看到一篇兼容性很强的图片无刷新裁剪上传的帖子，感觉很棒。分享下！~
废话不多说，上效果图。
一、首先建立如下的一个page
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<link href="tapmodo-Jcrop-1902fbc/css/jquery.Jcrop.min.css" rel="stylesheet" />
<script src="Scripts/jquery-1.7.1.min.js"></script>
<script src="tapmodo-Jcrop-1902fbc/js/jquery.Jcrop.min.js"></script>
<script src="data:imageCropperUpload.js"></script>
<script>
$(function () { var btn = $("#Button1"); btn.cropperUpload({
url: "WebForm1.aspx",
fileSuffixs: ["jpg", "png", "bmp"],
errorText: "{0}",
onComplete: function (msg) {
$("#testimg").attr("src", msg);
},
cropperParam: {//Jcrop参数设置，除onChange和onSelect不要使用，其他属性都可用
maxSize: [100, 100],//不要小于50，如maxSize:[40,24]
minSize: [70, 70],//不要小于50，如minSize:[40,24]
bgColor: "black",
bgOpacity: .4,
allowResize: false,
allowSelect: false,
animationDelay:50
},
perviewImageElementId: "fileList", //设置预览图片的元素id
perviewImgStyle: { width: '700px', height: '500px', border: '1px solid #ebebeb' }//设置预览图片的样式
}); var upload = btn.data("uploadFileData"); $("#files").click(function () {
upload.submitUpload();
});
});
</script>
</head>
<body>
<div style="width: 400px; height: 300px; float:left">
<input id="Button1" type="button" value="选择文件" />
<input id="files" type="button" value="上传截图" />
<div id="fileList" style="margin-top: 10px; padding-top:10px; border-top:1px solid #C0C0C0;font-size: 13px; width:400px"> </div>
</div> <div id="testdiv" style="padding-top: 580px">
<img alt="" src="" id="testimg"/>
</div>
</body>
</html>
HTML部分
说明一下以下这几个引用文件的关系
<link href="tapmodo-Jcrop-1902fbc/css/jquery.Jcrop.min.css" rel="stylesheet" />
<script src="Scripts/jquery-1.7.1.min.js"></script>
<script src="tapmodo-Jcrop-1902fbc/js/jquery.Jcrop.min.js"></script>
<script src="data:imageCropperUpload.js"></script>
引用文件
其中jquery.Jcrop.min.css和jquery.Jcrop.min.js是Jcrop插件必须的一个样式表文件和js文件，当然jquery是一定要引入的，最后面的imageCropperUpload.js文件就是自己写的插件，注意引用顺序不要弄错了，否则不起作用，上面示例中的代码我就不说了，都是很简单的设置。
下面是插件源码（注意：这个是原文博主自己写的插件，使用的时候把它copy下来保存为imageCropperUpload.js，就可以在页面上引用了）
(function ($) {
var defaultSettings = {
url: "", //上传地址
fileSuffixs: ["jpg", "png"], //允许上传的文件后缀名列表
errorText: "不能上传后缀为 {0} 的文件！", //错误提示文本，其中{0}将会被上传文件的后缀名替换
onCheckUpload: function (text) { //上传时检查文件后缀名不包含在fileSuffixs属性中时触发的回调函数，(text为错误提示文本)
},
onComplete: function (msg) { //上传完成后的回调函数[不管成功或失败，它都将被触发](msg为服务端的返回字符串)
alert(msg);
},
onChosen: function (file, obj, fileSize, errorTxt) { /*选择文件后的回调函数，(file为选中文件的本地路径;obj为当前的上传控件实例,
fileSize为上传文件大小，单位KB[只有在isFileSize为true时，此参数才有值],
errorTxt为获取文件大小时的错误文本提示) */
//alert(file);
},
cropperParam: {}, //图片截取参数设置，此参数即为Jcrop插件参数
isFileSize: false,//是否获取文件大小
perviewImageElementId: "",//用于预览上传图片的元素id（请传入一个div元素的id）
perviewImgStyle: null//用于设置图片预览时的样式（可不设置，在不设置的情况下多文件上传时只能显示一张图片），如{ width: '100px', height: '100px', border: '1px solid #ebebeb' }
};
$.fn.cropperUpload = function (settings) {
settings = $.extend({}, defaultSettings, settings || {});
return this.each(function () {
var self = $(this);
var upload = new UploadAssist(settings);
upload.createIframe(this);
//绑定当前按钮点击事件
self.bind("click", function (e) {
upload.chooseFile();
});
//将上传辅助类的实例，存放到当前对象中，方便外部获取
self.data("uploadFileData", upload);
//创建的iframe中的那个iframe，它的事件需要延迟绑定
window.setTimeout(function () {
$(upload.getIframeContentDocument().body).find("input[type='file']").change(function () {
if(!this.value) return;
var fileSuf = this.value.substring(this.value.lastIndexOf(".") + 1);
//检查是否为允许上传的文件
if (!upload.checkFileIsUpload(fileSuf, upload.settings.fileSuffixs)) {
