CWAC-Camera: Taking Pictures. Made Sensible.

Taking pictures or videos using a third-party app is fairly straightforward, using ACTION_IMAGE_CAPTURE or ACTION_VIDEO_CAPTURE. However, you as the developer have little control over what happens with the image or video, other than indicating where the result gets stored. Plus, different camera apps have slightly different behavior, meaning that you are prone to getting inconsistent results.

Taking pictures or videos using the built-in Camera class directly is eminently possible, but is full of edge and corner cases, not to mention its own set of per-device idiosyncracies. As a result, a ton of code is required to successfully show a preview, take a picture, and take a video.

CWAC-Camera is an effort to standardize that "ton of code" and hide it behind a scalable API. Here, "scalable" means "simple things are simple, but complex things may be a bit complex".

This Android library project (also available as a JAR)

Basic Usage

Step #1: Download the JAR and put it in the libs/ directory of your project (or, if you prefer, clone this GitHub repo and add it as a library project to your main project).

Step #2: Add a CameraFragment to your UI. You have two versions of CameraFragment to choose from:

• com.commonsware.cwac.camera.CameraFragment for use with native API Level 11+ fragments

• com.commonsware.cwac.camera.acl.CameraFragment for use with the Android Support package's backport of fragments and ActionBarSherlock, supporting API Level 9 and 10

(note: if you choose the latter, your project will also need to have the ActionBarSherlock library project)

The CameraFragment is responsible for rendering your preview, so you need to size and position it as desired.

Step #3: Call takePicture() on the CameraFragment when you want to take a picture, which will be stored in the default digital photos directory (e.g., DCIM) on external storage as Photo_yyyyMMdd_HHmmss.jpg, where yyyyMMdd_HHmmss is replaced by the current date and time.

Step #3b: Call startRecording() and stopRecording() on the CameraFragment to record a video. NOTE that this is presently only available on com.commonsware.cwac.camera.CameraFragment for use with native API Level 11+ fragments. The resulting video will be stored in the default videos directory (e.g., Movies) on external storage as Video_yyyyMMdd_HHmmss.mp4, where yyyyMMdd_HHmmss is replaced by the current date and time.

Step #4: Add android:largeHeap="true" to the <application> element in the manifest (a requirement which will hopefully be relaxed in the future).

And that's it.

CameraFragment (and its underlying CameraView) will handle:

• Showing the preview using an optimal preview frame size, and managing the aspect ratio of the on-screen preview View so that your previews do not appear stretched

• Dealing with configuration changes and screen rotation, so your camera activity can work in portrait or landscape

• Following the appropriate recipes for taking still pictures and videos, including choosing the largest-available image size for the resolution

• Opening and closing the camera at the appropriate times, so when you are in the foreground you have exclusive camera access, but other apps will have access to the camera while your activity is not in the foreground

• And more!

Simple Configuration

Of course, there are probably plenty of things that you will want to configure about the process of taking photos and videos. There are many hooks in CWAC-Camera to allow you to do just that.

Much of this configuration involves creating a custom CameraHost. CameraHost is your primary interface with the CWAC-Camera classes for configurating the behavior of the camera. CameraHost is an interface, one that you are welcome to implement in full. Most times, though, you will be better served extending SimpleCameraHost, the default implementation of CameraHost, so that you can override only those methods where you want behavior different from the default.

Given a customized CameraHost implementation, you can pass an instance of that to setHost() on your CameraFragment, to replace the default. Do this in onCreate() of a CameraFragment subclass (or, if practical, just after instantiating your fragment) to ensure that the right CameraHost is used everywhere.

Controlling the Names and Locations of Output Files

There are a series of methods that you can override on SimpleCameraHost to control where photos and videoes are stored once taken. These methods will be called for each takePicture() or startRecording() call, so you can create customized results for each distint photo or video.

Specifically:

• Override getPhotoFilename() to return the base name of the file to use to store the photo

• Override getPhotoDirectory() to return the name of the directory in which to store the photo

• Override getPhotoPath() to return the complete File object pointing to the desired file in the desired directory (the default implementation combines the results of getPhotoDirectory() and getPhotoFilename(), so overriding getPhotoPath() replaces all of that)

There are equivalent getVideoFilename(), getVideoDirectory(), and getVideoPath() for controlling the output of the next video to be taken.

