docs: Camera Features for developers

      </ol>

    </li>

    <li><a href="#saving-media">Saving Media Files</a></li>

    <li><a href="#camera-features">Camera Features</a>

      <ol>

        <li><a href="#check-feature">Checking feature availability</a></li>

        <li><a href="#using-features">Using camera features</a></li>

        <li><a href="#metering-focus-areas">Metering and focus areas</a></li>

        <li><a href="#face-detection">Face detection</a></li>

        <li><a href="#time-lapse-video">Time lapse video</a></li>

      </ol>

    </li>

  </ol>

  <h2>Key Classes</h2>

  <ol>

  </ol>

  <h2>See also</h2>

  <ol>

    <li><a href="{@docRoot}reference/android/hardware/Camera.html">Camera</a></li>

    <li><a href="{@docRoot}reference/android/media/MediaRecorder.html">MediaRecorder</a></li>

    <li><a href="{@docRoot}guide/topics/media/mediaplayer.html">Media Playback</a></li>

    <li><a href="{@docRoot}guide/topics/data/data-storage.html">Data Storage</a></li>

  </ol>

  </div>

<dl>

  <dt>{@link android.hardware.Camera}</dt>

  <dd>This class is the primary API for controlling device cameras. This class is used to take

pictures or videos when you are building a camera application.</a>.</dd>

pictures or videos when you are building a camera application.</dd>

  <dt>{@link android.view.SurfaceView}</dt>

  <dd>This class is used to present a live camera preview to the user.</dd>

<pre>

<uses-feature android:name="android.hardware.camera" />

</pre>

  <p>For a list of camera features, see the manifest <a

href="{@docRoot}guide/topics/manifest/uses-feature-element.html#features-reference">Features

  <p>For a list of camera features, see the manifest

<a href="{@docRoot}guide/topics/manifest/uses-feature-element.html#hw-features">Features

Reference</a>.</p>

  <p>Adding camera features to your manifest causes Android Market to prevent your application from

being installed to devices that do not include a camera or do not support the camera features you

<uses-permission android:name="android.permission.RECORD_AUDIO" />

</pre>

  </li>

  <li><strong>Location Permission</strong> - If your application tags images with GPS location

information, you must request location permission:

<pre>

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

</pre>

<p>For more information about getting user location, see

<a href="{@docRoot}guide/topics/location/obtaining-user-location.html">Obtaining User

Location</a>.</p>

  </li>

</ul>

your application, and you must intercept the {@link

android.app.Activity#onActivityResult(int, int, android.content.Intent) onActivityResult()}

method to receive the result of the intent and continue your application execution. For information

on how to receive the completed intent, see <a href="#intent-receive">Receiving Camera Intent

Result</a>.</p>

on how to receive the completed intent, see <a href="#intent-receive">Receiving camera intent

result</a>.</p>

<h3 id="intent-video">Video capture intent</h3>

<p>Camera hardware is a shared resource that must be carefully managed so your application does

not collide with other applications that may also want to use it. The following sections discusses

how to detect camera hardware, how to request access to a camera and how to release it when your

application is done using it.</p>

how to detect camera hardware, how to request access to a camera, how to capture pictures or video

and how to release the camera when your application is done using it.</p>

<p class="caution"><strong>Caution:</strong> Remember to release the {@link android.hardware.Camera}

object by calling the {@link android.hardware.Camera#release() Camera.release()} when your

          // ignore: tried to stop a non-existent preview

        }

        // make any resize, rotate or reformatting changes here

        // set preview size and make any resize, rotate or

        // reformatting changes here

        // start preview with new settings

        try {

}

</pre>

<p>If you want to set a specific size for your camera preview, set this in the {@code

surfaceChanged()} method as noted in the comments above. When setting preview size, you

<em>must use</em> values from {@link android.hardware.Camera.Parameters#getSupportedPreviewSizes}.

