Add proper abstractions to the grid layout engine.

The abstractions are needed so that they can work with both
QGraphicsLayouts and QtQuick.Layouts.

Since the plan is to move the engine to QtGui, this means that the
engine cannot have any references to anything in the QtWidgets module.

As a consequence of that several things had to be done:
* The style info object had to be redone with an abstraction layer
  to get rid of style and widget dependency. (Abstract class is
  called QAbstractLayoutStyleInfo)
* QGridLayoutEngine must be subclassed due to some specializations for
  QGraphicsLayoutItem, manifested as QGraphicsGridLayoutEngine.
* QGridLayoutItem must be subclassed due to some specializations for
  QGraphicsLayoutItem, manifested as QGraphicsGridLayoutEngineItem.

Did also some minor cleanups, reordered arguments so that all styleInfo
arguments are last in all function calls

This also fixes QTBUG-35099 (bug was spotted during this refactoring)

Task-number: QTBUG-35099

Change-Id: If49d40f71870dc8d99d2e145be158e3080b595fa
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 136 insertions, 0 deletions

diff --git a/src/gui/util/qlayoutpolicy.cpp b/src/gui/util/qlayoutpolicy.cpp
new file mode 100644
index 0000000000..9a154768eb
--- /dev/null
+++ b/src/gui/util/qlayoutpolicy.cpp
@@ -0,0 +1,136 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Quick Layouts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 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 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qlayoutpolicy_p.h"
+#include <QtCore/qdebug.h>
+#include <QtCore/qdatastream.h>
+
+QT_BEGIN_NAMESPACE
+
+void QLayoutPolicy::setControlType(ControlType type)
+{
+    /*
+        The control type is a flag type, with values 0x1, 0x2, 0x4, 0x8, 0x10,
+        etc. In memory, we pack it onto the available bits (CTSize) in
+        setControlType(), and unpack it here.
+
+        Example:
+
+            0x00000001 maps to 0
+            0x00000002 maps to 1
+            0x00000004 maps to 2
+            0x00000008 maps to 3
+            etc.
+    */
+
+    int i = 0;
+    while (true) {
+        if (type & (0x1 << i)) {
+            bits.ctype = i;
+            return;
+        }
+        ++i;
+    }
+}
+
+QLayoutPolicy::ControlType QLayoutPolicy::controlType() const
+{
+    return QLayoutPolicy::ControlType(1 << bits.ctype);
+}
+
+#ifndef QT_NO_DATASTREAM
+
+/*!
+    \relates QLayoutPolicy
+
+    Writes the size \a policy to the data stream \a stream.
+
+    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
+*/
+QDataStream &operator<<(QDataStream &stream, const QLayoutPolicy &policy)
+{
+    // The order here is for historical reasons. (compatibility with Qt4)
+    quint32 data = (policy.bits.horPolicy |         // [0, 3]
+                    policy.bits.verPolicy << 4 |    // [4, 7]
+                    policy.bits.hfw << 8 |          // [8]
+                    policy.bits.ctype << 9 |        // [9, 13]
+                    policy.bits.wfh << 14 |         // [14]
+                  //policy.bits.padding << 15 |     // [15]
+                    policy.bits.verStretch << 16 |  // [16, 23]
+                    policy.bits.horStretch << 24);  // [24, 31]
+    return stream << data;
+}
+
+#define VALUE_OF_BITS(data, bitstart, bitcount) ((data >> bitstart) & ((1 << bitcount) -1))
+
+/*!
+    \relates QLayoutPolicy
+
+    Reads the size \a policy from the data stream \a stream.
+
+    \sa{Serializing Qt Data Types}{Format of the QDataStream operators}
+*/
+QDataStream &operator>>(QDataStream &stream, QLayoutPolicy &policy)
+{
+    quint32 data;
+    stream >> data;
+    policy.bits.horPolicy =  VALUE_OF_BITS(data, 0, 4);
+    policy.bits.verPolicy =  VALUE_OF_BITS(data, 4, 4);
+    policy.bits.hfw =        VALUE_OF_BITS(data, 8, 1);
+    policy.bits.ctype =      VALUE_OF_BITS(data, 9, 5);
+    policy.bits.wfh =        VALUE_OF_BITS(data, 14, 1);
+    policy.bits.padding =   0;
+    policy.bits.verStretch = VALUE_OF_BITS(data, 16, 8);
+    policy.bits.horStretch = VALUE_OF_BITS(data, 24, 8);
+    return stream;
+}
+#endif // QT_NO_DATASTREAM
+
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug dbg, const QLayoutPolicy &p)
+{
+    dbg.nospace() << "QLayoutPolicy(horizontalPolicy = " << p.horizontalPolicy()
+                  << ", verticalPolicy = " << p.verticalPolicy() << ')';
+    return dbg.space();
+}
+#endif
+
+QT_END_NAMESPACE