Controlling Which Camera is Used

If you override useFrontFacingCamera() on SimpleCameraHost to return true, the front-facing camera will be used, instead of the default rear-facing camera.

Or, override getDeviceId() (available on CameraHost), and you can provide the ID of the specific camera you want. This would involve your choosing an available camera based on your own criteria. See the JavaDocs for Android's Camera class, notably getNumberOfCameras() and [getCameraInfo()](http://developer.android.com/reference/android/hardware/Camera.html#getCameraInfo(int, android.hardware.Camera.CameraInfo)) for more.

Controlling FFC Mirror Correction

By default, the pictures taken from the front-facing camera are a mirror image of what is shown on the preview. If you wish for the front-facing camera photos to match the preview, override mirrorFFC() on your CameraHost and have it return true, and CWAC-Camera will reverse the image for you before saving it.

Handling Exceptions

There are some exceptions that are thrown by the Camera class (and kin, like MediaRecorder). Those are passed to your host's handleException() method. The default implementation displays a Toast and logs the message to LogCat as an error, but you probably will want to replace that with something else that integrates better with your UI.

Wrapping the Preview UI

From a UI standpoint, the CameraFragment solely handles the preview pane. Presumably, you will need more to your UI than this, such as buttons to allow users to take pictures or record videos. You have two major options here:

1. You can put that UI as a peer to the CameraFragment, such as by having action bar items, as the demo apps do.

2. You can subclass CameraFragment and override onCreateView(). Chain to the superclass to get the CameraFragment's own UI, then wrap that in your own container with additional widgets, and return the combined UI from your onCreateView().

Advanced Configuration

In addition to the configuration hooks specified above, you can do more to tailor how photos and videos are taken.

Controlling Preview Sizes

Your CameraHost will be called with getPreviewSize(), where you need to return a valid Camera.Size indicating the desired size of the preview frames. getPreviewSize() is passed:

• the display orientation, in degrees, with 0 indicating landscape, 90 indicating portrait, etc.

• the available width and height for the preview

• the Camera.Parameters object, from which you can determine the valid preview sizes by calling getSupportedPreviewSizes()

The CameraUtils class contains a pair of static methods with stock algorithms for choosing the preview size:

1. getOptimalPreviewSize() uses the algorithm found in the SDK camera sample app

2. getBestAspectPreviewSize() finds the preview size that most closely matches the aspect ratio of our available space

SimpleCameraHost uses getBestAspectPreviewSize() for the default implementation of getPreviewSize(). You can override getPreviewSize() and substitute in your own selection algorithm. Just make sure that the returned size is one of the ones returned by getSupportedPreviewSizes().

Controlling Picture Sizes

Similarly, your CameraHost will be called with getPictureSize(), for you to return the desired Camera.Size of the still images taken by the camera. You are simply passed the Camera.Parameters, on which you can call getSupportedPictureSizes() to find out the possible picture sizes that you can choose from.

The CameraUtils class has a pair of methods for simple algorithms for choosing a picture size:

1. getLargestPictureSize() returns the Camera.Size that is the largest in area

2. getSmallestPictureSize() returns the Camera.Size that is the smallest in area

SimpleCameraHost uses getLargestPictureSize() for the default implementation of getPictureSize(). You can override getPictureSize() and substitute in your own selection algorithm. Just make sure that the returned size is one of the ones returned by getSupportedPictureSizes().

Arbitrary Preview Configuration

When setting up the camera preview, your CameraHost will be called with adjustPreviewParameters(), passing in a Camera.Parameters. Here, you can make any desired adjustments to the camera preview, except the preview size (which you should be handling in getPreviewSize()). adjustPreviewParameters() returns the revised Camera.Parameters, where the stock implementation in SimpleCameraHost just returns the passed-in parameters unmodified.

Arbitrary Photo Configuration

Shortly after you call takePicture() on your CameraFragment, your CameraHost will be called with adjustPictureParameters(), passing in a Camera.Parameters. Here, you can make any desired adjustments to the parameters related to taking photos, except the image size (which you should be handling in getPictureSize()). adjustPictureParameters() returns the revised Camera.Parameters, where the stock implementation in SimpleCameraHost just returns the passed-in parameters unmodified.

Arbitrary Video Configuration

Shortly after you call startRecording(), your CameraHost will be called with:

• configureRecorderAudio()

• configureRecorderProfile()

• configureRecorderOutput()

in that order. Here, you can help tailor the way videos get recorded. Each of these is passed the ID of the camera being used for recording plus the MediaRecorder instance that does the actual recording.

