77 lines
2.5 KiB
JavaScript
77 lines
2.5 KiB
JavaScript
import { invariant, noop, progress } from 'motion-utils';
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import { clamp } from './clamp.mjs';
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import { mix } from './mix/index.mjs';
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import { pipe } from './pipe.mjs';
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function createMixers(output, ease, customMixer) {
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const mixers = [];
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const mixerFactory = customMixer || mix;
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const numMixers = output.length - 1;
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for (let i = 0; i < numMixers; i++) {
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let mixer = mixerFactory(output[i], output[i + 1]);
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if (ease) {
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const easingFunction = Array.isArray(ease) ? ease[i] || noop : ease;
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mixer = pipe(easingFunction, mixer);
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}
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mixers.push(mixer);
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}
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return mixers;
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}
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/**
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* Create a function that maps from a numerical input array to a generic output array.
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*
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* Accepts:
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* - Numbers
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* - Colors (hex, hsl, hsla, rgb, rgba)
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* - Complex (combinations of one or more numbers or strings)
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*
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* ```jsx
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* const mixColor = interpolate([0, 1], ['#fff', '#000'])
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*
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* mixColor(0.5) // 'rgba(128, 128, 128, 1)'
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* ```
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*
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* TODO Revist this approach once we've moved to data models for values,
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* probably not needed to pregenerate mixer functions.
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*
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* @public
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*/
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function interpolate(input, output, { clamp: isClamp = true, ease, mixer } = {}) {
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const inputLength = input.length;
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invariant(inputLength === output.length, "Both input and output ranges must be the same length");
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/**
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* If we're only provided a single input, we can just make a function
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* that returns the output.
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*/
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if (inputLength === 1)
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return () => output[0];
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if (inputLength === 2 && output[0] === output[1])
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return () => output[1];
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const isZeroDeltaRange = input[0] === input[1];
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// If input runs highest -> lowest, reverse both arrays
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if (input[0] > input[inputLength - 1]) {
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input = [...input].reverse();
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output = [...output].reverse();
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}
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const mixers = createMixers(output, ease, mixer);
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const numMixers = mixers.length;
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const interpolator = (v) => {
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if (isZeroDeltaRange && v < input[0])
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return output[0];
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let i = 0;
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if (numMixers > 1) {
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for (; i < input.length - 2; i++) {
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if (v < input[i + 1])
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break;
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}
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}
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const progressInRange = progress(input[i], input[i + 1], v);
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return mixers[i](progressInRange);
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};
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return isClamp
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? (v) => interpolator(clamp(input[0], input[inputLength - 1], v))
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: interpolator;
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}
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export { interpolate };
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