本文介紹了Android camera , onPictureTaken(byte[] imgData, Camera camera) 方法 &PictureCallback 從未調用過的處理方法，對大家解決問題具有一定的參考價值，需要的朋友們下面隨著小編來一起學習吧！
問題描述
我有一個自定義相機應用程序，它可以在 SurfaceView 上預覽相機視頻輸出并嘗試拍照，這些照片應該由xzing"掃描儀 API 處理，以解碼圖像中的任何條形碼.
I have a custom camera app , that previews the camera video output on SurfaceView and attempts to take pictures , the pics should be will be processed by "xzing "scanner API to decode any barcodes in the image.
我的應用可以正確預覽并且不會拋出任何錯誤或期望，但是我的 onPictureTaken(byte[] imgData, Camera camera) 方法和PictureCallback 永遠不會被調用，因此我無法獲取圖像 &繼續進一步掃描.
My app previews correctly and does not throw any errors or expectations, however my onPictureTaken(byte[] imgData, Camera camera) method & PictureCallback are never called, therefore I’m unable to get the image & continue with further scanning.
以下是負責相機邏輯的活動的實際代碼.onPictureTaken(byte[] imgData, Camera camera) 方法 &PictureCallback 都在這個類中(ScanVinFromBarcodeActivity.java)見吹:
package com.ty.tyownerspoc.barcode;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.NotFoundException;
import com.google.zxing.RGBLuminanceSource;
import com.google.zxing.Reader;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.Point;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Display;
import android.view.SurfaceView;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.ty.tyownerspoc.R;
public class ScanVinFromBarcodeActivity extends Activity {
private Camera globalCamera;
private int cameraId = 0;
private TextView VINtext = null;
private View scanButton = null;
// bitmap from camera
private Bitmap bmpOfTheImageFromCamera = null;
// global flag whether a camera has been detected
private boolean isThereACamera = false;
// surfaceView for preview object
private FrameLayout frameLayoutBarcodeScanner = null;
private CameraPreview newCameraPreview = null;
private SurfaceView surfaceViewBarcodeScanner = null;
private int counter = 0;
private volatile boolean finishedPictureTask = false;
/*
* This method , finds FEATURE_CAMERA, opens the camera, set parameters ,
* add CameraPreview to layout, set camera surface holder, start preview
*/
private void initializeGlobalCamera() {
try {
if (!getPackageManager().hasSystemFeature(
PackageManager.FEATURE_CAMERA)) {
Toast.makeText(this, "No camera on this device",
Toast.LENGTH_LONG).show();
} else { // check for front camera ,and get the ID
cameraId = findFrontFacingCamera();
if (cameraId < 0) {
Toast.makeText(this, "No front facing camera found.",
Toast.LENGTH_LONG).show();
} else {
Log.d("ClassScanViewBarcodeActivity",
"camera was found , ID: " + cameraId);
// camera was found , set global camera flag to true
isThereACamera = true;
// OPEN
globalCamera = Camera.open(cameraId);
// pass surfaceView to CameraPreview
newCameraPreview = new CameraPreview(this, globalCamera);
// pass CameraPreview to Layout
frameLayoutBarcodeScanner.addView(newCameraPreview);
try {
globalCamera
.setPreviewDisplay(surfaceViewBarcodeScanner
.getHolder());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// PREVIEW
globalCamera.startPreview();
Log.d("ClassScanViewBarcodeActivity",
"camera opened & previewing");
}
}// end else ,check for front camera
}// end try
catch (Exception exc) {
// in case of exception release resources & cleanup
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
Log.d("ClassScanViewBarcodeActivity initializeGlobalCamera() exception:",
exc.getMessage());
}// end catch
}
// onCreate, instantiates layouts & surfaceView used for video preview
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_barcode_vin_scanner);
Log.d("ClassScanViewBarcodeActivity", "onCreate ");
// create surfaceView for previewing of camera image
frameLayoutBarcodeScanner = (FrameLayout) findViewById(R.id.FrameLayoutForPreview);
surfaceViewBarcodeScanner = (SurfaceView) findViewById(R.id.surfaceViewBarcodeScanner);
initializeGlobalCamera();
// create text area & scan button
VINtext = (TextView) findViewById(R.id.mytext);
scanButton = findViewById(R.id.webbutton);
// on click listener, onClick take a picture
scanButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
try {
// if true take a picture
