- Qt 5.5
- Qt Multimedia
- QML Video Example
- trace.h Example File
- Qt 5.5.1 Reference Documentation

# trace.h Example File

video/qmlvideo/trace.h

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the Qt Mobility Components.
    **
    ** $QT_BEGIN_LICENSE:LGPL21$
    ** 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 2.1 or version 3 as published by the Free
    ** Software Foundation and appearing in the file LICENSE.LGPLv21 and
    ** LICENSE.LGPLv3 included in the packaging of this file. Please review the
    ** following information to ensure the GNU Lesser General Public License
    ** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
    ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
    **
    ** As a special exception, The Qt Company gives you certain additional
    ** rights. These rights are described in The Qt Company LGPL Exception
    ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
    **
    ** $QT_END_LICENSE$
    **
    ****************************************************************************/

    #ifndef TRACE_H
    #define TRACE_H

    #include <QtCore/QDebug>

    #define ENABLE_TRACE
    //#define VERBOSE_TRACE

    namespace Trace {

    class NullDebug
    {
    public:
        template <typename T>
        NullDebug& operator<<(const T&) { return *this; }
    };

    inline NullDebug nullDebug() { return NullDebug(); }

    template <typename T>
    struct PtrWrapper
    {
        PtrWrapper(const T *ptr) : m_ptr(ptr) { }
        const T *const m_ptr;
    };

    } // namespace Trace

    template <typename T>
    inline QDebug& operator<<(QDebug &debug, const Trace::PtrWrapper<T> &wrapper)
    {
        QDebugStateSaver saver(debug);
        debug.nospace() << '[' << static_cast<const void *>(wrapper.m_ptr) << ']';
        return debug;
    }

    template<typename T>
    inline const void *qtVoidPtr(const T *ptr)
    { return static_cast<const void *>(ptr); }

    #define qtThisPtr() qtVoidPtr(this)

    #ifdef ENABLE_TRACE
            inline QDebug qtTrace() { return qDebug() << "[qmlvideo]"; }
    #    ifdef VERBOSE_TRACE
            inline QDebug qtVerboseTrace() { return qtTrace(); }
    #    else
            inline Trace::NullDebug qtVerboseTrace() { return Trace::nullDebug(); }
    #    endif
    #else
        inline Trace::NullDebug qtTrace() { return Trace::nullDebug(); }
        inline Trace::NullDebug qtVerboseTrace() { return Trace::nullDebug(); }
    #endif

    #endif // TRACE_H