css
* {
margin: 0;
padding: 0;
}
li {
list-style-type: none;
}
a,
input {
outline: none;
-webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}
#choose {
display: none;
}
canvas {
width: 100%;
border: 1px solid #000000;
}
#upload {
display: block;
margin: 10px;
height: 60px;
text-align: center;
line-height: 60px;
border: 1px solid;
border-radius: 5px;
cursor: pointer;
}
.touch {
background-color: #ddd;
}
.img-list {
margin: 10px 5px;
}
.img-list li {
position: relative;
display: inline-block;
width: 100px;
height: 100px;
margin: 5px 5px 20px 5px;
border: 1px solid rgb(100, 149, 198);
background: #fff no-repeat center;
background-size: cover;
}
.progress {
position: absolute;
width: 100%;
height: 20px;
line-height: 20px;
bottom: 0;
left: 0;
background-color: rgba(100, 149, 198, .5);
}
.progress span {
display: block;
width: 0;
height: 100%;
background-color: rgb(100, 149, 198);
text-align: center;
color: #FFF;
font-size: 13px;
}
.size {
position: absolute;
width: 100%;
height: 15px;
line-height: 15px;
bottom: -18px;
text-align: center;
font-size: 13px;
color: #666;
}
.tips {
display: block;
text-align: center;
font-size: 13px;
margin: 10px;
color: #999;
}
.pic-list {
margin: 10px;
line-height: 18px;
font-size: 13px;
}
.pic-list a {
display: block;
margin: 10px 0;
}
.pic-list a img {
vertical-align: middle;
max-width: 30px;
max-height: 30px;
margin: -4px 0 0 10px;
}html
<input type="file" id="choose" accept="image/*" multiple>
<ul class="img-list"></ul>
<a id="upload">上传图片</a>
<span class="tips">只允许上传jpg、png及gif</span>
<div class="pic-list">
你上传的图片(图片有效期为1分钟)：
</div>js
var filechooser = document.getElementById("choose");
// 用于压缩图片的canvas
var canvas = document.createElement("canvas");
var ctx = canvas.getContext('2d');
// 瓦片canvas
var tCanvas = document.createElement("canvas");
var tctx = tCanvas.getContext("2d");
var maxsize = 100 * 1024;
$("#upload").on("click", function() {
filechooser.click();
})
.on("touchstart", function() {
$(this).addClass("touch")
})
.on("touchend", function() {
$(this).removeClass("touch")
});
filechooser.onchange = function() {
if(!this.files.length) return;
var files = Array.prototype.slice.call(this.files);
if(files.length > 9) {
alert("最多同时只可上传9张图片");
return;
}
files.forEach(function(file, i) {
if(!/\/(?:jpeg|png|gif)/i.test(file.type)) return;
var reader = new FileReader();
var li = document.createElement("li");
// 获取图片大小
var size = file.size / 1024 > 1024 ? (~~(10 * file.size / 1024 / 1024)) / 10 + "MB" : ~~(file.size / 1024) + "KB";
li.innerHTML = '<div class="progress"><span></span></div><div class="size">' + size + '</div>';
$(".img-list").append($(li));
reader.onload = function() {
var result = this.result;
var img = new Image();
img.src = result;
$(li).css("background-image", "url(" + result + ")");
//如果图片大小小于100kb，则直接上传
if(result.length <= maxsize) {
img = null;
upload(result, file.type, $(li));
return;
}
// 图片加载完毕之后进行压缩，然后上传
if(img.complete) {
callback();
} else {
img.onload = callback;
}
function callback() {
var data = compress(img);
upload(data, file.type, $(li));
img = null;
}
};
reader.readAsDataURL(file);
})
};
// 使用canvas对大图片进行压缩
function compress(img) {
var initSize = img.src.length;
var width = img.width;
var 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
var ratio;
if((ratio = width * height / 4000000) > 1) {
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
var 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
var nw = ~~(width / count);
var nh = ~~(height / count);
tCanvas.width = nw;
tCanvas.height = nh;
for(var i = 0; i < count; i++) {
