我正在开发具有以下功能的条形码扫描应用程序:
• 访问设备相机，在 SurfaceView 上预览相机，并自动重新对焦
• 尝试使用两种方法解码条码
a) 在使用 onTouchEvent(MotionEvent event) 的 SurfaceView 触摸上，尝试拍摄条形码的照片，但得到 java.lang.RuntimeException: takePicture failed
b) 或者 Preferator ，可以在 onAutoFocus(boolean success, Camera camera) 成功时拍照，但不会调用 onAutoFocus()
我正在实现“AutoFocusCallback”，并在名为“ScanVinFromBarcodeActivity”的扫描 Activity 中设置回相机对象。
下面是我的“ScanVinFromBarcodeActivity”，它负责相机功能:
package com.t.t.barcode;
/* I removed import statements because of character limit*/
import com.t.t.R;
public class ScanVinFromBarcodeActivity extends Activity {
private Camera globalCamera;
private int cameraId = 0;
private TextView VINtext = null;
private Bitmap bmpOfTheImageFromCamera = null;
private boolean isThereACamera = false;
private RelativeLayout RelativeLayoutBarcodeScanner = null;
private CameraPreview newCameraPreview = null;
private SurfaceView surfaceViewBarcodeScanner = null;
private String VIN = null;
private boolean globalFocusedBefore = false;
//This method , finds FEATURE_CAMERA, opens the camera, set parameters ,
@SuppressLint("InlinedApi")
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 = getGlobalCamera(cameraId);
//PARAMETERS FOR AUTOFOCUS
globalCamera.getParameters().setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
//set auto focus callback , called when autofocus has completed
globalCamera.autoFocus(autoFocusCallback); //将 surfaceView 传递给 CameraPreview newCameraPreview = new CameraPreview(this, globalCamera) {
@Override
public boolean onTouchEvent(MotionEvent event) {
Log.d("ClassScanViewBarcodeActivity"," onTouchEvent(MotionEvent event) ");
takePicture();
return super.onTouchEvent(event);
}
};
// pass CameraPreview to Layout
RelativeLayoutBarcodeScanner.addView(newCameraPreview);
//give reference SurfaceView to camera object
globalCamera
.setPreviewDisplay(surfaceViewBarcodeScanner
.getHolder());
// PREVIEW
globalCamera.startPreview();
Log.d("ClassScanViewBarcodeActivity",
"camera opened & previewing");
}
}// end else
}// end try
catch (Exception exc) {
// resources & cleanup
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
Log.d("ClassScanViewBarcodeActivity initializeGlobalCamera() exception:",
exc.getMessage());
exc.printStackTrace();
}// 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
RelativeLayoutBarcodeScanner = (RelativeLayout) findViewById(R.id.LayoutForPreview);
surfaceViewBarcodeScanner = (SurfaceView) findViewById(R.id.surfaceViewBarcodeScanner);
initializeGlobalCamera();
}// end onCreate
@Override
protected void onResume() {
Log.d("ClassScanViewBarcodeActivity, onResume() globalCamera:",
String.valueOf(globalCamera));
initializeGlobalCamera();
super.onResume();
}
@Override
protected void onStop() {
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
super.onStop();
}
@Override
protected void onPause() {
if (globalCamera != null) {
globalCamera.stopPreview();
globalCamera.setPreviewCallback(null);
globalCamera.release();
globalCamera = null;
}
super.onPause();
}// end onPause()
// callback used by takePicture()
@SuppressLint("NewApi")
public void onPictureTaken(byte[] imgData, Camera camera) {
BinaryBitmap bitmap = null ;
try {
Log.d("ClassScanViewBarcodeActivity", "onPictureTaken()");
// 1)down-sampled the image via to prevent MemoryOutOfBounds exception.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4;
options.inPreferQualityOverSpeed =true;
bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
imgData, 0, imgData.length, options);
if (bmpOfTheImageFromCamera != null) {
// 2) Samsung galaxy S only , rotate to correct orientation
Matrix rotationMatrix90CounterClockWise = new Matrix();