upload.settings.onCheckUpload(upload.settings.errorText.replace("{0}", fileSuf));
return;
}
if (upload.settings.isFileSize) {
var size = perviewImage.getFileSize(this, upload.getIframeContentDocument());
var fileSize, errorTxt;
if (size == "error") {
errorTxt = upload.errorText;
} else {
fileSize = size;
}
//选中后的回调
upload.settings.onChosen(this.value, this, fileSize, errorTxt);
} else {
//选中后的回调
upload.settings.onChosen(this.value, this);
}
//是否开启了图片预览
if (upload.settings.perviewImageElementId) {
var main = perviewImage.createPreviewElement("closeImg", this.value, upload.settings.perviewImgStyle);
$("#" + upload.settings.perviewImageElementId).append(main);
var div = $(main).children("div").get(0);
perviewImage.beginPerview(this, div, upload.getIframeContentDocument(), upload);
}
});
//为创建的iframe内部的iframe绑定load事件
$(upload.getIframeContentDocument().body.lastChild).on("load", function () {
var dcmt = upload.getInsideIframeContentDocument();
upload.submitStatus = true;
if (dcmt.body.innerHTML) {
if (settings.onComplete) {
settings.onComplete(dcmt.body.innerHTML);
}
dcmt.body.innerHTML = "";
}
});
}, 100);
});
};
})(jQuery);
//上传辅助类
function UploadAssist(settings) {
//保存设置
this.settings = settings;
//创建的iframe唯一名称
this.iframeName = "upload" + this.getTimestamp();
//提交状态
this.submitStatus = true;
//针对IE上传获取文件大小时的错误提示文本
this.errorText = "请设置浏览器一些参数后再上传文件，方法如下（设置一次即可）：\n请依次点击浏览器菜单中的\n'工具->Internet选项->安全->可信站点->自定义级别'\n在弹出的自定义级别窗口中找到 'ActiveX控件和插件' 项，将下面的子项全部选为 '启用' 后，点击确定。\n此时不要关闭当前窗口，再点击 '站点' 按钮，在弹出的窗口中将下面复选框的 '√' 去掉，然后点击 '添加' 按钮并关闭当前窗口。\n最后一路 '确定' 完成并刷新当前页面。";
this.jcropApi;
return this;
}
UploadAssist.prototype = {
//辅助类构造器
constructor: UploadAssist,
//创建iframe
createIframe: function (/*插件中指定的dom对象*/elem) {
var html = "<html>"
+ "<head>"
+ "<title>upload</title>"
+ "<script>"
+ "function getDCMT(){return window.frames['dynamic_creation_upload_iframe'].document;}"
+ "</" + "script>"
+ "</head>"
+ "<body>"
+ "<form method='post' target='dynamic_creation_upload_iframe' enctype='multipart/form-data' action='" + this.settings.url + "'>"
+ "<input type='text' id='x1' name='x1' />"
+ "<input type='text' id='y1' name='y1' />"
+ "<input type='text' id='x2' name='x2' />"
+ "<input type='text' id='y2' name='y2' />"
+ "<input type='text' id='w' name='w' />"
+ "<input type='text' id='h' name='h' />"
+ "<input type='text' id='maxW' name='maxW' />"
+ "<input type='text' id='maxH' name='maxH' />"
+ "<input type='file' name='fileUpload' />"
+ "</form>"
+ "<iframe name='dynamic_creation_upload_iframe'></iframe>"
+ "</body>"
+ "</html>";
this.iframe = $("<iframe name='" + this.iframeName + "'></iframe>")[0];
this.iframe.style.width = "0px";
this.iframe.style.height = "0px";
this.iframe.style.border = "0px solid #fff";
this.iframe.style.margin = "0px";
elem.parentNode.insertBefore(this.iframe, elem);
var iframeDocument = this.getIframeContentDocument();
iframeDocument.write(html);
},
//获取时间戳
getTimestamp: function () {
return (new Date()).valueOf();
},
//设置图片缩放的最大高宽
setMaxWidthAndHeight: function (/*最大宽*/maxW,/*最大高*/maxH) {
this.getElement("maxW").value = maxW;
this.getElement("maxH").value = maxH;
},
//设置图片截取参数
setImageCropperObj: function (/*图片截取对象*/obj) {
this.getElement("x1").value = obj.x;
this.getElement("y1").value = obj.y;
this.getElement("x2").value = obj.x2;
this.getElement("y2").value = obj.y2;
this.getElement("w").value = obj.w;
this.getElement("h").value = obj.h;
},
//获取创建的iframe中的元素
getElement: function (id) {
var dcmt = this.getIframeContentDocument();
