我有一个公开 android 相机 API 的应用程序，我的目标是在我的活动“ScanVinFromBarcodeActivity”中使用相机，以便使用 (zxing liberary) 扫描条形码。
我面临的问题是预览（SurfaceView）上的相机输出似乎逆时针旋转了 90 度（纵向和横向）。
查看我的屏幕快照（您可以看到人和我的计算机逆时针旋转 90 度？？？：
顺便说一句，我的设备是 Galaxy S3。
我在扩展 SurfaceView 的 PreviewCamera 类中使用以下代码
相关片段：
surfaceChanged(SurfaceHolder holder, int format, int w, int h) method
{
.
.
.
/*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.
*/p.setRotation(90);
mCamera.setParameters(p);
.
.
.
}
但它没有效果，图像仍然是逆时针90度，而不是正确的0度。
CameraPreview.java 提供一个 SurfaceView 以便将来自相机的当前图像流式传输到屏幕，因此用户可以预览和查看相机看到的内容。
package com.ty.ownerspoc.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.
*/
p.setRotation(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 class CameraPreview
安卓活动（ScanVinFromBarcodeActivity）：
负责启动相机和布局。
package com.ty.ownerspoc.barcode;
import java.io.IOException;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.MultiFormatReader; //found via import at compile time, however was found at run time
import com.google.zxing.NotFoundException;
import com.google.zxing.RGBLuminanceSource;//found via import at compile time, however was found at run time
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.Point;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
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.ownerspoc.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;
/*
* 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);
globalCamera.takePicture(null, null, jpegCallback);
globalCamera.stopPreview();
// wait 2 secs , than start preview again
Thread.sleep(2000);
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();
}
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] imgData, Camera camera) {
try {
// get the bitmap from camera imageData
bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
imgData, 0, imgData.length);
BinaryBitmap bitmap = null;
if (bmpOfTheImageFromCamera != null) {
// 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());
}
}// end onPictureTaken()
};// jpegCallback implementation
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 activity
活动“ScanVinFromBarcodeActivity”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>
任何帮助将不胜感激。
谢谢