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关于 vue 项目中移动端实现用户选择照片、照片裁剪、一次上传多张图片功能（仿微信发朋友圈）。
最终要实现的效果如下图所示：
涉及的功能有
1、图片的选择
2、图片从手机相机选择、拍照
3、图片选择后的裁剪
4、图片在页面的显示效果
5、图片的删除
6、base64 图片转化为 file 类型的文件
7、图片的上传
首先安装 cropperjs 和 exif-js 裁剪依赖这两个包
cnpm install –save cropperjs exif-js
图片的上传相关代码
图片从手机相机选择、拍照
图片选择后的裁剪
initilize(opt) {
let self = this;
this.options = opt;
// 创建 dom
this.createElement();
this.resultObj = opt.resultObj;
// 初始化裁剪对象
this.cropper = new Cropper(this.preview, {
aspectRatio: opt.aspectWithRatio / opt.aspectHeightRatio,
autoCropArea: opt.autoCropArea || 0.8,
viewMode: 2,
guides: true,
cropBoxResizable: true, // 是否通过拖动来调整剪裁框的大小
cropBoxMovable: true, // 是否通过拖拽来移动剪裁框。dragCrop: false,
dragMode: "move", //‘crop’: 可以产生一个新的裁剪框 3‘move’: 只可以移动 3‘none’: 什么也不处理
center: true,
zoomable: true, // 是否允许放大图像。zoomOnTouch: true, // 是否可以通过拖动触摸来放大图像。scalable: true,
// minCropBoxHeight: 750,
// minCropBoxWidth: 750,
background: false,
checkOrientation: true,
checkCrossOrigin: true,
zoomable: false,
zoomOnWheel: false,
center: false,
toggleDragModeOnDblclick: false,
ready: function() {if (opt.aspectRatio == "Free") {
let cropBox = self.cropper.cropBox;
cropBox.querySelector("span.cropper-view-box").style.outline =
"none";
self.cropper.disable();}
}
});
},
// 创建一些必要的 DOM，用于图片裁剪
createElement() {
// 初始化图片为空对象
this.preview = null;
let str =
'<div><img id="clip_image"src="originUrl"></div><button type="button"id="cancel_clip"> 取消 </button><button type="button"id="clip_button"> 确定 </button>';
str +=
'<div class="crop_loading"><div class="crop_content"><div class="crop_text"> 图片修剪中...</div></div></div>';
str +=
'<div class="crop_success"><div class="crop_success_text"> 上传成功 </div></div></div>';
let body = document.getElementsByTagName("body")[0];
this.reagion = document.createElement("div");
this.reagion.id = "clip_container";
this.reagion.className = "container";
this.reagion.innerHTML = str;
body.appendChild(this.reagion);
this.preview = document.getElementById("clip_image");
// 绑定一些方法
this.initFunction();},
// 初始化一些函数绑定
initFunction() {
let self = this;
this.clickBtn = document.getElementById("clip_button");
this.cancelBtn = document.getElementById("cancel_clip");
// 确定事件
this.addEvent(this.clickBtn, "click", function() {self.crop();
});
// 取消事件
this.addEvent(this.cancelBtn, "click", function() {self.destoried();
});
// 清空 input 的值
this.addEvent(this.fileObj, "click", function() {this.value = "";});
},
// 外部接口，用于 input['file']对象 change 时的调用
clip(e, opt) {
let self = this;
this.fileObj = e.srcElement;
let files = e.target.files || e.dataTransfer.files;
if (!files.length) return false; // 不是图片直接返回
// 调用初始化方法
this.initilize(opt);
// 获取图片文件资源
this.picValue = files[0];
// 调用方法转成 url 格式
this.originUrl = this.getObjectURL(this.picValue);
// 每次替换图片要重新得到新的 url
if (this.cropper) {this.cropper.replace(this.originUrl);
}
},
// 图片转码方法
getObjectURL(file) {
let url = null;
if (window.createObjectURL != undefined) {
// basic
url = window.createObjectURL(file);
} else if (window.URL != undefined) {// mozilla(firefox)
url = window.URL.createObjectURL(file);
} else if (window.webkitURL != undefined) {
// webkit or chrome
url = window.webkitURL.createObjectURL(file);
}
return url;
},
// 点击确定进行裁剪
crop() {
let self = this;
let image = new Image();
let croppedCanvas;
let roundedCanvas;
// Crop
document.querySelector(".crop_loading").style.display = "block";
setTimeout(function() {croppedCanvas = self.cropper.getCroppedCanvas();
// Round
roundedCanvas = self.getRoundedCanvas(croppedCanvas);
let imgData = roundedCanvas.toDataURL();
image.src = imgData;
// 判断图片是否大于 100k, 不大于直接上传，反之压缩
if (imgData.length < 100 * 1024) {
// self.resultObj.src = imgData;
// 图片上传
self.postImg(imgData);
} else {image.onload = function() {
// 压缩处理
let data = self.compress(image, self.Orientation);
// self.resultObj.src = data;
// 图片上传
self.postImg(data);
};
}
}, 20);
},
// 获取裁剪图片资源
getRoundedCanvas(sourceCanvas) {let canvas = document.createElement("canvas");
let context = canvas.getContext("2d");
let width = sourceCanvas.width;
let height = sourceCanvas.height;
canvas.width = width;
