android - NPE并发图像处理类

Question

我有一个应用程序可以在位图上放置鱼眼失真。我得到了帮助，可以同时循环遍历位图，为手机处理器的每个核心分配一个线程。这应该使图像处理运行得更快。我收到 NPE，我认为 PartialProcessing.call() 方法没有返回 partialResult。有没有人有任何想法？谢谢

public class MultiProcessorFilter {



    private static final String TAG = "mpf";




    public Bitmap barrel (Bitmap input, float k){


          int []arr = new int[input.getWidth()*input.getHeight()];
          // replace the j, i for loops:
          int jMax = input.getHeight();
          int jMid = jMax / 2;
          int iMax = input.getWidth();
          int iMid = iMax / 2;

          ExecutorService threadPool = Executors.newFixedThreadPool(2);

          FutureTask<PartialResult> task1 = (FutureTask<PartialResult>) threadPool.submit(new PartialProcessing(0, jMid - 1, input, k, iMid, iMax)); 
          FutureTask<PartialResult> task2 = (FutureTask<PartialResult>) threadPool.submit(new PartialProcessing(jMid, jMax - 1,input, k, iMid, iMax)); 
          Log.e(TAG, "*********** about to call task1.get()");
          try{
          PartialResult result1 = task1.get();// blocks until the thread returns the result
          Log.e(TAG, "*********** just called task1.get()");
          result1.fill(arr);
          Log.e(TAG, "*********** result1 arr length = " + arr.length);
          PartialResult result2 = task2.get(); // blocks until the thread returns the result
          result2.fill(arr);

          }catch(Exception e){
              e.printStackTrace();
          }
          Bitmap dst2 = Bitmap.createBitmap(arr,input.getWidth(),input.getHeight(),input.getConfig());
        return dst2;


        }




    public class PartialResult {
           int startP;
           int endP;
           int[] storedValues;

           public PartialResult(int startp, int endp){

               this.startP = startp;
               this.endP = endp;

           }

           public void addValue(int p, int result) {
                 storedValues[p] = result;
           }

           public void fill(int[] arr) {
              for (int p = startP; p < endP; p++)
                 arr[p] = storedValues[p];
              }
           }




    public class PartialProcessing implements Callable<PartialResult> {
        int startJ;
        int endJ;

       // ... other members needed for the computation such as
        private int[] scalar;
        private float xscale;
        private float yscale;
        private float xshift;
        private float yshift;
        private float thresh = 1;
        private int [] s1;
        private int [] s2;
        private int [] s3;
        private int [] s4;
        private int [] s;
        private Bitmap input;
        private float k;
        private int startI;
        private int endI;


        public PartialProcessing(int startj, int endj, Bitmap input, float k, int starti, int endi) {

            this.startJ = startj;
            this.endJ = endj;
            this.input = input;
            this.k = k;
            this.startI = starti;
            this.endI = endi;

        }

        int [] getARGB(Bitmap buf,int x, int y){

            int rgb = buf.getPixel(y, x); // Returns by default ARGB.
            // int [] scalar = new int[4];
           //  scalar[0] = (rgb >>> 24) & 0xFF;
             scalar[1] = (rgb >>> 16) & 0xFF;
             scalar[2] = (rgb >>> 8) & 0xFF;
             scalar[3] = (rgb >>> 0) & 0xFF;
             return scalar;

        }

        //... add other methods needed for the computation that where in class Filters

        float getRadialX(float x,float y,float cx,float cy,float k){

            x = (x*xscale+xshift);
            y = (y*yscale+yshift);
            float res = x+((x-cx)*k*((x-cx)*(x-cx)+(y-cy)*(y-cy)));
            return res;
          }

          float getRadialY(float x,float y,float cx,float cy,float k){

            x = (x*xscale+xshift);
            y = (y*yscale+yshift);
            float res = y+((y-cy)*k*((x-cx)*(x-cx)+(y-cy)*(y-cy)));
            return res;
          }



          float calc_shift(float x1,float x2,float cx,float k){

            float x3 = (float)(x1+(x2-x1)*0.5);
            float res1 = x1+((x1-cx)*k*((x1-cx)*(x1-cx)));
            float res3 = x3+((x3-cx)*k*((x3-cx)*(x3-cx)));

            if(res1>-thresh && res1 < thresh)
              return x1;
            if(res3<0){
              return calc_shift(x3,x2,cx,k);
            }
            else{
              return calc_shift(x1,x3,cx,k);
            }
          }


          void sampleImage(Bitmap arr, float idx0, float idx1)
          {

             // s = new int [4];
            if(idx0<0 || idx1<0 || idx0>(arr.getHeight()-1) || idx1>(arr.getWidth()-1)){
              s[0]=0;
              s[1]=0;
              s[2]=0;
              s[3]=0;
              return;
            }

            float idx0_fl=(float) Math.floor(idx0);
            float idx0_cl=(float) Math.ceil(idx0);
            float idx1_fl=(float) Math.floor(idx1);
            float idx1_cl=(float) Math.ceil(idx1);



             s1 = getARGB(arr,(int)idx0_fl,(int)idx1_fl);
             s2 = getARGB(arr,(int)idx0_fl,(int)idx1_cl);
             s3 = getARGB(arr,(int)idx0_cl,(int)idx1_cl);
             s4 = getARGB(arr,(int)idx0_cl,(int)idx1_fl);

            float x = idx0 - idx0_fl;
            float y = idx1 - idx1_fl;

