camera

HTTP Camera live preview example

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:

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.

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Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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2 Comments
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Ali Usman
Ali Usman
5 years ago

cameraPreview = new CameraPreview(this);

Ali Usman
Ali Usman
5 years ago

problem with this line….
cameraPreview = new CameraPreview(this);
it is showing the error….
Cannot resolve symbol ‘CameraPreview’

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