Share style inheritance related helpers

Usage:

    # +material/material.pro
    include(../shared/shared.pri)

    // qquickmaterialstyle.cpp
    #include "qquickstyle_p.h"

    QQuickMaterialStyle *style =
        QQuickStyle::instance<QQuickMaterialStyle>(item);
    // ...

    QQuickMaterialStyle *parent =
        QQuickStyle::findParent<QQuickMaterialStyle>(this);
    // ...

    QList<QQuickMaterialStyle *> children =
        QQuickStyle::findChildren<QQuickMaterialStyle>(object);
    // ...

Change-Id: I2c01a1aa36805f16d83fa60ab25b2cc29e6a43cc
Reviewed-by: Mitch Curtis <mitch.curtis@theqtcompany.com>

5 files changed, 179 insertions, 100 deletions

diff --git a/src/imports/controls/controls.pro b/src/imports/controls/controls.pro
index 14e085dd..a7aec7e5 100644
--- a/src/imports/controls/controls.pro
+++ b/src/imports/controls/controls.pro
@@ -20,6 +20,7 @@ OTHER_FILES += \
     $$PWD/theme.json
 
 include(controls.pri)
+include(shared/shared.pri)
 include(designer/designer.pri)
 
 CONFIG += no_cxx_module
diff --git a/src/imports/controls/qquicktheme.cpp b/src/imports/controls/qquicktheme.cpp
index 7fec28c9..f0345df2 100644
--- a/src/imports/controls/qquicktheme.cpp
+++ b/src/imports/controls/qquicktheme.cpp
@@ -36,6 +36,7 @@
 
 #include "qquicktheme_p.h"
 #include "qquickthemedata_p.h"
+#include "qquickstyle_p.h"
 
 #include <QtCore/qset.h>
 #include <QtCore/qpointer.h>
@@ -100,100 +101,6 @@ QT_BEGIN_NAMESPACE
 
 Q_GLOBAL_STATIC_WITH_ARGS(QQuickThemeData, globalThemeData, (QString::fromLatin1(":/qtlabscontrols/theme.json")))
 
-static QQuickThemeAttached *themeInstance(QQmlEngine *engine)
-{
-    QQuickThemeAttached *theme = engine->property("_q_quicktheme").value<QQuickThemeAttached *>();
-    if (!theme) {
-        theme = new QQuickThemeAttached(*globalThemeData(), engine);
-        engine->setProperty("_q_quicktheme", QVariant::fromValue(theme));
-    }
-    return theme;
-}
-
-static QQuickThemeAttached *attachedTheme(QObject *object)
-{
-    if (object)
-        return qobject_cast<QQuickThemeAttached*>(qmlAttachedPropertiesObject<QQuickThemeAttached>(object, false));
-    return Q_NULLPTR;
-}
-
-static QQuickThemeAttached *findParentTheme(QObject *object)
-{
-    QQuickItem *item = qobject_cast<QQuickItem *>(object);
-    if (item) {
-        // lookup parent items
-        QQuickItem *parent = item->parentItem();
-        while (parent) {
-            QQuickThemeAttached *attached = attachedTheme(parent);
-            if (attached)
-                return attached;
-            parent = parent->parentItem();
-        }
-
-        // fallback to item's window theme
-        QQuickWindow *window = item->window();
-        if (window) {
-            QQuickThemeAttached *attached = attachedTheme(window);
-            if (attached)
-                return attached;
-        }
-    }
-
-    // lookup parent window theme
-    QQuickWindow *window = qobject_cast<QQuickWindow *>(object);
-    if (window) {
-        QQuickWindow *parentWindow = qobject_cast<QQuickWindow *>(window->parent());
-        if (parentWindow) {
-            QQuickThemeAttached *attached = attachedTheme(window);
-            if (attached)
-                return attached;
-        }
-    }
-
-    // fallback to global theme
-    if (object) {
-        QQmlEngine *engine = qmlEngine(object);
-        if (engine)
-            return themeInstance(engine);
-    }
-
-    return Q_NULLPTR;
-}
-
-static QList<QQuickThemeAttached *> findChildThemes(QObject *object)
-{
-    QList<QQuickThemeAttached *> themes;
-
-    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) {
-                    QQuickThemeAttached *theme = attachedTheme(childWindow);
-                    if (theme)
-                        themes += theme;
-                }
-            }
-        }
-    }
-
-    if (item) {
-        foreach (QQuickItem *child, item->childItems()) {
-            QQuickThemeAttached *theme = attachedTheme(child);
-            if (theme)
-                themes += theme;
-            else
-                themes += findChildThemes(child);
-        }
-    }
-
-    return themes;
-}
-
 class QQuickThemeAttachedPrivate : public QObjectPrivate, public QQuickItemChangeListener
 {
     Q_DECLARE_PUBLIC(QQuickThemeAttached)
@@ -433,20 +340,29 @@ void QQuickThemeAttachedPrivate::inherit(QQuickThemeAttached *theme)
 const QQuickThemeData &QQuickThemeAttachedPrivate::resolve() const
 {
     Q_Q(const QQuickThemeAttached);
-    QQuickThemeAttached *theme = findParentTheme(const_cast<QQuickThemeAttached *>(q));
+    QQuickThemeAttached *theme = QQuickStyle::findParent<QQuickThemeAttached>(const_cast<QQuickThemeAttached *>(q));
     return theme ? theme->d_func()->data : *globalThemeData();
 }
 
