CameraView

CameraView is a well documented, high-level library that makes capturing pictures and videos easy, addressing most of the common issues and needs, and still leaving you with flexibility where needed. See CHANGELOG.

compile 'com.otaliastudios:cameraview:1.4.1'

This was a fork of CameraKit-Android, originally a fork of Google's CameraView, but has been completely rewritten. See below for a list of what was done and licensing info.

Features

• Seamless image and video capturing
• Gestures support (tap to focus, pinch to zoom and much more)
• System permission handling
• Smart sizing behavior
  • Preview: Create a CameraView of any size
  • Preview: Center inside or center crop behaviors
  • Output: Handy utilities to set the output size
  • Output: Automatic cropping to match your CameraView preview bounds
• Built-in grid drawing
• Multiple capture methods
  • Take high-resolution pictures with capturePicture
  • Take quick snapshots as a freeze frame of the preview with captureSnapshot
• Control HDR, flash, zoom, white balance, exposure correction and more
• Frame processing support
• Metadata support for pictures and videos
  • Automatically detected orientation tags
  • Plug in location tags with setLocation() API
• CameraUtils to help with Bitmaps and orientations
• Error handling
• Thread safe, well tested
• Lightweight, no dependencies, just support ExifInterface
• Works down to API level 15

Docs

• Usage
  • Capturing Images
  • Capturing Video
  • Other camera events
• Gestures
• Sizing Behavior
  • Preview Size
  • Picture Size
• Camera Controls
• Frame Processing
• Other APIs
• Permissions Behavior
• Logging
• Device-specific issues
• Roadmap

Usage

To use the CameraView engine, simply add a CameraView to your layout:

<com.otaliastudios.cameraview.CameraView
    android:id="@+id/camera"
    android:keepScreenOn="true"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

CameraView has lots of XML attributes, so keep reading. Make sure you override onResume, onPause and onDestroy in your activity or fragment, and call CameraView.start(), stop() and destroy().

@Override
protected void onResume() {
    super.onResume();
    cameraView.start();
}

@Override
protected void onPause() {
    super.onPause();
    cameraView.stop();
}

@Override
protected void onDestroy() {
    super.onDestroy();
    cameraView.destroy();
}

Capturing Images

To capture an image just call CameraView.capturePicture(). Make sure you setup a CameraListener to handle the image callback.

camera.addCameraListener(new CameraListener() {
    @Override
    public void onPictureTaken(byte[] picture) {
        // Create a bitmap or a file...
        // CameraUtils will read EXIF orientation for you, in a worker thread.
        CameraUtils.decodeBitmap(picture, ...);
    }
});

camera.capturePicture();

You can also use camera.captureSnapshot() to capture a preview frame. This is faster, though will ensure lower quality output.

Capturing Video

To capture video just call CameraView.startRecordingVideo(file) to start, and CameraView.stopRecordingVideo() to finish. Make sure you setup a CameraListener to handle the video callback.

camera.addCameraListener(new CameraListener() {
    @Override
    public void onVideoTaken(File video) {
        // The File is the same you passed before.
        // Now it holds a MP4 video.
    }
});

// Select output file. Make sure you have write permissions.
File file = ...;

// Record a 2500 ms video:
camera.startRecordingVideo(file, 2500);

// Full version
camera.startRecordingVideo(file);
camera.postDelayed(new Runnable() {
    @Override
    public void run() {
        // This will trigger onVideoTaken().
        camera.stopRecordingVideo();
    }
}, 2500);

Other camera events

Make sure you can react to different camera events by setting up one or more CameraListener instances. All these are executed on the UI thread.

camera.addCameraListener(new CameraListener() {

    /**
     * Notifies that the camera was opened.
     * The options object collects all supported options by the current camera.
     */
    @Override
    public void onCameraOpened(CameraOptions options) {}

    /**
     * Notifies that the camera session was closed.
     */
    @Override
    public void onCameraClosed() {}

    /**
     * Notifies about an error during the camera setup or configuration.
     * At the moment, errors that are passed here are unrecoverable. When this is called,
     * the camera has been released and is presumably showing a black preview.
     *
     * This is the right moment to show an error dialog to the user.
     */
    @Override
    public void onCameraError(CameraException error) {}

    /**
     * Notifies that a picture previously captured with capturePicture()
     * or captureSnapshot() is ready to be shown or saved.
     *
     * If planning to get a bitmap, you can use CameraUtils.decodeBitmap()
     * to decode the byte array taking care about orientation.
     */
    @Override
    public void onPictureTaken(byte[] picture) {}

