CameraView/README.md

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.

compile 'com.otaliastudios:cameraview:1.0.0'

This is a fork of CameraKit-Android library, originally a fork of Google's CameraView library, but has been completely rewritten. See below for a list of what was done. Feel free to contribute - this is under active development.

Features

• Seamless image and video capturing
• Gestures support (tap to focus, pinch to zoom and much more)
• System permission handling
• Dynamic sizing behavior
  • Create a CameraView of any size
  • Center inside or center crop behaviors
  • Automatic output cropping to match your CameraView 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 (similar to Snapchat and Instagram)
• Control flash, zoom, white balance, exposure correction and more
• Metadata support for pictures and videos
  • Automatically detected orientation tags
  • Plug in location tags with setLocation() API
• CameraUtils to help with Bitmaps and orientations
• Lightweight, no dependencies, just support ExifInterface

Docs

• Usage
  • Capturing Images
  • Capturing Video
  • Other camera events
• Gestures
• Dynamic Sizing Behavior
  • Center Inside
  • Center Crop
• Camera Controls
• Other APIs
• Permissions Behavior
• Manifest file
• 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" />

Make sure you override onResume, onPause and onDestroy in your activity, 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.

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 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 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.
     */
    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

Dynamic Sizing Behavior

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.

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" />

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()	max480p max720p max1080p max2160p highest lowest	max480p
cameraWhiteBalance	setWhiteBalance()	auto incandescent fluorescent daylight cloudy	auto

cameraSessionType

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

• Sizing: capture and preview size are chosen among the available picture or video sizes, depending on the flag. When picture, we choose the max possible picture size and adapt the preview. When video, we respect the videoQuality choice and adapt the picture and the preview size.
• 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(CameraConstants.SESSION_TYPE_PICTURE);
cameraView.setSessionType(CameraConstants.SESSION_TYPE_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(CameraConstants.VIDEO_QUALITY_480P);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_720P);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_1080P);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_2160P);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_LOWEST);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_HIGHEST);
cameraView.setVideoQuality(CameraConstants.VIDEO_QUALITY_QVGA);

cameraWhiteBalance

Sets the desired white balance for the current session.

cameraView.setWhiteBalance(CameraConstants.WHITE_BALANCE_AUTO);
cameraView.setWhiteBalance(CameraConstants.WHITE_BALANCE_INCANDESCENT);
cameraView.setWhiteBalance(CameraConstants.WHITE_BALANCE_FLUORESCENT);
cameraView.setWhiteBalance(CameraConstants.WHITE_BALANCE_DAYLIGHT);
cameraView.setWhiteBalance(CameraConstants.WHITE_BALANCE_CLOUDY);

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.
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.
setLocation(double, double)	Sets latitude and longitude to be appended to picture/video metadata.
toggleFacing()	Toggles the facing value between Facing.FRONT and Facing.BACK.
toggleFlash()	Toggles the flash value between FLASH_OFF, FLASH_ON, and FLASH_AUTO.
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().

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

You can handle permissions yourself and then call CameraView.start() once they are acquired. If they are not, CameraView will request permissions to the user based on the sessionType that was set. In that case, you can restart the camera if you have a successful response from onRequestPermissionResults().

Manifest file

The library manifest file is not strict and only asks for camera permissions. This means that:

• If you wish to record videos, 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.

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
• 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

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

• fix CropOutput class presumably not working on rotated pictures
• test video and 'frame' capture behavior, I expect some bugs there
• simple APIs to draw grid lines
• check focus, not sure it exposes the right part of the image
• replace setCameraListener() with addCameraListener()
• better threading, for example ensure callbacks are called in the ui thread
• pinch to zoom support
• exposure correction APIs
• change demo app icon
• refactor package name
• new Gestures framework to map gestures to camera controls
• heavily reduced dependencies
• Camera2 integration
• publish to bintray
• check onPause / onStop / onSaveInstanceState consistency
• add a setPreferredAspectRatio API to choose the capture size. Preview size will adapt, and then, if let free, the CameraView will adapt as well
• animate grid lines similar to stock camera app
• add onRequestPermissionResults for easy permission callback
• better error handling, maybe with a onError(e) method in the public listener, or have each public method return a boolean