rotationMatrix90CounterClockWise.postRotate(90);
bmpOfTheImageFromCamera = Bitmap.createBitmap(
bmpOfTheImageFromCamera, 0, 0,
bmpOfTheImageFromCamera.getWidth(),
bmpOfTheImageFromCamera.getHeight(),
rotationMatrix90CounterClockWise, true);
// 3) calculate relative x,y & width & height , because SurfaceView coordinates are different than the coordinates of the image
guidanceRectangleCoordinatesCalculations newguidanceRectangleCoordinatesCalculations = new guidanceRectangleCoordinatesCalculations(
bmpOfTheImageFromCamera.getWidth(),
bmpOfTheImageFromCamera.getHeight());
// 4) crop & only take image/data that is within the bounding rectangle
Bitmap croppedBitmap = Bitmap
.createBitmap(
bmpOfTheImageFromCamera,
newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleStartX(),
newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleStartY(),
newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleEndX()
- newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleStartX(),
newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleEndY()
- newguidanceRectangleCoordinatesCalculations
.getGuidanceRectangleStartY());
//Bitmap to BinaryBitmap
bitmap = cameraBytesToBinaryBitmap(croppedBitmap);
//early cleanup
croppedBitmap.recycle();
croppedBitmap = null;
if (bitmap != null) {
// 7) decode the VIN
VIN = decodeBitmapToString(bitmap);
Log.("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
VIN);
if (VIN!=null)
{
//original before sharpen
byte [] bytesImage = bitmapToByteArray ( croppedBitmap );
savePicture(bytesImage, 0 , "original");
//after sharpen
croppedBitmap = sharpeningKernel (croppedBitmap);
bytesImage = bitmapToByteArray ( croppedBitmap );
savePicture(bytesImage, 0 , "sharpened");
Toast toast= Toast.makeText(getApplicationContext(),
"VIN:"+VIN, Toast.LENGTH_SHORT);
toast.setGravity(Gravity.TOP|Gravity.CENTER_HORIZONTAL, 0, 0);
toast.show();
}
} 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 {
// start previewing again onthe SurfaceView in case use wants to
// take another pic/scan
globalCamera.startPreview();
bitmap = null;
}
}// end onPictureTaken()
};//end
//autoFocuscallback
AutoFocusCallback autoFocusCallback = new AutoFocusCallback() {
@Override
public void onAutoFocus(boolean success, Camera camera) {
Log.d("***onAutoFocus(boolean success, Camera camera)","success: "+success);
if (success)
{
globalFocusedBefore = true;
takePicture();
}
}
};//end
public Camera getGlobalCamera(int CameraId)
{
if (globalCamera==null)
{
// OPEN
globalCamera = Camera.open( CameraId);
}
return globalCamera;
}
/* find camera on device */
public static 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()
/*
* created savePicture(byte [] data) for testing
*/
public void savePicture(byte[] data, double sizeInPercent , String title) {
Log.d("ScanVinFromBarcodeActivity ", "savePicture(byte [] data)");
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyymmddhhmmss");
String date = dateFormat.format(new Date());
String photoFile = "Picture_sample_sizePercent_" + sizeInPercent + "_" + title + "_"
+ 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();
}
}
/*
* Attempts to decode barcode data inside the input bitmap. Uses zxing API */
@SuppressWarnings("finally")
public String decodeBitmapToString(BinaryBitmap bitmap) {
Log.d("ClassScanViewBarcodeActivity",
"decodeBitmapToString(BinaryBitmap bitmap");
Reader reader = null;
Result result = null;
String textResult = null;
Hashtable<DecodeHintType, Object> decodeHints = null;
try {
decodeHints = new Hashtable<DecodeHintType, Object>();
decodeHints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