return dcmt.getElementById(id);
},
//获取创建的iframe中的document对象
getIframeContentDocument: function () {
return this.iframe.contentDocument || this.iframe.contentWindow.document;
},
//获取创建的iframe所在的window对象
getIframeWindow: function () {
return this.iframe.contentWindow || this.iframe.contentDocument.parentWindow;
},
//获取创建的iframe内部iframe的document对象
getInsideIframeContentDocument: function () {
return this.getIframeWindow().getDCMT();
},
//获取上传input控件
getUploadInput: function () {
var inputs = this.getIframeContentDocument().getElementsByTagName("input");
var uploadControl;
this.forEach(inputs, function () {
if (this.type === "file") {
uploadControl = this;
return false;
}
});
return uploadControl;
},
//forEach迭代函数
forEach: function (/*数组*/arr, /*代理函数*/fn) {
var len = arr.length;
for (var i = 0; i < len; i++) {
var tmp = arr[i];
if (fn.call(tmp, i, tmp) == false) {
break;
}
}
},
//提交上传
submitUpload: function () {
if (!this.submitStatus) return;
this.submitStatus = false;
this.getIframeContentDocument().forms[0].submit();
},
//检查文件是否可以上传
checkFileIsUpload: function (fileSuf, suffixs) {
var status = false;
this.forEach(suffixs, function (i, n) {
if (fileSuf.toLowerCase() === n.toLowerCase()) {
status = true;
return false;
}
});
return status;
},
//选择上传文件
chooseFile: function () {
if (this.settings.perviewImageElementId) {
$("#" + this.settings.perviewImageElementId).empty();
}
var uploadfile = this.getUploadInput();
$(uploadfile).val("").click();
}
};
//图片预览操作
var perviewImage = {
timers: [],
//获取预览元素
getElementObject: function (elem) {
if (elem.nodeType && elem.nodeType === 1) {
return elem;
} else {
return document.getElementById(elem);
}
},
//开始图片预览
beginPerview: function (/*文件上传控件实例*/file, /*需要显示的元素id或元素实例*/perviewElemId, /*上传页面所在的document对象*/ dcmt, /*上传辅助类实例*/upload) {
this.imageOperation(file, perviewElemId, dcmt, upload);
},
//图片预览操作
imageOperation: function (/*文件上传控件实例*/file, /*需要显示的元素id或元素实例*/perviewElemId, /*上传页面所在的document对象*/ dcmt, /*上传辅助类实例*/upload) {
for (var t = 0; t < this.timers.length; t++) {
window.clearInterval(this.timers[t]);
}
this.timers.length = 0;
var tmpParams = {
onChange: function (c) {
upload.setImageCropperObj(c);
},
onSelect: function (c) {
upload.setImageCropperObj(c);
}
};
var sWidth = 50, sHeight = 50;
if (upload.settings.cropperParam.minSize) {
var size = upload.settings.cropperParam.minSize;
sWidth = size[0] > sWidth ? size[0] : sWidth;
sHeight = size[1] > sHeight ? size[1] : sHeight;
}
var params = $.extend({}, tmpParams, upload.settings.cropperParam || {});
var preview_div = this.getElementObject(perviewElemId);
var MAXWIDTH = preview_div.clientWidth;
var MAXHEIGHT = preview_div.clientHeight;
upload.setMaxWidthAndHeight(MAXWIDTH, MAXHEIGHT);
if (file.files && file.files[0]) { //此处为Firefox，Chrome以及IE10的操作
preview_div.innerHTML = "";
var img = document.createElement("img");
preview_div.appendChild(img);
img.style.visibility = "hidden";
img.onload = function () {
var rect = perviewImage.clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
img.style.width = rect.width + 'px';
img.style.height = rect.height + 'px';
img.style.visibility = "visible";
var offsetWidth = (rect.width / 2) - (sWidth / 2);
var offsetHeight = (rect.height / 2) - (sHeight / 2);
var obj = {
x: offsetWidth,
y: offsetHeight,
x2: offsetWidth + sWidth,
y2: offsetHeight + sHeight,
w: sWidth,
h: sHeight
};
$(img).Jcrop(params, function () {
upload.jcropApi = this;
this.animateTo([obj.x, obj.y, obj.x2, obj.y2]);
upload.setImageCropperObj(obj);