if (isThereACamera) {
Log.d("ClassScanViewBarcodeActivity",
"setOnClickListener() isThereACamera: "+ isThereACamera);
//set picture format to JPEG, everytime makesure JPEg callback is called
Parameters parameters = globalCamera.getParameters();
parameters.setPictureFormat(ImageFormat.JPEG);
globalCamera.setParameters(parameters);
//take pic , should call Callback
globalCamera.takePicture(null, null, jpegCallback);
// wait 1 sec , than start preview again
Thread.sleep(1000);
//STOP
globalCamera.stopPreview();
//start previewing again onthe SurfaceView in case use wants to take another pic/scan
globalCamera.startPreview();
}
}// end try
catch (Exception exc) {
// in case of exception release resources & cleanup
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
Log.d("ClassScanViewBarcodeActivity setOnClickListener() exceprtion:",
exc.getMessage());
}// end catch
}// end on Click
});// end OnClickListener() implementation
}// end onCreate
@Override
protected void onResume() {
Log.d("ClassScanViewBarcodeActivity, onResume() globalCamera:",
String.valueOf(globalCamera));
if (globalCamera != null) {
// START PREVIEW
globalCamera.startPreview();
} else {
initializeGlobalCamera();
}
super.onResume();
}
@Override
protected void onStop() {
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
super.onStop();
}
//callback used by takePicture()
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] imgData, Camera camera) {
BinaryBitmap bitmap = null;
try {
Log.d("ClassScanViewBarcodeActivity" ,"onPictureTaken()");
//save image to sd card
savePicture(imgData);
// get the bitmap from camera imageData
bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
imgData, 0, imgData.length);
if (bmpOfTheImageFromCamera != null) {
//Galaxy S3 , incorrect rotation issue rotate to correct rotation
Matrix matrix = new Matrix();
matrix.postRotate(90);
Bitmap rotatedBitmap = Bitmap.createBitmap(bmpOfTheImageFromCamera, 0, 0, bmpOfTheImageFromCamera.getWidth(), bmpOfTheImageFromCamera.getHeight(), matrix, true);
// convert bitmap to binary bitmap
bitmap = cameraBytesToBinaryBitmap(rotatedBitmap);
if (bitmap != null) {
// decode the VIN
String VIN = decodeBitmapToString(bitmap);
Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
VIN);
VINtext.setText(VIN);
} else {
Log.d("ClassScanViewBarcodeActivity ,onPictureTaken(): bitmap=",String.valueOf(bitmap));
}
} else {
Log.d("ClassScanViewBarcodeActivity , onPictureTaken(): bmpOfTheImageFromCamera = ",
String.valueOf(bmpOfTheImageFromCamera));
}
}// end try
catch (Exception exc) {
exc.getMessage();
Log.d("ClassScanViewBarcodeActivity , scanButton.setOnClickListener(): exception = ",
exc.getMessage());
}
}// end onPictureTaken()
};// jpegCallback implementation
/*
* created savePicture(byte [] data) for testing
*/
public void savePicture(byte [] data)
{
Log.d( "ScanVinFromBarcodeActivity " , "savePicture(byte [] data)");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyymmddhhmmss");
String date = dateFormat.format(new Date());
String photoFile = "Picture_"+counter+"_"+ date + ".jpg";
File sdDir = Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
String filename =sdDir + File.separator + photoFile;
File pictureFile = new File(filename);
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
Toast.makeText(this, "New Image saved:" + photoFile,
Toast.LENGTH_LONG).show();
} catch (Exception error) {
Log.d( "File not saved: " , error.getMessage());
Toast.makeText(this, "Image could not be saved.",
Toast.LENGTH_LONG).show();
}
counter++;
}
private int findFrontFacingCamera() {
int cameraId = -1;
// Search for the front facing camera
int numberOfCameras = Camera.getNumberOfCameras();
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_BACK) {
Log.d("ClassScanViewBarcodeActivity , findFrontFacingCamera(): ",
"Camera found");
cameraId = i;
break;
}
}
return cameraId;
}// end findFrontFacingCamera()
@Override
protected void onPause() {
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
super.onPause();
}// end onPause()
public String decodeBitmapToString(BinaryBitmap bitmap) {
Reader reader = null;
Result result = null;
