android - View.post 没有加快图像处理速度？

Question

我正在尝试通过线程化来加速我的应用程序。它是一个在位图上放置鱼眼效果的应用程序。它运行良好，但运行速度非常慢。我已经记录了各种方法的一些处理时间，并将其精确定位到过滤器类中的 barrel() 方法。这个方法需要一个位图并循环通过它扭曲像素，这个循环需要大约 40 秒才能完成!我试过 AsyncTask 但这也需要 40 多秒。最后，我尝试了 View.post 机制，但这会产生相同的结果。有什么办法可以加快这个应用程序的速度吗？任何想法将不胜感激，谢谢马特。

.

public class TouchView extends View{


    private File tempFile;
    private byte[] imageArray;
    private Bitmap bgr;
    private Bitmap bm;
    private Bitmap bgr2 = null;;
    private Paint pTouch;
    private int centreX = 1;
    private int centreY = 1;
    private int radius = 50;
    private int Progress = 1;
    private static final String TAG = "*********TouchView";
    private Filters f = null;
    private boolean AsyncRunning = false;
   // private MyTask mt = null;



    public TouchView(Context context) {
        super(context);
       // TouchView(context, null);
    }




    public TouchView(Context context, AttributeSet attr) {
        super(context,attr);


       ........... code to get bitmap from camera shot.........

        bgr2 = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig());



       f = new Filters();





    }// end of touchView constructor


    public void findCirclePixels(){ 


              new Thread(new Runnable() {
                public void run() {
                    float prog = (float)Progress/150000;

                final Bitmap bgr3 = f.barrel(bgr,prog);
                  TouchView.this.post(new Runnable() {
                    public void run() {
                      TouchView.this.bgr2 = bgr3;
                      TouchView.this.invalidate();
                    }
                  });
                }
              }).start();





        }// end of changePixel()








    public void initSlider(final HorizontalSlider slider)
    {
      //  Log.e(TAG, "******setting up slider*********** ");
        slider.setOnProgressChangeListener(changeListener);
    }



    private OnProgressChangeListener changeListener = new OnProgressChangeListener() {


        @Override
        public void onProgressChanged(View v, int progress) {
            // TODO Auto-generated method stub


              setProgress(progress);
            //TouchView.this.Progress = progress;


        }
    };



    @Override
    public void onDraw(Canvas canvas){
        super.onDraw(canvas);


        canvas.drawBitmap(bgr2, 0, 0, null);




    }//end of onDraw




    protected void setProgress(int progress2) {
        //Log.e(TAG, "***********in SETPROGRESS");
        this.Progress = progress2;



        findCirclePixels();
        invalidate();


    }




}

.

import android.graphics.Bitmap;
import android.util.Log;

class Filters{
    float xscale;
    float yscale;
    float xshift;
    float yshift;
    int [] s;
    private String TAG = "Filters";
    long getRadXStart = 0;
    long getRadXEnd = 0;
    long startSample = 0;
    long endSample = 0;
    public Filters(){

        Log.e(TAG, "***********inside filter constructor");
    }

    public Bitmap barrel (Bitmap input, float k){
        //Log.e(TAG, "***********INSIDE BARREL METHOD ");

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

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

        Bitmap dst = Bitmap.createBitmap(width, height,input.getConfig() ); //output pic
       // Log.e(TAG, "***********dst bitmap created ");
          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;
        //  Log.e(TAG, "***********xscale ="+xscale);
          yscale = (height-yshift-yshift_2)/height;
        //  Log.e(TAG, "***********yscale ="+yscale);
        //  Log.e(TAG, "***********filter.barrel() about to loop through bm");
          /*for(int j=0;j<dst.getHeight();j++){
              for(int i=0;i<dst.getWidth();i++){
                float x = getRadialX((float)i,(float)j,centerX,centerY,k);
                float y = getRadialY((float)i,(float)j,centerX,centerY,k);
                sampleImage(input,x,y);
                int color = ((s[1]&0x0ff)<<16)|((s[2]&0x0ff)<<8)|(s[3]&0x0ff);
    //            System.out.print(i+" "+j+" \\");

                dst.setPixel(i, j, color);

              }
            }*/

          int origPixel;
          long startLoop = System.currentTimeMillis();
          for(int j=0;j<dst.getHeight();j++){
              for(int i=0;i<dst.getWidth();i++){
                 origPixel= input.getPixel(i,j);
                 getRadXStart = System.currentTimeMillis();
                float x = getRadialX((float)j,(float)i,centerX,centerY,k);
                getRadXEnd= System.currentTimeMillis();

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

                sampleImage(input,x,y);

                int color = ((s[1]&0x0ff)<<16)|((s[2]&0x0ff)<<8)|(s[3]&0x0ff);
    //            System.out.print(i+" "+j+" \\");

                if( Math.sqrt( Math.pow(i - centerX, 2) + ( Math.pow(j - centerY, 2) ) ) <= 150 ){
                dst.setPixel(i, j, color);
                }else{
                    dst.setPixel(i,j,origPixel);
                }
              }
            }
          long endLoop = System.currentTimeMillis();
          long loopDuration = endLoop - startLoop;
          long radXDuration = getRadXEnd - getRadXStart;
          long sampleDur = endSample - startSample;

          Log.e(TAG, "sample method took "+sampleDur+"ms");
          Log.e(TAG, "getRadialX took "+radXDuration+"ms");
          Log.e(TAG, "loop took "+loopDuration+"ms");

        //  Log.e(TAG, "***********filter.barrel()  looped through bm about to return dst bm");
        return dst;
    }

    void sampleImage(Bitmap arr, float idx0, float idx1)
    {
         startSample = System.currentTimeMillis();
        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);

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

      endSample = System.currentTimeMillis();
    }

    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;
    }

    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 thresh = 1;

    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);
      }
    }



}// end of filters class

Answer 1

float 学一般来说很糟糕，几乎在每台计算机上都是如此。然而，它在缺乏浮点协处理器支持的设备上确实很糟糕，例如一半的 Android 设备。所以，摆脱 float 学的每一点，例如:

• 您不需要通过浮点ceil() 和floor() 方法运行整数

• 您不需要计算 sqrt() 来与 150 进行比较，而不是跳过 sqrt() 并与22500

• 您不需要浮点pow() 来计算某物的平方；相反，使用称为“乘法”的高级数学运算

• 我怀疑半像素在你的计算中会很重要，所以你可能不需要 centerX 和 centerY 为 float 值

• 等等

在紧要关头，您可能需要使用诸如适用于 Android 的 Google map 插件之类的技巧。通常，您会想到十进制度数的纬度和经度，但这意味着大量的 float 学运算。 Google map 使用以微度(10^6 度)为单位的纬度和经度，以便能够以定点数学进行所有计算，同时保持合理的准确性。

是否所有这些都会使性能下降到您认为合理的水平，我不能说。但是，在开始提示 Android 代码的质量之前，您应该确保您的代码质量合理，就像您在上一条评论中所做的那样。