    /**
     * Notifies that a video capture has just ended. The file parameter is the one that
     * was passed to startCapturingVideo(File), or a fallback video file.
     */
    @Override
    public void onVideoTaken(File video) {}
    
    /**
     * Notifies that the device was tilted or the window offset changed.
     * The orientation passed can be used to align views (e.g. buttons) to the current
     * camera viewport so they will appear correctly oriented to the user.
     */
    @Override
    public void onOrientationChanged(int orientation) {}

    /**
     * Notifies that user interacted with the screen and started focus with a gesture,
     * and the autofocus is trying to focus around that area.
     * This can be used to draw things on screen.
     */    
    @Override
    public void onFocusStart(PointF point) {}
    
    /**
     * Notifies that a gesture focus event just ended, and the camera converged
     * to a new focus (and possibly exposure and white balance).
     */
    @Override
    public void onFocusEnd(boolean successful, PointF point) {}
    
    /**
     * Noitifies that a finger gesture just caused the camera zoom
     * to be changed. This can be used, for example, to draw a seek bar.
     */
    @Override
    public void onZoomChanged(float newValue, float[] bounds, PointF[] fingers) {}
    
    /**
     * Noitifies that a finger gesture just caused the camera exposure correction
     * to be changed. This can be used, for example, to draw a seek bar.
     */
    @Override 
    public void onExposureCorrectionChanged(float newValue, float[] bounds, PointF[] fingers) {}

});

Gestures

CameraView listen to lots of different gestures inside its bounds. You have the chance to map these gestures to particular actions or camera controls, using mapGesture(). This lets you emulate typical behaviors in a single line:

cameraView.mapGesture(Gesture.PINCH, GestureAction.ZOOM); // Pinch to zoom!
cameraView.mapGesture(Gesture.TAP, GestureAction.FOCUS_WITH_MARKER); // Tap to focus!
cameraView.mapGesture(Gesture.LONG_TAP, GestureAction.CAPTURE); // Long tap to shoot!

Simple as that. More gestures are coming. There are two things to be noted:

• Not every mapping is valid. For example, you can't control zoom with long taps, or start focusing by pinching.
• Some actions might not be supported by the sensor. Check out CameraOptions to know what's legit and what's not.

Gesture (XML)	Description	Can be mapped to
PINCH (cameraGesturePinch)	Pinch gesture, typically assigned to the zoom control.	zoom exposureCorrection none
TAP (cameraGestureTap)	Single tap gesture, typically assigned to the focus control.	focus focusWithMarker capture none
LONG_TAP (cameraGestureLongTap)	Long tap gesture.	focus focusWithMarker capture none
SCROLL_HORIZONTAL (cameraGestureScrollHorizontal)	Horizontal movement gesture.	zoom exposureCorrection none
SCROLL_VERTICAL (cameraGestureScrollVertical)	Vertical movement gesture.	zoom exposureCorrection none

Sizing Behavior

Preview Size

CameraView has a smart measuring behavior that will let you do what you want with a few flags. Measuring is controlled simply by layout_width and layout_height attributes, with this meaning:

• WRAP_CONTENT : try to stretch this dimension to respect the preview aspect ratio.
• MATCH_PARENT : fill this dimension, even if this means ignoring the aspect ratio.
• Fixed values (e.g. 500dp) : respect this dimension.

You can have previews of all sizes, not just the supported presets. Whaterever you do, the preview will never be distorted.

Center Inside

You can emulate a center inside behavior (like the ImageView scaletype) by setting both dimensions to wrap_content. The camera will get the biggest possible size that fits into your bounds, just like what happens with image views.

<com.otaliastudios.cameraview.CameraView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

This means that the whole preview is visible, and the image output matches what was visible during the capture.

Center Crop

You can emulate a center crop behavior by setting both dimensions to fixed values or to MATCH_PARENT. The camera view will fill the rect. If your dimensions don't match the aspect ratio of the internal preview surface, the surface will be cropped to fill the view, just like android:scaleType="centerCrop" on an ImageView.

<com.otaliastudios.cameraview.CameraView
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

This means that part of the preview is hidden, and the image output will contain parts of the scene that were not visible during the capture. If this is a problem, see cameraCropOutput.

