framer-motion
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A simple and powerful JavaScript animation library
50 lines (48 loc) • 2.12 kB
JavaScript
function buildProjectionTransform(delta, treeScale, latestTransform) {
let transform = "";
/**
* The translations we use to calculate are always relative to the viewport coordinate space.
* But when we apply scales, we also scale the coordinate space of an element and its children.
* For instance if we have a treeScale (the culmination of all parent scales) of 0.5 and we need
* to move an element 100 pixels, we actually need to move it 200 in within that scaled space.
*/
const xTranslate = delta.x.translate / treeScale.x;
const yTranslate = delta.y.translate / treeScale.y;
const zTranslate = latestTransform?.z || 0;
if (xTranslate || yTranslate || zTranslate) {
transform = `translate3d(${xTranslate}px, ${yTranslate}px, ${zTranslate}px) `;
}
/**
* Apply scale correction for the tree transform.
* This will apply scale to the screen-orientated axes.
*/
if (treeScale.x !== 1 || treeScale.y !== 1) {
transform += `scale(${1 / treeScale.x}, ${1 / treeScale.y}) `;
}
if (latestTransform) {
const { transformPerspective, rotate, rotateX, rotateY, skewX, skewY } = latestTransform;
if (transformPerspective)
transform = `perspective(${transformPerspective}px) ${transform}`;
if (rotate)
transform += `rotate(${rotate}deg) `;
if (rotateX)
transform += `rotateX(${rotateX}deg) `;
if (rotateY)
transform += `rotateY(${rotateY}deg) `;
if (skewX)
transform += `skewX(${skewX}deg) `;
if (skewY)
transform += `skewY(${skewY}deg) `;
}
/**
* Apply scale to match the size of the element to the size we want it.
* This will apply scale to the element-orientated axes.
*/
const elementScaleX = delta.x.scale * treeScale.x;
const elementScaleY = delta.y.scale * treeScale.y;
if (elementScaleX !== 1 || elementScaleY !== 1) {
transform += `scale(${elementScaleX}, ${elementScaleY})`;
}
return transform || "none";
}
export { buildProjectionTransform };