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export const PI = Math.PI;
export function sum(x: number, y: number) {
return x + y;
}
export function square(x: number) {
return x * x;
}
export function draw(
ctx: CanvasRenderingContext2D,
x: number,
y: number,
l: number,
r: number,
operation: "fill" | "clip",
) {
ctx.beginPath();
ctx.moveTo(x, y);
ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI);
ctx.lineTo(x + l, y);
ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI);
ctx.lineTo(x + l, y + l);
ctx.lineTo(x, y + l);
ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true);
ctx.lineTo(x, y);
ctx.lineWidth = 2;
ctx.fillStyle = "rgba(255, 255, 255, 0.7)";
ctx.strokeStyle = "rgba(255, 255, 255, 0.7)";
ctx.stroke();
ctx[operation]();
ctx.globalCompositeOperation = "destination-over";
// ctx.globalCompositeOperation = "xor"; // 卡片不出来是可切换
}
export function createImg(imgs: any[], onload: () => void) {
const img = document.createElement("img");
img.crossOrigin = "Anonymous";
img.onload = onload;
img.onerror = () => {
img.src = getRandomImg(imgs);
};
img.src = getRandomImg(imgs);
return img;
}
export function getRandomNumberByRange(start: number, end: number) {
return Math.round(Math.random() * (end - start) + start);
}
// 随机生成img src
export function getRandomImg(imgs: string[]) {
const len = imgs.length;
return len > 0
? imgs[getRandomNumberByRange(0, len - 1)]
: // : "https://picsum.photos/300/150/?image=" + getRandomNumberByRange(0, 1084);
"https://source.unsplash.com/300x150/?book,library";
}
type optType = {
leading?: boolean;
trailing?: boolean;
resultCallback?: (res: any) => void;
};
/**
* 节流函数
* @param fn 回调
* @param interval 时间间隔
* @param options 头节流,尾节流
* @returns function
*/
export function throttle(
fn: (args: any) => any,
interval: number,
options: optType = { leading: true, trailing: true },
) {
const { leading, trailing, resultCallback } = options;
let lastTime = 0;
let timer: NodeJS.Timeout | null = null;
const _throttle = function (this: any, ...args: any) {
return new Promise((resolve, reject) => {
const nowTime = new Date().getTime();
if (!lastTime && !leading) lastTime = nowTime;
const remainTime = interval - (nowTime - lastTime);
if (remainTime <= 0) {
if (timer) {
clearTimeout(timer);
timer = null;
}
const result = fn.apply(this, args);
if (resultCallback) resultCallback(result);
resolve(result);
lastTime = nowTime;
return;
}
if (trailing && !timer) {
timer = setTimeout(() => {
timer = null;
lastTime = !leading ? 0 : new Date().getTime();
const result = fn.apply(this, args);
if (resultCallback) resultCallback(result);
resolve(result);
}, remainTime);
}
});
};
_throttle.cancel = function () {
if (timer) clearTimeout(timer);
timer = null;
lastTime = 0;
};
return _throttle;
}