谷歌相机API应用程序在重新进入时崩溃

Question

我正在使用Google的Camera API制作一个非常基本的相机应用程序。 最初启动应用程序很好，但在离开并重新进入时，它会崩溃。我找到了类似的答案，但我无法将它们应用于我的特定代码/情况。我也尝试过弄乱onPause((，onResume等，但无济于事。为什么会发生这种情况，我该如何解决这个问题？

以下是相关方法和错误日志。

表面视图类：

public class ImageSurfaceView extends SurfaceView implements SurfaceHolder.Callback {
private Camera camera;
private SurfaceHolder surfaceHolder;
private String TAG = ImageSurfaceView.class.getSimpleName();
public ImageSurfaceView(Context context, Camera camera) {
super(context);
this.camera = camera;
surfaceHolder = getHolder();
surfaceHolder.addCallback(this);
surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
try {
this.camera.setPreviewDisplay(holder);
this.camera.startPreview();
this.camera.setDisplayOrientation(90);
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
if (holder.getSurface() == null){
// preview surface does not exist
return;
}
try {
camera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}
try {
Camera.Parameters params = camera.getParameters();
List<Camera.Size> supportedPreviewSizes = params.getSupportedPreviewSizes();
Camera.Size camPreviewSize = getOptimalPreviewSize(supportedPreviewSizes, width , height);
params.setPreviewSize(camPreviewSize.width ,camPreviewSize.height);
camera.setParameters(params);
} catch (RuntimeException e) {
Log.d(TAG, "Error getting camera parameters: " + e.getMessage());
}

try {
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
camera.release();
camera = null;
}
private void stopPreviewAndFreeCamera() {
if (camera != null) {
// Call stopPreview() to stop updating the preview surface.
camera.stopPreview();
// Important: Call release() to release the camera for use by other
// applications. Applications should release the camera immediately
// during onPause() and re-open() it during onResume()).
camera.release();
camera = null;
}
}
private 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;
}

}

暂停/恢复

protected void onPause() {
Log.d(TAG, " -> onPause");
if(camera != null){
releaseCamera();
}
super.onPause();
Log.d(TAG, " <- onPause");
}
private void releaseCamera(){
if (camera != null){
camera.release(); 
camera = null;
}
}
@Override
public void onResume() {
super.onResume();
Log.d(TAG, " -> OnResume");
if (camera == null) {
camera = checkDeviceCamera();
}
Log.d(TAG, " <- OnResume");
}

摄像方式：

private Camera checkDeviceCamera(){
Camera mCamera = null;
try {
mCamera = Camera.open();
} catch (Exception e) {
e.printStackTrace();
}
return mCamera;
}
private void startCamera() {
camera = checkDeviceCamera();
mImageSurfaceView = new ImageSurfaceView(MainActivity.this, camera);
cameraPreviewLayout = (FrameLayout) findViewById(R.id.camera_preview); //the framelayout
cameraPreviewLayout.addView(mImageSurfaceView); //adding surfaceview to framelayout
ImageButton captureButton = (ImageButton)findViewById(R.id.imageButton);
captureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
camera.takePicture(null, null, pictureCallback);
}
});
}
Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera cam) {
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
if (camera != null) {
camera.startPreview();
}
}
}, 0);
}
};

错误：

E/AndroidRuntime: FATAL EXCEPTION: main
Process: daniel816.com.danger, PID: 10594
java.lang.RuntimeException: Camera is being used after Camera.release() was called
at android.hardware.Camera.setPreviewSurface(Native Method)
at android.hardware.Camera.setPreviewDisplay(Camera.java:738)
at danielwei816.com.danger.ImageSurfaceView.surfaceCreated(ImageSurfaceView.java:33)
at android.view.SurfaceView.updateWindow(SurfaceView.java:634)
at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:256)
at android.view.View.dispatchWindowVisibilityChanged(View.java:10293)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1289)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1599)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1299)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6558)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
at android.view.Choreographer.doCallbacks(Choreographer.java:683)
at android.view.Choreographer.doFrame(Choreographer.java:619)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6316)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:872)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)

Answer 1

您有活动的生命周期(onResume，onPause等(和SurfaceView的生命周期(surfaceChanged，surfaceDestroy等(。 您在暂停时释放相机，但在 surfaceDestroy(稍后称为(中停止它。我认为这就是问题所在。