;
const Reg = /^(?:data:image\/){1}(?:\w)+?(?:;base64,){1}.+$/
/* export default */ function rotate(f, d = 0) {
// 1.在模块开发中可以把export default打开使用
// 2.旋转图片是一个异步函数,通过.then获取旋转后的图片信息
// 3.旋转函数接受两个参数
// 4.第一个参数:图片文件,支持文件格式或者base64
// 5.第二个参数是需要旋转的角度,需要输入数字
d = parseInt(d % 360);
const Cas = document.createElement('canvas');
Cas.style.display = 'none';
const Ctx = Cas.getContext('2d');
const Img = document.createElement('img');
Img.style.display = 'none';
const FR = new FileReader();
return new Promise((resolve, reject) => {
let type = 'image/png';
let pristine = '';
try {
function ImgLoad() {
Img.removeEventListener('load', ImgLoad);
const w = Img.width;
const h = Img.height;
const sinW = Math.round(Math.abs(Math.sin(Math.PI * d / 180).toFixed(5)) * w);
const sinH = Math.round(Math.abs(Math.sin(Math.PI * d / 180).toFixed(5)) * h);
const cosW = Math.round(Math.abs(Math.cos(Math.PI * d / 180).toFixed(5)) * w);
const cosH = Math.round(Math.abs(Math.cos(Math.PI * d / 180).toFixed(5)) * h);
const width = cosW + sinH;
const height = sinW + cosH;
let x = 0;
let y = 0;
if ((0 < d && d < 90) || (d <= -270 && -360 <= d)) {
x = sinH;
y = 0;
} else if ((90 <= d && d < 180) || (d <= -180 && -270 < d)) {
x = sinH + cosW;
y = cosH;
} else if ((180 <= d && d < 270) || (d <= -90 && -180 < d)) {
x = cosW;
y = sinW + cosH;
} else if ((270 <= d && d <= 360) || (d < 0 && -90 < d)) {
x = 0;
y = sinW;
}
let base64 = pristine;
if (d != 0) {
Cas.width = width;
Cas.height = height;
Ctx.translate(x, y);
Ctx.rotate(Math.PI * d / 180);
Ctx.drawImage(Img, 0, 0);
base64 = Cas.toDataURL(type);
}
resolve({
worked: {
width,
height,
base64,
},
pristine: {
width: w,
height: h,
base64: pristine,
},
})
}
Img.addEventListener('load', ImgLoad);
if (Reg.test(f)) {
Img.src = f;
pristine = f;
type = f.split(';')[0].split(':')[1];
} else {
function FRload() {
FR.removeEventListener('load', FRload);
pristine = FR.result;
Img.src = pristine;
type = f.type;
}
FR.addEventListener('load', FRload);
FR.readAsDataURL(f);
}
} catch (error) {
reject(error);
}
})
}
