检测到的人脸边界框 - Android

Question

在通过前置摄像头拍摄视频期间，我必须在检测到的面部上绘制一个矩形框。我用谷歌搜索，但找到了在图像上绘制边界框的答案，而不是实时视频捕获。为了获得所需的边界框，我可以添加什么以及在哪里添加：

CameraPreview(Context context) {
    super(context);

    mSurfaceView = new SurfaceView(context);
    addView(mSurfaceView);

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = mSurfaceView.getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
  /**  myRectPaint.setStrokeWidth(5);
    myRectPaint.setColor(Color.RED);
    myRectPaint.setStyle(Paint.Style.STROKE);**/
}

public void setCamera(Camera camera) {
    mCamera = camera;
    if (mCamera != null) {
        mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
        requestLayout();
        mCamera.setFaceDetectionListener(this);
    }

}

public void switchCamera(Camera camera) {
    setCamera(camera);
    try {
        camera.setPreviewDisplay(mHolder);
    } catch (IOException exception) {
        Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
    }
    Camera.Parameters parameters = camera.getParameters();
    parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
    parameters.setRotation(90);
    requestLayout();

    camera.setParameters(parameters);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    // We purposely disregard child measurements because act as a
    // wrapper to a SurfaceView that centers the camera preview instead
    // of stretching it.
    final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
    final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
    setMeasuredDimension(width, height);

    if (mSupportedPreviewSizes != null) {
        mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
    }
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    if (changed && getChildCount() > 0) {
        final View child = getChildAt(0);

        final int width = r - l;
        final int height = b - t;

        int previewWidth = width;
        int previewHeight = height;
        if (mPreviewSize != null) {
            previewWidth = mPreviewSize.width;
            previewHeight = mPreviewSize.height;
        }

        // Center the child SurfaceView within the parent.
        if (width * previewHeight > height * previewWidth) {
            final int scaledChildWidth = previewWidth * height / previewHeight;
            child.layout((width - scaledChildWidth) / 2, 0,
                        (width + scaledChildWidth) / 2, height);
        } else {
            final int scaledChildHeight = previewHeight * width / previewWidth;
            child.layout(0, (height - scaledChildHeight) / 2,
                        width, (height + scaledChildHeight) / 2);
        }
    }
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    // The Surface has been created, acquire the camera and tell it where
    // to draw.
    try {
        if (mCamera != null) {
            mCamera.setPreviewDisplay(holder);
            Camera.Parameters parameters = mCamera.getParameters();
            parameters.setRotation(90);
            mCamera.setParameters(parameters);
            mCamera.setFaceDetectionListener(this);
        }
    } catch (IOException exception) {
        Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
    }
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    // Surface will be destroyed when we return, so stop the preview.
    if (mCamera != null) {
        mCamera.stopPreview();
    }
}

private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio = (double) w / h;
    if (sizes == null)
        return null;

    Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = h;

    // Try to find an size match aspect ratio and size
    for (Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
            continue;
        if (Math.abs(size.height - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.height - targetHeight);
        }
    }

    // Cannot find the one match the aspect ratio, ignore the requirement
    if (optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Size size : sizes) {
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }
    }
    return optimalSize;
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    // Now that the size is known, set up the camera parameters and begin
    // the preview.
    Camera.Parameters parameters = mCamera.getParameters();
    parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
    requestLayout();

    mCamera.setParameters(parameters);
    mCamera.startPreview();
}

/*
 * (non-Javadoc)
 * @see
 * android.hardware.Camera.FaceDetectionListener#onFaceDetection(android
 * .hardware.Camera.Face[], android.hardware.Camera)
 */
@Override
public void onFaceDetection(Face[] faces, Camera camera) {
    Log.d("facedetection", "Faces Found: " + faces.length);
    /**for (int i = 0; i < faces.length; i++) {
        Face thisFace = faces[i];
        float x1 = thisFace.rect.centerX();
        float y1 = thisFace.rect.centerY();
        float x2 = x1 + thisFace.rect.width();
        float y2 = y1 + thisFace.rect.height();
     //   mPreviewSize..drawRoundRect(new RectF(x1, y1, x2, y2), 2, 2, myRectPaint);**/
        ViewFinderView view = ((ViewFinderView) (((Activity) getContext()).findViewById(R.id.viewfinder_view)));
        view.setFaces(Arrays.asList(faces));
 //   }
}
public CameraPreview(Context context, AttributeSet attr) {
    super(context, attr);
    mSurfaceView = new SurfaceView(context);
    addView(mSurfaceView);

    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    mHolder = mSurfaceView.getHolder();
    mHolder.addCallback(this);
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

Answer 1

您可以在另一个透明视图上添加注释和绘图。 在布局中，执行以下操作：

<FrameLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
>
    <MyCameraPreviewView
        android:id="@+id/previewView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
    />
    <MyOverlayView
        android:id="@+id/overlayView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
    />
</FrameLayout>

然后创建继承自 View 的覆盖视图并覆盖其 onDraw 方法以绘制矩形。