Add QQuickStyle

Now that we have a good place for it, we can share a common base class
for QQuickMaterialStyle and QQuickUniversalStyle. QQuickStyle implements
the inheritance pattern for attached styles, in one place.

Change-Id: I459d98f96ce7c6de1ce7ef716e859f459278d8ad
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>

12 files changed, 387 insertions, 315 deletions

diff --git a/src/controls/controls.pri b/src/controls/controls.pri
index 4db9fea4..005ee839 100644
--- a/src/controls/controls.pri
+++ b/src/controls/controls.pri
@@ -1,10 +1,12 @@
 HEADERS += \
     $$PWD/qquickproxytheme_p.h \
+    $$PWD/qquickstyle_p.h \
     $$PWD/qquickstyleselector_p.h \
     $$PWD/qquickstyleselector_p_p.h \
     $$PWD/qquickpaddedrectangle_p.h
 
 SOURCES += \
     $$PWD/qquickproxytheme.cpp \
+    $$PWD/qquickstyle.cpp \
     $$PWD/qquickstyleselector.cpp \
     $$PWD/qquickpaddedrectangle.cpp
diff --git a/src/controls/qquickstyle.cpp b/src/controls/qquickstyle.cpp
new file mode 100644
index 00000000..b83f8c2a
--- /dev/null
+++ b/src/controls/qquickstyle.cpp
@@ -0,0 +1,201 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Labs Controls module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qquickstyle_p.h"
+
+#include <QtQuick/private/qquickitem_p.h>
+
+QT_BEGIN_NAMESPACE
+
+static QQuickStyle *attachedStyle(const QMetaObject *type, QObject *object, bool create = false)
+{
+    if (!object)
+        return Q_NULLPTR;
+    int idx = -1;
+    return qobject_cast<QQuickStyle *>(qmlAttachedPropertiesObject(&idx, object, type, create));
+}
+
+static QQuickStyle *findParentStyle(const QMetaObject *type, QObject *object)
+{
+    QQuickItem *item = qobject_cast<QQuickItem *>(object);
+    if (item) {
+        // lookup parent items
+        QQuickItem *parent = item->parentItem();
+        while (parent) {
+            QQuickStyle *style = attachedStyle(type, parent);
+            if (style)
+                return style;
+            parent = parent->parentItem();
+        }
+
+        // fallback to item's window
+        QQuickWindow *window = item->window();
+        if (window) {
+            QQuickStyle *style = attachedStyle(type, window);
+            if (style)
+                return style;
+        }
+    }
+
+    // lookup parent window
+    QQuickWindow *window = qobject_cast<QQuickWindow *>(object);
+    if (window) {
+        QQuickWindow *parentWindow = qobject_cast<QQuickWindow *>(window->parent());
+        if (parentWindow) {
+            QQuickStyle *style = attachedStyle(type, window);
+            if (style)
+                return style;
+        }
+    }
+
+    // fallback to engine (global)
+    if (object) {
+        QQmlEngine *engine = qmlEngine(object);
+        if (engine) {
+            QByteArray name = QByteArray("_q_") + type->className();
+            QQuickStyle *style = engine->property(name).value<QQuickStyle*>();
+            if (!style) {
+                style = attachedStyle(type, engine, true);
+                engine->setProperty(name, QVariant::fromValue(style));
+            }
+            return style;
+        }
+    }
+
+    return Q_NULLPTR;
+}
+
+static QList<QQuickStyle *> findChildStyles(const QMetaObject *type, QObject *object)
+{
+    QList<QQuickStyle *> children;
+
+    QQuickItem *item = qobject_cast<QQuickItem *>(object);
+    if (!item) {
+        QQuickWindow *window = qobject_cast<QQuickWindow *>(object);
+        if (window) {
+            item = window->contentItem();
+
+            foreach (QObject *child, window->children()) {
+                QQuickWindow *childWindow = qobject_cast<QQuickWindow *>(child);
+                if (childWindow) {
+                    QQuickStyle *style = attachedStyle(type, childWindow);
+                    if (style)
+                        children += style;
+                }
+            }
+        }
+    }
+
+    if (item) {
+        foreach (QQuickItem *child, item->childItems()) {
+            QQuickStyle *style = attachedStyle(type, child);
