我想在imgPreview中显示图像，这是我从相机应用程序中获取的.. 我想用其下面的2/3按钮显示图像预览 我在imgPreview中得到了空白屏幕 代码
public class DgCamActivity extends Activity implements SensorEventListener {
private Camera mCamera;
private CameraPreview mPreview;
private SensorManager sensorManager = null;
private int orientation;
private ExifInterface exif;
private int deviceHeight;
private Button ibRetake;
private Button ibUse;
private Button ibCapture;
private FrameLayout flBtnContainer;
private File sdRoot;
private String dir;
private String fileName;
private ImageView rotatingImage;
private int degrees = -1;
private ImageView imgPreview;
File pictureFile ;
FrameLayout preview;
RelativeLayout as;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Setting all the path for the image
sdRoot = Environment.getExternalStorageDirectory();
dir = "/DCIM/Camera/";
// Getting all the needed elements from the layout
rotatingImage = (ImageView) findViewById(R.id.imageView1);
ibRetake = (Button) findViewById(R.id.ibRetake);
ibUse = (Button) findViewById(R.id.ibUse);
ibCapture = (Button) findViewById(R.id.ibCapture);
flBtnContainer = (FrameLayout) findViewById(R.id.flBtnContainer);
as = (RelativeLayout) findViewById(R.id.images);
imgPreview = (ImageView) findViewById(R.id.image);
// Getting the sensor service.
sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
preview = (FrameLayout) findViewById(R.id.camera_preview);
// Selecting the resolution of the Android device so we can create a
// proportional preview
Display display = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
deviceHeight = display.getHeight();
// Add a listener to the Capture button
ibCapture.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
mCamera.takePicture(null, null, mPicture);
}
});
// Add a listener to the Retake button
ibRetake.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Deleting the image from the SD card/
File discardedPhoto = new File(sdRoot, dir + fileName);
discardedPhoto.delete();
// Restart the camera preview.
mCamera.startPreview();
// Reorganize the buttons on the screen
flBtnContainer.setVisibility(LinearLayout.VISIBLE);
ibRetake.setVisibility(LinearLayout.GONE);
ibUse.setVisibility(LinearLayout.GONE);
}
});
// Add a listener to the Use button
ibUse.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Everything is saved so we can quit the app.
finish();
}
});
}
private void createCamera() {
// Create an instance of Camera
mCamera = getCameraInstance();
// Setting the right parameters in the camera
Camera.Parameters params = mCamera.getParameters();
params.setPictureSize(1600, 1200);
params.setPictureFormat(PixelFormat.JPEG);
params.setJpegQuality(85);
mCamera.setParameters(params);
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
// Calculating the width of the preview so it is proportional.
float widthFloat = (float) (deviceHeight) * 8 / 5;
int width = Math.round(widthFloat);
// Resizing the LinearLayout so we can make a proportional preview. This
// approach is not 100% perfect because on devices with a really small
// screen the the image will still be distorted - there is place for
// improvment.
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(width, deviceHeight);
preview.setLayoutParams(layoutParams);
// Adding the camera preview after the FrameLayout and before the button
// as a separated element.
preview.addView(mPreview, 0);
}
@Override
protected void onResume() {
super.onResume();
// Test if there is a camera on the device and if the SD card is
// mounted.
if (!checkCameraHardware(this)) {
Intent i = new Intent(this, NoCamera.class);
startActivity(i);
finish();
} else if (!checkSDCard()) {
Intent i = new Intent(this, NoSDCard.class);
startActivity(i);
finish();
}
// Creating the camera
createCamera();
// Register this class as a listener for the accelerometer sensor
sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
protected void onPause() {
super.onPause();
// release the camera immediately on pause event
releaseCamera();
// removing the inserted view - so when we come back to the app we
// won't have the views on top of each other.
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.removeViewAt(0);
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
/** Check if this device has a camera */
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}
private boolean checkSDCard() {
boolean state = false;
String sd = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(sd)) {
state = true;
}
return state;
}
/**
* A safe way to get an instance of the Camera object.
