释放异常相机预览后调用的方法 [英] Method called after release Exception Camera preview
问题描述
我有一个使用我的 CameraPreview 类的活动类 (CameraActivity).在OnResume"中，相机和预览被启动.在OnPause"中，我正在释放相机资源.当应用程序启动时，OnResume"内一切正常，但是当我通过意图启动另一个活动(例如，在浏览器中打开 url)然后回到我的活动时，在OnResume"发起的 CamerPreview 类中发生异常.请在下面找到代码:
I have one activity class(CameraActivity) which is using my CameraPreview class. In "OnResume" the camera and preview are initiated. In "OnPause", i am releasing camera resources. When application is started, everything works fine inside the "OnResume" but when i start another activity through intent (E.g. open url in browser) and then come back to my activity then exception is occured inside "OnResume" originating CamerPreview class. Please find below the code:
//CameraActivity 类
public void onResume(){
super.onResume();
Log.d("inside onResume, camera==="+mCamera, "inside onResume");
try {
if(mCamera==null)
{
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
autoFocusHandler = new Handler();
mCamera = getCameraInstance();
int rotation = this.getWindowManager().getDefaultDisplay().getRotation();
scanner = new ImageScanner();
scanner.setConfig(0, Config.X_DENSITY, 3);
scanner.setConfig(0, Config.Y_DENSITY, 3);
mPreview = new CameraPreview(this, mCamera, previewCb, autoFocusCB);
FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
preview.addView(mPreview);
}
} catch (Exception e) {
// TODO Auto-generated catch block
Log.e("onResume",Log.getStackTraceString(e));
}
public void onPause{
try {
super.onPause();
if (mCamera != null) {
previewing = false;
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
mCamera.release();
mCamera = null;
mPreview=null;
}
} catch (Exception e) {
// TODO Auto-generated catch block
Log.e("releaseCamera",Log.getStackTraceString(e));
}
}
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open();
} catch (Exception e){
Log.e("getCameraInstance",Log.getStackTraceString(e));
}
return c;
}
//下面是 CameraPreview 类:
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
Camera mCamera;
PreviewCallback previewCallback;
AutoFocusCallback autoFocusCallback;
private int rotation;
public int getRotation() {
return rotation;
}
public void setRotation(int rotation) {
this.rotation = rotation;
}
public CameraPreview(Context context, Camera camera,
PreviewCallback previewCb,
AutoFocusCallback autoFocusCb) {
super(context);
mCamera = camera;
previewCallback = previewCb;
autoFocusCallback = autoFocusCb;
/*
* Set camera to continuous focus if supported, otherwise use
* software auto-focus. Only works for API level >=9.
*/
/*
Camera.Parameters parameters = camera.getParameters();
for (String f : parameters.getSupportedFocusModes()) {
if (f == Parameters.FOCUS_MODE_CONTINUOUS_PICTURE) {
mCamera.setFocusMode(Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
autoFocusCallback = null;
break;
}
}
*/
// 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 {
if(mCamera==null){
mCamera=Camera.open();
}
mCamera.setPreviewDisplay(holder);
} catch (IOException e) {
Log.d("DBG", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Camera preview released in activity
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
/*
* 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
}
try{
mCamera.setPreviewDisplay(mHolder);
mCamera.setPreviewCallback(previewCallback);
mCamera.startPreview();
mCamera.autoFocus(autoFocusCallback);
} catch (Exception e){
Log.d("DBG", "Error starting camera preview: " + e.getMessage());
}
}
}
这是来自 logCat:
11-05 10:14:34.585: E/AndroidRuntime(7864): FATAL EXCEPTION: main
11-05 10:14:34.585: E/AndroidRuntime(7864): java.lang.RuntimeException: Method called after release()
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.hardware.Camera.setPreviewDisplay(Native Method)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.hardware.Camera.setPreviewDisplay(Camera.java:393)
11-05 10:14:34.585: E/AndroidRuntime(7864): at com.intagleo.qraugmented.detection.camera.CameraPreview.surfaceCreated(CameraPreview.java:74)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.SurfaceView.updateWindow(SurfaceView.java:552)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:215)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.View.dispatchWindowVisibilityChanged(View.java:4027)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewRoot.performTraversals(ViewRoot.java:790)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.view.ViewRoot.handleMessage(ViewRoot.java:1867)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.os.Handler.dispatchMessage(Handler.java:99)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.os.Looper.loop(Looper.java:130)
11-05 10:14:34.585: E/AndroidRuntime(7864): at android.app.ActivityThread.main(ActivityThread.java:3687)
11-05 10:14:34.585: E/AndroidRuntime(7864): at java.lang.reflect.Method.invokeNative(Native Method)
11-05 10:14:34.585: E/AndroidRuntime(7864): at java.lang.reflect.Method.invoke(Method.java:507)
11-05 10:14:34.585: E/AndroidRuntime(7864): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
11-05 10:14:34.585: E/AndroidRuntime(7864): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
11-05 10:14:34.585: E/AndroidRuntime(7864): at dalvik.system.NativeStart.main(Native Method)
编辑
我更新了surfaceDestroyed"并按照建议放置日志，但现在我在onPause"中遇到异常--> onSurfaceDestroyed.最初 onPause 执行良好.
