuickItem *item, QQuickItem *parent)
diff --git a/tests/auto/qquickmaterialstyle/data/tst_material.qml b/tests/auto/qquickmaterialstyle/data/tst_material.qml
index 5cfec8d3..e1e100d7 100644
--- a/tests/auto/qquickmaterialstyle/data/tst_material.qml
+++ b/tests/auto/qquickmaterialstyle/data/tst_material.qml
@@ -41,6 +41,7 @@
 import QtQuick 2.2
 import QtQuick.Window 2.2
 import QtTest 1.0
+import QtQuick.Templates 2.0 as T
 import QtQuick.Controls 2.0
 import QtQuick.Controls.Material 2.0
 
@@ -127,6 +128,7 @@ TestCase {
             visible: true
             property alias popup: popupInstance
             property alias label: labelInstance
+            property alias label2: labelInstance2
             Popup {
                 id: popupInstance
                 Label {
@@ -136,6 +138,14 @@ TestCase {
                 }
                 Component.onCompleted: open()
             }
+            T.Popup {
+                contentItem: Label {
+                    id: labelInstance2
+                    text: "test"
+                    color: Material.textSelectionColor
+                }
+                Component.onCompleted: open()
+            }
         }
     }
 
@@ -291,16 +301,19 @@ TestCase {
         var popupObject = popupComponent.createObject(testCase)
         compare(popupObject.popup.Material.textSelectionColor.toString(), popupObject.Material.textSelectionColor.toString())
         compare(popupObject.label.color.toString(), popupObject.Material.textSelectionColor.toString())
+        compare(popupObject.label2.color.toString(), popupObject.Material.textSelectionColor.toString())
 
         popupObject.Material[prop] = data.value1
         compare(popupObject.Material[prop], data.value1)
         compare(popupObject.popup.Material.textSelectionColor.toString(), popupObject.Material.textSelectionColor.toString())
         compare(popupObject.label.color.toString(), popupObject.Material.textSelectionColor.toString())
+        compare(popupObject.label2.color.toString(), popupObject.Material.textSelectionColor.toString())
 
         popupObject.Material[prop] = data.value2
         compare(popupObject.Material[prop], data.value2)
         compare(popupObject.popup.Material.textSelectionColor.toString(), popupObject.Material.textSelectionColor.toString())
         compare(popupObject.label.color.toString(), popupObject.Material.textSelectionColor.toString())
+        compare(popupObject.label2.color.toString(), popupObject.Material.textSelectionColor.toString())
 
         popupObject.destroy()
     }
@@ -500,11 +513,11 @@ TestCase {
         compare(control.Material[prop], "#80808080")
 
         // unknown
-        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":57:9: QML Button: unknown Material." + prop + " value: 123")
+        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":58:9: QML Button: unknown Material." + prop + " value: 123")
         control.Material[prop] = 123
-        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":57:9: QML Button: unknown Material." + prop + " value: foo")
+        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":58:9: QML Button: unknown Material." + prop + " value: foo")
         control.Material[prop] = "foo"
-        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":57:9: QML Button: unknown Material." + prop + " value: #1")
+        ignoreWarning(Qt.resolvedUrl("tst_material.qml") + ":58:9: QML Button: unknown Material." + prop + " value: #1")
         control.Material[prop] = "#1"
 
         control.destroy()