for(var 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);
}
//进行最小压缩
var ndata = canvas.toDataURL('image/jpeg', 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;
}
// 图片上传，将base64的图片转成二进制对象，塞进formdata上传
function upload(basestr, type, $li) {
var text = window.atob(basestr.split(",")[1]);
var buffer = new Uint8Array(text.length);
var pecent = 0,
loop = null;
for(var i = 0; i < text.length; i++) {
buffer[i] = text.charCodeAt(i);
}
var blob = getBlob([buffer], type);
var xhr = new XMLHttpRequest();
var formdata = getFormData();
formdata.append('imagefile', blob);
xhr.open('post', '/cupload');
xhr.onreadystatechange = function() {
if(xhr.readyState == 4 && xhr.status == 200) {
var jsonData = JSON.parse(xhr.responseText);
var imagedata = jsonData[0] || {};
var text = imagedata.path ? '上传成功' : '上传失败';
console.log(text + '：' + imagedata.path);
clearInterval(loop);
//当收到该消息时上传完毕
$li.find(".progress span").animate({
'width': "100%"
}, pecent < 95 ? 200 : 0, function() {
$(this).html(text);
});
if(!imagedata.path) return;
$(".pic-list").append('<a href="' + imagedata.path + '">' + imagedata.name + '（' + imagedata.size + '）<img src="' + imagedata.path + '" /></a>');
}
};
//数据发送进度，前50%展示该进度
xhr.upload.addEventListener('progress', function(e) {
if(loop) return;
pecent = ~~(100 * e.loaded / e.total) / 2;
$li.find(".progress span").css('width', pecent + "%");
if(pecent == 50) {
mockProgress();
}
}, false);
//数据后50%用模拟进度
function mockProgress() {
if(loop) return;
loop = setInterval(function() {
pecent++;
$li.find(".progress span").css('width', pecent + "%");
if(pecent == 99) {
clearInterval(loop);
}
}, 100)
}
xhr.send(formdata);
}
/**
* 获取blob对象的兼容性写法
* @param buffer
* @param format
* @returns {*}
*/
function getBlob(buffer, format) {
try {
return new Blob(buffer, {
type: format
});
} catch(e) {
var bb = new(window.BlobBuilder || window.WebKitBlobBuilder || window.MSBlobBuilder);
buffer.forEach(function(buf) {
bb.append(buf);
});
return bb.getBlob(format);
}
}
/**
* 获取formdata
*/
function getFormData() {
var isNeedShim = ~navigator.userAgent.indexOf('Android') &&
~navigator.vendor.indexOf('Google') &&
!~navigator.userAgent.indexOf('Chrome') &&
navigator.userAgent.match(/AppleWebKit\/(\d+)/).pop() <= 534;
return isNeedShim ? new FormDataShim() : new FormData()
}
/**
* formdata 补丁, 给不支持formdata上传blob的android机打补丁
* @constructor
*/
function FormDataShim() {
console.warn('using formdata shim');
var o = this,
parts = [],
boundary = Array(21).join('-') + (+new Date() * (1e16 * Math.random())).toString(36),
oldSend = XMLHttpRequest.prototype.send;
this.append = function(name, value, filename) {
parts.push('--' + boundary + '\r\nContent-Disposition: form-data; name="' + name + '"');
if(value instanceof Blob) {
parts.push('; filename="' + (filename || 'blob') + '"\r\nContent-Type: ' + value.type + '\r\n\r\n');
parts.push(value);
} else {
parts.push('\r\n\r\n' + value);
}
parts.push('\r\n');
};
// Override XHR send()
XMLHttpRequest.prototype.send = function(val) {
var fr,
data,
oXHR = this;
if(val === o) {
// Append the final boundary string
parts.push('--' + boundary + '--\r\n');
// Create the blob
data = getBlob(parts);
// Set up and read the blob into an array to be sent
fr = new FileReader();
fr.onload = function() {
oldSend.call(oXHR, fr.result);
};
fr.onerror = function(err) {
throw err;
};
fr.readAsArrayBuffer(data);
// Set the multipart content type and boudary
this.setRequestHeader('Content-Type', 'multipart/form-data; boundary=' + boundary);
XMLHttpRequest.prototype.send = oldSend;
} else {
oldSend.call(this, val);
}
};
}温馨提示：记得引入JQ哦