});
};
var reader = new FileReader();
reader.onload = function (evt) {
img.src = evt.target.result;
};
reader.readAsDataURL(file.files[0]);
} else { //此处为IE6，7，8，9的操作
file.select();
var src = dcmt.selection.createRange().text;
var div_sFilter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + src + "')";
var img_sFilter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='image',src='" + src + "')";
preview_div.innerHTML = "";
var img = document.createElement("div");
preview_div.appendChild(img);
img.style.filter = img_sFilter;
img.style.visibility = "hidden";
img.style.width = "100%";
img.style.height = "100%";
function setImageDisplay() {
var rect = perviewImage.clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
preview_div.innerHTML = "";
var div = document.createElement("div");
div.style.width = rect.width + 'px';
div.style.height = rect.height + 'px';
div.style.filter = div_sFilter;
var offsetWidth = (rect.width / 2) - (sWidth / 2);
var offsetHeight = (rect.height / 2) - (sHeight / 2);
var obj = {
x: offsetWidth,
y: offsetHeight,
x2: offsetWidth + sWidth,
y2: offsetHeight + sHeight,
w: sWidth,
h: sHeight
};
preview_div.appendChild(div);
$(div).Jcrop(params, function () {
upload.jcropApi = this;
this.animateTo([obj.x, obj.y, obj.x2, obj.y2]);
upload.setImageCropperObj(obj);
});
}
//图片加载计数
var tally = 0;
var timer = window.setInterval(function () {
if (img.offsetHeight != MAXHEIGHT) {
window.clearInterval(timer);
setImageDisplay();
} else {
tally++;
}
//如果超过两秒钟图片还不能加载，就停止当前的轮询
if (tally > 20) {
window.clearInterval(timer);
setImageDisplay();
}
}, 100);
this.timers.push(timer);
}
},
//按比例缩放图片
clacImgZoomParam: function (maxWidth, maxHeight, width, height) {
var param = { width: width, height: height };
if (width > maxWidth || height > maxHeight) {
var rateWidth = width / maxWidth;
var rateHeight = height / maxHeight;
if (rateWidth > rateHeight) {
param.width = maxWidth;
param.height = Math.round(height / rateWidth);
} else {
param.width = Math.round(width / rateHeight);
param.height = maxHeight;
}
}
param.left = Math.round((maxWidth - param.width) / 2);
param.top = Math.round((maxHeight - param.height) / 2);
return param;
},
//创建图片预览元素
createPreviewElement: function (/*关闭图片名称*/name, /*上传时的文件名*/file, /*预览时的样式*/style) {
var img = document.createElement("div");
img.title = file;
img.style.overflow = "hidden";
for (var s in style) {
img.style[s] = style[s];
}
var text = document.createElement("div");
text.style.width = style.width;
text.style.overflow = "hidden";
text.style.textOverflow = "ellipsis";
text.style.whiteSpace = "nowrap";
text.innerHTML = file;
var main = document.createElement("div");
main.appendChild(img);
main.appendChild(text);
return main;
},
//获取上传文件大小
getFileSize: function (/*上传控件dom对象*/file, /*上传控件所在的document对象*/dcmt) {
var fileSize;
if (file.files && file.files[0]) {
fileSize = file.files[0].size;
} else {
file.select();
var src = dcmt.selection.createRange().text;
try {
var fso = new ActiveXObject("Scripting.FileSystemObject");
var fileObj = fso.getFile(src);
fileSize = fileObj.size;
} catch (e) {
return "error";
}
}
fileSize = ((fileSize / 1024) + "").split(".")[0];
return fileSize;
}
};
JS部分
这里也给出Jcrop插件的下载地址，有需要的可以去下载
二、服务端（这里是asp.net的webform作为示例）
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
var x = Request.Params["x1"]; //水平偏移量
var y = Request.Params["y1"]; //垂直偏移量
var x2 = Request.Params["x2"]; //水平偏移量 + 截取宽度
var y2 = Request.Params["y2"]; //垂直偏移量 + 截取高度
var w = Request.Params["w"]; //截取宽度