decodeHints.put(DecodeHintType.PURE_BARCODE, Boolean.TRUE);
reader = new MultiFormatReader();
if (bitmap != null) {
result = reader.decode(bitmap, decodeHints);
if (result != null) {
Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
String.valueOf(result));
Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
String.valueOf(result.getBarcodeFormat().toString()));
textResult = result.getText();
} else {
Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
String.valueOf(result));
}
} else {
Log.d("decodeBitmapToString (BinaryBitmap bitmap): bitmap = ",
String.valueOf(bitmap));
}
} catch (NotFoundException e) {
// TODO Auto-generated catch block
textResult = "Unable to decode. Please try again.";
e.printStackTrace();
Log.d("ClassScanViewBarcodeActivity, NotFoundException:",
e.getMessage());
} catch (ChecksumException e) {
textResult = "Unable to decode. Please try again.";
e.printStackTrace();
Log.d("ClassScanViewBarcodeActivity, ChecksumException:",
e.getMessage());
} catch (FormatException e) {
textResult = "Unable to decode. Please try again.";
e.printStackTrace();
Log.d("ClassScanViewBarcodeActivity, FormatException:",
e.getMessage());
}
finally {
//cleanup
reader = null;
result = null;
decodeHints = null;
return textResult;
}
}// end decodeBitmapToString ()
@SuppressWarnings("finally")
public BinaryBitmap cameraBytesToBinaryBitmap(Bitmap bitmap) {
Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap):",
"");
BinaryBitmap binaryBitmap = null;
RGBLuminanceSource source = null;
HybridBinarizer bh = null;
try {
if (bitmap != null) {
//bitmap.getPixels(pixels, 0, bitmap.getWidth(), 0, 0,bitmap.getWidth(), bitmap.getHeight());
//RGBLuminanceSource source = new RGBLuminanceSource(bitmap.getWidth(), bitmap.getHeight(), pixels);
source = new RGBLuminanceSource(bitmap);
bh = new HybridBinarizer(source);
binaryBitmap = new BinaryBitmap(bh);
} else {
Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap): bitmap = ",
String.valueOf(bitmap));
}
} catch (Exception exc) {
exc.printStackTrace();
} finally {
source = null;
bh = null;
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()
public Bitmap sharpeningKernel (Bitmap bitmap)
{
if (bitmap!=null)
{
int result = 0 ;
int pixelAtXY = 0;
for (int i=0 ; i<bitmap.getWidth(); i++)
{
for (int j=0 ; j<bitmap.getHeight(); j++)
{
//piecewise multiply with kernel
//add multiplication result to total / sum of kernel values
/* Conceptual kernel
* int kernel [][]=
{{0,-1,0},
{-1,5,-1},
{0,-1,0}};
*/
pixelAtXY = bitmap.getPixel(i, j);
result = ((pixelAtXY * -1) + (pixelAtXY * -1) + (pixelAtXY * 5)+ (pixelAtXY * -1) + (pixelAtXY * -1));
bitmap.setPixel(i, j,result);
}
}
}
return bitmap;
}//end
public byte [] bitmapToByteArray (Bitmap bitmap)
{
ByteArrayOutputStream baoStream = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100,
baoStream);
return baoStream.toByteArray();
}
public void takePicture()
{
Log.d("ClassScanViewBarcodeActivity","takePicture()");
try {
// if true take a picture
if (isThereACamera) {
Log.d("ClassScanViewBarcodeActivity",
"setOnClickListener() isThereACamera: "
+ isThereACamera);
// set picture format to JPEG, everytime makesure JPEg
globalCamera.getParameters().setPictureFormat(ImageFormat.JPEG);
if ( globalFocusedBefore = true)
{
// take pic , should call Callback
globalCamera.takePicture(null, null, jpegCallback);
//reset autofocus flag
globalFocusedBefore = false;
}
}
}// 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());
exc.printStackTrace();
}// end catch
}// end takePicture()
}// end activity class
下面是我的预览类，它显示来自相机的实时图像
package com.t.t.barcode;
