Renderscript Documentation and Advice - Android -

i have been following guide on how use render-script on android.

http://www.jayway.com/2014/02/11/renderscript-on-android-basics/

my code (i got wrapper class script):

public class pixelcalcscriptwrapper {      private allocation inallocation;     private allocation outallocation;     renderscript rs;     scriptc_pixelscalc script;      public pixelcalcscriptwrapper(context context){         rs = renderscript.create(context);         script = new scriptc_pixelscalc(rs, context.getresources(), r.raw.pixelscalc);     };      public void setinallocation(bitmap bmp){         inallocation = allocation.createfrombitmap(rs,bmp);     };      public void setoutallocation(bitmap bmp){         outallocation = allocation.createfrombitmap(rs,bmp);     };      public void foreach_root(){         script.foreach_root(inallocation, outallocation);     } } 

this methods calls script:

public bitmap processbmp(bitmap bmp, bitmap bmpcopy) {      pixelcalcscriptwrapper.setinallocation(bmp);     pixelcalcscriptwrapper.setoutallocation(bmpcopy);     pixelcalcscriptwrapper.foreach_root();      return bmpcopy; }; 

and here script:

#pragma version(1) #pragma rs java_package_name(test.foo)  void root(const uchar4 *in, uchar4 *out, uint32_t x, uint32_t y) {     float3 pixel = convert_float4(in[0]).rgb;      if(pixel.z < 128) {         pixel.z = 0;     }else{         pixel.z = 255;     }     if(pixel.y < 128) {         pixel.y = 0;     }else{         pixel.y = 255;     }     if(pixel.x < 128) {         pixel.x = 0;     }else{         pixel.x = 255;     }      out->xyz = convert_uchar3(pixel); } 

now can find documentation ?

for example, have these questions:

1) convert_float4(in[0]) ?

2) rgb return here convert_float4(in[0]).rgb;?

3) float3 ?

4) don't know start line out->xyz = convert_uchar3(pixel);

5) assuming in parameters, in , out allocations passed? x , y?

1) in kernel, in pointer 4-element unsigned char, is, represents pixel color r, g, b , values in 0-255 range. convert_float4 casts each of 4 uchar float. in particular code using, doesn't make sense work floats, since you're doing simple threshold, , had worked uchar data directly. using floats better aimed when doing other types of image processing algorithms need have precision (example: blurring image).

2) .rgb suffix shorthand return first 3 values of float4, i.e. r, g, , b values. if had used .r give first value regular float, if had used .g give second value float, etc... these 3 values assigned float3 variable, represents pixel 3 color channels (that is, no alpha channel).

3) see #2.

4) convert_uchar3 again cast converts float3 pixel variable uchar3 variable. assigning 3 values each of x, y, , z elements in order. time mention x, y , z interchangeable r, g , b. statement have used out->rgb, , have been more readable way. note out uchar4, , doing this, assigning first 3 "rgb" or "xyz" elements in pointer, fourth element left undefined here.

5) yes, in input pixel, out output pixel. x , y x, , y coordinates of pixel in overall image. kernel function going called once every pixel in image/allocation you're working with, , it's know coordinate you're @ when processing image. in particular example since it's thresholding pixels in same way, coordinates irrelevant.

good documentation on renderscript hard find. recommend take @ these 2 videos though, give better sense of how renderscript works:

andevcon: deep dive renderscript

google i/o 2013 - high performance applications renderscript

keep in mind both videos couple years old, minor details may have changed on recent apis, overall, best sources of information rs.