window-generator.js

window-generator.js

#!/usr/bin/env node

function window(values = [], step = 1, size = 1) {
  function* _window()  {
    for (let i = 0; i < values.length; i += step) {
      const items = values.slice(i, i + size);
      yield items;
    }
  }

  const generator = _window();

  generator.step = _step => {
    step = _step;
    return generator;
  };

  generator.size = _size => {
    size = _size;
    return generator;
  };

  return generator;
}

function debug(properties = [], name) {
  const numberOfProperties = properties.length;
  const lastIndex = numberOfProperties - 1;
  
  return function debugWithProperties(values = []) {
    let output = `${name}: `;
    for (let i = 0; i < values.length; i++) {
      const property = properties[i % numberOfProperties];
      output += `${property}=${values[i]}`;
      
      const isAtEnd = i + 1 === values.length;
      if (i % numberOfProperties === lastIndex && !isAtEnd) {
        output += '\n';
      } else {
        output += ' ';
      }
    }

    console.log(output);
  }
}

const rgb = debug(['r', 'g', 'b'], 'pixel');

const pixels = new Uint8Array([
  123, 123, 123, 0.8,
  255, 255, 255, 1.0,
  100, 100, 100, 0.5
]);

for (const value of window(pixels).step(4).size(3)) {
  console.log('value:', value);
  rgb(value);
}

// Array.from(
//   window(pixels).step(4).size(3)
// ).map(
//   ([ r, g, b]) => console.log(r, g, b)
// );