<em>Do not</em> set arbitrary values in the {@link

android.hardware.Camera.Parameters#setPreviewSize setPreviewSize()} method.</p>

<h3 id="preview-layout">Placing preview in a layout</h3>

<p>A camera preview class, such as the example shown in the previous section, must be placed in the

since users typically prefer to see a preview before starting a recording, that process is not

discussed here.</p>

<p class="note"><strong>Tip:</strong> If your application is typically used for recording video, set

{@link android.hardware.Camera.Parameters#setRecordingHint} to {@code true} prior to starting your

preview. This setting can help reduce the time it takes to start recording.</p>

<h4 id="configuring-mediarecorder">Configuring MediaRecorder</h4>

<p>When using the {@link android.media.MediaRecorder} class to record video, you must perform

configuration steps in a <em>specific order</em> and then call the {@link

  <li>{@link android.media.MediaRecorder#setAudioSamplingRate(int) setAudioSamplingRate()}</li>

</ul>

<h4 id="start-stop-mediarecorder">Starting and Stopping MediaRecorder</h4>

<h4 id="start-stop-mediarecorder">Starting and stopping MediaRecorder</h4>

<p>When starting and stopping video recording using the {@link android.media.MediaRecorder} class,

you must follow a specific order, as listed below.</p>

<p>For more information about saving files on an Android device, see <a

href="{@docRoot}guide/topics/data/data-storage.html">Data Storage</a>.</p>

<h2 id="camera-features">Camera Features</h2>

<p>Android supports a wide array of camera features you can control with your camera application,

such as picture format, flash mode, focus settings, and many more. This section lists the common

camera features, and briefly discusses how to use them. Most camera features can be accessed and set

using the through {@link android.hardware.Camera.Parameters} object. However, there are several

important features that require more than simple settings in {@link

android.hardware.Camera.Parameters}. These features are covered in the following sections:<p>

<ul>

  <li><a href="#metering-focus-areas">Metering and focus areas</a></li>

  <li><a href="#face-detection">Face detection</a></li>

  <li><a href="#time-lapse-video">Time lapse video</a></li>

</ul>

<p>For general information about how to use features that are controlled through {@link

android.hardware.Camera.Parameters}, review the <a href="#using-features">Using camera

features</a> section. For more detailed information about how to use features controlled through the

camera parameters object, follow the links in the feature list below to the API reference

documentation.</p>

<p class="table-caption" id="table1">

  <strong>Table 1.</strong> Common camera features sorted by the Android API Level in which they

were introduced.</p>

<table>

  <tr>

    <th>Feature</th>  <th>API Level</th>  <th>Description</th>

  </tr>

  <tr>

    <td><a href="#face-detection">Face Detection</a></td>

    <td>14</td>

    <td>Identify human faces within a picture and use them for focus, metering and white

balance</td>

  </tr>

  <tr>

    <td><a href="#metering-focus-areas">Metering Areas</a></td>

    <td>14</td>

    <td>Specify one or more areas within an image for calculating white balance</td>

  </tr>

  <tr>

    <td><a href="#metering-focus-areas">Focus Areas</a></td>

    <td>14</td>

    <td>Set one or more areas within an image to use for focus</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setAutoWhiteBalanceLock White Balance Lock}</td>

    <td>14</td>

    <td>Stop or start automatic white balance adjustments</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setAutoExposureLock Exposure Lock}</td>

    <td>14</td>

    <td>Stop or start automatic exposure adjustments</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera#takePicture Video Snapshot}</td>

    <td>14</td>

    <td>Take a picture while shooting video (frame grab)</td>

  </tr>

  <tr>

    <td><a href="#time-lapse-video">Time Lapse Video</a></td>

    <td>11</td>

    <td>Record frames with set delays to record a time lapse video</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera#open(int) Multiple Cameras}</td>

    <td>9</td>

    <td>Support for more than one camera on a device, including front-facing and back-facing

cameras</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#getFocusDistances Focus Distance}</td>

    <td>9</td>

    <td>Reports distances between the camera and objects that appear to be in focus</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setZoom Zoom}</td>

    <td>8</td>

    <td>Set image magnification</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setExposureCompensation Exposure

Compensation}</td>

    <td>8</td>

    <td>Increase or decrease the light exposure level</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setGpsLatitude GPS Data}</td>

    <td>5</td>

    <td>Include or omit geographic location data with the image</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setWhiteBalance White Balance}</td>

    <td>5</td>

    <td>Set the white balance mode, which affects color values in the captured image</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setFocusMode Focus Mode}</td>