+            if (style)
+                children += style;
+            else
+                children += findChildStyles(type, child);
+        }
+    }
+
+    return children;
+}
+
+QQuickStyle::QQuickStyle(QObject *parent) : QObject(parent)
+{
+    QQuickItem *item = qobject_cast<QQuickItem *>(parent);
+    if (item)
+        QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Parent);
+}
+
+QQuickStyle::~QQuickStyle()
+{
+    QQuickItem *item = qobject_cast<QQuickItem *>(parent());
+    if (item)
+        QQuickItemPrivate::get(item)->removeItemChangeListener(this, QQuickItemPrivate::Parent);
+
+    setParentStyle(Q_NULLPTR);
+}
+
+QList<QQuickStyle *> QQuickStyle::childStyles() const
+{
+    return m_childStyles;
+}
+
+QQuickStyle *QQuickStyle::parentStyle() const
+{
+    return m_parentStyle;
+}
+
+void QQuickStyle::setParentStyle(QQuickStyle *style)
+{
+    if (m_parentStyle != style) {
+        QQuickStyle *oldParent = m_parentStyle;
+        if (m_parentStyle)
+            m_parentStyle->m_childStyles.removeOne(this);
+        m_parentStyle = style;
+        if (style)
+            style->m_childStyles.append(this);
+        parentStyleChange(style, oldParent);
+    }
+}
+
+void QQuickStyle::init()
+{
+    QQuickStyle *parentStyle = findParentStyle(metaObject(), parent());
+    if (parentStyle)
+        setParentStyle(parentStyle);
+
+    QList<QQuickStyle *> children = findChildStyles(metaObject(), parent());
+    foreach (QQuickStyle *child, children)
+        child->setParentStyle(this);
+}
+
+void QQuickStyle::parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent)
+{
+    Q_UNUSED(newParent);
+    Q_UNUSED(oldParent);
+}
+
+void QQuickStyle::itemParentChanged(QQuickItem *item, QQuickItem *parent)
+{
+    QQuickStyle *style = attachedStyle(metaObject(), item);
+    if (style) {
+        QQuickStyle *parentStyle = findParentStyle(metaObject(), parent);
+        if (parentStyle)
+            style->setParentStyle(parentStyle);
+    }
+}
+
+QT_END_NAMESPACE
diff --git a/src/controls/qquickstyle_p.h b/src/controls/qquickstyle_p.h
new file mode 100644
index 00000000..3d4431cd
--- /dev/null
+++ b/src/controls/qquickstyle_p.h
@@ -0,0 +1,86 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the Qt Labs Controls module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQUICKSTYLE_P_H
+#define QQUICKSTYLE_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtQml/qqml.h>
+#include <QtCore/qlist.h>
+#include <QtCore/qobject.h>
+#include <QtCore/qpointer.h>
+#include <QtQuick/private/qquickitemchangelistener_p.h>
+
+QT_BEGIN_NAMESPACE
+
+class QQuickStyle : public QObject, public QQuickItemChangeListener
+{
+    Q_OBJECT
+
+public:
+    explicit QQuickStyle(QObject *parent = Q_NULLPTR);
+    ~QQuickStyle();
+
+protected:
+    void init();
+
+    QList<QQuickStyle *> childStyles() const;
+
+    QQuickStyle *parentStyle() const;
+    void setParentStyle(QQuickStyle *style);
+
+    virtual void parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent);
+
+    void itemParentChanged(QQuickItem *item, QQuickItem *parent) Q_DECL_OVERRIDE;
+
+private:
+    QList<QQuickStyle *> m_childStyles;
+    QPointer<QQuickStyle> m_parentStyle;
+};
+
+QT_END_NAMESPACE
+
+#endif // QQUICKSTYLE_P_H
diff --git a/src/imports/controls/controls.pro b/src/imports/controls/controls.pro
index 8c83eb6a..c3c5702c 100644
--- a/src/imports/controls/controls.pro
+++ b/src/imports/controls/controls.pro
@@ -19,7 +19,6 @@ RESOURCES += \
     $$PWD/qtlabscontrolsplugin.qrc
 
 include(controls.pri)
-include(shared/shared.pri)
 include(designer/designer.pri)
 
 CONFIG += no_cxx_module
diff --git a/src/imports/controls/material/material.pro b/src/imports/controls/material/material.pro
index 8391740d..06b9ed7d 100644
--- a/src/imports/controls/material/material.pro
+++ b/src/imports/controls/material/material.pro
@@ -17,7 +17,6 @@ RESOURCES += \
     $$PWD/qtlabsmaterialstyleplugin.qrc
 
 include(material.pri)
-include(../shared/shared.pri)
 
