feat: 初始化

uni_modules/lime-shared/animation/bezier.ts

@@ -0,0 +1,82 @@
+export function cubicBezier(p1x : number, p1y : number, p2x : number, p2y : number):(x: number)=> number {
+	const ZERO_LIMIT = 1e-6;
+	// Calculate the polynomial coefficients,
+	// implicit first and last control points are (0,0) and (1,1).
+	const ax = 3 * p1x - 3 * p2x + 1;
+	const bx = 3 * p2x - 6 * p1x;
+	const cx = 3 * p1x;
+
+	const ay = 3 * p1y - 3 * p2y + 1;
+	const by = 3 * p2y - 6 * p1y;
+	const cy = 3 * p1y;
+
+	function sampleCurveDerivativeX(t : number) : number {
+		// `ax t^3 + bx t^2 + cx t` expanded using Horner's rule
+		return (3 * ax * t + 2 * bx) * t + cx;
+	}
+
+	function sampleCurveX(t : number) : number {
+		return ((ax * t + bx) * t + cx) * t;
+	}
+
+	function sampleCurveY(t : number) : number {
+		return ((ay * t + by) * t + cy) * t;
+	}
+
+	// Given an x value, find a parametric value it came from.
+	function solveCurveX(x : number) : number {
+		let t2 = x;
+		let derivative : number;
+		let x2 : number;
+
+		// https://trac.webkit.org/browser/trunk/Source/WebCore/platform/animation
+		// first try a few iterations of Newton's method -- normally very fast.
+		// http://en.wikipedia.org/wikiNewton's_method
+		for (let i = 0; i < 8; i++) {
+			// f(t) - x = 0
+			x2 = sampleCurveX(t2) - x;
+			if (Math.abs(x2) < ZERO_LIMIT) {
+				return t2;
+			}
+			derivative = sampleCurveDerivativeX(t2);
+			// == 0, failure
+			/* istanbul ignore if */
+			if (Math.abs(derivative) < ZERO_LIMIT) {
+				break;
+			}
+			t2 -= x2 / derivative;
+		}
+
+		// Fall back to the bisection method for reliability.
+		// bisection
+		// http://en.wikipedia.org/wiki/Bisection_method
+		let t1 = 1;
+		/* istanbul ignore next */
+		let t0 = 0;
+
+		/* istanbul ignore next */
+		t2 = x;
+		/* istanbul ignore next */
+		while (t1 > t0) {
+			x2 = sampleCurveX(t2) - x;
+			if (Math.abs(x2) < ZERO_LIMIT) {
+				return t2;
+			}
+			if (x2 > 0) {
+				t1 = t2;
+			} else {
+				t0 = t2;
+			}
+			t2 = (t1 + t0) / 2;
+		}
+
+		// Failure
+		return t2;
+	}
+
+	return function (x : number) : number {
+		return sampleCurveY(solveCurveX(x));
+	}
+
+	// return solve;
+}