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);
来源：https://stackoverflow.com/questions/16311693/customize-camera-view-for-android-using-zbar