Move the private code into a private/ folder

It's nice to have a similar include hierarchy at build time and install
time.

It also makes things more explicit

src/private/quick/QWidgetAdapter_quick.cpp

@@ -0,0 +1,154 @@
+/*  This file is part of KDDockWidgets.
+
+  Copyright (C) 2019 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com
+  Author: Sérgio Martins <sergio.martins@kdab.com>
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY;
+
+
+
+  without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/**
+ * @file
+ * @brief A class that is QWidget when building for QtWidgets, and QObject when building for QtQuick.
+ *
+ * Allows to have the same code base supporting both stacks.
+ *
+ * @author Sérgio Martins \<sergio.martins@kdab.com\>
+ */
+
+#include "QWidgetAdapter_quick_p.h"
+#include "FloatingWindow_p.h"
+
+#include <QResizeEvent>
+#include <QMouseEvent>
+#include <QWindow>
+
+using namespace KDDockWidgets;
+
+QWidgetAdapter::QWidgetAdapter(QQuickItem *parent, Qt::WindowFlags)
+    : QQuickItem(parent)
+{
+    this->setParent(parent); // also set parentItem
+
+    connect(this, &QQuickItem::widthChanged, this, [this] {
+        onResize(size());
+    });
+
+    connect(this, &QQuickItem::heightChanged, this, [this] {
+        onResize(size());
+    });
+}
+
+QWidgetAdapter::~QWidgetAdapter()
+{
+}
+
+void QWidgetAdapter::raiseAndActivate()
+{
+}
+
+bool QWidgetAdapter::onResize(QSize) { return false; }
+void QWidgetAdapter::onLayoutRequest() {}
+void QWidgetAdapter::onMousePress() {}
+void QWidgetAdapter::onMouseMove(QPoint) {}
+void QWidgetAdapter::onMouseRelease() {}
+void QWidgetAdapter::onCloseEvent(QCloseEvent *) {}
+
+
+void QWidgetAdapter::raise() {}
+
+FloatingWindow * QWidgetAdapter::floatingWindow() const
+{
+    return nullptr;
+}
+
+QRect QWidgetAdapter::geometry() const
+{
+    QRect r = rect();
+    r.moveTopLeft(QPointF(x(), y()).toPoint());
+    return r;
+}
+
+QRect QWidgetAdapter::rect() const
+{
+    return QRectF(0, 0, width(), height()).toRect();
+}
+
+void QWidgetAdapter::show()
+{
+    setVisible(true);
+}
+
+void QWidgetAdapter::setFixedHeight(int height)
+{
+    qDebug() << Q_FUNC_INFO << height << this;
+    setHeight(height);
+}
+
+void QWidgetAdapter::setFixedWidth(int width)
+{
+    qDebug() << Q_FUNC_INFO << width << this;
+    setWidth(width);
+}
+
+void QWidgetAdapter::setGeometry(QRect rect)
+{
+    qDebug() << Q_FUNC_INFO << rect << this;
+    setWidth(rect.width());
+    setHeight(rect.height());
+    setX(rect.x());
+    setY(rect.y());
+}
+
+void QWidgetAdapter::grabMouse() {}
+void QWidgetAdapter::releaseMouse() {}
+void QWidgetAdapter::setMinimumSize(QSize sz)
+{
+    m_minimumSize = sz;
+}
+
+void QWidgetAdapter::resize(QSize sz)
+{
+    qDebug() << Q_FUNC_INFO << sz << this;
+    setWidth(sz.width());
+    setHeight(sz.height());
+}
+
+QWindow *QWidgetAdapter::windowHandle() const { return nullptr; }
+
+void QWidgetAdapter::move(int x, int y)
+{
+    qDebug() << Q_FUNC_INFO << x << y << this;
+    setX(x);
+    setY(y);
+}
+
+void QWidgetAdapter::setParent(QQuickItem *p)
+{
+    QQuickItem::setParent(p);
+    QQuickItem::setParentItem(p);
+}
+
+void QWidgetAdapter::setFlag(Qt::WindowType f, bool on)
+{
+    if (auto w = windowHandle()) {
+        w->setFlag(f, on);
+    } else {
+        qWarning() << Q_FUNC_INFO << "Implement me";
+    }
+}
+