使用Android Camera2，应用无限期陷入STATE_WAITING_PRECAPTURE或STATE_WAITING_NON_PRECAPTURE

Question

我正在使用Android Camera2 API。我想知道什么时候适合：

1. 最初显示 TakePicture 按钮（即相机已准备好捕捉 图片）。
2. 再次显示此按钮（如果拍摄过程失败，当然还有完成时）因为我在点击它时隐藏它（捕捉图片）。

我在takePicture.setVisibility(View.GONE)和lockFocus() takePicture.setVisibility(View.VISIBLE)中尝试了unlockFocus()。 虽然这在大多数时间都有效，但有时按钮会消失并且再也不会出现（当我拍摄照片的过程失败时），特别是当它非常快速地点击它时（一旦它出现在屏幕上）。此时没有错误也没有发生崩溃。

代码取自googlesamples/android-Camera2Basic。

更新

我在takePicture.setVisibility(View.VISIBLE)内尝试了onCaptureSequenceCompleted。该按钮确实出现，但点击它时不会重新启动捕获图片的过程（参见this seven-second video）。发生这种情况时，不会调用onCaptureFailed。但是，由于 STATE_WAITING_PRECAPTURE 不满足STATE_WAITING_NON_PRECAPTURE，会无限期地卡在aeState或if 中条件。

           case STATE_WAITING_PRECAPTURE: {
                // CONTROL_AE_STATE can be null on some devices
                Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                if (aeState == null ||
                        aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
                        aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
                    mState = STATE_WAITING_NON_PRECAPTURE;
                }
                break;
            }
            case STATE_WAITING_NON_PRECAPTURE: {
                // CONTROL_AE_STATE can be null on some devices
                Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
                    mState = STATE_PICTURE_TAKEN;
                    captureStillPicture();
                }
                break;
            }

Answer 1

我认为应该是这样

 case STATE_WAITING_PRECAPTURE:
              {
                JQLog.d(TAG, "STATE_WAITING_PRECAPTURE");
                // CONTROL_AE_STATE can be null on some devices
                Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                if (aeState == null
                    || aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE
                    || aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED
                    || aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
                  state = STATE_WAITING_NON_PRECAPTURE;
                }
                break;
              }