Android的AutoFocusCallback不会被调用或不返回 [英] Android AutoFocusCallback is not being called or not returning
本文介绍了Android的AutoFocusCallback不会被调用或不返回的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在开发一个吧code扫描应用程序，它具有以下的功能：
I’m developing a barcode scanning app that has the following the functionality:
•接入设备的摄像头，在SurfaceView preVIEW摄像头，并自动重新调整
• Access device camera , preview camera on SurfaceView , and automatically refocus
•Attemtps脱使用2种方法code吧code
• Attemtps to decode barcode using 2 methods
a）在SurfaceView触摸使用的的onTouchEvent（MotionEvent事件），企图采取的吧code的画面，但得到的 java.lang.RuntimeException的：takePicture失败
a) On SurfaceView touch using onTouchEvent(MotionEvent event), attempts to take a picture of the barcode , but gets java.lang.RuntimeException: takePicture failed
B）或 preferably ，可以在 onAutoFocus（布尔成功，相机摄像头），但onAutoFocus（）不会被调用成功的图片
b) Or Preferably , can take a picture on success of onAutoFocus(boolean success, Camera camera) , but onAutoFocus() does not get called
我实施AutoFocusCallback并设置回我的扫描活动相机对象调用的ScanVinFromBar codeActivity。
I’m implementing the "AutoFocusCallback" and setting back to the camera object in my scanning activity called "ScanVinFromBarcodeActivity".
下面是我的ScanVinFromBar codeActivity这需要相机功能，护理：
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）; //传递surfaceView到相机preVIEW newCamera preVIEW =新相机preVIEW（这一点，globalCamera）{
globalCamera.autoFocus(autoFocusCallback); // pass surfaceView to 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preVIEW类，从摄像头显示的实时图像
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
截图活动界面：
任何帮助将AP preciated，谢谢你。
Any help will be appreciated , Thanks.
推荐答案
正在调用preVIEW类的自动对焦上的onCreate 它应该被称为在表面形成或表面改 因为一旦相机preVIEW已经开始发生的自动对焦 已经在这个codeI一看都在研究这一点，这是工作
you are calling autofocus on Oncreate in preview class it should be called at surface created or surface changed since autofocus occurs once the camerapreview has been started have a look on this code i have worked on this and it is working
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 {
}
}
}
});
}
在初始化相机（或打开相机在这种情况下）
when you initialize camera(or open camera in this case)
private void openCamera(boolean start_preview) {
tryautofocus();//call this after setting camera parameters
}
这篇关于Android的AutoFocusCallback不会被调用或不返回的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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