62,041
社区成员
发帖
与我相关
我的任务
分享如何将前端压缩的图片保存到本地
前端将图片压缩之后，怎样点击“确认按钮”后将该图保存到本地的磁盘中去？
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="CutImg.WebForm1" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>html5前端图片压缩</title>
<meta name="viewport"
content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
<meta http-equiv="Cache-Control" content="no-cache" />
<meta name="viewport"
content="width=device-width, initial-scale=1.0, user-scalable=0" />
<meta content="telephone=no" name="format-detection" />
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
<script type="text/javascript">
/**
* 图片压缩，大仙造
* @param fil
* @param id
*/
function getUrl(fil, id) {
var Cnv = document.getElementById('myCanvas');
var Cntx = Cnv.getContext('2d');//获取2d编辑容器
var imgss = new Image();
var agoimg = document.getElementById("ago");
for (var intI = 0; intI < fil.length; intI++) {
var tmpFile = fil[intI];
var reader = new FileReader();
reader.readAsDataURL(tmpFile);
reader.onload = function (e) {
url = e.target.result;
imgss.src = url;
agoimg.src = url;
agoimg.onload = function () {
//等比缩放
var m = imgss.width / imgss.height;
Cnv.height = 300;//该值影响缩放后图片的大小
Cnv.width = 300 * m;
//img放入画布中
//设置起始坐标，结束坐标
Cntx.drawImage(agoimg, 0, 0, 300 * m, 300);
}
}
}
}
function pressss() {//
//获取canvas压缩后的图片数据
var Pic = document.getElementById("myCanvas").toDataURL("image/png");
var imgs = document.getElementById("press");
imgs.src = Pic;
//上传
// 去除多余，得到base64编码的图片字节流
Pic = Pic.replace(/^data:image\/(png|jpg);base64,/, "");
//可以用ajax提交到后台，提交后可以直接存数据库，也可以保存成图片，此处略，
//技术交流495120021
//
}
</script>
</head>
<body>
<form runat="server">
<div>
<input type="file" runat="server" id="fileId" name="fileId" onchange="getUrl(this.files,this.id);"/>
</div>
<canvas id="myCanvas" style="display: none"></canvas>
old img-><img src="" alt="" id="ago" style="width: 500px;" />
<input type="button" value="ya suo->" onclick="pressss()" />
new img-><img src="" alt="" runat="server" id="press" />
<asp:Button ID="btnSubmit" Text=" 确 认 添 加 " runat="server" class="btn btn-primary active pull-right" OnClick="btnSubmit_Click"/>
</form>
</body>
</html>
...全文
请发表友善的回复…
发表回复
娃都会打酱油了 2018-10-08
- 打赏
- 举报
stevenjin 2018-10-08
- 打赏
- 举报
2.后台
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace CutImg
{
public partial class WebForm1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string str = HttpContext.Current.Request["title"];
HttpPostedFile rq = Request.Files["imagefile"];
if (rq!=null)
{
Bitmap nImage = new Bitmap(rq.InputStream);
string fileName = Guid.NewGuid().ToString().Replace("-", "") + ".png";//获取文件名
string filePath = Server.MapPath(@"~\UploadImages\");
//路径不存在则创建
if (!Directory.Exists(filePath))
{
Directory.CreateDirectory(filePath);
}
nImage.Save(filePath+fileName);
}
}
private void Base64StringToImage(string inputStr)
{
if (string.IsNullOrWhiteSpace(inputStr))
return;
try
{
string filePath = "E:\\bb.jpg";
byte[] arr = Convert.FromBase64String(inputStr.Substring(inputStr.IndexOf("base64,") + 7).Trim('\0'));
using (MemoryStream ms = new MemoryStream(arr))
{
Bitmap bmp = new Bitmap(ms);
//新建第二个bitmap类型的bmp2变量。
Bitmap bmp2 = new Bitmap(bmp, bmp.Width, bmp.Height);
//将第一个bmp拷贝到bmp2中
Graphics draw = Graphics.FromImage(bmp2);
draw.DrawImage(bmp, 0, 0);
draw.Dispose();
bmp2.Save(filePath, System.Drawing.Imaging.ImageFormat.Jpeg);
ms.Close();
}
}
catch (Exception ex)
{
}
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
}
}
}stevenjin 2018-10-08
- 打赏
- 举报
参照前辈的指点，这样实现了。失真很少，只是后台自己写的方式有些欠妥，请指正！
1.前台
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="CutImg.WebForm1" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" name="viewport">
<title>移动端图片压缩上传demo</title>
<style>
*{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;}
</style>
</head>
<body>
<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>
<script src="jquery-1.10.2.min.js"></script>
<script>
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('title', 'ok');
alert(blob);
formdata.append('imagefile', blob);
xhr.open('post', 'WebForm1.aspx');
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('--' 
