blur.js

// TODO Optimize edge cases.
// TODO Optimize index calculation.
// TODO Optimize arguments.
export function blurX(source, target, r) {
  var n = source.width,
      m = source.height,
      w = (r << 1) + 1;
  for (var j = 0; j < m; ++j) {
    for (var i = 0, sr = 0; i < n + r; ++i) {
      if (i < n) {
        sr += source.data[i + j * n];
      }
      if (i >= r) {
        if (i >= w) {
          sr -= source.data[i - w + j * n];
        }
        target.data[i - r + j * n] = sr / Math.min(i + 1, n - 1 + w - i, w);
      }
    }
  }
}

// TODO Optimize edge cases.
// TODO Optimize index calculation.
// TODO Optimize arguments.
export function blurY(source, target, r) {
  var n = source.width,
      m = source.height,
      w = (r << 1) + 1;
  for (var i = 0; i < n; ++i) {
    for (var j = 0, sr = 0; j < m + r; ++j) {
      if (j < m) {
        sr += source.data[i + j * n];
      }
      if (j >= r) {
        if (j >= w) {
          sr -= source.data[i + (j - w) * n];
        }
        target.data[i + (j - r) * n] = sr / Math.min(j + 1, m - 1 + w - j, w);
      }
    }
  }
}