*/
public static Camera getCameraInstance() {
Camera c = null;
try {
// attempt to get a Camera instance
c = Camera.open();
} catch (Exception e) {
// Camera is not available (in use or does not exist)
}
// returns null if camera is unavailable
return c;
}
private PictureCallback mPicture = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
// Replacing the button after a photho was taken.
flBtnContainer.setVisibility(View.GONE);
as.setVisibility(View.VISIBLE);
ibRetake.setVisibility(View.VISIBLE);
ibUse.setVisibility(View.VISIBLE);
previewCapturedImage();
// File name of the image that we just took.
fileName = "IMG_" + new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date()).toString() + ".jpg";
// Creating the directory where to save the image. Sadly in older
// version of Android we can not get the Media catalog name
File mkDir = new File(sdRoot, dir);
mkDir.mkdirs();
// Main file where to save the data that we recive from the camera
pictureFile = new File(sdRoot, dir + fileName);
try {
FileOutputStream purge = new FileOutputStream(pictureFile);
purge.write(data);
purge.close();
} catch (FileNotFoundException e) {
Log.d("DG_DEBUG", "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d("DG_DEBUG", "Error accessing file: " + e.getMessage());
}
// Adding Exif data for the orientation. For some strange reason the
// ExifInterface class takes a string instead of a file.
try {
exif = new ExifInterface("/sdcard/" + dir + fileName);
exif.setAttribute(ExifInterface.TAG_ORIENTATION, "" + orientation);
exif.saveAttributes();
} catch (IOException e) {
e.printStackTrace();
}
}
};
private void previewCapturedImage() {
try {
// hide video preview
imgPreview.setVisibility(View.VISIBLE);
preview.setVisibility(View.GONE);
// bimatp factory
BitmapFactory.Options options = new BitmapFactory.Options();
// downsizing image as it throws OutOfMemory Exception for larger
// images
options.inSampleSize = 8;
final Bitmap bitmap = BitmapFactory.decodeFile(pictureFile.getPath(),
options);
imgPreview.setImageBitmap(bitmap);
} catch (NullPointerException e) {
e.printStackTrace();
}
}
/**
* Putting in place a listener so we can get the sensor data only when
* something changes.
*/
public void onSensorChanged(SensorEvent event) {
synchronized (this) {
if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
RotateAnimation animation = null;
if (event.values[0] < 4 && event.values[0] > -4) {
if (event.values[1] > 0 && orientation != ExifInterface.ORIENTATION_ROTATE_90) {
// UP
orientation = ExifInterface.ORIENTATION_ROTATE_90;
animation = getRotateAnimation(270);
degrees = 270;
} else if (event.values[1] < 0 && orientation != ExifInterface.ORIENTATION_ROTATE_270) {
// UP SIDE DOWN
orientation = ExifInterface.ORIENTATION_ROTATE_270;
animation = getRotateAnimation(90);
degrees = 90;
}
} else if (event.values[1] < 4 && event.values[1] > -4) {
if (event.values[0] > 0 && orientation != ExifInterface.ORIENTATION_NORMAL) {
// LEFT
orientation = ExifInterface.ORIENTATION_NORMAL;
animation = getRotateAnimation(0);
degrees = 0;
} else if (event.values[0] < 0 && orientation != ExifInterface.ORIENTATION_ROTATE_180) {
// RIGHT
orientation = ExifInterface.ORIENTATION_ROTATE_180;
animation = getRotateAnimation(180);
degrees = 180;
}
}
if (animation != null) {
rotatingImage.startAnimation(animation);
}
}
}
}
/**
* Calculating the degrees needed to rotate the image imposed on the button
* so it is always facing the user in the right direction
*
* @param toDegrees
* @return
*/
private RotateAnimation getRotateAnimation(float toDegrees) {
float compensation = 0;
if (Math.abs(degrees - toDegrees) > 180) {
compensation = 360;
}
// When the device is being held on the left side (default position for
// a camera) we need to add, not subtract from the toDegrees.
if (toDegrees == 0) {
compensation = -compensation;
}
// Creating the animation and the RELATIVE_TO_SELF means that he image
// will rotate on it center instead of a corner.
RotateAnimation animation = new RotateAnimation(degrees, toDegrees - compensation, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
// Adding the time needed to rotate the image
animation.setDuration(250);
// Set the animation to stop after reaching the desired position. With
// out this it would return to the original state.
animation.setFillAfter(true);
return animation;
}
/**
* STUFF THAT WE DON'T NEED BUT MUST BE HEAR FOR THE COMPILER TO BE HAPPY.
*/
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
}