Android RenderScript - Syntax Error

Question

My current script is:

#pragma version(1)
#pragma rs java_package_name(foo.bar)

rs_allocation inPixels;
int height;
int width;
int threeBythree[];

void root(const uchar4 *in, uchar4 *out, uint32_t x, uint32_t y) {
    float3 pixel = convert_float4(in[0]).rgb;

    if(x==0 || x==width || y==0 || y==height){
        pixel.r = 0;
        pixel.g = 191;
        pixel.b = 255;
    }else{ //do image processing here

        float3 pixelNH = convert_float4(rsGetElementAt_uchar4(inPixels, x+1, y)).rgb;
        float3 pixelNV = convert_float4(rsGetElementAt_uchar4(inPixels, x, y+1)).rgb;

        int grayAvg = (pixel.r + pixel.g + pixel.b)/3;
        int grayAvgNH = (pixelNH.r + pixelNH.g + pixelNH.b)/3;
        int grayAvgNV = (pixelNV.r + pixelNV.g + pixelNV.b)/3;

        int edgeOperatorValue = 2*grayAvg - grayAvgNH - grayAvgNV;

        if(edgeOperatorValue < 0){
            edgeOperatorValue = -1 * edgeOperatorValue;
        };

        pixel.r = edgeOperatorValue;
        pixel.g = edgeOperatorValue;
        pixel.b = edgeOperatorValue;
    };

    out->xyz = convert_uchar3(pixel);
}

after following this advice here: Renderscript, what is the `in` parameter?

I replaced my code with that one (it doesnt matter if they do not do the same thing I just want it to compile for now):

uchar4 RS_KERNEL root(uchar4 in, uint32_t x, uint32_t y) {
  // x and y aren't used, so you can remove those from the above signature too.
  uchar4 out;
  float3 pixel = convert_float4(in).rgb;

  pixel.r = (pixel.r + pixel.g + pixel.b)/3;
  // This seems buggy to me below, since pixel.r was just modified.
  // I think you need another temporary variable (assuming you are trying to make this work and getting weird behavior).
  pixel.g = (pixel.r + pixel.g + pixel.b)/3;
  pixel.b = (pixel.r + pixel.g + pixel.b)/3;

  //int topRight
  //float4 f4 = rsUnpackColor8888(*(uchar*)rsGetElementAt(inPixels, x+1, y+1));

  out.xyz = convert_uchar3(pixel);
  return out;
}

and this is what I get now:

/home/Projects/android/bar/app/src/main/rs/edgedetect.rs:8:17: error: expected ';' after top level declarator

What is it complaining about ? (line 8 btw is uchar4 RS_KERNEL root(uchar4 in, uint32_t x, uint32_t y) {)

EDIT: In my build.gradle:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion '19.1.0'

    defaultConfig {
        applicationId "foo.bar"
        minSdkVersion 15
        targetSdkVersion 19
        versionCode 1
        versionName "1.0"

        renderscriptTargetApi 19
        renderscriptSupportModeEnabled true //not applicable for rs targetapi 21+
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

Answer 1

This type of error appears when you use variables which have not been defined. I'll agree that it's not very clear.

If you notice, you defined the following variable:

uchar4 out;

Then later, you use it like this:

out.xyz = convert_uchar3(pixel);

Except, you're trying to access a property of a variable which was never defined.

Try initializing it like this:

uchar4 out = in;

If this gets rid of your error, then this was your problem. If for some reason you cant use out = in, then look into other ways of initializing the out variable.

Answer 2

You are using

buildToolsVersion '19.1.0'

which doesn't have headers that support "RS_KERNEL". Try replacing that with

__attribute__((kernel))