qtmultimedia/doc/src/camera.qdoc

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// XXX OMG its so bad
// namespace warning
// why mention control?
// bad brief
// control list
// links?

/*!

\page camera.html

\title Camera
\brief An API to control camera devices.

The Camera API provides control of system camera devices. Providing support
for still or video image capture with sound support.

\tableofcontents


\section1 Namespace

The QtMobility APIs are placed into the \i{QtMobility} namespace. This is done
to facilitate the future migration of QtMobility APIs into Qt. See the
\l {Quickstart guide} for an example on how the
namespace impacts on application development.


\section1 Overview

The Camera API allows high level control of various aspects of still images
and video. Camera is a part of the Multimedia API and this relationship is
apparent when you notice that certain core classes are subclassed from some
Multimedia base classes including \l QMediaObject and \l QMediaControl.



\section1 Still Images

In order to capture an image we need to create a \l QCamera object and use
it to initialize a \l QVideoWidget, so we can see where the camera is
pointing - a viewfinder. The camera object is also used to initialize a new
QCameraImageCapture object, imageCapture. All that is then needed is to start
the camera, lock it so that the settings are not changed while the image
capture occurs, capture the image, and finally unlock the camera ready for
the next photo.

    \code
        camera = new QCamera;
        viewFinder = new QCameraViewfinder;
        camera->setViewfinder(viewFinder);
        viewFinder->show();

        imageCapture = new QCameraImageCapture(camera);

        camera->setCaptureMode(QCamera::CaptureStillImage);
        camera->start();

        //on half pressed shutter button
        camera->searchA{QCameraFocus::FocusMode}{ndLock();

        //on shutter button pressed
        imageCapture->capture();

        //on shutter button released
        camera->unlock();
    \endcode

Alternatively, we could have used a QGraphicsVideoItem as a viewfinder.


\section1 Video Clips

Previously we saw code that allowed the capture of a still image. Recording
video requires the use of a \l QMediaRecorder object and a \l
QAudioCaptureSource for sound.

To record video we need to create a camera object as before but this time as
well as creating a viewfinder, we will also initialize a media recorder object.

    \code
    camera = new QCamera;
    mediaRecorder = new QMediaRecorder(camera);

    camera->setCaptureMode(QCamera::CaptureVideo);
    camera->start();

    //on shutter button pressed
    mediaRecorder->record();
    \endcode

Signals from the \i mediaRecorder can be connected to slots to react to
changes in the state of the recorder or error events. Recording itself
starts with the \l {QMediaRecorder::record()}{record()} function of
mediaRecorder being called, this causes the signal \l
{QMediaRecorder::stateChanged()}{stateChanged()} to be emitted. The
recording process can be changed with the \l {QMediaRecorder::record()}{record()},
\l {QMediaRecorder::pause()}{pause()}, \l {QMediaRecorder::stop()}{stop()} and
\l {QMediaRecorder::setMuted()}{setMuted()} slots in \l QMediaRecorder.

When the camera is in video mode, as decided by the application, then as the
shutter button is pressed the camera is locked as before but instead the
\l {QMediaRecorder::record()}{record()} function in \l QMediaRecorder is used.



\section1 Focus

Focusing is managed by the classes \l QCameraFocus and \l QCameraFocusControl.
QCameraFocus allows the developer to set the general policy by means of the
enums for the \l {QCameraFocus::FocusMode}{FocusMode} and the
\l {QCameraFocus::FocusPointMode}{FocusPointMode}. \l {QCameraFocus::FocusMode}{FocusMode}
deals with settings such as \l {QCameraFocus::FocusMode}{AutoFocus},
\l {QCameraFocus::FocusMode}{ContinuousFocus} and \l {QCameraFocus::FocusMode}{InfinityFocus}, whereas \l {QCameraFocus::FocusMode}{FocusPointMode} deals with the various focus zones within the view. \l {QCameraFocus::FocusMode}{FocusPointMode} has support for face recognition, center focus and a custom
focus where the focus point can be specified.



\section1 Cancelling Asynchronous Operations

Various operations such as image capture and auto focusing occur
asynchrously. These operations can often be cancelled by the start of a new
operation as long as this is supported by the backend. For image capture,
the operation can be cancelled by calling
\l {QCameraImageCapture::cancelCapture()}{cancelCapture()}. For AutoFocus,
autoexposure or white balance cancellation can be done by calling
\i {QCamera::unlock(QCamera::LockFocus)}.



\section1 Camera Controls

    \table
        \header
            \o Control Name
            \o Description
        \row
            \o camera
            \o the interface for system camera devices
        \row
            \o exposure
            \o Includes: flash mode; flash power; metering mode; aperture; shutter speed, iso setting
        \row
            \o focus
            \o Includes: optical zoom; digital zoom; focus point; focus zones
        \row
            \o image processing
            \o white balance; contrast; saturation; sharpen; denoise
        \row
            \o locks
            \o handles the locking and unlocking of camera devices
    \endtable


\section1 Classes
\annotatedlist camera


*/