image_manipulation.ts

/// <reference path="../node_modules/assemblyscript/dist/assemblyscript.d.ts" />

export function invert(byteSize: i32): i32 {
  for (var i = 0; i < byteSize; i += 4) {
    let pos = i + byteSize; 
    store<u8>(pos, 255 - load<u8>(i));
    store<u8>(pos + 1, 255 - load<u8>(i + 1));
    store<u8>(pos + 2, 255 - load<u8>(i + 2));
    store<u8>(pos + 3, 255);
  }
  return 0;
}


export function grayscale(byteSize: i32): i32 {
  for (var i = 0; i < byteSize; i += 4) {
    let pos = i+byteSize;
    const avg = u8(0.3  *  load<u8>(i) + 0.59 * load<u8>(i + 1) + 0.11 * load<u8>(i + 2));
    store<u8>(pos, avg);
    store<u8>(pos + 1, avg);
    store<u8>(pos + 2, avg);
    store<u8>(pos + 3, 255);
  }
  return 0;
}

export function sepia(byteSize: i32): i32 {
  for (var i = 0; i < byteSize; i += 4) {
    let pos = i+byteSize;
    const avg = 0.3  *  load<u8>(i) + 0.59 * load<u8>(i + 1) + 0.11 * load<u8>(i + 2);
    store<u8>(pos, u8(min(avg + 100, 255)));
    store<u8>(pos + 1, u8(min(avg + 50, 255)));
    store<u8>(pos + 2, u8(avg));
    store<u8>(pos + 3, 255);
  }
  return 0;
}

@inline
function addConvolveValue(pos:i32, oldValue:u8, length:i32): i32 {
  return pos >= 0 && pos < length ? load<u8>(pos) : oldValue;
}

export function convolve(byteSize:i32, w:i32, offset:i32, v00:i32, v01:i32, v02:i32, v10:i32, v11:i32, v12:i32, v20:i32, v21:i32, v22:i32): i32 {
  let divisor = (v00 + v01 + v02 + v10 + v11 + v12 + v20 + v21 + v22) || 0;
  if (divisor === 0) {
    divisor = 1;
  }
  for(let i = 0; i < byteSize; i++){
      if ((i + 1) % 4 === 0) {
        store<u8>(i+byteSize, load<u8>(i));
        
      } else {
        let oldValue = load<u8>(i);
        let prev = i - w * 4;
        let next = i + w * 4;
        let res = v00 * addConvolveValue(prev - 4, oldValue, byteSize)  +
                  v01 * addConvolveValue(prev, oldValue, byteSize)      +
                  v02 * addConvolveValue(prev + 4, oldValue, byteSize)  +
                  v10 * addConvolveValue(i - 4, oldValue, byteSize)     +
                  v11 * oldValue +
                  v12 * addConvolveValue(i + 4, oldValue, byteSize)     +
                  v20 * addConvolveValue(next - 4, oldValue, byteSize)  +
                  v21 * addConvolveValue(next , oldValue, byteSize)     +
                  v22 * addConvolveValue(next + 4, oldValue, byteSize);
        res /= divisor;
        res += offset;
        store<u8>(i+byteSize, u8(res));
      }
  }
  return 0;
}