這裏需要用到jquery Jcrop 插件實現前端選擇圖片區域效果
然後使用canvas裁剪圖片，並把base64位的toDataURL圖片轉換成blob
最後使用XMLHttpRequest上傳到服務器。
預覽效果：
整體代碼：
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"/>
<meta name="description" id="description1" content="1">
<meta name="renderer" content="webkit">
<meta name="format-detection" content="telephone=no">
<title>圖片上傳</title>
<style type="text/css">
* {
box-sizing: border-box; /* h5 */
-moz-box-sizing: border-box; /* Firefox */
-webkit-box-sizing: border-box; /* Safari */
margin: 0;
padding: 0;
outline: 0 none;
font-weight: inherit;
font-style: inherit;
font-family: inherit;
vertical-align: baseline;
}
.jcrop-holder {
direction: ltr;
text-align: center;
margin: 0 auto;
/* IE10 touch compatibility */
-ms-touch-action: none;
}
/* Selection Border */
.jcrop-vline,
.jcrop-hline {
background: #ffffff url("Jcrop.gif");
font-size: 0;
position: absolute;
}
.jcrop-vline {
height: 100%;
width: 1px !important;
}
.jcrop-vline.right {
right: 0;
}
.jcrop-hline {
height: 1px !important;
width: 100%;
}
.jcrop-hline.bottom {
bottom: 0;
}
/* Invisible click targets */
.jcrop-tracker {
height: 100%;
width: 100%;
/* "turn off" link highlight */
-webkit-tap-highlight-color: transparent;
/* disable callout, image save panel */
-webkit-touch-callout: none;
/* disable cut copy paste */
-webkit-user-select: none;
}
/* Selection Handles */
.jcrop-handle {
background-color: #333333;
border: 1px #eeeeee solid;
width: 7px;
height: 7px;
font-size: 1px;
}
.jcrop-handle.ord-n {
left: 50%;
margin-left: -4px;
margin-top: -4px;
top: 0;
}
.jcrop-handle.ord-s {
bottom: 0;
left: 50%;
margin-bottom: -4px;
margin-left: -4px;
}
.jcrop-handle.ord-e {
margin-right: -4px;
margin-top: -4px;
right: 0;
top: 50%;
}
.jcrop-handle.ord-w {
left: 0;
margin-left: -4px;
margin-top: -4px;
top: 50%;
}
.jcrop-handle.ord-nw {
left: 0;
margin-left: -4px;
margin-top: -4px;
top: 0;
}
.jcrop-handle.ord-ne {
margin-right: -4px;
margin-top: -4px;
right: 0;
top: 0;
}
.jcrop-handle.ord-se {
bottom: 0;
margin-bottom: -4px;
margin-right: -4px;
right: 0;
}
.jcrop-handle.ord-sw {
bottom: 0;
left: 0;
margin-bottom: -4px;
margin-left: -4px;
}
/* Dragbars */
.jcrop-dragbar.ord-n,
.jcrop-dragbar.ord-s {
height: 7px;
width: 100%;
}
.jcrop-dragbar.ord-e,
.jcrop-dragbar.ord-w {
height: 100%;
width: 7px;
}
.jcrop-dragbar.ord-n {
margin-top: -4px;
}
.jcrop-dragbar.ord-s {
bottom: 0;
margin-bottom: -4px;
}
.jcrop-dragbar.ord-e {
margin-right: -4px;
right: 0;
}
.jcrop-dragbar.ord-w {
margin-left: -4px;
}
/* The "jcrop-light" class/extension */
.jcrop-light .jcrop-vline,
.jcrop-light .jcrop-hline {
background: #ffffff;
filter: alpha(opacity=70) !important;
opacity: .70!important;
}
.jcrop-light .jcrop-handle {
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
background-color: #000000;
border-color: #ffffff;
border-radius: 3px;
}
/* The "jcrop-dark" class/extension */
.jcrop-dark .jcrop-vline,
.jcrop-dark .jcrop-hline {
background: #000000;
filter: alpha(opacity=70) !important;
opacity: 0.7 !important;
}
.jcrop-dark .jcrop-handle {
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
background-color: #ffffff;
border-color: #000000;
border-radius: 3px;
}
/* Simple macro to turn off the antlines */
.solid-line .jcrop-vline,
.solid-line .jcrop-hline {
background: #ffffff;
}
/* Fix for twitter bootstrap et al. */
.jcrop-holder img,
img.jcrop-preview {
max-width: none;
}
.uploadPics {
position: relative;
margin: 0 auto;
width: 380px;
background-color: #fff;
border-top: 3px solid #ed2828;
height: 460px;
overflow: hidden;
}
.uploadPics > img {
position: absolute;
top: 20px;
right: 10px;
cursor: pointer;
}
.uploadPics .picTil {
