autoFocus抛出异常

Question

我已经尝试了一切,但我仍然无法解决这个问题.

我正在应用程序中实现相机功能,一切正常,除了自动对焦.当我调用autoFocus()时,它会抛出异常,我无法理解为什么.我在Desire HD上运行代码.

码:

@Override
protected void onStart() {
     super.onStart();

     //grab seurface view and callback
     cameraView = (CameraSurfaceView) findViewById(R.id.cameraView);
     try{
        camera = Camera.open();
        cameraView.setCamera(camera);
        //release previous autofocus and assign new one
        camera.cancelAutoFocus();
        camera.autoFocus(new Camera.AutoFocusCallback() {

                public void onAutoFocus(boolean success, Camera camera) {
                // TODO Auto-generated method stub

                }});
    }
    catch (Exception e) {
        //had an issue accessing the camera prompt user
        //TODO create user prompt
        e.printStackTrace();
    }
}

堆栈跟踪:

01-11 16:09:38.456: W/System.err(26546): java.lang.RuntimeException: autoFocus failed
01-11 16:09:38.456: W/System.err(26546):    at android.hardware.Camera.native_autoFocus(Native Method)
01-11 16:09:38.456: W/System.err(26546):    at android.hardware.Camera.autoFocus(Camera.java:680)
01-11 16:09:38.456: W/System.err(26546):    at com.myapp.MyActivity.onStart(BarcodeScannerActivity.java:57)
01-11 16:09:38.466: W/System.err(26546):    at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1201)
01-11 16:09:38.466: W/System.err(26546):    at android.app.Activity.performStart(Activity.java:3955)
01-11 16:09:38.466: W/System.err(26546):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1845)
01-11 16:09:38.466: W/System.err(26546):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893)
01-11 16:09:38.466: W/System.err(26546):    at android.app.ActivityThread.access$1500(ActivityThread.java:135)
01-11 16:09:38.466: W/System.err(26546):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1054)
01-11 16:09:38.466: W/System.err(26546):    at android.os.Handler.dispatchMessage(Handler.java:99)
01-11 16:09:38.466: W/System.err(26546):    at android.os.Looper.loop(Looper.java:150)
01-11 16:09:38.476: W/System.err(26546):    at android.app.ActivityThread.main(ActivityThread.java:4385)
01-11 16:09:38.476: W/System.err(26546):    at java.lang.reflect.Method.invokeNative(Native Method)
01-11 16:09:38.476: W/System.err(26546):    at java.lang.reflect.Method.invoke(Method.java:507)
01-11 16:09:38.476: W/System.err(26546):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
01-11 16:09:38.476: W/System.err(26546):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
01-11 16:09:38.476: W/System.err(26546):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

使用SurfaceHolder.Callback - > surfaceCreated来了解何时可以启动AutoFocus.如果未创建曲面所有者(持续一段时间),则自动对焦将失败.

Answer 2

您可能需要确保手机支持自动对焦.检查这个很容易:

Camera.Parameters p = mCamera.getParameters();
List<String> focusModes = p.getSupportedFocusModes();

if(focusModes != null && focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
    //Phone supports autofocus!
}
else {
    //Phone does not support autofocus!
}