/**
 * 转换为运算角度
 * @param { number } deg 数学角度
 * @return { number } 运算角度
 */
export declare const getAngle: (deg: number) => number;
/**
 * 根据角度计算圆上的点
 * @param { number } deg 运算角度
 * @param { number } r 半径
 * @return { Array<number> } 坐标[x, y]
 */
export declare const getArcPointerByDeg: (deg: number, r: number) => [number, number];
/**
 * 根据点计算切线方程
 * @param { number } x 横坐标
 * @param { number } y 纵坐标
 * @return { Array<number> } [斜率, 常数]
 */
export declare const getTangentByPointer: (x: number, y: number) => Array<number>;
export declare const fanShapedByArc: (ctx: CanvasRenderingContext2D, minRadius: number, maxRadius: number, start: number, end: number, gutter: number) => void;
export declare const roundRectByArc: (ctx: CanvasRenderingContext2D, ...[x, y, w, h, r]: number[]) => void;
/**
 * 创建线性渐变色
 */
export declare const getLinearGradient: (ctx: CanvasRenderingContext2D, x: number, y: number, w: number, h: number, background: string) => any;