 CONFIG += no_cxx_module
 load(qml_plugin)
diff --git a/src/imports/controls/material/qquickmaterialstyle.cpp b/src/imports/controls/material/qquickmaterialstyle.cpp
index 24fbb62c..a3d2329a 100644
--- a/src/imports/controls/material/qquickmaterialstyle.cpp
+++ b/src/imports/controls/material/qquickmaterialstyle.cpp
@@ -35,12 +35,8 @@
 ****************************************************************************/
 
 #include "qquickmaterialstyle_p.h"
-#include "qquickstyle_p.h"
 
-#include <QtQml/qqmlengine.h>
-#include <QtQuick/qquickitem.h>
-#include <QtQuick/qquickwindow.h>
-#include <QtQuick/private/qquickitem_p.h>
+#include <QtLabsControls/private/qquickstyle_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -419,7 +415,7 @@ static const QColor switchDisabledTrackColorDark = "#19FFFFFF";
 static const QColor checkBoxUncheckedRippleColorLight = "#10000000";
 static const QColor checkBoxUncheckedRippleColorDark = "#20FFFFFF";
 
-QQuickMaterialStyle::QQuickMaterialStyle(QObject *parent) : QObject(parent),
+QQuickMaterialStyle::QQuickMaterialStyle(QObject *parent) : QQuickStyle(parent),
     m_explicitTheme(false),
     m_explicitPrimary(false),
     m_explicitAccent(false),
@@ -427,31 +423,12 @@ QQuickMaterialStyle::QQuickMaterialStyle(QObject *parent) : QObject(parent),
     m_primary(defaultPrimary),
     m_accent(defaultAccent)
 {
-    QQuickItem *item = qobject_cast<QQuickItem *>(parent);
-    if (item)
-        QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Parent);
-}
-
-QQuickMaterialStyle::~QQuickMaterialStyle()
-{
-    QQuickItem *item = qobject_cast<QQuickItem *>(parent());
-    if (item)
-        QQuickItemPrivate::get(item)->removeItemChangeListener(this, QQuickItemPrivate::Parent);
-
-    reparent(Q_NULLPTR);
+    init(); // TODO: lazy init?
 }
 
 QQuickMaterialStyle *QQuickMaterialStyle::qmlAttachedProperties(QObject *object)
 {
-    QQuickMaterialStyle *style = new QQuickMaterialStyle(object);
-    QQuickMaterialStyle *parent = QQuickStyle::findParent<QQuickMaterialStyle>(object);
-    if (parent)
-        style->reparent(parent);
-
-    QList<QQuickMaterialStyle *> childStyles = QQuickStyle::findChildren<QQuickMaterialStyle>(object);
-    foreach (QQuickMaterialStyle *child, childStyles)
-        child->reparent(style);
-    return style;
+    return new QQuickMaterialStyle(object);
 }
 
 QQuickMaterialStyle::Theme QQuickMaterialStyle::theme() const
@@ -464,9 +441,7 @@ void QQuickMaterialStyle::setTheme(Theme theme)
     m_explicitTheme = true;
     if (m_theme != theme) {
         m_theme = theme;
-        foreach (QQuickMaterialStyle *child, m_childStyles) {
-            child->inheritTheme(theme);
-        }
+        propagateTheme();
         emit themeChanged();
         emit paletteChanged();
     }
@@ -476,20 +451,27 @@ void QQuickMaterialStyle::inheritTheme(Theme theme)
 {
     if (!m_explicitTheme && m_theme != theme) {
         m_theme = theme;
-        foreach (QQuickMaterialStyle *child, m_childStyles) {
-            child->inheritTheme(theme);
-        }
+        propagateTheme();
         emit themeChanged();
         emit paletteChanged();
     }
 }
 
+void QQuickMaterialStyle::propagateTheme()
+{
+    foreach (QQuickStyle *child, childStyles()) {
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(child);
+        if (material)
+            material->inheritTheme(m_theme);
+    }
+}
+
 void QQuickMaterialStyle::resetTheme()
 {
     if (m_explicitTheme) {
         m_explicitTheme = false;
-        QQuickMaterialStyle *attachedParent = QQuickStyle::findParent<QQuickMaterialStyle>(parent());
-        inheritTheme(attachedParent ? attachedParent->theme() : defaultTheme);
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(parentStyle());
+        inheritTheme(material ? material->theme() : defaultTheme);
     }
 }
 