String textResult = null;
try {
reader = new MultiFormatReader();
if (bitmap != null) {
result = reader.decode(bitmap);
if (result != null) {
textResult = result.getText();
} else {
Log.d("ClassScanViewBarcodeActivity , String decodeBitmapToString (BinaryBitmap bitmap): result = ",
String.valueOf(result));
}
} else {
Log.d("ClassScanViewBarcodeActivity , String decodeBitmapToString (BinaryBitmap bitmap): bitmap = ",
String.valueOf(bitmap));
}
/*
* byte[] rawBytes = result.getRawBytes(); BarcodeFormat format =
* result.getBarcodeFormat(); ResultPoint[] points =
* result.getResultPoints();
*/
} catch (NotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ChecksumException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (FormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return textResult;
}// end decodeBitmapToString (BinaryBitmap bitmap)
public BinaryBitmap cameraBytesToBinaryBitmap(Bitmap bitmap) {
BinaryBitmap binaryBitmap = null;
if (bitmap != null) {
int[] pixels = new int[bitmap.getHeight() * bitmap.getWidth()];
bitmap.getPixels(pixels, 0, 0, bitmap.getWidth() - 1,
bitmap.getHeight() - 1, bitmap.getWidth(),
bitmap.getHeight());
RGBLuminanceSource source = new RGBLuminanceSource(
bitmap.getWidth(), bitmap.getHeight(), pixels);
HybridBinarizer bh = new HybridBinarizer(source);
binaryBitmap = new BinaryBitmap(bh);
} else {
Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap): bitmap = ",
String.valueOf(bitmap));
}
return binaryBitmap;
}
@SuppressLint("NewApi")
@SuppressWarnings("deprecation")
/*
* The method getScreenOrientation() return screen orientation either
* landscape or portrait. IF width < height , than orientation = portrait,
* ELSE landscape For backwards compatibility we use to methods to detect
* the orientation. The first method is for API versions prior to 13 or
* HONEYCOMB.
*/
public int getScreenOrientation() {
int currentapiVersion = android.os.Build.VERSION.SDK_INT;
// if API version less than 13
Display getOrient = getWindowManager().getDefaultDisplay();
int orientation = Configuration.ORIENTATION_UNDEFINED;
if (currentapiVersion < android.os.Build.VERSION_CODES.HONEYCOMB) {
// Do something for API version less than HONEYCOMB
if (getOrient.getWidth() == getOrient.getHeight()) {
orientation = Configuration.ORIENTATION_SQUARE;
} else {
if (getOrient.getWidth() < getOrient.getHeight()) {
orientation = Configuration.ORIENTATION_PORTRAIT;
} else {
orientation = Configuration.ORIENTATION_LANDSCAPE;
}
}
} else {
// Do something for API version greater or equal to HONEYCOMB
Point size = new Point();
this.getWindowManager().getDefaultDisplay().getSize(size);
int width = size.x;
int height = size.y;
if (width < height) {
orientation = Configuration.ORIENTATION_PORTRAIT;
} else {
orientation = Configuration.ORIENTATION_LANDSCAPE;
}
}
return orientation;
}// end getScreenOrientation()
}// end class ScanVinFromBarcodeActivity
用于在 SurfaceView 上顯示實時攝像頭的預覽類 (CameraPreview.java):
package com.ty.tyownerspoc.barcode;
import java.io.IOException;
import java.util.List;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;
import android.hardware.Camera.CameraInfo;
/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
private Context context;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
this.context = context;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the
// preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null) {
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e) {
// ignore: tried to stop a non-existent preview
}
Camera.Parameters p = mCamera.getParameters();
// get width & height of the SurfaceView
int SurfaceViewWidth = this.getWidth();
int SurfaceViewHeight = this.getHeight();
List<Size> sizes = p.getSupportedPreviewSizes();
Size optimalSize = getOptimalPreviewSize(sizes, SurfaceViewWidth, SurfaceViewHeight);
// set parameters
p.setPreviewSize(optimalSize.width, optimalSize.height);
/*rotate the image by 90 degrees clockwise , in order to correctly displayed the image , images seem to be -90 degrees (counter clockwise) rotated
* I even tried setting it to p.setRotation(0); , but still no effect.