padding: 20px;
font-size: 16px;
color: #323232;
border-bottom: 1px solid #f3f3f3;
}
.uploadPics .picCont {
margin: 20px;
padding: 15px;
width: 300px;
height: 337px;
background-color: #f2f2f5;
}
.uploadPics .picCont > p {
margin-top: 20px;
text-align: center;
}
.uploadPics .picFooter {
text-align: center;
}
.uploadPics .picFooter .btn {
display: inline-block;
margin: 20px;
width: 130px;
height: 35px;
font-size: 18px;
line-height: 35px;
color: #fff;
border-radius: 5px;
cursor: pointer;
}
.uploadPics .picFooter .upload {
background-color: #aaa;
}
.uploadPics .picFooter .confirm {
background-color: #ed2828;
}
#myCan{
position: absolute;
top: 50px;
right: 50px;
}
</style>
</head>
<body>
<div class="uploadPics">
<img src="../images/AvatarClose.png" alt="" onclick="ClosePage()" />
<div class="picTil">上傳頭像</div>
<div class="picCont" style="width:300px;height:300px;margin:20px auto 0;padding:0;" >
<div id=imgfield style=overflow:hidden;width:100%;height:100% ></div>
</div>
<div class="picFooter">
<input type="file" id="fileimg" name="fileimg" style="display:none" onchange="imgchange()" />
<span class="btn upload" onclick="getimg()">上傳</span>
<span class="btn confirm" onclick="subform()">確認</span>
</div>
</div>
<canvas id="myCan" width="200" height="200"></canvas>
</body>
<script type="text/javascript" src="http://182.92.213.51:1070/html/js/inc/jquery-1.8.3.min.js"></script>
<script type="text/javascript" src="http://182.92.213.51:1070/html/js/inc/jquery.Jcrop.js"></script>
<script type="text/javascript">
function subform() {
if($("#imgfield").html()){
//獲取裁剪完後的base64圖片url,轉換爲blob
var data=document.getElementById("myCan").toDataURL();
var formData=new FormData();
formData.append("imageName",dataURLtoBlob(data));
var httprequest=new XMLHttpRequest();
var apiurl=""; //上傳圖片的api接口，自行填寫
httprequest.open('POST',apiurl,true);
httprequest.send(formData);
httprequest.onreadystatechange= function () {
if(httprequest.status==200 && httprequest.readyState==4){
var json=JSON.parse(httprequest.responseText);
console.log(json)
}else{
alert("上傳圖片失敗！api錯誤")
}
};
}else{
alert("請選擇圖片!")
}
}
function getimg() {
$("#fileimg").click();
}
function imgchange() {
var localimg = $("#fileimg").get(0).files[0];
if(!localimg){
return;
}
var fileName = localimg.name;
var fileSize = localimg.size;
var fileType=fileName.substring(fileName.lastIndexOf('.'),fileName.length).toLowerCase();
if(fileType!='.gif' && fileType!='.jpeg' && fileType!='.png' && fileType!='.jpg')
{
alert("上傳失敗，請上傳jpg,png格式的圖片");
return;
}
var size=3*1024*1024;
if(fileSize>size){
alert("上傳失敗，請上傳3MB以內的圖片。");
return;
}
var reader=new FileReader();
//將文件讀取爲DataURL
reader.readAsDataURL(localimg);
reader.onload= function (e) {
var localimghtml = '<img id="cropbox" src="' + e.target.result + '" >';
$("#imgfield").html(localimghtml);
initJcrop();
};
}
function initJcrop(){
$('#cropbox').Jcrop({
onSelect: updateCoords,
aspectRatio: 1,
boxWidth: 300,
boxHeight: 300
}, function () {
//圖片實際尺寸
var bb = this.getBounds();
var bWidth= Number(bb[0]) / 2;
var bHeight= Number(bb[1]) / 2;
this.setSelect([0, 0, bWidth,bHeight]);
var ss = this.getWidgetSize();
var aheight = (300 - Number(ss[1])) / 2 + "px";
$(".jcrop-holder").css("margin-top", aheight);
});
}
function updateCoords(c){
// console.log(c);
var img=document.getElementById("cropbox");
var ctx=document.getElementById("myCan").getContext("2d");
//img,開始剪切的x,Y座標寬高，放置圖像的x,y座標寬高。
ctx.drawImage(img,c.x,c.y, c.w, c.h,0,0,200,200);
}
//**dataURL to blob**
function dataURLtoBlob(dataurl) {
var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new Blob([u8arr], { type: mime });
}
</script>
</html>