Customize Camera View for Android using zbar

问题:

I am new in android development. My app should activate the camera to scan a QR code and decode it to a string. This works fine, but I have one more requirement: to present the camera view in a frame and with a logo in one of the corners. I did not find an appropriate API in zbar sdk to make the frame and attach the logo. This is my code:

ZBarScannerActivity.java:

package com.myCompany.android;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.Bundle;
import android.os.Handler;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Toast;
import net.sourceforge.zbar.Config;
import net.sourceforge.zbar.Image;
import net.sourceforge.zbar.ImageScanner;
import net.sourceforge.zbar.Symbol;
import net.sourceforge.zbar.SymbolSet;

public class ZBarScannerActivity extends Activity implements Camera.PreviewCallback, ZBarConstants {

    private static final String TAG = "ZBarScannerActivity";
    private CameraPreview mPreview;
    private Camera mCamera;
    private ImageScanner mScanner;
    private Handler mAutoFocusHandler;
    private boolean mPreviewing = true;

    static {
        System.loadLibrary("iconv");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Hide the window title.
       requestWindowFeature(Window.FEATURE_NO_TITLE);
       getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        mAutoFocusHandler = new Handler();

        // Create and configure the ImageScanner;
        setupScanner();

        // Create a RelativeLayout container that will hold a SurfaceView,
        // and set it as the content of our activity.
        mPreview = new CameraPreview(this, this, autoFocusCB);

        setContentView(mPreview);
    }

    public void setupScanner() {
        mScanner = new ImageScanner();
        mScanner.setConfig(0, Config.X_DENSITY, 3);
        mScanner.setConfig(0, Config.Y_DENSITY, 3);

        int[] symbols = getIntent().getIntArrayExtra(SCAN_MODES);
        if (symbols != null) {
            mScanner.setConfig(Symbol.NONE, Config.ENABLE, 0);
            for (int symbol : symbols) {
                mScanner.setConfig(symbol, Config.ENABLE, 1);
            }
            //test customization
         }
    }

    @Override
    protected void onResume() {
        super.onResume();

        // Open the default i.e. the first rear facing camera.
        mCamera = Camera.open();
        mPreviewing = true;
        mPreview.setCamera(mCamera);
    }

    @Override
    protected void onPause() {
        super.onPause();

        // Because the Camera object is a shared resource, it's very
        // important to release it when the activity is paused.
        if (mCamera != null) {
            mPreview.setCamera(null);
            mCamera.cancelAutoFocus();
            mCamera.setPreviewCallback(null);
            mCamera.stopPreview();
            mCamera.release();
            mPreviewing = false;
            mCamera = null;
        }
    }

    public void onPreviewFrame(byte[] data, Camera camera) {
        Camera.Parameters parameters = camera.getParameters();
        Camera.Size size = parameters.getPreviewSize();

        Image barcode = new Image(size.width, size.height, "Y800");
        barcode.setData(data);

        int result = mScanner.scanImage(barcode);

        if (result != 0) {
            mCamera.cancelAutoFocus();
            mCamera.setPreviewCallback(null);
            mCamera.stopPreview();
            mPreviewing = false;
            SymbolSet syms = mScanner.getResults();
            for (Symbol sym : syms) {
                String symData = sym.getData();
                if (!TextUtils.isEmpty(symData)) {
                    Intent dataIntent = new Intent();
                    dataIntent.putExtra(SCAN_RESULT, symData);
                    dataIntent.putExtra(SCAN_RESULT_TYPE, sym.getType());
                    setResult(Activity.RESULT_OK, dataIntent);
                    finish();
                    break;
                }
            }
        }
    }
    private Runnable doAutoFocus = new Runnable() {
        public void run() {
            if(mCamera != null && mPreviewing) {
                mCamera.autoFocus(autoFocusCB);
            }
        }
    };

    // Mimic continuous auto-focusing
    Camera.AutoFocusCallback autoFocusCB = new Camera.AutoFocusCallback() {
        public void onAutoFocus(boolean success, Camera camera) {
            mAutoFocusHandler.postDelayed(doAutoFocus, 1000);
        }
    };

    public void launchQRScanner(View v) {
        if (isCameraAvailable()) {

            //Toast.makeText(this, "Analyzing Image", Toast.LENGTH_LONG).show();

            Intent intent = new Intent(this, ZBarScannerActivity.class);
            intent.putExtra(ZBarConstants.SCAN_MODES, new int[]{Symbol.QRCODE});
            startActivityForResult(intent, ZBAR_QR_SCANNER_REQUEST);
        } else {
            Toast.makeText(this, "Camera Unavailable", Toast.LENGTH_SHORT).show();
        }
    }

    public boolean isCameraAvailable() {
        PackageManager pm = getPackageManager();
        return pm.hasSystemFeature(PackageManager.FEATURE_CAMERA);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        //getMenuInflater().inflate(R.menu.activity_qrimport_token, menu);
        return true;
    }

   /* @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        switch (requestCode) {
            case ZBAR_SCANNER_REQUEST:
                Toast.makeText(this, data.getStringExtra(ZBarConstants.SCAN_RESULT), Toast.LENGTH_LONG).show();
                break;
            case ZBAR_QR_SCANNER_REQUEST:

                playSound();

                if (resultCode == RESULT_OK) {
                    Toast.makeText(this, data.getStringExtra(ZBarConstants.SCAN_RESULT), Toast.LENGTH_LONG).show();
                    Toast.makeText(this, "Scan Result = " + data.getStringExtra(ZBarConstants.SCAN_RESULT), Toast.LENGTH_SHORT).show();

                    // put whatever you want to do with the code here
                    //TextView tv = new TextView(this);
                    //tv.setText(data.getStringExtra(ZBarConstants.SCAN_RESULT));
                    Log.d("Data",""+data.getStringExtra(ZBarConstants.SCAN_RESULT));
                    //setContentView(tv);
                }
                break;
        }
    }*/