@@ -503,11 +485,9 @@ void QQuickMaterialStyle::setPrimary(QQuickMaterialStyle::Color color)
     m_explicitPrimary = true;
     if (m_primary != color) {
         m_primary = color;
+        propagatePrimary();
         emit primaryChanged();
         emit paletteChanged();
-
-        foreach (QQuickMaterialStyle *child, m_childStyles)
-            child->inheritPrimary(color);
     }
 }
 
@@ -515,18 +495,26 @@ void QQuickMaterialStyle::inheritPrimary(QQuickMaterialStyle::Color color)
 {
     if (!m_explicitPrimary && m_primary != color) {
         m_primary = color;
-        foreach (QQuickMaterialStyle *child, m_childStyles)
-            child->inheritPrimary(color);
+        propagatePrimary();
         emit primaryChanged();
     }
 }
 
+void QQuickMaterialStyle::propagatePrimary()
+{
+    foreach (QQuickStyle *child, childStyles()) {
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(child);
+        if (material)
+            material->inheritPrimary(m_primary);
+    }
+}
+
 void QQuickMaterialStyle::resetPrimary()
 {
     if (m_explicitPrimary) {
         m_explicitPrimary = false;
-        QQuickMaterialStyle *attachedParent = QQuickStyle::findParent<QQuickMaterialStyle>(parent());
-        inheritPrimary(attachedParent ? attachedParent->primary() : defaultPrimary);
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(parentStyle());
+        inheritPrimary(material ? material->primary() : defaultPrimary);
     }
 }
 
@@ -540,11 +528,9 @@ void QQuickMaterialStyle::setAccent(QQuickMaterialStyle::Color color)
     m_explicitAccent = true;
     if (m_accent != color) {
         m_accent = color;
+        propagateAccent();
         emit accentChanged();
         emit paletteChanged();
-
-        foreach (QQuickMaterialStyle *child, m_childStyles)
-            child->inheritAccent(color);
     }
 }
 
@@ -552,18 +538,26 @@ void QQuickMaterialStyle::inheritAccent(QQuickMaterialStyle::Color color)
 {
     if (!m_explicitAccent && m_accent != color) {
         m_accent = color;
-        foreach (QQuickMaterialStyle *child, m_childStyles)
-            child->inheritAccent(color);
+        propagateAccent();
         emit accentChanged();
     }
 }
 
+void QQuickMaterialStyle::propagateAccent()
+{
+    foreach (QQuickStyle *child, childStyles()) {
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(child);
+        if (material)
+            material->inheritAccent(m_accent);
+    }
+}
+
 void QQuickMaterialStyle::resetAccent()
 {
     if (m_explicitAccent) {
         m_explicitAccent = false;
-        QQuickMaterialStyle *attachedParent = QQuickStyle::findParent<QQuickMaterialStyle>(parent());
-        inheritAccent(attachedParent ? attachedParent->accent() : defaultAccent);
+        QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(parentStyle());
+        inheritAccent(material ? material->accent() : defaultAccent);
     }
 }
 
@@ -743,28 +737,14 @@ QColor QQuickMaterialStyle::color(QQuickMaterialStyle::Color color, QQuickMateri
     return colors[color][shade];
 }
 
-void QQuickMaterialStyle::reparent(QQuickMaterialStyle *style)
-{
-    if (m_parentStyle != style) {
-        if (m_parentStyle)
-            m_parentStyle->m_childStyles.remove(this);
-        m_parentStyle = style;
-        if (style) {
-            style->m_childStyles.insert(this);
-            inheritPrimary(style->primary());
-            inheritAccent(style->accent());
-            inheritTheme(style->theme());
-        }
-    }
-}
-
-void QQuickMaterialStyle::itemParentChanged(QQuickItem *item, QQuickItem *parentItem)
+void QQuickMaterialStyle::parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent)
 {
-    QQuickMaterialStyle *style = QQuickStyle::instance<QQuickMaterialStyle>(item);
-    if (style) {
-        QQuickMaterialStyle *parent = QQuickStyle::findParent<QQuickMaterialStyle>(parentItem);
-        if (parent)
-            style->reparent(parent);
+    Q_UNUSED(oldParent);
+    QQuickMaterialStyle *material = qobject_cast<QQuickMaterialStyle *>(newParent);
+    if (material) {
+        inheritPrimary(material->primary());
+        inheritAccent(material->accent());
+        inheritTheme(material->theme());
     }
 }
 
diff --git a/src/imports/controls/material/qquickmaterialstyle_p.h b/src/imports/controls/material/qquickmaterialstyle_p.h
index 1d2033e7..69891b9c 100644
--- a/src/imports/controls/material/qquickmaterialstyle_p.h
+++ b/src/imports/controls/material/qquickmaterialstyle_p.h
@@ -48,18 +48,14 @@
 // We mean it.
 //
 
