konva/lib/filters/Threshold.js

HTML5 2d canvas library for interactive graphics, design editors, whiteboards, and diagrams.

import { Factory } from "../Factory.js";
import { Node } from "../Node.js";
import { getNumberValidator } from "../Validators.js";
/**
 * Threshold Filter. Pushes any value above the mid point to
 *  the max and any value below the mid point to the min.
 *  This affects the alpha channel.
 * @function
 * @name Threshold
 * @memberof Konva.Filters
 * @param {Object} imageData
 * @author ippo615
 * @example
 * node.cache();
 * node.filters([Konva.Filters.Threshold]);
 * node.threshold(0.1);
 */
export const Threshold = function (imageData) {
    const level = this.threshold() * 255, data = imageData.data, len = data.length;
    for (let i = 0; i < len; i += 1) {
        data[i] = data[i] < level ? 0 : 255;
    }
};
Factory.addGetterSetter(Node, 'threshold', 0.5, getNumberValidator(), Factory.afterSetFilter);
/**
 * get/set threshold. With {@link Konva.Filters.Threshold} it is a value between 0 and 1, default 0.5. With {@link Konva.Filters.Mask} it is the colour distance to the background, 0 to 255, default 10.
 * @name threshold
 * @method
 * @memberof Konva.Node.prototype
 * @param {Number} threshold
 * @returns {Number}
 */