           // s[0]= (int) (s1[0]*(1-x)*(1-y) + s2[0]*(1-x)*y + s3[0]*x*y + s4[0]*x*(1-y));
            s[1]= (int) (s1[1]*(1-x)*(1-y) + s2[1]*(1-x)*y + s3[1]*x*y + s4[1]*x*(1-y));
            s[2]= (int) (s1[2]*(1-x)*(1-y) + s2[2]*(1-x)*y + s3[2]*x*y + s4[2]*x*(1-y));
            s[3]= (int) (s1[3]*(1-x)*(1-y) + s2[3]*(1-x)*y + s3[3]*x*y + s4[3]*x*(1-y));


          }


        // this will be called on some new thread
        @Override public PartialResult call() {
            PartialResult partialResult = new PartialResult(startJ, endJ);

            float centerX=input.getWidth()/2; //center of distortion
            float centerY=input.getHeight()/2;



            int width = input.getWidth(); //image bounds
            int height = input.getHeight();



              xshift = calc_shift(0,centerX-1,centerX,k);

              float newcenterX = width-centerX;
              float xshift_2 = calc_shift(0,newcenterX-1,newcenterX,k);

              yshift = calc_shift(0,centerY-1,centerY,k);

              float newcenterY = height-centerY;
              float yshift_2 = calc_shift(0,newcenterY-1,newcenterY,k);

              xscale = (width-xshift-xshift_2)/width;

              yscale = (height-yshift-yshift_2)/height;


            int p = startI; // not 0! at the start since we don't start at j = 0
            int origPixel = 0;
            int color = 0;
            for (int j = startJ; j <  endJ; j++){
                for (int i = startI; i < endI; i++, p++){
                    //... copy the rest of the code


                     origPixel = input.getPixel(i,j);

            float x = getRadialX((float)j,(float)i,centerX,centerY,k);


            float y = getRadialY((float)j,(float)i,centerX,centerY,k);

            sampleImage(input,x,y);

             color = ((s[1]&0x0ff)<<16)|((s[2]&0x0ff)<<8)|(s[3]&0x0ff);

             if(((i-centerX)*(i-centerX) + (j-centerY)*(j-centerY)) <= 5500){

                //arr[p]=color;
                 partialResult.addValue(p, color);

            }else{

                //arr[p]=origPixel;
                partialResult.addValue(p, origPixel);



            }

                }






                   // partialResult.addValue(p, color);
        }
            return partialResult;
    }


}

}//end of MultiProcesorFilter

.

07-25 18:29:29.263: WARN/System.err(2289): java.util.concurrent.ExecutionException: java.lang.NullPointerException
07-25 18:29:29.263: WARN/System.err(2289):     at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:223)
07-25 18:29:29.263: WARN/System.err(2289):     at java.util.concurrent.FutureTask.get(FutureTask.java:82)
07-25 18:29:29.268: WARN/System.err(2289):     at com.tecmark.MultiProcessorFilter.barrel(MultiProcessorFilter.java:39)
07-25 18:29:29.268: WARN/System.err(2289):     at com.tecmark.TouchView$2.run(TouchView.java:147)
07-25 18:29:29.268: WARN/System.err(2289):     at java.lang.Thread.run(Thread.java:1096)
07-25 18:29:29.268: WARN/System.err(2289): Caused by: java.lang.NullPointerException
07-25 18:29:29.268: WARN/System.err(2289):     at com.tecmark.MultiProcessorFilter$PartialProcessing.sampleImage(MultiProcessorFilter.java:170)
07-25 18:29:29.273: WARN/System.err(2289):     at com.tecmark.MultiProcessorFilter$PartialProcessing.call(MultiProcessorFilter.java:245)
07-25 18:29:29.273: WARN/System.err(2289):     at com.tecmark.MultiProcessorFilter$PartialProcessing.call(MultiProcessorFilter.java:1)
07-25 18:29:29.273: WARN/System.err(2289):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-25 18:29:29.273: WARN/System.err(2289):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-25 18:29:29.278: WARN/System.err(2289):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
07-25 18:29:29.278: WARN/System.err(2289):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
07-25 18:29:29.278: WARN/System.err(2289):     ... 1 more

[更新]

07-25 22:41:41.121: WARN/System.err(2212): Caused by: java.lang.NullPointerException
07-25 22:41:41.126: WARN/System.err(2212):     at com.tecmark.MultiProcessorFilter$PartialResult.addValue(MultiProcessorFilter.java:70)
07-25 22:41:41.126: WARN/System.err(2212):     at com.tecmark.MultiProcessorFilter$PartialProcessing.call(MultiProcessorFilter.java:262)
07-25 22:41:41.126: WARN/System.err(2212):     at com.tecmark.MultiProcessorFilter$PartialProcessing.call(MultiProcessorFilter.java:1)
07-25 22:41:41.126: WARN/System.err(2212):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-25 22:41:41.131: WARN/System.err(2212):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-25 22:41:41.131: WARN/System.err(2212):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
07-25 22:41:41.131: WARN/System.err(2212):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
07-25 22:41:41.131: WARN/System.err(2212):     ... 1 more

Answer 1

在 sampleImage 方法中，

// s = new int [4];

数组 s 的初始化被注释掉了，我没有注意到它在其他地方被初始化

如果s确实没有初始化那么

s[0]=0; // just curious isn't this line 170 in MultiProcessorFilter.java?

会抛出NPE