使用 Google Vision BarCode Reader 访问 AutoFocus/Flash

Question

我在这里玩的是条形码扫描仪的原始示例：

https://github.com/googlesamples/android-vision/blob/master/visionSamples/barcode-reader/app/src/main/java/com/google/android/gms/samples/vision/barcodereader/BarcodeCaptureActivity.java

他们可以像这样在相机工厂内启动 AutoFocus/Flash：

    // Creates and starts the camera.  Note that this uses a higher resolution in comparison
    // to other detection examples to enable the barcode detector to detect small barcodes
    // at long distances.
    CameraSource.Builder builder = new CameraSource.Builder(getApplicationContext(), barcodeDetector)
            .setFacing(CameraSource.CAMERA_FACING_BACK)
            .setRequestedPreviewSize(1600, 1024)
            .setRequestedFps(15.0f);

    // make sure that auto focus is an available option
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        builder = builder.setFocusMode(
                autoFocus ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE : null);
    }

    mCameraSource = builder
            .setFlashMode(useFlash ? Camera.Parameters.FLASH_MODE_TORCH : null)
            .build();

但是cameraSource builder上的这个方法在当前版本中已经消失了，所以这个设置不能被访问。另外我需要在使用过程中更改 FlashMode，所以这也不是办法。我发现了这个访问相机的丑陋解决方案：

public static Camera getCamera(@NonNull CameraSource cameraSource) {
    Field[] declaredFields = CameraSource.class.getDeclaredFields();

    for (Field field : declaredFields) {
        if (field.getType() == Camera.class) {
            field.setAccessible(true);
            try {
                Camera camera = (Camera) field.get(cameraSource);
                if (camera != null) {
                    return camera;
                }

                return null;
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }

            break;
        }
    }

    return null;
}

虽然有效，但无济于事：调用 getParameters().setFocusMode() 时出现此异常：

Attempt to invoke virtual method 'android.hardware.Camera$Parameters android.hardware.Camera.getParameters()' on a null object reference

显然我正在做的不是正确的方法，但似乎没有关于它的文档。

感谢您的提示。

Answer 1

只要优化你的代码如下，你必须在构建Camera Source类之后调用这个方法。

private Camera camera = null;
boolean flashmode=false;
private void flashOnButton() {
    camera=getCamera(mCameraSource);
    if (camera != null) {
        try {
            Camera.Parameters param = camera.getParameters();
         param.setFlashMode(!flashmode?Camera.Parameters.FLASH_MODE_TORCH :Camera.Parameters.FLASH_MODE_OFF);
            camera.setParameters(param);
            flashmode = !flashmode;
            if(flashmode){
                showToast("Flash Switched ON");
            }
            else {
                showToast("Flash Switched Off");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}
private static Camera getCamera(@NonNull CameraSource cameraSource) {
    Field[] declaredFields = CameraSource.class.getDeclaredFields();

    for (Field field : declaredFields) {
        if (field.getType() == Camera.class) {
            field.setAccessible(true);
            try {
                Camera camera = (Camera) field.get(cameraSource);
                if (camera != null) {
                    return camera;
                }
                return null;
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
            break;
        }
    }
    return null;
}

这将帮助您使用 camerasource 对象在 Google Vision Api 中启用 flash。

Answer 2

这是一个工作的 kotlin 变体：

private var flashmode: Boolean = false
private var camera: Camera? = null

private fun flashOnButton() {
    camera = getCamera(cameraSource)

    if (camera != null) {
        try {
            val param = camera!!.parameters

            param.setFlashMode(if (!flashmode) Camera.Parameters.FLASH_MODE_TORCH else Camera.Parameters.FLASH_MODE_OFF)
            camera?.parameters = param
            flashmode = !flashmode
        } catch (e: java.lang.Exception) {
            e.printStackTrace()
        }
    }
}

private fun getCamera(cameraSource: CameraSource): Camera? {
    val declaredFields = CameraSource::class.java.declaredFields

    for (field in declaredFields) {
        if (field.type === Camera::class.java) {
            field.isAccessible = true

            try {
                val camera = field.get(cameraSource) as Camera
                return if (camera != null) {
                    camera
                } else null
            } catch (e: IllegalAccessException) {
                e.printStackTrace()
            }

            break
        }
    }

    return null
}

此解决方案目前有效。但是我不知道如何处理这个问题，将来不再支持android.hardware.Camera。 也许没有android.hardware.Camera 有更好的解决方案？

Answer 3

直接使用CameraSource即可。

https://github.com/googlesamples/android-vision/blob/master/visionSamples/barcode-reader/app/src/main/java/com/google/android/gms/samples/vision/barcodereader/ui/camera/CameraSource.java

您将能够使用闪光灯/对焦。

CameraSource
.setFlashMode()
.setFocusMode()