Picture Size

On top of this, you can control the actual size of the output picture, among the list of available sizes. It is the size of the final JPEG picture. This can be achieved directly through XML, or using the SizeSelector class:

cameraView.setPictureSize(new SizeSelector() {
    @Override
    public List<Size> select(List<Size> source) {
        // Receives a list of available sizes.
        // Must return a list of acceptable sizes.
    }
});

In practice, this is way easier using XML attributes or leveraging the SizeSelectors utilities:

Constraint	XML attr	SizeSelector
min. width	app:cameraPictureSizeMinWidth="100"	SizeSelectors.minWidth(100)
min. height	app:cameraPictureSizeMinHeight="100"	SizeSelectors.minHeight(100)
max. width	app:cameraPictureSizeMaxWidth="3000"	SizeSelectors.maxWidth(3000)
max. height	app:cameraPictureSizeMaxHeight="3000"	SizeSelectors.maxHeight(3000)
min. area	app:cameraPictureSizeMinArea="1000000"	SizeSelectors.minArea(1000000)
max. area	app:cameraPictureSizeMaxArea="5000000"	SizeSelectors.maxArea(5000000)
aspect ratio	app:cameraPictureSizeAspectRatio="1:1"	SizeSelectors.aspectRatio(AspectRatio.of(1,1), 0)
smallest	app:cameraPictureSizeSmallest="true"	SizeSelectors.smallest()
biggest (default)	app:cameraPictureSizeBiggest="true"	SizeSelectors.biggest()

If you declare more than one XML constraint, the resulting selector will try to match all the constraints. Be careful - it is very likely that applying lots of constraints will give empty results.

SizeSelectors utilities

For more versatility, or to address selection issues with multiple constraints, we encourage you to use SizeSelectors utilities, that will let you merge different selectors.

This selector will try to find square sizes bigger than 1000x2000. If none is found, it falls back to just square sizes:

SizeSelector width = SizeSelectors.minWidth(1000);
SizeSelector height = SizeSelectors.minWidth(2000);
SizeSelector dimensions = SizeSelectors.and(width, height); // Matches sizes bigger than 1000x2000.
SizeSelector ratio = SizeSelectors.aspectRatio(AspectRatio.of(1, 1), 0); // Matches 1:1 sizes.

SizeSelector result = SizeSelectors.or(
    SizeSelectors.and(ratio, dimensions), // Try to match both constraints
    ratio, // If none is found, at least try to match the aspect ratio
    SizeSelectors.biggest() // If none is found, take the biggest
);
camera.setPictureSize(result);

Camera controls

Most camera parameters can be controlled through XML attributes or linked methods.

<com.otaliastudios.cameraview.CameraView
    android:id="@+id/camera"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:keepScreenOn="true"
    app:cameraFacing="back"
    app:cameraFlash="off"
    app:cameraGrid="off"
    app:cameraSessionType="picture"
    app:cameraCropOutput="false"  
    app:cameraJpegQuality="100"
    app:cameraVideoQuality="480p"
    app:cameraWhiteBalance="auto"
    app:cameraHdr="off"
    app:cameraAudio="on"
    app:cameraPlaySounds="true"/>

XML Attribute	Method	Values	Default Value
cameraSessionType	setSessionType()	picture video	picture
cameraFacing	setFacing()	back front	back
cameraFlash	setFlash()	off on auto torch	off
cameraGrid	setGrid()	off draw3x3 draw4x4 drawPhi	off
cameraCropOutput	setCropOutput()	true false	false
cameraJpegQuality	setJpegQuality()	0 < n <= 100	100
cameraVideoQuality	setVideoQuality()	lowest highest maxQvga max480p max720p max1080p max2160p	max480p
cameraWhiteBalance	setWhiteBalance()	auto incandescent fluorescent daylight cloudy	auto
cameraHdr	setHdr()	off on	off
cameraAudio	setAudio()	off on	on
cameraPlaySounds	setPlaySounds()	true false	true

cameraSessionType

What to capture - either picture or video. This has a couple of consequences:

• Sizing: picture and preview size are chosen among the available picture or video sizes, depending on the flag. The picture size is chosen according to the given size selector. When video, in addition, we try to match the videoQuality aspect ratio.
• Picture capturing: due to sizing behavior, capturing pictures in video mode might lead to inconsistent results. In this case it is encouraged to use captureSnapshot instead, which will capture preview frames. This is fast and thus works well with slower camera sensors.
• Picture capturing: while recording a video, image capturing might work, but it is not guaranteed (it's device dependent)
• Permission behavior: when requesting a video session, the record audio permission will be requested. If this is needed, the audio permission should be added to your manifest or the app will crash.

cameraView.setSessionType(SessionType.PICTURE);
cameraView.setSessionType(SessionType.VIDEO);

cameraFacing

Which camera to use, either back facing or front facing.

cameraView.setFacing(Facing.BACK);
cameraView.setFacing(Facing.FRONT);

cameraFlash

Flash mode, either off, on, auto or torch.

