image-sequencer/src/modules/EdgeDetect/Module.js

/*
* Detect Edges in an Image
*/
module.exports = function edgeDetect(options, UI) {

  var defaults = require('./../../util/getDefaults.js')(require('./info.json'));
  options.blur = options.blur || defaults.blur;
  options.highThresholdRatio = options.highThresholdRatio || defaults.highThresholdRatio;
  options.lowThresholdRatio = options.lowThresholdRatio || defaults.lowThresholdRatio;
  options.hysteresis = options.hysteresis || defaults.hysteresis;

  var output;

  // The function which is called on every draw.
  function draw(input, callback, progressObj) {

    progressObj.stop(true);
    progressObj.overrideFlag = true;

    var step = this;

    // Blur the image
    const internalSequencer = ImageSequencer({ inBrowser: false, ui: false });
    return internalSequencer.loadImage(input.src, function() {
      internalSequencer.importJSON([{ 'name': 'blur', 'options': { blur: options.blur } }]);
      return internalSequencer.run(function onCallback(internalOutput) {
        require('get-pixels')(internalOutput, function(err, blurPixels) {
          if (err) {
            return;
          }

          // Extra Manipulation function used as an enveloper for applying gaussian blur and Convolution
          function changePixel(r, g, b, a) {
            return [(r + g + b) / 3, (r + g + b) / 3, (r + g + b) / 3, a];
          }

          function extraManipulation() {
            return require('./EdgeUtils')(blurPixels, options.highThresholdRatio, options.lowThresholdRatio, options.hysteresis);
          }

          function output(image, datauri, mimetype) {
            step.output = { src: datauri, format: mimetype };
          }

          return require('../_nomodule/PixelManipulation.js')(input, {
            output: output,
            ui: options.step.ui,
            changePixel: changePixel,
            extraManipulation: extraManipulation,
            format: input.format,
            image: options.image,
            inBrowser: options.inBrowser,
            callback: callback
          });
        });
      });
    });
  }

  return {
    options: options,
    draw: draw,
    output: output,
    UI: UI
  };
};