我可以使用setDisplayOrientation（90）方法将相机预览从纵向旋转到横向，但预览看起来不真实，并且在横向模式下拉伸。我已经阅读了多篇与之相关的帖子，但是无法通过所需的视图取得成功。我试着在root的android Jellybeans版本上试试这个。 你能否建议改善横向模式预览的方法？
下面是我的CameraPreview和Activity类的代码集：
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;
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = null;
private SurfaceHolder mHolder;
private Camera mCamera;
List<Size> sizes;
Camera.Size mPreviewSize;
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
mHolder = getHolder();
mHolder.addCallback(this);
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) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
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
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
setCamera(mCamera);
try {
mCamera.setDisplayOrientation(90);
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
public void setCamera(Camera camera) {
if (mCamera == camera) { return; }
mCamera = camera;
if (mCamera != null) {
requestLayout();
try {
mCamera.setPreviewDisplay(mHolder);
} catch (IOException e) {
e.printStackTrace();
}
if(mCamera != null){
//Setting the camera's aspect ratio
Camera.Parameters parameters = mCamera.getParameters();
sizes = parameters.getSupportedPreviewSizes();
Size optimalSize = getOptimalPreviewSize(sizes, getResources().getDisplayMetrics().widthPixels, getResources().getDisplayMetrics().heightPixels);
mCamera.setDisplayOrientation(90);
parameters.setPreviewSize(optimalSize.width, optimalSize.height);
mCamera.setParameters(parameters);
}
/*
Important: Call startPreview() to start updating the preview surface. Preview must
be started before you can take a picture.
*/
mCamera.startPreview();
}
}
public Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio=(double)h / w;
if (sizes == null) return null;
Camera.Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
for (Camera.Size size : sizes) {
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Camera.Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
setMeasuredDimension(width, height);
sizes = mCamera.getParameters().getSupportedPreviewSizes();
if (sizes != null) {
mPreviewSize = getOptimalPreviewSize(sizes, width, height);
}
}
}
public class TestCameraActivity extends Activity {
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
protected static final String TAG = null;
private PictureCallback mPicture;
/** Called when the activity is first created. */
Context ctx;
Camera mCamera;
CameraPreview mPreview;
Camera.Size optimalSize;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
boolean cameraAvailable = checkCameraHardware(this);
if(cameraAvailable){
mCamera = getCameraInstance();
}else Toast.makeText(this, "No Camera Available",Toast.LENGTH_LONG).show();
double aspectRatio =0;
mPreview = new CameraPreview(this,mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
mPicture = getPictureCallback();
if(mCamera != null){
//Setting the camera's aspect ratio
Camera.Parameters parameters = mCamera.getParameters();
List<Size> sizes = parameters.getSupportedPreviewSizes();
optimalSize = mPreview.getOptimalPreviewSize(sizes, getResources().getDisplayMetrics().widthPixels, getResources().getDisplayMetrics().heightPixels);
aspectRatio = (float)optimalSize.width/optimalSize.height;
}
// if(optimalSize!= null){
// FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, (int)(getResources().getDisplayMetrics().widthPixels*aspectRatio));
// preview.setLayoutParams(params);
// LayoutParams surfaceParams = new LayoutParams(LayoutParams.MATCH_PARENT, (int)(getResources().getDisplayMetrics().widthPixels*aspectRatio));
// mPreview.setLayoutParams(surfaceParams);
// }
mPreview.setCamera(mCamera);
Button capture = (Button) findViewById(R.id.button_capture);
capture.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mCamera.takePicture(null, null, mPicture);
}
});
}
private PictureCallback getPictureCallback() {
PictureCallback picture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d(TAG, "Error creating media file, check storage permissions: " );
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
};
return picture;};
@Override
protected void onPause() {
super.onPause();
releaseCamera(); // release the camera immediately on pause event
}
private void releaseCamera(){
if (mCamera != null){
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open(); // attempt to get a Camera instance
}
catch (Exception e){
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), "MyCameraApp");
if (! mediaStorageDir.exists()){
if (! mediaStorageDir.mkdirs()){
Log.d("MyCameraApp", "failed to create directory");
return null;
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
/** 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;`enter code here`
} else {
// no camera on this device
return false;
}
}
}
答案 0 :(得分：1)
您传递给setDisplayOrientation的值不是固定的：它取决于个人camera's orientation（其中＆＃34;顶部＆＃34;相机所在的位置）作为设备本身的当前方向。通过将其设置为常量值，您的预览可能在一个方向上看起来正确，但在另一个方向上将如您所述。
documentation提供了设置此值时需要考虑的数学运算：
public static void setCameraDisplayOrientation(Activity activity,
int cameraId, android.hardware.Camera camera) {
android.hardware.Camera.CameraInfo info =
new android.hardware.Camera.CameraInfo();
android.hardware.Camera.getCameraInfo(cameraId, info);
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
int degrees = 0;
switch (rotation) {
case Surface.ROTATION_0: degrees = 0; break;
case Surface.ROTATION_90: degrees = 90; break;
case Surface.ROTATION_180: degrees = 180; break;
case Surface.ROTATION_270: degrees = 270; break;
}
int result;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
result = (info.orientation + degrees) % 360;
result = (360 - result) % 360; // compensate the mirror
} else { // back-facing
result = (info.orientation - degrees + 360) % 360;
}
camera.setDisplayOrientation(result);
}