    <td>5</td>

    <td>Set how the camera focuses on a subject such as automatic, fixed, macro or infinity</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setSceneMode Scene Mode}</td>

    <td>5</td>

    <td>Apply a preset mode for specific types of photography situations such as night, beach, snow

or candlelight scenes</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setJpegQuality JPEG Quality}</td>

    <td>5</td>

    <td>Set the compression level for a JPEG image, which increases or decreases image output file

quality and size</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setFlashMode Flash Mode}</td>

    <td>5</td>

    <td>Turn flash on, off, or use automatic setting</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setColorEffect Color Effects}</td>

    <td>5</td>

    <td>Apply a color effect to the captured image such as black and white, sepia tone or negative.

</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setAntibanding Anti-Banding}</td>

    <td>5</td>

    <td>Reduces the effect of banding in color gradients due to JPEG compression</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setPictureFormat Picture Format}</td>

    <td>1</td>

    <td>Specify the file format for the picture</td>

  </tr>

  <tr>

    <td>{@link android.hardware.Camera.Parameters#setPictureSize Picture Size}</td>

    <td>1</td>

    <td>Specify the pixel dimensions of the saved picture</td>

  </tr>

</table>

<p class="note"><strong>Note:</strong> These features are not supported on all devices due to

hardware differences and software implementation. For information on checking the availability

of features on the device where your application is running, see <a href="#check-feature">Checking

feature availability</a>.</p>

<h3 id="check-feature">Checking feature availability</h3>

<p>The first thing to understand when setting out to use camera features on Android devices is that

not all camera features are supported on all devices. In addition, devices that support a particular

feature may support them to different levels or with different options. Therefore, part of your

decision process as you develop a camera application is to decide what camera features you want to

support and to what level. After making that decision, you should plan on including code in your

camera application that checks to see if device hardware supports those features and fails

gracefully if a feature is not available.</p>

<p>You can check the availabilty of camera features by getting an instance of a camera’s parameters

object, and checking the relevant methods. The following code sample shows you how to obtain a

{@link android.hardware.Camera.Parameters} object and check if the camera supports the autofocus

feature:</p>

<pre>

// get Camera parameters

Camera.Parameters params = mCamera.getParameters();

List<String> focusModes = params.getSupportedFocusModes();

if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {

  // Autofocus mode is supported

}

</pre>

<p>You can use the technique shown above for most camera features. The

{@link android.hardware.Camera.Parameters} object provides a {@code getSupported...()}, {@code

is...Supported()} or {@code getMax...()} method to determine if (and to what extent) a feature is

supported.</p>

<p>If your application requires certain camera features in order to function properly, you can

require them through additions to your application manifest. When you declare the use of specific

camera features, such as flash and auto-focus, the Android Market restricts your application from

being installed on devices which do not support these features. For a list of camera features that

can be declared in your app manifest, see the manifest

<a href="{@docRoot}guide/topics/manifest/uses-feature-element.html#hw-features"> Features

Reference</a>.</p>

<h3 id="using-features">Using camera features</h3>

<p>Most camera features are activated and controlled using a {@link

android.hardware.Camera.Parameters} object. You obtain this object by first getting an instance of

the {@link android.hardware.Camera} object, calling the {@link

android.hardware.Camera#getParameters getParameters()} method, changing the returned parameter

object and then setting it back into the camera object, as demonstrated in the following example

code:</p>

<pre>

// get Camera parameters

Camera.Parameters params = mCamera.getParameters();

// set the focus mode

params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);

// set Camera parameters

mCamera.setParameters(params);

</pre>

<p>This technique works for nearly all camera features, and most parameters can be changed at any

time after you have obtained an instance of the {@link android.hardware.Camera} object. Changes to

parameters are typically visible to the user immediately in the application’s camera preview.