var h = Request.Params["h"]; //截取高度
var maxW = Request.Params["maxW"];//客户端截取时，图片的最大宽度
var maxH = Request.Params["maxH"];//客户端截取时，图片的最大高度 HttpFileCollection files = Request.Files;
var fileName = string.Empty;
for (var i = ; i < files.Count; i++)
{
//首先将图片缩放到与客户端截取时的大小一致
using (var bitmap = GenerateThumbnail(int.Parse(maxW), int.Parse(maxH), files[i].InputStream))
{
fileName = DateTime.Now.Ticks + ".jpg";
var newFileName = Server.MapPath("/uploadImg") + "/" + fileName; //开始截取
ImageCropper(bitmap, int.Parse(w), int.Parse(h), int.Parse(x), int.Parse(y), newFileName,
System.Drawing.Imaging.ImageFormat.Jpeg);
}
} //上传成功，这里只输出文件名，作为示例这样就够了
Response.Write("/uploadImg/" + fileName); //上传失败
// Response.Write("error");
Response.Flush();
Response.End();
}
/// <summary>
/// 生成指定大小的图片
/// </summary>
/// <param name="maxWidth">生成图片的最大宽度</param>
/// <param name="maxHeight">生成图片的最大高度</param>
/// <param name="imgFileStream">图片文件流对象</param>
private System.Drawing.Bitmap GenerateThumbnail(int maxWidth, int maxHeight, System.IO.Stream imgFileStream)
{
using (var img = System.Drawing.Image.FromStream(imgFileStream))
{
var sourceWidth = img.Width;
var sourceHeight = img.Height; var thumbWidth = sourceWidth; //要生成的图片的宽度
var thumbHeight = sourceHeight; //要生成图片的的高度 //计算生成图片的高度和宽度
if (sourceWidth > maxWidth || sourceHeight > maxHeight)
{
var rateWidth = (double) sourceWidth/maxWidth;
var rateHeight = (double) sourceHeight/maxHeight; if (rateWidth > rateHeight)
{
thumbWidth = maxWidth;
thumbHeight = (int) Math.Round(sourceHeight/rateWidth);
}
else
{
thumbWidth = (int) Math.Round(sourceWidth/rateHeight);
thumbHeight = maxHeight;
}
} var bmp = new System.Drawing.Bitmap(thumbWidth, thumbHeight);
//从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
using (var gr = System.Drawing.Graphics.FromImage(bmp))
{
//设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//下面这个也设成高质量
gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
//下面这个设成High
gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //把原始图像绘制成上面所设置宽高的缩小图
var rectDestination = new System.Drawing.Rectangle(, , thumbWidth, thumbHeight);
gr.DrawImage(img, rectDestination, , , sourceWidth, sourceHeight,
System.Drawing.GraphicsUnit.Pixel);
return bmp;
}
}
}
/// <summary>
/// 截取图片中的一部分
/// </summary>
/// <param name="img">待截取的图片</param>
/// <param name="cropperWidth">截取图片的宽</param>
/// <param name="cropperHeight">截取图片的高</param>
/// <param name="offsetX">水平偏移量</param>
/// <param name="offsetY">垂直偏移量</param>
/// <param name="savePath">截取后的图片保存位置</param>
/// <param name="imgFormat">截取后的图片保存格式</param>
private void ImageCropper(System.Drawing.Image img, int cropperWidth, int cropperHeight, int offsetX,
int offsetY, string savePath,
System.Drawing.Imaging.ImageFormat imgFormat)
{
using (var bmp = new System.Drawing.Bitmap(cropperWidth, cropperHeight))
{
//从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
using (var gr = System.Drawing.Graphics.FromImage(bmp))
{
//设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
//下面这个也设成高质量
gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
//下面这个设成High
gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //把原始图像绘制成上面所设置宽高的截取图
var rectDestination = new System.Drawing.Rectangle(offsetX, offsetY, cropperWidth, cropperHeight);
gr.DrawImage(img, , , rectDestination,
System.Drawing.GraphicsUnit.Pixel); //保存截取的图片
bmp.Save(savePath, imgFormat);
}
}
}
}
服务器端
服务端其实也很简单，我想应该都看得明白吧！关键是思路，我们首先将图片缩放到和客户端截取时相同的大小，然后再在这个缩放的图上进行截取 就这么简单，这样就能保证截取到相同位置的图片，好了 最后感谢原文博主。