如何在Android CameraX中使用手动对焦？

Question

我正在尝试在CameraX中手动对焦，就像在Camera2 API中一样。

在Camera2 API中，我使用以下代码：

final CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE); 

captureBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_OFF); 

captureBuilder.set(CaptureRequest.LENS_FOCUS_DISTANCE, mLensFocusDistance);

在Android相机X中，是否可以进行手动对焦？如果可以，如何操作？

提前致谢。

- moLand

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你解决了在 CameraX 中如何实现这个功能吗？ - Ehsan Khaveh

目前没有相机X能够使用 https://groups.google.com/a/android.com/forum/#!searchin/camerax-developers/focus%7Csort:date/camerax-developers/ySfolLe_AS8/hOhHRViaCgAJ - moLand

Answer 1

使用Camera2Interop.Extender访问低级别的camera2 API，可以在CameraX中使用手动对焦。您需要像这样为预览构建器设置两个额外选项：

void setFocusDistance(ExtendableBuilder<?> builder, float distance) {
    Camera2Interop.Extender extender = new Camera2Interop.Extender(builder);
    extender.setCaptureRequestOption(CaptureRequest.CONTROL_AF_MODE, CameraMetadata.CONTROL_AF_MODE_OFF);
    extender.setCaptureRequestOption(CaptureRequest.LENS_FOCUS_DISTANCE, distance);
}

在构建CameraX预览请求时使用它：

float focusDistance = 0F; // example: infinite focus
Preview.Builder previewBuilder = new Preview.Builder();
setFocusDistance(previewBuilder, focusDistance);
preview = previewBuilder.build();
preview.setSurfaceProvider(viewFinder.getSurfaceProvider());

请注意，您也可以以此方式设置其他camera2 CaptureRequest选项。

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以下是如何查找LENS_INFO_MINIMUM_FOCUS_DISTANCE（通常为约10f）的方法：

theCamera = cameraProvider.bindToLifecycle(...
CameraCharacteristics camChars = Camera2CameraInfo
   .extractCameraCharacteristics(theCamera.getCameraInfo());
float discoveredMinFocusDistance = camChars
   .get(CameraCharacteristics.LENS_INFO_MINIMUM_FOCUS_DISTANCE);
Log.i("dev", "found it! " + discoveredMinFocusDistance);

- Mikhail

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不幸的是，这仅适用于启动相机时，而不是在其运行时 :/ - Fattie

@Fattie 是的，你现在应该重新启动相机以更新对焦模式 :( - Mikhail

这是荒谬的！哇啊！:O - Fattie

Answer 2

你应该将 TouchListener 设置到 textureView 上，然后设置焦点（Kotlin）：

private fun setUpTapToFocus() {
    textureView.setOnTouchListener { _, event ->
        if (event.action != MotionEvent.ACTION_UP) {
            return false
        }

        val cameraControl = CameraX.getCameraControl(CameraX.LensFacing.BACK) // you can set it to front                     
        val factory = TextureViewMeteringPointFactory(textureView)
        val point = factory.createPoint(event.x, event.y)
        val action = FocusMeteringAction.Builder.from(point).build()
        cameraControl.startFocusAndMetering(action)
        return true
    }
}

希望这有所帮助。

- Misha Akopov

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谢谢您的回答，@Misha。然而，这与点击对焦是相同的。我正在尝试设置对焦级别。 - moLand

是的，从我所读的内容来看，我认为手动对焦意味着通过轻敲来对焦 :) - Misha Akopov