// Copyright (C) 2015 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
\example declarative-camera
\title QML Camera Application
\ingroup multimedia_examples
\ingroup camera_examples_qml
\examplecategory {Multimedia}
\examplecategory {Mobile}
\brief This Qt Quick based application shows how to use the API to capture a
still image or video.

\image qml-camera.png
       {Camera app in landscape mode showing live preview and capture controls}

This example demonstrates how to access camera functions via QML.
It shows how to change settings and capture images or video.

\include examples-run.qdocinc

\section1 Application structure

Most of the QML code in this example supports the user interface. Custom types
that support the requirements have been implemented using existing Qt Quick
controls.

\section1 Using screen orientation to select layout

The orientation and control layout state logic is encapsulated in a separate
Item, \c controlLayout like so:

\snippet declarative-camera/declarative-camera.qml 1

The \c stillControls and \c videoControls objects both bind to the \c state
and \c buttonsWidth properties of this Item, as shown in \c stillControls:

\snippet declarative-camera/declarative-camera.qml 2

To support debugging, a message about layout state change is logged.

Here is the portrait layout:

\image qml-declarative-portrait.png
       {Camera app in portrait mode showing live preview and capture controls}

You can see the \c state property is initially set as \c PhotoCapture.

Then the \c states themselves are defined like so:

\snippet declarative-camera/declarative-camera.qml 0

\section1 Controls for capturing

Controls for capturing are implemented in \c PhotoCaptureControls.qml and
VideoCaptureControls.qml. They each are based on a \l FocusScope that defines
common buttons dimensions and margins that are used by the control buttons and
then declares the buttons.

This generates a column on the right hand side of the screen which includes,
listed top to bottom, the following controls:
\div {class="multi-column"}
    \div {class="doc-column"}
        \list
        \li A \c Capture or \c Record button, which initiates capturing.
        \li A \c{capture properties} button that displays the icon of the current
        white balance mode selected and when pressed uses a pop-up to displays
        the following option's icons:
            \list
            \li Flash mode (if available)
            \li White balance modes
            \li Exposure compensation
            \endlist
        \li A \c View button, once something has been captured.
        \li A button which displays the currently selected capture device and
        when pressed provides a list of available devices to switch to, using a
        pop-up.
        \li A \c{Switch To} button that displays the alternate capture mode
        (video or photo) depending on the current active selection and switches
        the mode when pressed.
        \li A \c Quit button, that exits the application.
        \endlist
    \enddiv
    \div {class="doc-column"}
        \inlineimage CaptureControls.png
                     {Photo capture control panel}
    \enddiv
    \div {class="doc-column"}
        \inlineimage VideoCaptureControls.png
                     {Video capture control panel}
    \enddiv
\enddiv

\section1 Image capturing

The button that triggers this is defined in CameraButton.qml:
but its interaction with the camera is in the controls types, lets look at
PhotoCaptureControls:

\snippet declarative-camera/PhotoCaptureControls.qml 0

\section1 Zoom control

\div {class="multi-column"}
    \div {class="doc-column"}
    Implemented in \c ZoomControl.qml the ZoomControl type is based on an Item
    and creates a bar that represents the zoom level, which can also be dragged.
    It uses an exponential calculation method to determine the zoom factor given
    the position of the \c grove.

    The bar is only visible if the initialZoom is greater than 1. This means
    the currently active camera has a zoom function.
    \enddiv
    \div {class="doc-column"}
        \inlineimage ZoomControl.png
                     {Adjustable zoom level bar}
    \enddiv
\enddiv

\snippet declarative-camera/ZoomControl.qml 0

In PhotoCaptureControls.qml and VideoCaptureControls.qml the signal \c zoomTo
will set the selected camera's \l{Camera::}{zoomFactor} property to the
calculated \c target value, as well as updating the ZoomControl bar.

\snippet declarative-camera/VideoCaptureControls.qml 0

\section1 Flash and torch control

\image FlashControls.png
       {Toggle between Flash and Torch mode}

Defined in \c FlashControl.qml this enables flash mode selection and torch
functionality to be toggled via a Switch. As with the zoom control, the switches
are only visible on top of the preview window if the active device supports
these functions.

Here we check if the functions are supported:

\snippet declarative-camera/FlashControl.qml 0

Here we implement the \c flashModeControl switch, which also directly controls
the Camera device.

\snippet declarative-camera/FlashControl.qml 1

Torch control is implemented in a similar way.
*/