-#include <QtQml/qqml.h>
-#include <QtCore/qset.h>
 #include <QtGui/qcolor.h>
-#include <QtCore/qobject.h>
-#include <QtCore/qpointer.h>
-#include <QtQuick/private/qquickitemchangelistener_p.h>
+#include <QtLabsControls/private/qquickstyle_p.h>
 
 QT_BEGIN_NAMESPACE
 
 class QQuickMaterialStylePrivate;
 
-class QQuickMaterialStyle : public QObject, public QQuickItemChangeListener
+class QQuickMaterialStyle : public QQuickStyle
 {
     Q_OBJECT
     Q_PROPERTY(Theme theme READ theme WRITE setTheme RESET resetTheme NOTIFY themeChanged FINAL)
@@ -147,13 +143,13 @@ public:
     Q_ENUM(Shade)
 
     explicit QQuickMaterialStyle(QObject *parent = Q_NULLPTR);
-    ~QQuickMaterialStyle();
 
     static QQuickMaterialStyle *qmlAttachedProperties(QObject *object);
 
     Theme theme() const;
     void setTheme(Theme theme);
     void inheritTheme(Theme theme);
+    void propagateTheme();
     void resetTheme();
 
     QColor primaryColorLight() const;
@@ -161,6 +157,7 @@ public:
     Color primary() const;
     void setPrimary(Color color);
     void inheritPrimary(Color color);
+    void propagatePrimary();
     void resetPrimary();
 
     QColor primaryColorDark() const;
@@ -168,6 +165,7 @@ public:
     Color accent() const;
     void setAccent(Color color);
     void inheritAccent(Color color);
+    void propagateAccent();
     void resetAccent();
 
     QColor accentColor() const;
@@ -211,13 +209,9 @@ Q_SIGNALS:
     void paletteChanged();
 
 protected:
-    void reparent(QQuickMaterialStyle *theme);
-    void itemParentChanged(QQuickItem *item, QQuickItem *parent) Q_DECL_OVERRIDE;
+    void parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent) Q_DECL_OVERRIDE;
 
