With this example we are going to demonstrate how to create Live Camera preview in Android. The Android SDK includes a Camera class that is used to set image capture settings, start/stop preview, snap pictures, and retrieve frames for encoding for video. It is a handy abstraction of the real hardware device
What we are essentially going to do is setup a web camera to publish static images in a predefined URL and then grab these images from our application and present them as motion pictures
In short, to create live camera previews you should:
- extend the SurfaceView class and implement the SurfaceHolder.Callback interface
- provide our implementation using the device’s camera
- use the setContentView method of our Activity in order to set the activity content to that specific
- use the setPreviewDisplay method to set the Surface to be used for the live preview
as shown in the code snippets below:
package com.javacodegeeks.android.camera;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
public class HttpCamera {
private static final int CONNECT_TIMEOUT = 1000;
private static final int SOCKET_TIMEOUT = 1000;
private final String url;
private final Rect bounds;
private final boolean preserveAspectRatio;
private final Paint paint = new Paint();
public HttpCamera(String url, int width, int height, boolean preserveAspectRatio) {
this.url = url;
bounds = new Rect(0, 0, width, height);
this.preserveAspectRatio = preserveAspectRatio;
paint.setFilterBitmap(true);
paint.setAntiAlias(true);
}
private Bitmap retrieveBitmap() throws IOException {
Bitmap bitmap = null;
InputStream in = null;
int response = -1;
try {
URL url = new URL(this.url);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.setConnectTimeout(CONNECT_TIMEOUT);
httpConn.setReadTimeout(SOCKET_TIMEOUT);
httpConn.setRequestMethod("GET");
httpConn.connect();
response = httpConn.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
in = httpConn.getInputStream();
bitmap = BitmapFactory.decodeStream(in);
}
return bitmap;
}
catch (Exception e) {
return null;
}
finally {
if (in != null) try {
in.close();
} catch (IOException e) {
/* ignore */
}
}
}
public boolean captureAndDraw(Canvas canvas) throws IOException {
Bitmap bitmap = retrieveBitmap();
if (bitmap == null) throw new IOException("Response Code: ");
//render it to canvas, scaling if necessary
if (bounds.right == bitmap.getWidth() && bounds.bottom == bitmap.getHeight()) {
canvas.drawBitmap(bitmap, 0, 0, null);
} else {
Rect dest;
if (preserveAspectRatio) {
dest = new Rect(bounds);
dest.bottom = bitmap.getHeight() * bounds.right / bitmap.getWidth();
dest.offset(0, (bounds.bottom - dest.bottom)/2);
}
else {
dest = bounds;
}
canvas.drawBitmap(bitmap, null, dest, paint);
}
return true;
}
}
package com.javacodegeeks.android.camera;
import android.content.Context;
import android.graphics.Canvas;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class HttpCameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String url = "http://10.0.2.2:8080";
private CanvasThread canvasThread;
private SurfaceHolder holder;
private HttpCamera camera;
private int viewWidth;
private int viewHeight;
public HttpCameraPreview(Context context, int viewWidth, int viewHeight) {
super(context);
holder = getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);
this.viewWidth = viewWidth;
this.viewHeight = viewHeight;
canvasThread = new CanvasThread();
}
@Override
public void surfaceChanged(SurfaceHolder holder2, int format, int w, int h) {
try {
Canvas c = holder.lockCanvas(null);
camera.captureAndDraw(c);
if (c != null) {
holder.unlockCanvasAndPost(c);
}
}
catch (Exception e) {
Log.e(getClass().getSimpleName(), "Error when surface changed", e);
camera = null;
}
}
@Override
public void surfaceCreated(SurfaceHolder arg0) {
try {
camera = new HttpCamera(url, viewWidth, viewHeight, true);
canvasThread.setRunning(true);
canvasThread.start();
}
catch (Exception e) {
Log.e(getClass().getSimpleName(), "Error while creating surface", e);
camera = null;
}
}
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
camera = null;
boolean retry = true;
canvasThread.setRunning(false);
while (retry) {
try {
canvasThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
private class CanvasThread extends Thread {
private boolean running;
public void setRunning(boolean running){
this.running = running;
}
public void run() {
while (running) {
Canvas c = null;
try {
c = holder.lockCanvas(null);
synchronized (holder) {
camera.captureAndDraw(c);
}
}
catch (Exception e) {
Log.e(getClass().getSimpleName(), "Error while drawing canvas", e);
}
finally {
if (c != null) {
holder.unlockCanvasAndPost(c);
}
}
}
}
}
}
package com.javacodegeeks.android.camera;
import android.app.Activity;
import android.os.Bundle;
import android.view.Display;
import android.view.SurfaceView;
import android.view.Window;
public class MyCamAppActivity extends Activity {
private int viewWidth;
private int viewHeight;
private SurfaceView cameraPreview;
private static final boolean useHttpCamera = true;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
calculateDisplayDimensions();
if (useHttpCamera) {
cameraPreview = new HttpCameraPreview(this, viewWidth, viewHeight);
}
else {
cameraPreview = new CameraPreview(this);
}
setContentView(cameraPreview);
}
private void calculateDisplayDimensions() {
Display display = getWindowManager().getDefaultDisplay();
viewWidth = display.getWidth();
viewHeight = display.getHeight();
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.javacodegeeks.android.camera"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".MyCamAppActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-sdk android:minSdkVersion="3" />
<uses-permission android:name="android.permission.CAMERA"/>
<uses-permission android:name="android.permission.INTERNET" />
</manifest>
This was an example of how to create Live Camera previews in Android.
Related Article:
cameraPreview = new CameraPreview(this);
problem with this line….
cameraPreview = new CameraPreview(this);
it is showing the error….
Cannot resolve symbol ‘CameraPreview’