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46 lines
1.1 KiB
TypeScript
46 lines
1.1 KiB
TypeScript
import { Factory } from '../Factory';
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import { Filter, Node } from '../Node';
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import { getNumberValidator } from '../Validators';
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/**
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* Posterize Filter. Adjusts the channels so that there are no more
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* than n different values for that channel. This is also applied
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* to the alpha channel.
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* @function
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* @name Posterize
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* @author ippo615
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* @memberof Konva.Filters
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* @param {Object} imageData
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* @example
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* node.cache();
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* node.filters([Konva.Filters.Posterize]);
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* node.levels(0.8); // between 0 and 1
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*/
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export const Posterize: Filter = function (imageData) {
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// level must be between 1 and 255
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const levels = Math.round(this.levels() * 254) + 1,
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data = imageData.data,
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len = data.length,
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scale = 255 / levels;
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for (let i = 0; i < len; i += 1) {
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data[i] = Math.floor(data[i] / scale) * scale;
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}
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};
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Factory.addGetterSetter(
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Node,
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'levels',
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0.5,
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getNumberValidator(),
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Factory.afterSetFilter
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);
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/**
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* get/set levels. Must be a number between 0 and 1. Use with {@link Konva.Filters.Posterize} filter.
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* @name Konva.Node#levels
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* @method
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* @param {Number} level between 0 and 1
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* @returns {Number}
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*/
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