The stock SimpleCameraHost does the following:

• In configureRecorderAudio(), SimpleCameraHost calls setAudioSource(MediaRecorder.AudioSource.CAMCORDER) on the MediaRecorder

• In configureRecorderProfile(), SimpleCameraHost calls setProfile(CamcorderProfile.get(cameraId, CamcorderProfile.QUALITY_HIGH)) on the MediaRecorder

• In configureRecorderOutput(), SimpleCameraHost calls setOutputFile(getVideoPath().getAbsolutePath()) on the MediaRecorder (where getVideoPath() was described earlier in this document)

While these are reasonable defaults, you are welcome to override these implementations to do something else.

Overriding Photo Saving

The default SimpleCameraHost logic for saving photos uses the getPhotoPath() and related methods discussed above. Actually saving the photo is done in saveImage(), called on your CameraHost, where SimpleCameraHost has a saveImage() implementation that writes the supplied byte[] out to the desired location.

You are welcome to override saveImage() and do something else with the byte[], such as send it over the Internet. saveImage() is called on a background thread, so you do not have to do your own asynchronous work.

Another use for this is to find out when the saving is complete, so that you can use the resulting image. Just override saveImage(), chain to the superclass implementation, and when that returns, the image is ready for use.

Choosing a DeviceProfile

TBD

Working Directly with CameraView

TBD

Known Limitations

1. Taking videos in portrait mode will result in the video files still being stored as landscape, but with a bit in the MPEG-4 header indicating that the output should be rotated. Unfortunately, many video players ignore this header. This is a function of how MediaRecorder works, and there is no current workaround in CWAC-Camera for this behavior.

2. Taking photos in portrait mode, for some devices, will have a similar effect: the photo is saved in landscape, with an EXIF field in the JPEG indicating that the results should be rotated. CWAC-Camera detects this and tries to correct it, so the image is saved in portrait. However, this may consume too much memory at present, which is why Step #4 above calls for you to add android:largeHeap="true". This will hopefully be rectified in a future version of this component.

3. The front-facing camera on the Nexus 4 does not work with the chosen camera settings.

4. The Galaxy Nexus portrait-mode preview images are lower resolution than expected.

5. While a picture or video is being taken, on some devices, the aspect ratio of the preview gets messed up. The aspect ratio is corrected by CWAC-Camera once the picture or video is completed, but more work is needed to try to prevent this in the first place, or at least mask it a bit better for photos.

6. Switching between cameras (e.g., rear-facing to front-facing) on the Nexus S ("crespo") does not work, resulting in a crash.

Tested Devices

• Galaxy Nexus
• HTC One S
• Nexus 4
• Nexus 7
• Nexus 10
• Nexus One
• Nexus S
• Motorola RAZR i
• Samsung Galaxy S3
• Samsung Galaxy S4 (GT-I9500)

Dependencies

This project depends on the Android Support package and ActionBarSherlock at compile time, if you are using the Android library project. It also depends on the Android Support package and ActionBarSherlock at runtime if you are using the .acl flavor of CameraFragment.

Version

This is version v0.0.2 of this module, meaning it is very much a proof of concept. Much more testing is required on a wider array of devices, and more camera-related features need to be exposed, either through wrapper logic on the existing CameraFragment or CameraHost APIs, or by ensuring that developers can configure those features independently without causing problems for things like the camera preview.

Demo

In the demo/ sub-project you will find a sample project demonstrating the use of CameraFragment for the native API Level 11 implementation of fragments. The demo-v9/ sub-project has a similar sample for the CameraFragment that works with ActionBarSherlock.

License

The code in this project is licensed under the Apache Software License 2.0, per the terms of the included LICENSE file.

Questions

If you have questions regarding the use of this code, please post a question on StackOverflow tagged with commonsware and android. Be sure to indicate what CWAC module you are having issues with, and be sure to include source code and stack traces if you are encountering crashes.

If you have encountered what is clearly a bug, or if you have a feature request, please post an issue. Be certain to include complete steps for reproducing the issue.

Do not ask for help via Twitter.

Also, if you plan on hacking on the code with an eye for contributing something back, please open an issue that we can use for discussing implementation details. Just lobbing a pull request over the fence may work, but it may not.

Release Notes

• v0.0.2: bug fixes
• v0.0.1: initial release

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