On the software side, parameter changes may take several frames to actually take effect as the

camera hardware processes the new instructions and then sends updated image data.</p>

<p class="caution"><strong>Important:</strong> Some camera features cannot be changed at will. In

particular, changing the size or orientation of the camera preview requires that you first stop the

preview, change the preview size, and then restart the preview. Starting with Android 4.0 (API

Level 14) preview orientation can be changed without restarting the preview.</p>

<p>Other camera features require more code in order to implement, including:</p>

<ul>

  <li>Metering and focus areas</li>

  <li>Face detection</li>

  <li>Time lapse video</li>

</ul>

<p>A quick outline of how to implement these features is provided in the following sections.</p>

<h3 id="metering-focus-areas">Metering and focus areas</h3>

<p>In some photographic scenarios, automatic focusing and light metering may not produce the

desired results. Starting with Android 4.0 (API Level 14), your camera application can provide

additional controls to allow your app or users to specify areas in an image to use for determining

focus or light level settings and pass these values to the camera hardware for use in capturing

images or video.</p>

<p>Areas for metering and focus work very similarly to other camera features, in that you control

them through methods in the {@link android.hardware.Camera.Parameters} object. The following code

demonstrates setting two light metering areas for an instance of

{@link android.hardware.Camera}:</p>

<pre>

// Create an instance of Camera

mCamera = getCameraInstance();

// set Camera parameters

Camera.Parameters params = mCamera.getParameters();

if (params.getMaxNumMeteringAreas() > 0){ // check that metering areas are supported

    List<Camera.Area> meteringAreas = new ArrayList<Camera.Area>();

    Rect areaRect1 = new Rect(-100, -100, 100, 100);    // specify an area in center of image

    meteringAreas.add(new Camera.Area(areaRect1, 600)); // set weight to 60%

    Rect areaRect2 = new Rect(800, -1000, 1000, -800);  // specify an area in upper right of image

    meteringAreas.add(new Camera.Area(areaRect2, 400)); // set weight to 40%

    params.setMeteringAreas(meteringAreas);

}

mCamera.setParameters(params);

</pre>

<p>The {@link android.hardware.Camera.Area} object contains two data parameters: A {@link

android.graphics.Rect} object for specifying an area within the camera’s field of view and a weight

value, which tells the camera what level of importance this area should be given in light metering

or focus calculations.</p>

<p>The {@link android.graphics.Rect} field in a {@link android.hardware.Camera.Area} object

describes a rectangular shape mapped on a 2000 x 2000 unit grid. The coordinates -1000, -1000

represent the top, left corner of the camera image, and coordinates 1000, 1000 represent the

bottom, right corner of the camera image, as shown in the illustration below.</p>

<img src='images/camera-area-coordinates.png' />

<p class="img-caption">

  <strong>Figure 1.</strong> The red lines illustrate the coordinate system for specifying a

{@link android.hardware.Camera.Area} within a camera preview. The blue box shows the location and

shape of an camera area with the {@link android.graphics.Rect} values 333,333,667,667.

</p>

<p>The bounds of this coordinate system always correspond to the outer edge of the image visible in

the camera preview and do not shrink or expand with the zoom level. Similarly, rotation of the image

preview using {@link android.hardware.Camera#setDisplayOrientation Camera.setDisplayOrientation()}

does not remap the coordinate system.</p>

<h3 id="face-detection">Face detection</h3>

<p>For pictures that include people, faces are usually the most important part of the picture, and

should be used for determining both focus and white balance when capturing an image. The Android 4.0

(API Level 14) framework provides APIs for identifying faces and calculating picture settings using

face recognition technology.</p>

<p class="note"><strong>Note:</strong> While the face detection feature is running,

{@link android.hardware.Camera.Parameters#setWhiteBalance},

{@link android.hardware.Camera.Parameters#setFocusAreas} and

{@link android.hardware.Camera.Parameters#setMeteringAreas} have no effect.</p>

<p>Using the face detection feature in your camera application requires a few general steps:</p>

<ul>

  <li>Check that face detection is supported on the device</li>

  <li>Create a face detection listener</li>

  <li>Add the face detection listener to your camera object</li>

  <li>Start face detection after preview (and after <em>every</em> preview restart)</li>

</ul>

<p>The face detection feature is not supported on all devices. You can check that this feature is

supported by calling {@link android.hardware.Camera.Parameters#getMaxNumDetectedFaces}. An

example of this check is shown in the {@code startFaceDetection()} sample method below.</p>

