Android多线程

Question

我有一段代码正在删除位图背景，起初该代码大约花费40s>来删除每个位图背景，但我在hauwei y320 -u30上将其优化为大约12s ，四核分别为1.3GHz，在Galaxy s3 Quadcore上为6s 。与第一个产品相比，这是一个很好的选择，它还不够好。我希望华为的产品在2s到3s范围内开始，因为基本用户可能会有一个低端设备，我在使用异步任务固定为2 fixedthreadpool和Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND + Process.THREAD_PRIORITY_MORE_FAVORABLE)线程优先级，但是我想知道，多线程是每个时间范围内运行多个任务的能力，但是没有一种方法可以运行2 or 3一个任务上有2 or 3线程，例如在我的情况下，在我的后台删除代码上运行这些线程，由于在运行此代码时，我的ap中没有其他线程，因此确保这可以产生更好的性能。 p也正在运行，我的代码每次运行时都有所有资源，我在网上查找，但找不到任何与此相关的内容，以下是我的代码：

public class ImageBackgrndRemover extends AppCompatActivity {



private BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");

                //instantia


                if(!alreadyRun) {

                    BackgroundRemover remover = null;
                    if(remover == null)
                    {
                        remover = new BackgroundRemover();
                        remover.executeOnExecutor(AsyncTask.DUAL_THREAD_EXECUTOR);

                    }


                }

            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

private LoadingAnimation add;
ImageView iv;
Scalar color;
Mat dst;
private boolean alreadyRun;
public static final String TAG = "Grabcut demo";


@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_image_backgrnd_remover);
    iv = (ImageView) this.findViewById(R.id.imagePreview);



}

private int calculatePercentage(int percentage, int target)
{
    int k = (int)(target*(percentage/100.0f));
    return k;

}
private Bitmap backGrndErase()
{

    color = new Scalar(255, 0, 0, 255);
    dst = new Mat();
    Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.myshirt);
    Log.d(TAG, "bitmap: " + bitmap.getWidth() + "x" + bitmap.getHeight());


    bitmap = ResizeImage.getResizedBitmap(bitmap, calculatePercentage(40, bitmap.getWidth()), calculatePercentage(40, bitmap.getHeight()));

    // Bitmap bitmap2 = ImageCornerMoulder.getRoundedCornerBitmap(bmp, calculatePercentage(5, bmp.getHeight()));


    bitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);
    Log.d(TAG, "bitmap 8888: " + bitmap.getWidth() + "x" + bitmap.getHeight());


    //GrabCut part
    Mat img = new Mat();
    Utils.bitmapToMat(bitmap, img);
    Log.d(TAG, "img: " + img);

    int r = img.rows();
    int c = img.cols();

    Point p1 = new Point(c/10, r/10);
    Point p2 = new Point(c-c/10, r-r/10);

    int border = 20;
    int border2 = border + border;
    Rect rect2 = new Rect(border,border,img.cols()-border2,img.rows()-border2);


    Rect rect = new Rect(p1,p2);

    Log.d(TAG, "rect: " + rect);

    Mat mask = new Mat();
    debugger(""+mask.type());
    mask.setTo(new Scalar(125));
    Mat fgdModel = new Mat();
    fgdModel.setTo(new Scalar(255, 255, 255));
    Mat bgdModel = new Mat();
    bgdModel.setTo(new Scalar(255, 255, 255));

    Mat imgC3 = new Mat();
    Imgproc.cvtColor(img, imgC3, Imgproc.COLOR_RGBA2RGB);
    Log.d(TAG, "imgC3: " + imgC3);

    Log.d(TAG, "Grabcut begins");
    Imgproc.grabCut(imgC3, mask, rect2, bgdModel, fgdModel, 2, Imgproc.GC_INIT_WITH_RECT);

    Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(3.0));


    Core.compare(mask, source, mask, Core.CMP_EQ);
    Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));
    img.copyTo(foreground, mask);
    Imgproc.rectangle(img, p1, p2, color);

    Mat background = new Mat();
    try {
        background = Utils.loadResource(getApplicationContext(),
                R.drawable.blackcolor );
    } catch (IOException e) {

        e.printStackTrace();
    }
    Mat tmp = new Mat();
    Imgproc.resize(background, tmp, img.size());

    background = tmp;

    Mat tempMask = new Mat(foreground.size(), CvType.CV_8UC1, new Scalar(255, 255, 255));
    Imgproc.cvtColor(foreground, tempMask, 6/* COLOR_BGR2GRAY */);
    //Imgproc.threshold(tempMask, tempMask, 254, 255, 1 /* THRESH_BINARY_INV */);