/* I removed imports due to character limit on Stackoverflow*/
package com.t.t.barcode;
/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
private Context context;
//
private int guidanceRectangleStartX;
private int guidanceRectangleStartY;
private int guidanceRectangleEndX;
private int guidanceRectangleEndY;
//
private ImageView imageView = null;
private Bitmap guidanceScannerFrame = null;
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);
setWillNotDraw(false);
setFocusable(true);
requestFocus();
guidanceScannerFrame = getBitmapFromResourcePath("res/drawable/scanner_frame.png");
}
public void drawGuidance(Canvas canvas)
{
Paint paintRed = new Paint();
paintRed.setStyle(Paint.Style.STROKE);
paintRed.setStrokeWidth(6f);
paintRed.setAntiAlias(true);
paintRed.setColor(Color.RED);
//drawMiddleline
canvas.drawLine(0,this.getHeight()/2, this.getWidth(),this.getHeight()/2, paintRed);
if (guidanceScannerFrame!=null)
{
Paint paint = new Paint();
paint.setFilterBitmap(true);
int diffInWidth =0;
int diffInHeight = 0;
try
{
diffInWidth = this.getWidth() - guidanceScannerFrame.getScaledWidth(canvas);
diffInHeight = this.getHeight() - guidanceScannerFrame.getScaledHeight(canvas);
//
canvas.drawBitmap(guidanceScannerFrame,(diffInWidth/2),(diffInHeight/2) , paint);
}
catch (NullPointerException exc)
{
exc.printStackTrace();
}
/*create rectangle that is relative to the SurfaceView coordinates and fits inside the Bitmap rectangle,
* this coordinates will later be used to crop inside of the Bitmap to take in the only the barcode's picture*/
Paint paintGray = new Paint();
paintGray.setStyle(Paint.Style.STROKE);
paintGray.setStrokeWidth(2f);
paintGray.setAntiAlias(true);
paintGray.setColor(Color.GRAY);
//drawRect
canvas.drawRect((diffInWidth/2), (diffInHeight/2), (diffInWidth/2)+guidanceScannerFrame.getScaledWidth(canvas),(diffInHeight/2)+guidanceScannerFrame.getScaledHeight(canvas), paintGray);
this.guidanceRectangleStartX = this.getWidth()/12;
this.guidanceRectangleStartY= this.getHeight()/3;
this.guidanceRectangleEndX = this.getWidth()-this.getWidth()/12;
this.guidanceRectangleEndY =(this.getHeight()/3)+( 2 *(this.getHeight()/3));
}
}
@Override
public void onDraw(Canvas canvas) {
//drawGuidance
drawGuidance(canvas);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the
// preview.
try {
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);
p.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
/*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);
mCamera.setPreviewDisplay(holder);
mCamera.startPreview();
} catch (IOException e) {
e.printStackTrace();
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
@SuppressLint("InlinedApi")
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
}
// 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;
}
public Bitmap getBitmapFromResourcePath (String path)
{
InputStream in =null;
Bitmap guidanceBitmap = null;
try
{
if (path!=null)
{
in = this.getClass().getClassLoader().getResourceAsStream(path);
guidanceBitmap = BitmapFactory.decodeStream(in);
}
}
catch (Exception exc)
{
exc.printStackTrace();
}
finally
{
if (in!=null)
{
try {
in.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return guidanceBitmap;
}
public int getGuidanceRectangleStartX() {
return guidanceRectangleStartX;
}
public int getGuidanceRectangleStartY() {
return guidanceRectangleStartY;
}
public int getGuidanceRectangleEndX() {
return guidanceRectangleEndX;
}
public int getGuidanceRectangleEndY() {
return guidanceRectangleEndY;
}
}//end preview class
屏幕截图 Activity GUI:
任何帮助将不胜感激，谢谢。
最佳答案
