android - 必须先启动预览模式才能拍照

Question

我们使用 cwac-camera 在我们的应用程序中获得了这样的堆栈跟踪:

java.lang.IllegalStateException: Preview mode must have started before you can take a picture
at com.commonsware.cwac.camera.CameraView.takePicture(CameraView.java:329)
at com.commonsware.cwac.camera.CameraView.takePicture(CameraView.java:277)
at com.github.randoapp.camera.RandoCameraHost.onAutoFocus(RandoCameraHost.java:119)
at com.commonsware.cwac.camera.CameraView.onAutoFocus(CameraView.java:411)
at android.hardware.Camera$EventHandler.handleMessage(Camera.java:824)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4898)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1008)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:775)
at dalvik.system.NativeStart.main(Native Method)

我们认为，这可能是因为用户过早按下拍照键。解决方案是在预览初始化时禁用按钮，仅在完成时启用。问题是:使用什么事件来启用按钮？是否有预览最终初始化的事件或回调sayon​​g？

Answer 1

We believe that this can be happenning because of users pressing take picture too early

这是一个明显的可能性。

What event to use for button enabling? Is there event or callback sayong that preview is finally initialized?

CameraHost 中的

autoFocusAvailable() 是目前最好的选择。它在预览开始之前调用，inPreview 设置为 true。

我已经提交了an issue做得比这更好。