    Mat vals = new Mat(1, 1, CvType.CV_8UC3, new Scalar(0.0));
    dst = new Mat();
    background.setTo(vals, tempMask);
    Imgproc.resize(foreground, tmp, mask.size());
    foreground = tmp;
    Core.add(background, foreground, dst, tempMask);
    Log.d(TAG, "Convert to Bitmap");


    //removing blackbaground started
    /***
    Mat tmp2 = new Mat();
    Mat alpha = new Mat();
    Imgproc.cvtColor(dst, tmp2, Imgproc.COLOR_BGR2GRAY);
    Imgproc.threshold(tmp2, alpha, 100, 255, Imgproc.THRESH_BINARY);


    List<Mat> rgb = new ArrayList<Mat>(3);
    Core.split(dst, rgb);


    List<Mat> rgba = new ArrayList<Mat>(4);
    rgba.add(rgb.get(0));
    rgba.add(rgb.get(1));
    rgba.add(rgb.get(2));
    rgba.add(alpha);
    Core.merge(rgba, dst);
     Bitmap output = Bitmap.createBitmap(dst.width(), dst.height(), Bitmap.Config.ARGB_8888);
     Utils.matToBitmap(dst, output);
     ***/
    //removing back ended


   Utils.matToBitmap(dst, bitmap);



    //release MAT part
    img.release();
    imgC3.release();
    mask.release();
    fgdModel.release();
    bgdModel.release();
    alreadyRun = true;
    return  bitmap;

}

private void showLoadingIndicator()
{

    android.support.v4.app.FragmentManager fm = getSupportFragmentManager();
    add = LoadingAnimation.newInstance("b");
    add.show(fm, "");
    add.setCancelable(false);

}

private void dismissLoadingIndicator()
{
    try {
        add.dismiss();
    }catch (Exception e)
    {
        e.printStackTrace();
    }

}
private class BackgroundRemover extends AsyncTask<Void, Void, Bitmap>
{

    @Override
    protected void onPreExecute()
    {
        showLoadingIndicator();
    }

    @Override
    protected Bitmap doInBackground(Void... voids) {


        Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND +
                Process.THREAD_PRIORITY_MORE_FAVORABLE);

        try{


            return backGrndErase();

        }catch (Exception e)
        {
            System.err.println("Failed to remove background");
        }

        return null;
    }
    @Override
    protected void onPostExecute(Bitmap bitmap) {


      //  iv.setBackgroundResource(R.drawable.blackcolor);
        iv.setImageBitmap(bitmap);

        dismissLoadingIndicator();
    }
}


@Override
public void onResume()
{
    super.onResume();
    if (!OpenCVLoader.initDebug()) {
        Log.d(TAG, "Internal OpenCV library not found. Using OpenCV Manager for initialization");
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
    } else {
        Log.d(TAG, "OpenCV library found inside package. Using it!");


        mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);

    }
}


private static Bitmap makeBlackTransparent(Bitmap image) {
    // convert image to matrix
    Mat src = new Mat(image.getWidth(), image.getHeight(), CvType.CV_8UC4);
    Utils.bitmapToMat(image, src);

    // init new matrices
    Mat dst = new Mat(image.getWidth(), image.getHeight(), CvType.CV_8UC4);
    Mat tmp = new Mat(image.getWidth(), image.getHeight(), CvType.CV_8UC4);
    Mat alpha = new Mat(image.getWidth(), image.getHeight(), CvType.CV_8UC4);

    // convert image to grayscale
    Imgproc.cvtColor(src, tmp, Imgproc.COLOR_BGR2GRAY);

    // threshold the image to create alpha channel with complete transparency in black background region and zero transparency in foreground object region.
    Imgproc.threshold(tmp, alpha, 100, 255, Imgproc.THRESH_BINARY);

    // split the original image into three single channel.
    List<Mat> rgb = new ArrayList<Mat>(3);
    Core.split(src, rgb);

    // Create the final result by merging three single channel and alpha(BGRA order)
    List<Mat> rgba = new ArrayList<Mat>(4);
    rgba.add(rgb.get(0));
    rgba.add(rgb.get(1));
    rgba.add(rgb.get(2));
    rgba.add(alpha);
    Core.merge(rgba, dst);

    // convert matrix to output bitmap
    Bitmap output = Bitmap.createBitmap(image.getWidth(), image.getHeight(), Bitmap.Config.ARGB_8888);
    Utils.matToBitmap(dst, output);
    return output;
}

public void debugger(String s){
    Log.v("", "########### " + s);
}

}