 private:
-    QPointer<QQuickMaterialStyle> m_parentStyle;
-    QSet<QQuickMaterialStyle *> m_childStyles;
-
     bool m_explicitTheme;
     bool m_explicitPrimary;
     bool m_explicitAccent;
diff --git a/src/imports/controls/shared/qquickstyle_p.h b/src/imports/controls/shared/qquickstyle_p.h
deleted file mode 100644
index 0fd4f612..00000000
--- a/src/imports/controls/shared/qquickstyle_p.h
+++ /dev/null
@@ -1,157 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2015 The Qt Company Ltd.
-** Contact: http://www.qt.io/licensing/
-**
-** This file is part of the Qt Labs Controls module of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL3$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see http://www.qt.io/terms-conditions. For further
-** information use the contact form at http://www.qt.io/contact-us.
-**
-** GNU Lesser General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU Lesser
-** General Public License version 3 as published by the Free Software
-** Foundation and appearing in the file LICENSE.LGPLv3 included in the
-** packaging of this file. Please review the following information to
-** ensure the GNU Lesser General Public License version 3 requirements
-** will be met: https://www.gnu.org/licenses/lgpl.html.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 2.0 or later as published by the Free
-** Software Foundation and appearing in the file LICENSE.GPL included in
-** the packaging of this file. Please review the following information to
-** ensure the GNU General Public License version 2.0 requirements will be
-** met: http://www.gnu.org/licenses/gpl-2.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QQUICKSTYLE_P_H
-#define QQUICKSTYLE_P_H
-
-//
-//  W A R N I N G
-//  -------------
-//
-// This file is not part of the Qt API.  It exists purely as an
-// implementation detail.  This header file may change from version to
-// version without notice, or even be removed.
-//
-// We mean it.
-//
-
-#include <QtQml/qqml.h>
-#include <QtQml/qqmlengine.h>
-#include <QtQuick/qquickitem.h>
-#include <QtQuick/qquickwindow.h>
-
-QT_BEGIN_NAMESPACE
-
-namespace QQuickStyle
-{
-    template <typename T>
-    static T *instance(QObject *object)
-    {
-        if (object)
-            return qobject_cast<T*>(qmlAttachedPropertiesObject<T>(object, false));
-        return Q_NULLPTR;
-    }
-
-    template <typename T>
-    static T *findParent(QObject *object)
-    {
-        QQuickItem *item = qobject_cast<QQuickItem *>(object);
-        if (item) {
-            // lookup parent items
-            QQuickItem *parent = item->parentItem();
-            while (parent) {
-                T *attached = instance<T>(parent);
-                if (attached)
-                    return attached;
-                parent = parent->parentItem();
-            }
-
-            // fallback to item's window
-            QQuickWindow *window = item->window();
-            if (window) {
-                T *attached = instance<T>(window);
-                if (attached)
-                    return attached;
-            }
-        }
-
-        // lookup parent window
-        QQuickWindow *window = qobject_cast<QQuickWindow *>(object);
-        if (window) {
-            QQuickWindow *parentWindow = qobject_cast<QQuickWindow *>(window->parent());
-            if (parentWindow) {
-                T *attached = instance<T>(window);
-                if (attached)
-                    return attached;
-            }
-        }
-
-        // fallback to engine (global)
-        if (object) {
-            QQmlEngine *engine = qmlEngine(object);
-            if (engine) {
-                QByteArray name = QByteArray("_q_") + T::staticMetaObject.className();
-                T *instance = engine->property(name).value<T*>();
-                if (!instance) {
-                    instance = new T(engine);
-                    engine->setProperty(name, QVariant::fromValue(instance));
-                }
-                return instance;
-            }
-        }
-
-        return Q_NULLPTR;
-    }
-
-    template <typename T>
-    static QList<T *> findChildren(QObject *object)
-    {
-        QList<T *> children;
-
-        QQuickItem *item = qobject_cast<QQuickItem *>(object);
-        if (!item) {
-            QQuickWindow *window = qobject_cast<QQuickWindow *>(object);
-            if (window) {
-                item = window->contentItem();
-
-                foreach (QObject *child, window->children()) {
-                    QQuickWindow *childWindow = qobject_cast<QQuickWindow *>(child);
-                    if (childWindow) {
-                        T *attached = instance<T>(childWindow);
-                        if (attached)
-                            children += attached;
-                    }
-                }
-            }
-        }
-
-        if (item) {
-            foreach (QQuickItem *child, item->childItems()) {
-                T *attached = instance<T>(child);
-                if (attached)
-                    children += attached;
-                else
-                    children += findChildren<T>(child);
-            }
-        }
-
-        return children;
-    }
-}
-
-QT_END_NAMESPACE
-
-#endif // QQUICKSTYLE_P_H
diff --git a/src/imports/controls/shared/shared.pri b/src/imports/controls/shared/shared.pri
deleted file mode 100644
index 2979a615..00000000
--- a/src/imports/controls/shared/shared.pri
+++ /dev/null
@@ -1,4 +0,0 @@
-INCLUDEPATH += $$PWD
-
-HEADERS += \
-    $$PWD/qquickstyle_p.h
diff --git a/src/imports/controls/universal/qquickuniversalstyle.cpp b/src/imports/controls/universal/qquickuniversalstyle.cpp
index 10c4e812..f2bfd70d 100644
--- a/src/imports/controls/universal/qquickuniversalstyle.cpp
+++ b/src/imports/controls/universal/qquickuniversalstyle.cpp
@@ -35,10 +35,9 @@
 ****************************************************************************/
 
 #include "qquickuniversalstyle_p.h"
-#include "qquickstyle_p.h"
 
-#include <QtGui/qguiapplication.h>
-#include <QtQuick/private/qquickitem_p.h>
+#include <QtCore/qdebug.h>
+#include <QtLabsControls/private/qquickstyle_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -134,34 +133,15 @@ static QColor qquickuniversal_accent_color(QQuickUniversalStyle::Accent accent)
     return colors[accent];
 }
 
-QQuickUniversalStyle::QQuickUniversalStyle(QObject *parent) : QObject(parent),
+QQuickUniversalStyle::QQuickUniversalStyle(QObject *parent) : QQuickStyle(parent),
     m_hasTheme(false), m_hasAccent(false), m_theme(DefaultTheme), m_accent(DefaultAccent)
 {
-    QQuickItem *item = qobject_cast<QQuickItem *>(parent);
-    if (item)
-        QQuickItemPrivate::get(item)->addItemChangeListener(this, QQuickItemPrivate::Parent);
-}
-
-QQuickUniversalStyle::~QQuickUniversalStyle()
-{
-    QQuickItem *item = qobject_cast<QQuickItem *>(parent());
-    if (item)
-        QQuickItemPrivate::get(item)->removeItemChangeListener(this, QQuickItemPrivate::Parent);
-
-    reparent(Q_NULLPTR);
+    init(); // TODO: lazy init?
 }
 