*/
mCamera.setDisplayOrientation(90);
mCamera.setParameters(p);
// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e) {
Log.d("CameraPreview , surfaceCreated() , orientation: ",
String.valueOf(e.getMessage()));
}
}// end surfaceChanged()
static Size getOptimalPreviewSize(List <Camera.Size>sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
final double MAX_DOWNSIZE = 1.5;
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 (Camera.Size size : sizes) {
double ratio = (double) size.width / size.height;
double downsize = (double) size.width / w;
if (downsize > MAX_DOWNSIZE) {
//if the preview is a lot larger than our display surface ignore it
//reason - on some phones there is not enough heap available to show the larger preview sizes
continue;
}
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
//keep the max_downsize requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
double downsize = (double) size.width / w;
if (downsize > MAX_DOWNSIZE) {
continue;
}
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
//everything else failed, just take the closest match
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;
}
}//end Preview class
ScanVinFromBarcodeActivity"活動的布局 (activity_barcode_vin_scanner.xml):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:padding="20dip" >
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:padding="20dip"
android:text="@string/decode_label"
android:textColor="@color/mbackground1" />
<TextView
android:id="@+id/mytext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@color/mbackground2"
android:gravity="center_horizontal"
android:padding="20dip"
android:textColor="@color/mytextcolor" />
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:padding="20dip"
android:text="@string/continue_label"
android:textColor="@color/mytextcolor" />
<Button
android:id="@+id/webbutton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/web_button"
android:textColor="@color/mytextcolor" />
<FrameLayout
android:id="@+id/FrameLayoutForPreview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1">
<SurfaceView
android:id="@+id/surfaceViewBarcodeScanner"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</FrameLayout>
</LinearLayout>
任何幫助將不勝感激.
謝謝
Updated & working onTakePicturen method, the that works , the PictureCallback returns (stopPreview & StartPreview were moved to inside this method in its finally block).
public void onPictureTaken(byte[] imgData, Camera camera) {
BinaryBitmap bitmap;
try {
Log.d("ClassScanViewBarcodeActivity" ,"onPictureTaken()");
//save image to sd card
savePicture(imgData);
// get the bitmap from camera imageData
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 8;
//down sample
bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
imgData, 0, imgData.length,options);
if (bmpOfTheImageFromCamera != null) {
Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): bmpOfTheImageFromCamera getByteCount(): ",
String.valueOf(bmpOfTheImageFromCamera.getByteCount()));
//Galaxy S3 , incorrect rotation issue rotate to correct rotation
/*Matrix matrix = new Matrix();
matrix.postRotate(90);
Bitmap rotatedBitmap = Bitmap.createBitmap(bmpOfTheImageFromCamera, 0, 0, bmpOfTheImageFromCamera.getWidth(), bmpOfTheImageFromCamera.getHeight(), matrix, true);*/
// convert bitmap to binary bitmap
bitmap = cameraBytesToBinaryBitmap(bmpOfTheImageFromCamera);
if (bitmap != null) {
// decode the VIN
String VIN = decodeBitmapToString(bitmap);
Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
VIN);
VINtext.setText(VIN);
} else {
Log.d("ClassScanViewBarcodeActivity ,onPictureTaken(): bitmap=",String.valueOf(bitmap));
}
} else {
Log.d("ClassScanViewBarcodeActivity , onPictureTaken(): bmpOfTheImageFromCamera = ",
String.valueOf(bmpOfTheImageFromCamera));
}
}// end try
catch (Exception exc) {
exc.getMessage();
Log.d("ClassScanViewBarcodeActivity , scanButton.setOnClickListener(): exception = ",
exc.getMessage());
}
finally
{
globalCamera.stopPreview();
//start previewing again onthe SurfaceView in case use wants to take another pic/scan
globalCamera.startPreview();
}
}// end onPictureTaken()
};// jpegCallback implementation
推薦答案
我能找到的唯一可能是罪魁禍首的是，您在 jpegCallback 返回之前再次開始預覽.根據 javadoc，這是不允許的:
The only thing I can find that might be the culprit is that you're starting the preview again before the jpegCallback has returned. According to the javadoc, this is not allowed:
調用此方法后，在 JPEG 回調返回之前，不得調用 startPreview() 或拍攝另一張照片.
After calling this method, you must not call startPreview() or take another picture until the JPEG callback has returned.
回調實際上是放在 UI 線程隊列中 - 它將在您的 Thread.sleep() 中暫停，并且同一個線程將調用 stopPreview() 并且startPreview() 在真正進入回調之前.一般來說，如果你在 UI 線程上調用 Thread.sleep() - 你做錯了.因此，希望如果您刪除 sleep() 并將其后的內容放入 jpegCallback 您的問題應該得到解決.
The callback is actually put on the UI thread queue - which will be suspended in your Thread.sleep() and the same thread will have called stopPreview() and startPreview() before actually coming to the callback. Generally speaking, if you call Thread.sleep() on the UI thread - you're doing it wrong. So, hopefully if you remove the sleep() and put what comes after it in the jpegCallback your problem should be solved.
這篇關于Android camera , onPictureTaken(byte[] imgData, Camera camera) 方法 &PictureCallback 從未調用過的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！
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