qtmultimedia/src/imports/multimedia/qdeclarativemultimediaglobal.cpp

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#include "qdeclarativemultimediaglobal_p.h"

#include <qcamerainfo.h>
#include <qjsengine.h>

QT_BEGIN_NAMESPACE

/*!
\qmltype QtMultimedia
\inqmlmodule QtMultimedia
\ingroup multimedia_qml
\since QtMultimedia 5.4
\brief Provides a global object with useful functions from Qt Multimedia.

The \c QtMultimedia object is a global object with utility functions and properties.

It is not instantiable; to use it, call the members of the global \c QtMultimedia object directly.
For example:

\qml
import QtQuick 2.0
import QtMultimedia 5.4

Camera {
    deviceId: QtMultimedia.defaultCamera.deviceId
}
\endqml

*/

/*!
    \qmlproperty object QtMultimedia::QtMultimedia::defaultCamera
    \readonly

    The \c defaultCamera object provides information about the default camera on the system.

    Its properties are \c deviceId, \c displayName, \c position and \c orientation. See
    \l{QtMultimedia::QtMultimedia::availableCameras}{availableCameras} for a description of each
    of them.

    If there is no default camera, \c defaultCamera.deviceId will contain an empty string.

    \note This property is static; it is not updated if the system's default camera changes after the
    application started.
*/

/*!
    \qmlproperty list<object> QtMultimedia::QtMultimedia::availableCameras
    \readonly

    This property provides information about the cameras available on the system.

    Each object in the list has the following properties:

    \table
    \row
    \li \c deviceId
    \li
    This read-only property holds the unique identifier of the camera.

    You can choose which device to use with a \l Camera object by setting its
    \l{Camera::deviceId}{deviceId} property to this value.

    \row
    \li \c displayName
    \li
    This read-only property holds the human-readable name of the camera.
    You can use this property to display the name of the camera in a user interface.

    \row
    \li \c position
    \li
    This read-only property holds the physical position of the camera on the hardware system.
    Please see \l{Camera::position}{Camera.position} for more information.

    \row
    \li \c orientation
    \li
    This read-only property holds the physical orientation of the camera sensor.
    Please see \l{Camera::orientation}{Camera.orientation} for more information.

    \endtable

    \note This property is static; it is not updated when cameras are added or removed from
    the system, like USB cameras on a desktop platform.

    The following example shows how to display a list of available cameras. The user can change
    the active camera by selecting one of the items in the list.

    \qml
    import QtQuick 2.0
    import QtMultimedia 5.4

    Item {

        Camera {
            id: camera
        }

        VideoOutput {
            anchors.fill: parent
            source: camera
        }

        ListView {
            anchors.fill: parent

            model: QtMultimedia.availableCameras
            delegate: Text {
                text: modelData.displayName

                MouseArea {
                    anchors.fill: parent
                    onClicked: camera.deviceId = modelData.deviceId
                }
            }
        }
    }

    \endqml
*/

namespace QDeclarativeMultimedia {

#define FREEZE_SOURCE "(function deepFreeze(o) { "\
                      "    var prop, propKey;" \
                      "    Object.freeze(o);" \
                      "    for (propKey in o) {" \
                      "        prop = o[propKey];" \
                      "        if (!o.hasOwnProperty(propKey) || !(typeof prop === \"object\") || " \
                      "            Object.isFrozen(prop)) {" \
                      "            continue;" \
                      "        }" \
                      "        deepFreeze(prop);" \
                      "    }" \
                      "})"

static void deepFreeze(QJSEngine *jsEngine, const QJSValue &obj)
{
    QJSValue freezeFunc = jsEngine->evaluate(QString::fromUtf8(FREEZE_SOURCE));
    freezeFunc.call(QJSValueList() << obj);
}

static QJSValue cameraInfoToJSValue(QJSEngine *jsEngine, const QCameraInfo &camera)
{
    QJSValue o = jsEngine->newObject();
    o.setProperty(QStringLiteral("deviceId"), camera.deviceName());
    o.setProperty(QStringLiteral("displayName"), camera.description());
    o.setProperty(QStringLiteral("position"), int(camera.position()));
    o.setProperty(QStringLiteral("orientation"), camera.orientation());
    return o;
}

QJSValue initGlobalObject(QQmlEngine *qmlEngine, QJSEngine *jsEngine)
{
    Q_UNUSED(qmlEngine)

    QJSValue globalObject = jsEngine->newObject();

    // property object defaultCamera
    globalObject.setProperty(QStringLiteral("defaultCamera"),
                             cameraInfoToJSValue(jsEngine, QCameraInfo::defaultCamera()));

    // property list<object> availableCameras
    QList<QCameraInfo> cameras = QCameraInfo::availableCameras();
    QJSValue availableCameras = jsEngine->newArray(cameras.count());
    for (int i = 0; i < cameras.count(); ++i)
        availableCameras.setProperty(i, cameraInfoToJSValue(jsEngine, cameras.at(i)));
    globalObject.setProperty(QStringLiteral("availableCameras"), availableCameras);

    // freeze global object to prevent properties to be modified from QML
    deepFreeze(jsEngine, globalObject);

    return globalObject;
}

}

QT_END_NAMESPACE