javascript实现自由编辑图片代码详解

import Cropper from 'cropperjs';
import 'cropperjs/dist/cropper.css';

this.state = {
width: 640, //图片展示宽
height: 360, //图片展示高 
imgWidth: 640, //图片实际宽
imgHeight: 360, //图片实际高
imgLeft: 0, //图片左偏移
imgTop: 0, //图片上偏移
editing: false //是否编辑中
}
//展示图片的基本dom结构，我们使用外div内img的形式，来跟数据结合控制裁剪图片的展示
const { width, height, imgWidth, imgHeight, imgLeft, imgTop, editing } = this.state;
const containerStyle = {
width: `${width}px`,
height: `${height}px`
}
const imgStyle = {
width: `${imgWidth}px`,
height: `${imgHeight}px`,
left: `${imgLeft}px`,
top: `${imgTop}px`
}
.img-container {
overflow: hidden;
position: relative;
}
.crop-img {
position: absolute;
left: 0;
top: 0;
}
<div 
className="img-container" 
style={containerStyle}
>
<img 
className="crop-img"
src={picture} 
style={imgStyle} 
alt="pic"
></img>
</div>

.edit-container {
position: absolute;
left: 0;
right: 0;
top: 0;
bottom: 0;
}
<div 
className="img-container" 
style={containerStyle}
>
<img 
className="crop-img"
src={picture} 
style={imgStyle} 
alt="pic"
></img>
</div>
//cropper初始化
this.myRef = React.createRef();
this.myCropper = new Cropper(this.myRef.current, options);
//options配置
const options = {
dragMode: 'move', //使裁剪时图片可拖动
background: false, //因为我们现在是全屏可编辑，需要隐藏掉默认的背景
}
//当然还有许多常见的配置项，如编辑框尺寸比例等，大家可自行查看api
//裁剪保存
save() {
const cropBoxData = this.myCropper.getCropBoxData(); //获取裁剪框数据
const canvasData = this.myCropper.getCanvasData(); //获取图片数据
this.setState({
width: cropBoxData.width,
height: cropBoxData.height,
imgLeft: canvasData.left - cropBoxData.left,
imgTop: canvasData.top - cropBoxData.top,
imgWidth: canvasData.width,
imgHeight: canvasData.height
})
}

const options = {
dragMode: 'move',
background: false,
//控件初始化后重置相应配置
ready: () => {
const { width, height, imgWidth, imgHeight, imgLeft, imgTop } = this.state;
//根据实际需要出现裁图功能进行定位，此处left和top仅为测试暂时默认值定义
const left = 50; 
const top = 50;
this.myCropper.setCanvasData({
width: imgWidth,
height: imgHeight,
left: left,
top: top
});
this.myCropper.setCropBoxData({
left: left - imgLeft,
top: top - imgTop,
width: width,
height: height
})
}
}
this.myCropper = new Cropper(this.myRef.current, options);