    /*private void playSound() 
    {
        MediaPlayer mp = MediaPlayer.create(getBaseContext(), R.raw.camera_shutter);  
        mp.start();             

        mp.setOnCompletionListener(new OnCompletionListener()
        {                    
            @Override                 
            public void onCompletion(MediaPlayer mp) 
            {                       
                mp.release();       
            }              
        }); 

    }*/
}

CameraPreview.java:

package com.myCompany.android;

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PreviewCallback;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import java.io.IOException;
import java.util.List;

class CameraPreview extends ViewGroup implements SurfaceHolder.Callback {
    private final String TAG = "CameraPreview";

    SurfaceView mSurfaceView;
    SurfaceHolder mHolder;
    Size mPreviewSize;
    List<Size> mSupportedPreviewSizes;
    Camera mCamera;
    PreviewCallback mPreviewCallback;
    AutoFocusCallback mAutoFocusCallback;

    CameraPreview(Context context, PreviewCallback previewCallback, AutoFocusCallback autoFocusCb) {
        super(context);

        mPreviewCallback = previewCallback;
        mAutoFocusCallback = autoFocusCb;
        mSurfaceView = new SurfaceView(context);
        addView(mSurfaceView);

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

    public void setCamera(Camera camera) {
        mCamera = camera;
        if (mCamera != null) {
            mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
            requestLayout();
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // We purposely disregard child measurements because act as a
        // wrapper to a SurfaceView that centers the camera preview instead
        // of stretching it.
        final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(width, height);

        if (mSupportedPreviewSizes != null) {
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
        }
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (changed && getChildCount() > 0) {
            final View child = getChildAt(0);

            final int width = r - l;
            final int height = b - t;

            int previewWidth = width;
            int previewHeight = height;
            if (mPreviewSize != null) {
                previewWidth = mPreviewSize.width;
                previewHeight = mPreviewSize.height;
            }

            // Center the child SurfaceView within the parent.
            if (width * previewHeight > height * previewWidth) {
                final int scaledChildWidth = previewWidth * height / previewHeight;
                child.layout((width - scaledChildWidth) / 2, 0,
                        (width + scaledChildWidth) / 2, height);
            } else {
                final int scaledChildHeight = previewHeight * width / previewWidth;
                child.layout(0, (height - scaledChildHeight) / 2,
                        width, (height + scaledChildHeight) / 2);
            }
        }
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.
        try {
            if (mCamera != null) {
                mCamera.setPreviewDisplay(holder);
            }
        } catch (IOException exception) {
            Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        if (mCamera != null) {
            mCamera.cancelAutoFocus();
            mCamera.stopPreview();
        }
    }


    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null) return null;

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        if (holder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // Now that the size is known, set up the camera parameters and begin
        // the preview.
        Camera.Parameters parameters = mCamera.getParameters();
        parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
        requestLayout();

        mCamera.setParameters(parameters);
        mCamera.setPreviewCallback(mPreviewCallback);
        mCamera.startPreview();
        mCamera.autoFocus(mAutoFocusCallback);
    }

}

How to customize the camera view for android? I saw some suggested solutions for iPhone, but zbar API for Android is totally different and much smaller. I would be appreciated to get any idea/hint...

回答1:

To present a frame in cameraview, add an imageview in the framelayout(camerapreview) in main.xml .

   <FrameLayout
     android:id="@+id/cameraPreview"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:layout_weight="1" >
     <ImageView
        android:id="@+id/imageView1"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:alpha="0.6"
        android:src="@drawable/overlay" />
   </FrameLayout>

Use this code to make the frame(imageview) visible. As the frame(imageview) is already present in the framelayout in main.xml we need to remove it first.

    FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
    ImageView iv=(ImageView) findViewById(R.id.imageView1);
    preview.addView(mPreview);
    preview.removeView(iv);
    preview.addView(iv);

To scan the camerapreview only from your frame you need to use setCrop().Adjust the size of camerapreview according to the frame.

    barcode.setData(data);
  //this is in portrait mode
  //barcode.setCrop(left,top,width,height). 
    barcode.setCrop(100,230,600,10);

This worked for me and hope it will solve your problem too. Please excuse me for my grammatical mistakes. Thank you.

回答2:

I think it's easier then you thought:

In the example code provided by the ZBar guy there are those two lines in the onCreate() method:

FrameLayout preview = (FrameLayout) findViewById(R.id.cameraPreview);
preview.addView(mPreview);

which are responsible for adding the "preview view" to the camerPreview Layout.

Find the mentioned lines in your code, create a new ImageView and also add it to the preview-Layout like this:

ImageView v = new ImageView(this);
v.setImageResource(R.drawable.icon);
preview.addView(v);

Adjust the size and the position of your view v and you are done!

回答3:

I faced the same problem. The solution is simply add the CameraPrevie in your xml inside a frameLayout, and just after that the image you want to put on top of is.

eg.:

 <FrameLayout
    android:id="@+id/captionFrame"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:layout_marginBottom="20dp"
    android:layout_marginTop="50dp" >

    <FrameLayout
        android:id="@+id/cameraPreview"
        android:layout_width="300dp"
        android:layout_height="200dp"
        android:layout_gravity="center"
        android:paddingLeft="-5dp" >

    </FrameLayout>

    <ImageView
        android:id="@+id/watermark"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right|bottom"
        android:src="@drawable/watermark" />

</FrameLayout>

and populate it from your activity:

Camera mCamera = getCameraInstance();

ImageScanner scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);

CameraPreview mPreview = new CameraPreview(this, mCamera, null, autoFocusCallB);
FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
 preview.addView(mPreview);