 void QQuickThemeAttachedPrivate::itemParentChanged(QQuickItem *item, QQuickItem *)
 {
-    QQuickThemeAttached *theme = attachedTheme(item);
+    QQuickThemeAttached *theme = QQuickStyle::instance<QQuickThemeAttached>(item);
     if (theme) {
-        QQuickThemeAttached *parent = findParentTheme(theme);
+        QQuickThemeAttached *parent = QQuickStyle::findParent<QQuickThemeAttached>(theme);
         if (parent)
             theme->setParentTheme(parent);
     }
 }
 
+QQuickThemeAttached::QQuickThemeAttached(QObject *parent) :
+    QObject(*(new QQuickThemeAttachedPrivate(*globalThemeData())), parent)
+{
+    Q_D(QQuickThemeAttached);
+    QQuickItem *item = qobject_cast<QQuickItem *>(parent);
+    if (item)
+        QQuickItemPrivate::get(item)->addItemChangeListener(d, QQuickItemPrivate::Parent);
+}
+
 QQuickThemeAttached::QQuickThemeAttached(const QQuickThemeData &data, QObject *parent) :
     QObject(*(new QQuickThemeAttachedPrivate(data)), parent)
 {
@@ -469,15 +385,15 @@ QQuickThemeAttached::~QQuickThemeAttached()
 QQuickThemeAttached *QQuickThemeAttached::qmlAttachedProperties(QObject *object)
 {
     QQuickThemeAttached *theme = Q_NULLPTR;
-    QQuickThemeAttached *parent = findParentTheme(object);
+    QQuickThemeAttached *parent = QQuickStyle::findParent<QQuickThemeAttached>(object);
     if (parent) {
         theme = new QQuickThemeAttached(parent->d_func()->data, object);
         theme->setParentTheme(parent);
     } else {
-        theme = new QQuickThemeAttached(*globalThemeData(), object);
+        theme = new QQuickThemeAttached(object);
     }
 
-    QList<QQuickThemeAttached *> childThemes = findChildThemes(object);
+    QList<QQuickThemeAttached *> childThemes = QQuickStyle::findChildren<QQuickThemeAttached>(object);
     foreach (QQuickThemeAttached *child, childThemes)
         child->setParentTheme(theme);
     return theme;
diff --git a/src/imports/controls/qquicktheme_p.h b/src/imports/controls/qquicktheme_p.h
index 02ad5619..0d204537 100644
--- a/src/imports/controls/qquicktheme_p.h
+++ b/src/imports/controls/qquicktheme_p.h
@@ -73,6 +73,7 @@ class QQuickThemeAttached : public QObject
     Q_PROPERTY(QColor textColor READ textColor WRITE setTextColor RESET resetTextColor NOTIFY textColorChanged FINAL)
 
 public:
+    explicit QQuickThemeAttached(QObject *parent = Q_NULLPTR);
     explicit QQuickThemeAttached(const QQuickThemeData &data, QObject *parent = Q_NULLPTR);
     ~QQuickThemeAttached();
 
diff --git a/src/imports/controls/shared/qquickstyle_p.h b/src/imports/controls/shared/qquickstyle_p.h
new file mode 100644
index 00000000..0fd4f612
--- /dev/null
+++ b/src/imports/controls/shared/qquickstyle_p.h
@@ -0,0 +1,157 @@
+/****************************************************************************
+**
+** 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
new file mode 100644
index 00000000..2979a615
--- /dev/null
+++ b/src/imports/controls/shared/shared.pri
@@ -0,0 +1,4 @@
+INCLUDEPATH += $$PWD
+
+HEADERS += \
+    $$PWD/qquickstyle_p.h