 QQuickUniversalStyle *QQuickUniversalStyle::qmlAttachedProperties(QObject *object)
 {
-    QQuickUniversalStyle *style = new QQuickUniversalStyle(object);
-    QQuickUniversalStyle *parentStyle = QQuickStyle::findParent<QQuickUniversalStyle>(object);
-    if (parentStyle)
-        style->reparent(parentStyle);
-
-    QList<QQuickUniversalStyle *> children = QQuickStyle::findChildren<QQuickUniversalStyle>(object);
-    foreach (QQuickUniversalStyle *child, children)
-        child->reparent(style);
-    return style;
+    return new QQuickUniversalStyle(object);
 }
 
 QQuickUniversalStyle::Theme QQuickUniversalStyle::theme() const
@@ -174,8 +154,7 @@ void QQuickUniversalStyle::setTheme(Theme theme)
     m_hasTheme = true;
     if (m_theme != theme) {
         m_theme = theme;
-        foreach (QQuickUniversalStyle *child, m_childStyles)
-            child->inheritTheme(theme);
+        propagateTheme();
         emit themeChanged();
         emit paletteChanged();
     }
@@ -185,19 +164,27 @@ void QQuickUniversalStyle::inheritTheme(Theme theme)
 {
     if (!m_hasTheme && m_theme != theme) {
         m_theme = theme;
-        foreach (QQuickUniversalStyle *child, m_childStyles)
-            child->inheritTheme(theme);
+        propagateTheme();
         emit themeChanged();
         emit paletteChanged();
     }
 }
 
+void QQuickUniversalStyle::propagateTheme()
+{
+    foreach (QQuickStyle *child, childStyles()) {
+        QQuickUniversalStyle *universal = qobject_cast<QQuickUniversalStyle *>(child);
+        if (universal)
+            universal->inheritTheme(m_theme);
+    }
+}
+
 void QQuickUniversalStyle::resetTheme()
 {
     if (m_hasTheme) {
         m_hasTheme = false;
-        QQuickUniversalStyle *parentStyle = QQuickStyle::findParent<QQuickUniversalStyle>(parent());
-        inheritTheme(parentStyle ? parentStyle->theme() : DefaultTheme);
+        QQuickUniversalStyle *universal = qobject_cast<QQuickUniversalStyle *>(parentStyle());
+        inheritTheme(universal ? universal->theme() : DefaultTheme);
     }
 }
 
@@ -215,8 +202,7 @@ void QQuickUniversalStyle::setAccent(Accent accent)
     m_hasAccent = true;
     if (m_accent != accent) {
         m_accent = accent;
-        foreach (QQuickUniversalStyle *child, m_childStyles)
-            child->inheritAccent(accent);
+        propagateAccent();
         emit accentChanged();
     }
 }
@@ -225,18 +211,26 @@ void QQuickUniversalStyle::inheritAccent(Accent accent)
 {
     if (!m_hasAccent && m_accent != accent) {
         m_accent = accent;
-        foreach (QQuickUniversalStyle *child, m_childStyles)
-            child->inheritAccent(accent);
+        propagateAccent();
         emit accentChanged();
     }
 }
 
+void QQuickUniversalStyle::propagateAccent()
+{
+    foreach (QQuickStyle *child, childStyles()) {
+        QQuickUniversalStyle *universal = qobject_cast<QQuickUniversalStyle *>(child);
+        if (universal)
+            universal->inheritAccent(m_accent);
+    }
+}
+
 void QQuickUniversalStyle::resetAccent()
 {
     if (m_hasAccent) {
         m_hasAccent = false;
-        QQuickUniversalStyle *parentStyle = QQuickStyle::findParent<QQuickUniversalStyle>(parent());
-        inheritAccent(parentStyle ? parentStyle->accent() : DefaultAccent);
+        QQuickUniversalStyle *universal = qobject_cast<QQuickUniversalStyle *>(parentStyle());
+        inheritAccent(universal ? universal->accent() : DefaultAccent);
     }
 }
 
@@ -370,27 +364,13 @@ QColor QQuickUniversalStyle::getColor(SystemColor role) const
     return m_theme == QQuickUniversalStyle::Dark ? qquickuniversal_dark_color(role) : qquickuniversal_light_color(role);
 }
 
