/**
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* 转换尺寸 canvas缩放后 返回的尺寸不对 要做调整
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* @param {[type]} width canvas的CSS宽度
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* @param {[type]} height canvas的CSS高度
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* @param {[type]} canvasWidth canvas的画布宽度
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* @param {[type]} canvasHeight canvas的画布高度
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* @param {[type]} obj 需要转换的尺寸对象
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* @return {[type]} 转换后的尺寸对象
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*/
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const transSize = function (width, height, canvasWidth, canvasHeight, obj) {
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if (!obj) {
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return {
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width: 0,
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height: 0,
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left: 0,
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top: 0,
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right: 0,
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bottom: 0
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};
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}
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const res = {};
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let _ratio;
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const ratio = canvasWidth / canvasHeight;
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// 如果宽高比大于画布的宽高比 则比例以高度来计算 反之以宽度计算
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if (width / height > ratio) {
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_ratio = height / canvasHeight;
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const _width = (width - height * ratio) / 2;
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res.width = typeof obj.width === 'number' ? obj.width * _ratio : obj.width;
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res.height = typeof obj.height === 'number' ? obj.height * _ratio : obj.height;
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res.top = obj.top * _ratio;
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res.bottom = obj.bottom * _ratio;
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res.left = obj.left * _ratio + _width;
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res.right = obj.right * _ratio + _width;
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} else {
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_ratio = width / canvasWidth;
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const _height = (height - width / ratio) / 2;
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res.width = typeof obj.width === 'number' ? obj.width * _ratio : obj.width;
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res.height = typeof obj.height === 'number' ? obj.height * _ratio : obj.height;
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res.top = obj.top * _ratio + _height;
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res.bottom = obj.bottom * _ratio + _height;
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res.left = obj.left * _ratio;
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res.right = obj.right * _ratio;
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}
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// console.log('trans', res, 'obj', obj);
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// console.trace('transSize callStack');
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return res;
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};
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// 防抖
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const debounce = function (fn, delay = 500) {
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var timer = null;
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return function () {
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// eslint-disable-next-line @typescript-eslint/no-this-alias
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var _this = this;
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var args = arguments;
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if (timer) clearTimeout(timer);
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timer = setTimeout(function () {
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fn.apply(_this, args);
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}, delay);
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};
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};
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// 节流
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const throttle = function (fn, delay = 300) {
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var lastTime, timer;
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return function () {
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// eslint-disable-next-line @typescript-eslint/no-this-alias
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var _this = this;
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var args = arguments;
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var nowTime = Date.now();
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if (lastTime && nowTime - lastTime < delay) {
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if (timer) clearTimeout(timer);
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timer = setTimeout(function () {
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lastTime = nowTime;
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fn.apply(_this, args);
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}, delay);
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} else {
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lastTime = nowTime;
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fn.apply(_this, args);
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}
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};
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};
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/**
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* 执行指定次数的定时器
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* @param {回调} func
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* @param {等待时间} w
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* @param {重复次数} t
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*/
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const interval = function (func, w, t) {
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const interv = function () {
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if (typeof t === 'undefined' || t-- > 0) {
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setTimeout(interv, w);
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try {
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// eslint-disable-next-line no-useless-call
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func.call(null);
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} catch (e) {
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t = 0;
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throw e.toString();
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}
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}
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};
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setTimeout(interv, w);
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};
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export default {
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debounce,
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interval,
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throttle,
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transSize
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};
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