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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtMultimedia module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** 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, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.1, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "qabstractvideosurface_p.h"
QT_BEGIN_NAMESPACE
/*!
\class QAbstractVideoSurface
\brief The QAbstractVideoSurface class is a base class for video presentation surfaces.
\preliminary
\since 4.6
The QAbstractVideoSurface class defines the standard interface that video producers use to
inter-operate with video presentation surfaces. It is not supposed to be instantiated directly.
Instead, you should subclass it to create new video surfaces.
A video surface presents a continuous stream of identically formatted frames, where the format
of each frame is compatible with a stream format supplied when starting a presentation.
A list of pixel formats a surface can present is given by the supportedPixelFormats() function,
and the isFormatSupported() function will test if a complete video format is supported. In
some cases when a format is not supported; isFormatSupported() may suggest a similar format.
For example if a surface supports fixed set of resolutions it may suggest the smallest
supported resolution that contains the proposed resolution.
The start() function takes a supported format and enables a video surface. Once started a
surface will begin displaying the frames it receives in the present() function. Surfaces may
hold a reference to the buffer of a presented video frame until a new frame is presented or
streaming is stopped. The stop() function will disable a surface and a release any video
buffers it holds references to.
*/
/*!
\enum QAbstractVideoSurface::Error
This enum describes the errors that may be returned by the error() function.
\value NoError No error occurred.
\value UnsupportedFormatError A video format was not supported.
\value IncorrectFormatError A video frame was not compatible with the format of the surface.
\value StoppedError The surface has not been started.
\value ResourceError The surface could not allocate some resource.
*/
/*!
Constructs a video surface with the given \a parent.
*/
QAbstractVideoSurface::QAbstractVideoSurface(QObject *parent)
: QObject(*new QAbstractVideoSurfacePrivate, parent)
{
}
/*!
\internal
*/
QAbstractVideoSurface::QAbstractVideoSurface(QAbstractVideoSurfacePrivate &dd, QObject *parent)
: QObject(dd, parent)
{
}
/*!
Destroys a video surface.
*/
QAbstractVideoSurface::~QAbstractVideoSurface()
{
}
/*!
\fn QAbstractVideoSurface::supportedPixelFormats(QAbstractVideoBuffer::HandleType type) const
Returns a list of pixel formats a video surface can present for a given handle \a type.
The pixel formats returned for the QAbstractVideoBuffer::NoHandle type are valid for any buffer
that can be mapped in read-only mode.
Types that are first in the list can be assumed to be faster to render.
*/
/*!
Tests a video \a format to determine if a surface can accept it. If the format isn't supported
the surface may suggest a \a similar format that is supported.
Returns true if the format is supported by the surface, and false otherwise.
*/
bool QAbstractVideoSurface::isFormatSupported(
const QVideoSurfaceFormat &format, QVideoSurfaceFormat *similar) const
{
Q_UNUSED(similar);
return supportedPixelFormats(format.handleType()).contains(format.pixelFormat());
}
/*!
\fn QAbstractVideoSurface::supportedFormatsChanged()
Signals that the set of formats supported by a video surface has changed.
\sa supportedPixelFormats(), isFormatSupported()
*/
/*!
Returns the format of a video surface.
*/
QVideoSurfaceFormat QAbstractVideoSurface::surfaceFormat() const
{
return d_func()->format;
}
/*!
\fn QAbstractVideoSurface::surfaceFormatChanged(const QVideoSurfaceFormat &format)
Signals that the configured \a format of a video surface has changed.
\sa surfaceFormat(), start()
*/
/*!
Starts a video surface presenting \a format frames.
Returns true if the surface was started, and false if an error occurred.
\sa isStarted(), stop()
*/
bool QAbstractVideoSurface::start(const QVideoSurfaceFormat &format)
{
Q_D(QAbstractVideoSurface);
bool wasStarted = d->started;
d->started = true;
d->format = format;
d->error = NoError;
emit surfaceFormatChanged(d->format);
if (!wasStarted)
emit startedChanged(true);
return true;
}
/*!
Stops a video surface presenting frames and releases any resources acquired in start().
\sa isStarted(), start()
*/
void QAbstractVideoSurface::stop()
{
Q_D(QAbstractVideoSurface);
if (d->started) {
d->format = QVideoSurfaceFormat();
d->started = false;
emit startedChanged(false);
emit surfaceFormatChanged(d->format);
}
}
/*!
Indicates whether a video surface has been started.
Returns true if the surface has been started, and false otherwise.
*/
bool QAbstractVideoSurface::isStarted() const
{
return d_func()->started;
}
/*!
\fn QAbstractVideoSurface::startedChanged(bool started)
Signals that the \a started state of a video surface has changed.
\sa isStarted(), start(), stop()
*/
/*!
\fn QAbstractVideoSurface::present(const QVideoFrame &frame)
Presents a video \a frame.
Returns true if the frame was presented, and false if an error occurred.
Not all surfaces will block until the presentation of a frame has completed. Calling present()
on a non-blocking surface may fail if called before the presentation of a previous frame has
completed. In such cases the surface may not return to a ready state until it's had an
opportunity to process events.
If present() fails for any other reason the surface will immediately enter the stopped state
and an error() value will be set.
A video surface must be in the started state for present() to succeed, and the format of the
video frame must be compatible with the current video surface format.
\sa error()
*/
/*!
Returns the last error that occurred.
If a surface fails to start(), or stops unexpectedly this function can be called to discover
what error occurred.
*/
QAbstractVideoSurface::Error QAbstractVideoSurface::error() const
{
return d_func()->error;
}
/*!
Sets the value of error() to \a error.
*/
void QAbstractVideoSurface::setError(Error error)
{
Q_D(QAbstractVideoSurface);
d->error = error;
}
QT_END_NAMESPACE
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