-void QQuickUniversalStyle::reparent(QQuickUniversalStyle *style)
-{
-    if (m_parentStyle != style) {
-        if (m_parentStyle)
-            m_parentStyle->m_childStyles.remove(this);
-        m_parentStyle = style;
-        if (style) {
-            style->m_childStyles.insert(this);
-            inheritTheme(style->theme());
-            inheritAccent(style->accent());
-        }
-    }
-}
-
-void QQuickUniversalStyle::itemParentChanged(QQuickItem *item, QQuickItem *parent)
+void QQuickUniversalStyle::parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent)
 {
-    QQuickUniversalStyle *style = QQuickStyle::instance<QQuickUniversalStyle>(item);
-    if (style) {
-        QQuickUniversalStyle *parentStyle = QQuickStyle::findParent<QQuickUniversalStyle>(parent);
-        if (parentStyle)
-            style->reparent(parentStyle);
+    Q_UNUSED(oldParent);
+    QQuickUniversalStyle *universal = qobject_cast<QQuickUniversalStyle *>(newParent);
+    if (universal) {
+        inheritTheme(universal->theme());
+        inheritAccent(universal->accent());
     }
 }
 
diff --git a/src/imports/controls/universal/qquickuniversalstyle_p.h b/src/imports/controls/universal/qquickuniversalstyle_p.h
index e8e9eafb..3bf0bb5d 100644
--- a/src/imports/controls/universal/qquickuniversalstyle_p.h
+++ b/src/imports/controls/universal/qquickuniversalstyle_p.h
@@ -48,18 +48,14 @@
 // We mean it.
 //
 
-#include <QtCore/qset.h>
-#include <QtCore/qpointer.h>
-#include <QtCore/qobject.h>
 #include <QtGui/qcolor.h>
-#include <QtQml/qqml.h>
-#include <QtQuick/private/qquickitemchangelistener_p.h>
+#include <QtLabsControls/private/qquickstyle_p.h>
 
 QT_BEGIN_NAMESPACE
 
 class QQuickUniversalStylePrivate;
 
-class QQuickUniversalStyle : public QObject, public QQuickItemChangeListener
+class QQuickUniversalStyle : public QQuickStyle
 {
     Q_OBJECT
     Q_PROPERTY(Theme theme READ theme WRITE setTheme RESET resetTheme NOTIFY themeChanged FINAL)
@@ -93,7 +89,6 @@ class QQuickUniversalStyle : public QObject, public QQuickItemChangeListener
 
 public:
     explicit QQuickUniversalStyle(QObject *parent = Q_NULLPTR);
-    ~QQuickUniversalStyle();
 
     static QQuickUniversalStyle *qmlAttachedProperties(QObject *object);
 
@@ -103,6 +98,7 @@ public:
     Theme theme() const;
     void setTheme(Theme theme);
     void inheritTheme(Theme theme);
+    void propagateTheme();
     void resetTheme();
 
     enum Accent {
@@ -132,10 +128,10 @@ public:
     Accent accent() const;
     void setAccent(Accent accent);
     void inheritAccent(Accent accent);
+    void propagateAccent();
     void resetAccent();
 
     QColor accentColor() const;
-
     QColor altHighColor() const;
     QColor altLowColor() const;
     QColor altMediumColor() const;
@@ -196,16 +192,13 @@ Q_SIGNALS:
     void paletteChanged();
 
 protected:
-    void reparent(QQuickUniversalStyle *parent);
-    void itemParentChanged(QQuickItem *item, QQuickItem *parent) Q_DECL_OVERRIDE;
+    void parentStyleChange(QQuickStyle *newParent, QQuickStyle *oldParent) Q_DECL_OVERRIDE;
 
 private:
     bool m_hasTheme;
     bool m_hasAccent;
     QQuickUniversalStyle::Theme m_theme;
     QQuickUniversalStyle::Accent m_accent;
-    QPointer<QQuickUniversalStyle> m_parentStyle;
-    QSet<QQuickUniversalStyle *> m_childStyles;
 };
 
 QT_END_NAMESPACE
diff --git a/src/imports/controls/universal/universal.pro b/src/imports/controls/universal/universal.pro
index 4e96256b..41cef97d 100644
--- a/src/imports/controls/universal/universal.pro
+++ b/src/imports/controls/universal/universal.pro
@@ -17,7 +17,6 @@ RESOURCES += \
     $$PWD/qtlabsuniversalstyleplugin.qrc
 
 include(universal.pri)
-include(../shared/shared.pri)
 
 CONFIG += no_cxx_module
 load(qml_plugin)