I updated "surfaceDestroyed" and put logs as suggested but now i am getting exception in "onPause" --> onSurfaceDestroyed. Initially onPause was executing fine.
1- 通过方法getCameraInstance"在activity类的onResume"中创建相机实例，并将mCamera实例传递给CameraPreview类.我尝试更改它，以便仅在onSurfaceCreated"内部创建相机实例并将 mCamera 实例分配回活动类，但它不起作用.我还通过调试注意到CameraPreview"类的 previewCallBack 成员第一次有效，但第二次CameraPreview"类的previewCallBack"成员为空.
1- The camera instance is created in "onResume" of activity class through method "getCameraInstance" and passes mCamera instance to CameraPreview Class. I tried to change it so that camera instance is created only onside "onSurfaceCreated" and assigned back the mCamera instance to the activity class but it did not work. I also noticed through debug that previewCallBack member of "CameraPreview" class is valid the first time but second time the "previewCallBack" member of "CameraPreview" class is null.
请注意，第一次调用onResume"时，一切正常，但当它在 onPause 后第二次运行时，最初会发生异常，尽管 onResume 中的代码相同.
Note that first time when "onResume" is called, everything works fine but when it runs second time after onPause then exception is occured originally although code is the same in onResume.
11-06 01:25:28.375: I/onResume(4332): INITIATED
// Workinf fine till now. Now opening another intent activity
11-06 01:26:23.500: I/onPause(4332): INITIATED
11-06 01:26:23.804: "OnSurfaceDestroyed": "Initiated"
11-06 01:26:23.945: E/AndroidRuntime(4332): FATAL EXCEPTION: main
11-06 01:26:23.945: E/AndroidRuntime(4332): java.lang.RuntimeException: Method called after release()
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.hardware.Camera.stopPreview(Native Method)
11-06 01:26:23.945: E/AndroidRuntime(4332): at com.intagleo.qraugmented.detection.camera.CameraPreview.surfaceDestroyed(CameraPreview.java:85)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.SurfaceView.reportSurfaceDestroyed(SurfaceView.java:596)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.SurfaceView.updateWindow(SurfaceView.java:490)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:215)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.View.dispatchWindowVisibilityChanged(View.java:4027)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:720)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewRoot.performTraversals(ViewRoot.java:790)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.view.ViewRoot.handleMessage(ViewRoot.java:1867)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.os.Handler.dispatchMessage(Handler.java:99)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.os.Looper.loop(Looper.java:130)
11-06 01:26:23.945: E/AndroidRuntime(4332): at android.app.ActivityThread.main(ActivityThread.java:3687)
11-06 01:26:23.945: E/AndroidRuntime(4332): at java.lang.reflect.Method.invokeNative(Native Method)
11-06 01:26:23.945: E/AndroidRuntime(4332): at java.lang.reflect.Method.invoke(Method.java:507)
11-06 01:26:23.945: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
11-06 01:26:23.945: E/AndroidRuntime(4332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
11-06 01:26:23.945: E/AndroidRuntime(4332): at dalvik.system.NativeStart.main(Native Method)
推荐答案
由于你已经将相机添加到 FrameLayout 中，像这样:
As you have added the camera to the FrameLayout, like this:
FrameLayout preview = (FrameLayout)findViewById(R.id.cameraPreview);
preview.addView(mPreview);
surfaceCreated 方法将被调用，因此 mCamera.setPreviewDisplay(holder); 将被调用.
The surfaceCreated method will be called and so mCamera.setPreviewDisplay(holder); will be called.
当您创建/打开一个新相机时，FrameLayout 仍然有您以前的相机，因此除了您的新相机之外，还将调用它的 surfaceCreated.
When you create/open a new camera, the FrameLayout still has your previous camera and so its surfaceCreated will be called in addition to your new camera.
你应该做的是，当你释放你的相机(在 onPause() 方法上)时，从 FrameLayout 中移除你以前的相机，如下所示:
What you should do, is remove your previous camera from FrameLayout when you release your camera (on onPause() method) like this:
preview.removeView(mPreview);
希望对你有帮助.
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