Merge "Remove references to sample application" into ics-mr0

process of directly controlling the camera. As Android's own Camera application does, the

recommended way to access the camera is to open {@link android.hardware.Camera} on a separate thread

that's launched from {@link android.app.Activity#onCreate onCreate()}. This approach is a good idea

since it can take a while and might bog down the UI thread. However, in the sample application

associated with this lesson, opening the camera is deferred to the {@link

since it can take a while and might bog down the UI thread. In a more basic implementation,

opening the camera can be deferred to the {@link

android.app.Activity#onResume onResume()} method to facilitate code reuse and keep the flow of

control simple.</p>

<pre>

private void openCameraPerIdAndSetPreview() {

    if (! safeCameraOpen(mCameraId)) {

        mCameraId = getFirstRearCameraID();

        safeCameraOpen(mCameraId);

    }

    mPreview.setCamera(mCamera);

}

</pre>

<p>Since API level 9, the camera framework supports multiple cameras. If you use the

legacy API and call {@link android.hardware.Camera#open open()} without an

argument, you get the first rear-facing camera. Dealing with multiple cameras

is an advanced topic and beyond the scope of this lesson. If you are really

interested, check out the implementation of {@code getFirstRearCameraID()} in

the sample app (downloadable at the top).</p>

<p>Calling {@link android.hardware.Camera#open Camera.open()} throws an

exception if the camera is already in use by another application, so we wrap it

in a {@code try} block.</p>

    try {

        releaseCameraAndPreview();

        mCamera = Camera.open(mCameraId);

        mCamera = Camera.open(id);

        qOpened = (mCamera != null);

    } catch (Exception e) {

        Log.e(getString(R.string.app_name), "failed to open Camera");

}

</pre>

<p>Since API level 9, the camera framework supports multiple cameras. If you use the

legacy API and call {@link android.hardware.Camera#open open()} without an

argument, you get the first rear-facing camera.</p>

<h2 id="camera-preview">Create the Camera Preview</h2>

<pre>

class Preview extends ViewGroup implements SurfaceHolder.Callback {

...

    SurfaceView mSurfaceView;

    SurfaceHolder mHolder;

...

    Preview(Context context) {

        super(context);

</pre>

<p>The preview class must be passed to the {@link android.hardware.Camera} object before the live

image preview can be started, as seen in {@code setCamera()} method of the sample,

as shown in the next section.</p>

image preview can be started, as shown in the next section.</p>

<h3 id="TaskStartPreview">Set and Start the Preview</h2>

<p>A camera instance and its related preview must be created in a specific

order, with the camera object being first. In the sample application, the

order, with the camera object being first. In the snippet below, the

process of initializing the camera is encapsulated so that {@link

android.hardware.Camera#startPreview Camera.startPreview()} is called by the

{@code setCamera()} method, whenever the user does something to change the

<h2 id="TaskSettings">Modify Camera Settings</h2>

<p>Camera settings change the way that the camera takes pictures, from the zoom

level to exposure compensation. This example doesn’t do a whole lot with camera

settings, but the APIs provide a wide array of options. The {@code surfaceChanged()} method in the

sample app demonstrates how to get and set camera parameters:</p>

level to exposure compensation. This example changes only the preview size;

see the source code of the Camera application for many more.</p>

<pre>

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

method to take a picture once the preview is started. You can create {@link

android.hardware.Camera.PictureCallback} and {@link

android.hardware.Camera.ShutterCallback} objects and pass them into {@link

android.hardware.Camera#takePicture Camera.takePicture()}.  Since the Android

Camera application already does a great job capturing JPEG images, you should

probably implement the raw-image callback.</p>

android.hardware.Camera#takePicture Camera.takePicture()}.</p>

<p>If you want to grab images continously, you can create a {@link

android.hardware.Camera.PreviewCallback} that implements {@link

<h2 id="TaskRestartPreview">Restart the Preview</h2>

<p>After a picture is taken, you must to restart the preview before the user

can take another picture. In the example, the restart is done by overloading

the shutter button, as shown below.</p>

can take another picture. In this example, the restart is done by overloading

the shutter button.</p>

<pre>

@Override

}

</pre>

<p>In the example application, this procedure is also part of the {@code

<p>Earlier in the lesson, this procedure was also part of the {@code

setCamera()} method, so initializing a camera always begins with stopping the

preview.</p>

<h2>Try it out</h2>

<div class="download-box">

 <a href="{@docRoot}shareables/training/PhotoIntentActivity.zip" class="button">Download the Intent sample</a>

 <a href="{@docRoot}shareables/training/PhotoIntentActivity.zip" class="button">Download the sample</a>

 <p class="filename">PhotoIntentActivity.zip</p>

</div>