60 lines
2.4 KiB
Plaintext
60 lines
2.4 KiB
Plaintext
import { interpolate, defaultOffset } from 'motion-dom';
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import { clamp } from 'motion-utils';
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import { calcInset } from './inset.mjs';
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import { resolveOffset } from './offset.mjs';
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import { ScrollOffset } from './presets.mjs';
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const point = { x: 0, y: 0 };
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function getTargetSize(target) {
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return "getBBox" in target && target.tagName !== "svg"
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? target.getBBox()
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: { width: target.clientWidth, height: target.clientHeight };
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}
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function resolveOffsets(container, info, options) {
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const { offset: offsetDefinition = ScrollOffset.All } = options;
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const { target = container, axis = "y" } = options;
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const lengthLabel = axis === "y" ? "height" : "width";
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const inset = target !== container ? calcInset(target, container) : point;
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/**
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* Measure the target and container. If they're the same thing then we
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* use the container's scrollWidth/Height as the target, from there
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* all other calculations can remain the same.
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*/
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const targetSize = target === container
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? { width: container.scrollWidth, height: container.scrollHeight }
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: getTargetSize(target);
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const containerSize = {
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width: container.clientWidth,
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height: container.clientHeight,
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};
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/**
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* Reset the length of the resolved offset array rather than creating a new one.
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* TODO: More reusable data structures for targetSize/containerSize would also be good.
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*/
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info[axis].offset.length = 0;
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/**
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* Populate the offset array by resolving the user's offset definition into
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* a list of pixel scroll offets.
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*/
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let hasChanged = !info[axis].interpolate;
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const numOffsets = offsetDefinition.length;
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for (let i = 0; i < numOffsets; i++) {
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const offset = resolveOffset(offsetDefinition[i], containerSize[lengthLabel], targetSize[lengthLabel], inset[axis]);
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if (!hasChanged && offset !== info[axis].interpolatorOffsets[i]) {
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hasChanged = true;
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}
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info[axis].offset[i] = offset;
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}
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/**
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* If the pixel scroll offsets have changed, create a new interpolator function
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* to map scroll value into a progress.
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*/
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if (hasChanged) {
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info[axis].interpolate = interpolate(info[axis].offset, defaultOffset(offsetDefinition), { clamp: false });
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info[axis].interpolatorOffsets = [...info[axis].offset];
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}
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info[axis].progress = clamp(0, 1, info[axis].interpolate(info[axis].current));
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}
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export { resolveOffsets };
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