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基于Google Vision Face Tracker的 Face Tracker 应用程序。默认情况下，人脸跟踪器使用后置/后置摄像头，但我想用前置摄像头检测人脸。

这是 google vision 提供的 CameraSourcePreview 代码：

package com.google.android.gms.samples.vision.face.facetracker.ui.camera;

import android.content.Context;
import android.content.res.Configuration;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;

import com.google.android.gms.common.images.Size;
import com.google.android.gms.vision.CameraSource;

import java.io.IOException;

public class CameraSourcePreview extends ViewGroup {
    private static final String TAG = "CameraSourcePreview";

    private Context mContext;
    private SurfaceView mSurfaceView;
    private boolean mStartRequested;
    private boolean mSurfaceAvailable;
    private CameraSource mCameraSource;

    private GraphicOverlay mOverlay;

    public CameraSourcePreview(Context context, AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        mStartRequested = false;
        mSurfaceAvailable = false;

        mSurfaceView = new SurfaceView(context);
        mSurfaceView.getHolder().addCallback(new SurfaceCallback());
        addView(mSurfaceView);
    }

    public void start(CameraSource cameraSource) throws IOException {
        if (cameraSource == null) {
            stop();
        }

        mCameraSource = cameraSource;

        if (mCameraSource != null) {
            mStartRequested = true;
            startIfReady();
        }
    }

    public void start(CameraSource cameraSource, GraphicOverlay overlay) throws IOException {
        mOverlay = overlay;
        start(cameraSource);
    }

    public void stop() {
        if (mCameraSource != null) {
            mCameraSource.stop();
        }
    }

    public void release() {
        if (mCameraSource != null) {
            mCameraSource.release();
            mCameraSource = null;
        }
    }

    private void startIfReady() throws IOException {
        if (mStartRequested && mSurfaceAvailable) {
            mCameraSource.start(mSurfaceView.getHolder());
            if (mOverlay != null) {
                Size size = mCameraSource.getPreviewSize();
                int min = Math.min(size.getWidth(), size.getHeight());
                int max = Math.max(size.getWidth(), size.getHeight());
                if (isPortraitMode()) {
                    // Swap width and height sizes when in portrait, since it will be rotated by
                    // 90 degrees
                    mOverlay.setCameraInfo(min, max, mCameraSource.getCameraFacing());
                } else {
                    mOverlay.setCameraInfo(max, min, mCameraSource.getCameraFacing());
                }
                mOverlay.clear();
            }
            mStartRequested = false;
        }
    }

    private class SurfaceCallback implements SurfaceHolder.Callback {
        @Override
        public void surfaceCreated(SurfaceHolder surface) {
            mSurfaceAvailable = true;
            try {
                startIfReady();
            } catch (IOException e) {
                Log.e(TAG, "Could not start camera source.", e);
            }
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder surface) {
            mSurfaceAvailable = false;
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        }
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        int width = 640;
        int height = 480;
        if (mCameraSource != null) {
            Size size = mCameraSource.getPreviewSize();
            if (size != null) {
                width = size.getWidth();
                height = size.getHeight();
            }
        }

        // Swap width and height sizes when in portrait, since it will be rotated 90 degrees
        if (isPortraitMode()) {
            int tmp = width;
            width = height;
            height = tmp;
        }

        final int layoutWidth = right - left;
        final int layoutHeight = bottom - top;

        // Computes height and width for potentially doing fit width.
        int childWidth = layoutWidth;
        int childHeight = (int)(((float) layoutWidth / (float) width) * height);

        // If height is too tall using fit width, does fit height instead.
        if (childHeight > layoutHeight) {
            childHeight = layoutHeight;
            childWidth = (int)(((float) layoutHeight / (float) height) * width);
        }

        for (int i = 0; i < getChildCount(); ++i) {
            getChildAt(i).layout(0, 0, childWidth, childHeight);
        }

        try {
            startIfReady();
        } catch (IOException e) {
            Log.e(TAG, "Could not start camera source.", e);
        }
    }

    private boolean isPortraitMode() {
        int orientation = mContext.getResources().getConfiguration().orientation;
        if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
            return false;
        }
        if (orientation == Configuration.ORIENTATION_PORTRAIT) {
            return true;
        }

        Log.d(TAG, "isPortraitMode returning false by default");
        return false;
    }
}

我用这种方法调用相机源：

private void startCameraSource() {

        // check that the device has play services available.
        int code = GoogleApiAvailability.getInstance().isGooglePlayServicesAvailable(
                getApplicationContext());
        if (code != ConnectionResult.SUCCESS) {
            Dialog dlg =
                    GoogleApiAvailability.getInstance().getErrorDialog(this, code, RC_HANDLE_GMS);
            dlg.show();
        }

        if (mCameraSource != null) {
            try {
                mPreview.start(mCameraSource, mGraphicOverlay);
            } catch (IOException e) {
                Log.e(TAG, "Unable to start camera source.", e);
                mCameraSource.release();
                mCameraSource = null;
            }
        }
    }

与默认手机摄像头应用相比，Face Tracker 前置摄像头仍然太暗。

如何在面部跟踪器谷歌视觉中照亮前置摄像头？与表面观点有关吗？

<com.google.android.gms.samples.vision.face.facetracker.ui.camera.CameraSourcePreview
    android:id="@+id/preview"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1.00"
    android:weightSum="1">

<com.google.android.gms.samples.vision.face.facetracker.ui.camera.GraphicOverlay
    android:id="@+id/faceOverlay"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight="0.79" />

</com.google.android.gms.samples.vision.face.facetracker.ui.camera.CameraSourcePreview>
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1 回答 1

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它根本与 SurfaceView 无关。这是相机 API 配置错误。您必须在 CameraSource.java 文件中进行一些额外的更改。你可以在这个 GitHub 存储库中找到它

首先，您需要知道这是一个曝光问题。它是指相机允许在镜头上接收的光。您需要知道您的相机是否支持曝光补偿。您必须从 Camera.Parameters 实例中查询getMinExposureCompensation()和getMaxExposureCompensation() 。如文档所述，如果两种方法都返回 0，则不支持曝光补偿，您无能为力。

幸运的是，大多数情况下，所有手机都支持这一特性。现在您可以通过调用getExposureCompensation()来检查当前相机的曝光，这将返回默认值（通常为 0，表示未调整曝光）。现在，为了防止出现暗图像，您只需使用setExposureCompensation()将新曝光设置在最小值和最大值之间，并将Camera.Parameters 应用于您的相机。

最后，您可以使用setAutoExposureLock()、getAutoExposureLock()锁定曝光以避免丢失配置，最重要的是：在设置曝光锁定之前，您必须确保isAutoExposureLockSupported()返回 true。

祝你好运！

于 2017-04-15T03:23:53.203 回答