cameraView.setFlash(Flash.OFF);
cameraView.setFlash(Flash.ON);
cameraView.setFlash(Flash.AUTO);
cameraView.setFlash(Flash.TORCH);

cameraGrid

Lets you draw grids over the camera preview. Supported values are off, draw3x3 and draw4x4 for regular grids, and drawPhi for a grid based on the golden ratio constant, often used in photography.

cameraView.setGrid(Grid.OFF);
cameraView.setGrid(Grid.DRAW_3X3);
cameraView.setGrid(Grid.DRAW_4X4);
cameraView.setGrid(Grid.DRAW_PHI);

cameraCropOutput

Whether the output picture should be cropped to fit the aspect ratio of the preview surface. This can guarantee consistency between what the user sees and the final output, if you fixed the camera view dimensions. This does not support videos.

cameraJpegQuality

Sets the JPEG quality of pictures.

cameraView.setJpegQuality(100);
cameraView.setJpegQuality(50);

cameraVideoQuality

Sets the desired video quality.

cameraView.setVideoQuality(VideoQuality.LOWEST);
cameraView.setVideoQuality(VideoQuality.HIGHEST);
cameraView.setVideoQuality(VideoQuality.MAX_QVGA);
cameraView.setVideoQuality(VideoQuality.MAX_480P);
cameraView.setVideoQuality(VideoQuality.MAX_720P);
cameraView.setVideoQuality(VideoQuality.MAX_1080P);
cameraView.setVideoQuality(VideoQuality.MAX_2160P);

cameraWhiteBalance

Sets the desired white balance for the current session.

cameraView.setWhiteBalance(WhiteBalance.AUTO);
cameraView.setWhiteBalance(WhiteBalance.INCANDESCENT);
cameraView.setWhiteBalance(WhiteBalance.FLUORESCENT);
cameraView.setWhiteBalance(WhiteBalance.DAYLIGHT);
cameraView.setWhiteBalance(WhiteBalance.CLOUDY);

cameraHdr

Turns on or off HDR captures.

cameraView.setHdr(Hdr.OFF);
cameraView.setHdr(Hdr.ON);

cameraAudio

Turns on or off audio stream while recording videos.

cameraView.setAudio(Audio.OFF);
cameraView.setAudio(Audio.ON);

cameraPlaySounds

Controls whether we should play platform-provided sounds during certain events (shutter click, focus completed). Please note that:

• on API < 16, this flag is always set to false
• the Camera1 engine will always play shutter sounds regardless of this flag

cameraView.setPlaySounds(true);
cameraView.setPlaySounds(false);

Frame Processing

We support frame processors that will receive data from the camera preview stream:

cameraView.addFrameProcessor(new FrameProcessor() {
    @Override
    @WorkerThread
    public void process(Frame frame) {
        byte[] data = frame.getData();
        int rotation = frame.getRotation();
        long time = frame.getTime();
        Size size = frame.getSize();
        int format = frame.getFormat();
        // Process...
    }
}

For your convenience, the FrameProcessor method is run in a background thread so you can do your job in a synchronous fashion. Once the process method returns, internally we will re-use the Frame instance and apply new data to it. So:

• you can do your job synchronously in the process() method
• if you must hold the Frame instance longer, use frame = frame.freeze() to get a frozen instance that will not be affected

Frame API	Type	Description
frame.getData()	byte[]	The current preview frame, in its original orientation.
frame.getTime()	long	The preview timestamp, in System.currentTimeMillis() reference.
frame.getRotation()	int	The rotation that should be applied to the byte array in order to see what the user sees.
frame.getSize()	Size	The frame size, before any rotation is applied, to access data.
frame.getFormat()	int	The frame ImageFormat. This will always be ImageFormat.NV21 for now.
frame.freeze()	Frame	Clones this frame and makes it immutable. Can be expensive because requires copying the byte array.
frame.release()	-	Disposes the content of this frame. Should be used on frozen frames to release memory.

Other APIs

Other APIs not mentioned above are provided, and are well documented and commented in code.

