nv21转Bitmap

                                            //从相机中取一帧照片
                                            CameraPreviewData cameraPreviewData = camelist.getCameraPreviewData();
                                            //这一帧照片的格式
                                            byte[] nv21Data = cameraPreviewData.nv21Data;
                                            //nv21转Bitmap
                                            NV21ToBitmap nv21ToBitmap = new NV21ToBitmap(FaceApplication.getContext());
                                            bitmap = nv21ToBitmap.nv21ToBitmap(nv21Data, cameraPreviewData.width, cameraPreviewData.height);

nv21转Bitmap类：

package megvii.testfacepass.utils;

import android.content.Context;
import android.graphics.Bitmap;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.Scri