您在预览类中调用 Oncreate 上的自动对焦 它应该在表面创建或表面改变时调用 因为一旦启动相机预览就会发生自动对焦 看看这段代码，我已经处理过了，它正在运行
private void tryAutoFocus() {
if( MyDebug.LOG )
Log.d(TAG, "tryAutoFocus");
if( camera == null ) {
if( MyDebug.LOG )
Log.d(TAG, "no camera");
}
else if( !this.has_surface ) {
if( MyDebug.LOG )
Log.d(TAG, "preview surface not yet available");
}
else if( !this.is_preview_started ) {
if( MyDebug.LOG )
Log.d(TAG, "preview not yet started");
}
else if( is_taking_photo ) {
if( MyDebug.LOG )
Log.d(TAG, "currently taking a photo");
}
else {
// if a focus area is set, we always call autofocus even if it isn't supported, so we get the focus box
// otherwise, it's only worth doing it when autofocus has an effect (i.e., auto or macro mode)
Camera.Parameters parameters = camera.getParameters();
String focus_mode = parameters.getFocusMode();
if( has_focus_area || focus_mode.equals(Camera.Parameters.FOCUS_MODE_AUTO) || focus_mode.equals(Camera.Parameters.FOCUS_MODE_MACRO) ) {
if( MyDebug.LOG )
Log.d(TAG, "try to start autofocus");
Camera.AutoFocusCallback autoFocusCallback = new Camera.AutoFocusCallback() {
@Override
public void onAutoFocus(boolean success, Camera camera) {
if( MyDebug.LOG )
Log.d(TAG, "autofocus complete: " + success);
focus_success = success ? FOCUS_SUCCESS : FOCUS_FAILED;
focus_complete_time = System.currentTimeMillis();
if(_automationStarted){
takeSnapPhoto();
}
}
};
this.focus_success = FOCUS_WAITING;
this.focus_complete_time = -1;
camera.autoFocus(autoFocusCallback);
}
}
}
public void surfaceCreated(SurfaceHolder holder) {
if( MyDebug.LOG )
Log.d(TAG, "surfaceCreated()");
// The Surface has been created, acquire the camera and tell it where to draw.
this.has_surface = true;
this.openCamera(false); // if setting up for the first time, we wait until the surfaceChanged call to start the preview
this.setWillNotDraw(false); // see http://stackoverflow.com/questions/2687015/extended-surfaceviews-ondraw-method-never-called
}
public void surfaceDestroyed(SurfaceHolder holder) {
if( MyDebug.LOG )
Log.d(TAG, "surfaceDestroyed()");
// Surface will be destroyed when we return, so stop the preview.
// Because the CameraDevice object is not a shared resource, it's very
// important to release it when the activity is paused.
this.has_surface = false;
this.closeCamera();
}
public void takeSnapPhoto() {
camera.setOneShotPreviewCallback(new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
Camera.Parameters parameters = camera.getParameters();
int format = parameters.getPreviewFormat();
//YUV formats require more conversion
if (format == ImageFormat.NV21 || format == ImageFormat.YUY2 || format == ImageFormat.NV16) {
int w = parameters.getPreviewSize().width;
int h = parameters.getPreviewSize().height;
// Get the YuV image
YuvImage yuv_image = new YuvImage(data, format, w, h, null);
// Convert YuV to Jpeg
Rect rect = new Rect(0, 0, w, h);
ByteArrayOutputStream output_stream = new ByteArrayOutputStream();
yuv_image.compressToJpeg(rect, 100, output_stream);
byte[] byt = output_stream.toByteArray();
FileOutputStream outStream = null;
try {
// Write to SD Card
File file = createFileInSDCard(FOLDER_PATH, "Image_"+System.currentTimeMillis()+".jpg");
//Uri uriSavedImage = Uri.fromFile(file);
outStream = new FileOutputStream(file);
outStream.write(byt);
outStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
}
}
});
}
当你初始化相机时(或在这种情况下打开相机)
private void openCamera(boolean start_preview) {
tryautofocus();//call this after setting camera parameters
}
关于java - Android AutoFocusCallback 未被调用或未返回，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19804233/
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