<p>In order to be notified and respond to the detection of a face, your camera application must set

a listener for face detection events. In order to do this, you must create a listener class that

implements the {@link android.hardware.Camera.FaceDetectionListener} interface as shown in the

example code below.</p>

<pre>

class MyFaceDetectionListener implements Camera.FaceDetectionListener {

    @Override

    public void onFaceDetection(Face[] faces, Camera camera) {

        if (faces.length > 0){

            Log.d("FaceDetection", "face detected: "+ faces.length +

                    " Face 1 Location X: " + faces[0].rect.centerX() +

                    "Y: " + faces[0].rect.centerY() );

        }

    }

}

</pre>

<p>After creating this class, you then set it into your application’s

{@link android.hardware.Camera} object, as shown in the example code below:</p>

<pre>

mCamera.setFaceDetectionListener(new MyFaceDetectionListener());

</pre>

<p>Your application must start the face detection function each time you start (or restart) the

camera preview. Create a method for starting face detection so you can call it as needed, as shown

in the example code below.</p>

<pre>

public void startFaceDetection(){

    // Try starting Face Detection

    Camera.Parameters params = mCamera.getParameters();

    // start face detection only *after* preview has started

    if (params.getMaxNumDetectedFaces() > 0){

        // camera supports face detection, so can start it:

        mCamera.startFaceDetection();

    }

}

</pre>

<p>You must start face detection <em>each time</em> you start (or restart) the camera preview. If

you use the preview class shown in <a href="#camera-preview">Creating a preview class</a>, add your

{@link android.hardware.Camera#startFaceDetection startFaceDetection()} method to both the

{@link android.view.SurfaceHolder.Callback#surfaceCreated surfaceCreated()} and {@link

android.view.SurfaceHolder.Callback#surfaceChanged surfaceChanged()} methods in your preview class,

as shown in the sample code below.</p>

<pre>

public void surfaceCreated(SurfaceHolder holder) {

    try {

        mCamera.setPreviewDisplay(holder);

        mCamera.startPreview();

        startFaceDetection(); // start face detection feature

    } catch (IOException e) {

        Log.d(TAG, "Error setting camera preview: " + e.getMessage());

    }

}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {

    if (mHolder.getSurface() == null){

        // preview surface does not exist

        Log.d(TAG, "mHolder.getSurface() == null");

        return;

    }

    try {

        mCamera.stopPreview();

    } catch (Exception e){

        // ignore: tried to stop a non-existent preview

        Log.d(TAG, "Error stopping camera preview: " + e.getMessage());

    }

    try {

        mCamera.setPreviewDisplay(mHolder);

        mCamera.startPreview();

        startFaceDetection(); // re-start face detection feature

    } catch (Exception e){

        // ignore: tried to stop a non-existent preview

        Log.d(TAG, "Error starting camera preview: " + e.getMessage());

    }

}

</pre>

<p class="note"><strong>Note:</strong> Remember to call this method <em>after</em> calling

{@link android.hardware.Camera#startPreview startPreview()}. Do not attempt to start face detection

in the {@link android.app.Activity#onCreate onCreate()} method of your camera app’s main activity,

as the preview is not available by this point in your application's the execution.</p>

<h3 id="time-lapse-video">Time lapse video</h3>

<p>Time lapse video allows users to create video clips that combine pictures taken a few seconds or

minutes apart. This feature uses {@link android.media.MediaRecorder} to record the images for a time

lapse sequence. </p>

<p>To record a time lapse video with {@link android.media.MediaRecorder}, you must configure the

recorder object as if you are recording a normal video, setting the captured frames per second to a

low number and using one of the time lapse quality settings, as shown in the code example below.</p>

<pre>

// Step 3: Set a CamcorderProfile (requires API Level 8 or higher)

mMediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_TIME_LAPSE_HIGH));

...

// Step 5.5: Set the video capture rate to a low number

mMediaRecorder.setCaptureRate(0.1); // capture a frame every 10 seconds

</pre>

<p>These settings must be done as part of a larger configuration procedure for {@link

android.media.MediaRecorder}. For  a full configuration code example, see <a

href="#configuring-mediarecorder">Configuring MediaRecorder</a>. Once the configuration is complete,

you start the video recording as if you were recording a normal video clip. For more information

about configuring and running {@link android.media.MediaRecorder}, see <a

href="#capture-video">Capturing videos</a>.</p>