Using the Camera API

Android SDK supports the connectivity to the built-in camera. Using the camera to take photos is relatively easy. It is somewhat harder to setup the camera preview to work properly.

In our main activity, we create the Preview object. This object will create the Camera object and return it to the CameraDemo activity.

Next we register couple of call-back method with the Camera to be performed when the user takes a photo.

shutterCallback is called when the shutter is opened and picture is taken. rawCallback and jpegCallback will get the data for the raw and jpeg encoding of the photo. It's up to you to do something with this data, such as save it to the SD card.

CameraDemo.java
Code:

package com.example;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.FrameLayout;

public class CameraDemo extends Activity {
private static final String TAG = "CameraDemo";
Camera camera;
Preview preview;
Button buttonClick;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

preview = new Preview(this);
((FrameLayout) findViewById(R.id.preview)).addView(preview);

buttonClick = (Button) findViewById(R.id.buttonClick);
buttonClick.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
preview.camera.takePicture(shutterCallback, rawCallback,
jpegCallback);
}
});

Log.d(TAG, "onCreate'd");
}

ShutterCallback shutterCallback = new ShutterCallback() {
public void onShutter() {
Log.d(TAG, "onShutter'd");
}
};

/** Handles data for raw picture */
PictureCallback rawCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
Log.d(TAG, "onPictureTaken - raw");
}
};

/** Handles data for jpeg picture */
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
FileOutputStream outStream = null;
try {
// write to local sandbox file system
// outStream =
// CameraDemo.this.openFileOutput(String.format("%d.jpg",
// System.currentTimeMillis()), 0);
// Or write to sdcard
outStream = new FileOutputStream(String.format(
"/sdcard/%d.jpg", System.currentTimeMillis()));
outStream.write(data);
outStream.close();
Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
Log.d(TAG, "onPictureTaken - jpeg");
}
};

}

Preview class handles the preview from the camera. It subclasses SurfaceView class so that it can be placed in the UI itself. It also implements the SurfaceHolder.Callback interface so it gets the callbacks when the UI becomes available.

Preview.java
Code:

package com.example;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

class Preview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "Preview";

SurfaceHolder mHolder;
public Camera camera;

Preview(Context context) {
super(context);

// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
camera = Camera.open();
try {
camera.setPreviewDisplay(holder);

camera.setPreviewCallback(new PreviewCallback() {

public void onPreviewFrame(byte[] data, Camera arg1) {
FileOutputStream outStream = null;
try {
outStream = new FileOutputStream(String.format(
"/sdcard/%d.jpg", System.currentTimeMillis()));
outStream.write(data);
outStream.close();
Log.d(TAG, "onPreviewFrame - wrote bytes: "
+ data.length);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
Preview.this.invalidate();
}
});
} catch (IOException e) {
e.printStackTrace();
}
}

public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
// Because the CameraDevice object is not a shared resource, it's very
// important to release it when the activity is paused.
camera.stopPreview();
camera = null;
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(w, h);
camera.setParameters(parameters);
camera.startPreview();
}

@Override
public void draw(Canvas canvas) {
super.draw(canvas);
Paint p = new Paint(Color.RED);
Log.d(TAG, "draw");
canvas.drawText("PREVIEW", canvas.getWidth() / 2,
canvas.getHeight() / 2, p);
}
}

The layout is fairly straight forward. We have the FrameLayout as the placeholder for the Preview to be attached to. This is done programmatically in CameraDemo.onCreate().

/res/layout/main.xml

Code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent" android:id="@+id/layout">
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content" android:text="Camera Demo"
android:textSize="24sp" />

<FrameLayout android:id="@+id/preview"
android:layout_weight="1" android:layout_width="fill_parent"
android:layout_height="fill_parent">
</FrameLayout>

<Button android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="@+id/buttonClick"
android:text="Click" android:layout_gravity="center"></Button>

</LinearLayout>


And finally remember to add <uses-permission android:name="android.permission.CAMERA" /> to your AndroidManifest.xml file.

The final app looks like this:




Source Code:

/static/tutorials/CameraDemo.zip

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