Method	Description
isStarted()	Returns true if start() was called succesfully. This does not mean that camera is open or showing preview.
mapGesture(Gesture, GestureAction)	Maps a certain gesture to a certain action. No-op if the action is not supported.
getGestureAction(Gesture)	Returns the action currently mapped to the given gesture.
clearGesture(Gesture)	Clears any action mapped to the given gesture.
getCameraOptions()	If camera was started, returns non-null object with information about what is supported.
getExtraProperties()	If camera was started, returns non-null object with extra information about the camera sensor. Not very useful at the moment.
setZoom(float), getZoom()	Sets a zoom value, where 0 means camera zoomed out and 1 means zoomed in. No-op if zoom is not supported, or camera not started.
setExposureCorrection(float), getExposureCorrection()	Sets exposure compensation EV value, in camera stops. No-op if this is not supported. Should be between the bounds returned by CameraOptions.
toggleFacing()	Toggles the facing value between Facing.FRONT and Facing.BACK.
setLocation(Location)	Sets location data to be appended to picture/video metadata.
setLocation(double, double)	Sets latitude and longitude to be appended to picture/video metadata.
getLocation()	Retrieves location data previously applied with setLocation().
startAutoFocus(float, float)	Starts an autofocus process at the given coordinates, with respect to the view dimensions.
getPreviewSize()	Returns the size of the preview surface. If CameraView was not constrained in its layout phase (e.g. it was wrap_content), this will return the same aspect ratio of CameraView.
getSnapshotSize()	Returns getPreviewSize(), since a snapshot is a preview frame.
getPictureSize()	Returns the size of the output picture. The aspect ratio is consistent with getPreviewSize().
setVideoMaxSize(long)	Set a max file size (in bytes) for a video recording. There is no file size limit by default unless set by the user.

Take also a look at public methods in CameraUtils, CameraOptions, ExtraProperties.

Permissions behavior

CameraView needs two permissions:

• android.permission.CAMERA : required for capturing pictures and videos
• android.permission.RECORD_AUDIO : required for capturing videos with Audio.ON (the default)

Declaration

The library manifest file declares the android.permission.CAMERA permission, but not the audio one. This means that:

• If you wish to record videos with Audio.ON (the default), you should also add android.permission.RECORD_AUDIO to required permissions

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

• If you want your app to be installed only on devices that have a camera, you should add:

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

If you don't request this feature, you can use CameraUtils.hasCameras() to detect if current device has cameras, and then start the camera view.

Handling

On Marshmallow+, the user must explicitly approve our permissions. You can

• handle permissions yourself and then call cameraView.start() once they are acquired
• or call cameraView.start() anyway: CameraView will present a permission request to the user based on whether they are needed or not with the current configuration.

In the second case, you should restart the camera if you have a successful response from onRequestPermissionResults().

Logging

CameraView will log a lot of interesting events related to the camera lifecycle. These are important to identify bugs. The default logger will simply use Android Log methods posting to logcat.

You can attach and detach external loggers using CameraLogger.registerLogger():

CameraLogger.registerLogger(new Logger() {
    @Override
    public void log(@LogLevel int level, String tag, String message, @Nullable Throwable throwable) {
        // For example...
        Crashlytics.log(message);
    }
});

Make sure you enable the logger using CameraLogger.setLogLevel(@LogLevel int). The default will only log error events.

Device-specific issues

There are a couple of known issues if you are working with certain devices. The emulator is one of the most tricky in this sense.

• Devices, or activities, with hardware acceleration turned off: this can be the case with emulators. In this case we will use SurfaceView as our surface provider. That is intrinsically flawed and can't deal with all we want to do here (runtime layout changes, scaling, etc.). So, nothing to do in this case.
• Devices with no support for MediaRecorder: the emulator does not support it, officially. This means that video/audio recording is flawed. Again, not our fault.

Roadmap

This is what was done since the library was forked. I have kept the original structure, but practically all the code was changed.

• a huge number of serious bugs fixed
• decent orientation support for both pictures and videos
• less dependencies
• EXIF support
• real tap-to-focus support
• pinch-to-zoom support
• simpler APIs, docs and heavily commented code
• new captureSnapshot API
• new setLocation and setWhiteBalance APIs
• new setGrid APIs, to draw 3x3, 4x4 or golden ratio grids
• option to pass a File when recording a video
• other minor API additions
• replacing Method and Permissions stuff with simpler sessionType
• smart measuring and sizing behavior, replacing bugged adjustViewBounds
• measure CameraView as center crop or center inside
• add multiple CameraListeners for events
• gesture framework support, map gestures to camera controls
• pinch gesture support
• tap & long tap gesture support
• scroll gestures support
• MediaActionSound support
• Hdr controls
• zoom and exposure correction controls
• Tests!
• CameraLogger APIs for logging and bug reports
• Better threading, start() in worker thread and callbacks in UI
• Frame processor support
• inject external loggers
• error handling
• capture size selectors

These are still things that need to be done, off the top of my head:

• Camera2 integration
• animate grid lines similar to stock camera app
• add onRequestPermissionResults for easy permission callback
• decent code coverage

Contributing and licenses

The original project which served as a starting point for this library, CameraKit-Android, is licensed under the MIT license. Additional work is now licensed under the MIT license as well.

You are welcome to contribute with suggestions or pull requests, this is under active development. To contact me, send an email.