在运行时更改 Android Camera 2 的 Flash 设置

Question

基本上，我想做的是通过在应用程序中单击按钮来更改 CONTROL_AE_MODE。用户可以使用自动闪光（ON_AUTO_FLASH），打开（ON_ALWAYS_FLASH）或关闭（CONTROL_AE_MODE_OFF）。

在这个例子中：https://github.com/googlesamples/android-Camera2Basic/blob/master/Application/src/main/java/com/example/android/camera2basic/Camera2BasicFragment.java

第818行，他们设置了一次闪光灯：

// Use the same AE and AF modes as the preview.
            captureBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
            setAutoFlash(captureBuilder);

            // Orientation
            int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
            captureBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));

            CameraCaptureSession.CaptureCallback CaptureCallback
                    = new CameraCaptureSession.CaptureCallback() {

                @Override
                public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                               @NonNull CaptureRequest request,
                                               @NonNull TotalCaptureResult result) {
                    showToast("Saved: " + mFile);
                    Log.d(TAG, mFile.toString());
                    unlockFocus();
                }
            };

            mCaptureSession.stopRepeating();
            mCaptureSession.capture(captureBuilder.build(), CaptureCallback, null);

然后在第 840 行构建 CaptureSession。

有没有办法在预览完成后更改CONTROL_AE_MODE？

我尝试重新制作会话，效果还不错：

if(flashMode == CameraView.CAMERA_FLASH_ON){
            Log.e("CAMERA 2", "FLASH ON");
            mPreviewCaptureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH);
        }else if(flashMode == CameraView.CAMERA_FLASH_OFF){
            Log.e("CAMERA 2", "FLASH OFF");
            mPreviewCaptureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_OFF);
        }else if(flashMode == CameraView.CAMERA_FLASH_AUTO){
            Log.e("CAMERA 2", "FLASH AUTO");
            mPreviewCaptureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
        }
        mFlashMode = flashMode;
        if (mCameraCaptureSession != null) {
            mCameraCaptureSession.close();
            mCameraCaptureSession = null;
       }
  createCameraPreviewSession();

出于某种原因，CONTROL_AE_MODE_OFF 会使整个预览变黑。我尝试在文档中查找更新方法，但没有找到任何内容。

非常感谢任何教程或文档。

Answer 1

我不知道为什么你的预览会变黑，但你不需要手动关闭捕获会话。来自 .close() 方法的文档：

Using createCaptureSession(List , CameraCaptureSession.StateCallback, Handler) directly without closing is the recommended approach for quickly switching to a new session, since unchanged target outputs can be reused more efficiently.

因此您可以重用现有的 CaptureRequest.Builder，设置更改后的值，构建新的 PreviewRequest 并使用这个新请求启动新会话，如下所示：

try {
    // Change some capture settings
    mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
    // Build new request (we can't just edit existing one, as it is immutable)
    mPreviewRequest = mPreviewRequestBuilder.build();
    // Set new repeating request with our changed one
    mCaptureSession.setRepeatingRequest(mPreviewRequest, mCaptureCallback, mBackgroundHandler);
} catch (CameraAccessException e) {
    e.printStackTrace();
}

它会快得多（几乎没有任何可见的预览冻结）。

Answer 2

您想要的是禁用闪光灯，而不是 auto-exposure (AE)，因此您想使用 CONTROL_AE_MODE_ON 而不是 CONTROL_AE_MODE_OFF。

如documentation所述：

CONTROL_AE_MODE_ON

The camera device's autoexposure routine is active, with no flash control.

Answer 3

如 @cyborg86pl 所述，切换闪光灯模式时不应切换 CONTROL_AE_MODE。相反，您可以在 FLASH_MODE 之间切换。这是我的案例的一个工作示例：

  when (currentFlashState) {
        FlashState.AUTO -> {
          previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH)
        }
        FlashState.ON -> {
          previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON)
          previewRequestBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH)
        }
        FlashState.OFF -> {
          previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON)
          previewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF)
        }
      }
 previewRequest = previewRequestBuilder.build()
 captureSession.setRepeatingRequest(previewRequest, captureCallback, backgroundHandler)

在运行时更改 Android Camera 2 的 Flash 设置

Changing Flash setting of Android Camera 2 at runtime

java

mobile

android

android-camera2