canvas.height = height;
context.imageSmoothingEnabled = true;
context.drawImage(sourceCanvas, 0, 0, width, height);
context.globalCompositeOperation = "destination-in";
context.beginPath();
context.rect(0, 0, width, height);
context.fill();
return canvas;
},
// 销毁原来的对象
destoried() {
let self = this;
// 移除事件
this.removeEvent(this.clickBtn, "click", null);
this.removeEvent(this.cancelBtn, "click", null);
this.removeEvent(this.fileObj, "click", null);
// 移除裁剪框
this.reagion.parentNode.removeChild(this.reagion);
// 销毁裁剪对象
this.cropper.destroy();
this.cropper = null;
},
// 图片上传
postImg(imageData) {console.log(imageData);
this.$emit("callback", imageData);
// 这边写图片的上传
let self = this;
self.destoried();
this.imgList.push(imageData);
},
// 图片旋转
rotateImg(img, direction, canvas) {
// 最小与最大旋转方向，图片旋转 4 次后回到原方向
const min_step = 0;
const max_step = 3;
if (img == null) return;
//img 的高度和宽度不能在 img 元素隐藏后获取，否则会出错
let height = img.height;
let width = img.width;
let step = 2;
if (step == null) {step = min_step;}
if (direction == "right") {
step++;
// 旋转到原位置，即超过最大值
step > max_step && (step = min_step);
} else {
step--;
step < min_step && (step = max_step);
}
// 旋转角度以弧度值为参数
let degree = (step * 90 * Math.PI) / 180;
let ctx = canvas.getContext("2d");
switch (step) {
case 0:
canvas.width = width;
canvas.height = height;
ctx.drawImage(img, 0, 0);
break;
case 1:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, 0, -height);
break;
case 2:
canvas.width = width;
canvas.height = height;
ctx.rotate(degree);
ctx.drawImage(img, -width, -height);
break;
case 3:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img, -width, 0);
break;
}
},
// 图片压缩
compress(img, Orientation) {let canvas = document.createElement("canvas");
let ctx = canvas.getContext("2d");
// 瓦片 canvas
let tCanvas = document.createElement("canvas");
let tctx = tCanvas.getContext("2d");
let initSize = img.src.length;
let width = img.width;
let height = img.height;
// 如果图片大于四百万像素，计算压缩比并将大小压至 400 万以下
let ratio;
if ((ratio = (width * height) / 4000000) > 1) {console.log("大于 400 万像素");
ratio = Math.sqrt(ratio);
width /= ratio;
height /= ratio;
} else {ratio = 1;}
canvas.width = width;
canvas.height = height;
// 铺底色
ctx.fillStyle = "#fff";
ctx.fillRect(0, 0, canvas.width, canvas.height);
// 如果图片像素大于 100 万则使用瓦片绘制
let count;
if ((count = (width * height) / 1000000) > 1) {count = ~~(Math.sqrt(count) + 1); // 计算要分成多少块瓦片
// 计算每块瓦片的宽和高
let nw = ~~(width / count);
let nh = ~~(height / count);
tCanvas.width = nw;
tCanvas.height = nh;
for (let i = 0; i < count; i++) {for (let j = 0; j < count; j++) {
tctx.drawImage(
img,
i * nw * ratio,
j * nh * ratio,
nw * ratio,
nh * ratio,
0,
0,
nw,
nh
);
ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);
}
}
} else {ctx.drawImage(img, 0, 0, width, height);
}
// 修复 ios 上传图片的时候 被旋转的问题
if (Orientation != "" && Orientation != 1) {switch (Orientation) {
case 6: // 需要顺时针（向左）90 度旋转
this.rotateImg(img, "left", canvas);
break;
case 8: // 需要逆时针（向右）90 度旋转
this.rotateImg(img, "right", canvas);
break;
case 3: // 需要 180 度旋转
this.rotateImg(img, "right", canvas); // 转两次
this.rotateImg(img, "right", canvas);
break;
}
}
// 进行最小压缩
let ndata = canvas.toDataURL("image/png", 0.1);
console.log("压缩前：" + initSize);
console.log("压缩后：" + ndata.length);
console.log("压缩率：" + ~~((100 * (initSize - ndata.length)) / initSize) + "%"
);
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
return ndata;
},
// 添加事件
addEvent(obj, type, fn) {if (obj.addEventListener) {obj.addEventListener(type, fn, false);
} else {obj.attachEvent("on" + type, fn);
}
},
// 移除事件
removeEvent(obj, type, fn) {if (obj.removeEventListener) {obj.removeEventListener(type, fn, false);
} else {obj.detachEvent("on" + type, fn);
}
}图片在页面的显示效果
暂无
图片的删除
base64 图片转化为 file 类型的文件
bytes = window.atob(this.imgList[i].split(‘,’)[1]);
var array = [];
array.push(bytes.charCodeAt(j));
var blob = new Blob([new Uint8Array(array)], {type: 'image/jpeg'});
form.append("file", blob, Date.now() + '.jpg');
图片的上传
暂无
最终效果：
图片裁剪参考：https://blog.csdn.net/ch83430…
ps: 需要源码的请联系我（请尊重一下别人的劳动成果，源码需要付费 10 元哦。）：
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