新手入门，实现了图片预览和上传，但是不懂压缩，在网上找了一段压缩函数，但是一直套不进去，请前辈指点，如何在现有html、js、php基础上加入压缩，谢谢o(∩_∩)o 。。。代码如下：
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title></title>
<script type="text/javascript" src="http://cdn.bootcss.com/jquery/3.1.1/jquery.min.js"></script>
<style>
.LXXUploadPic{
margin-left:10px;
margin-top:10px;
}
.LXXUploadPic td{
width:64px;
height:64px;
background:#f3f3f3;
position: relative;
text-align:center;
}
input[type='file']{
width: 100%;
height: 100%;
overflow: hidden;
position:absolute;
right:0;
top:0;
opacity: 0;
cursor:pointer;
}
.displaynone{
width:10px!important;
background:url()!important;
}
</style>
</head>
<body id="top">
<form action="upload.php" method="post" enctype="multipart/form-data" id="formid">
<p id="LXXUploadPic" LXXCol="3" LXXRow="1" LXXWidth="100" LXXHeight="100"></p>
<input type="button" onclick="get();" class="queding" value="确定"/>
</form>
<script type="text/javascript">
function get(){
document.getElementById("formid").submit();
}
//配置项
var colNumber = 1; //列数
var rowNumber = 2; //行数
var width = 300; //框高
var height = 100; //框宽
/**
根据配置项搭建UI
*/
function makeUI(){
//从html标签读取配置项
var htmlColNumber = $('#LXXUploadPic').attr('LXXCol');
var htmlRowNumber = $('#LXXUploadPic').attr('LXXRow');
colNumber = htmlColNumber ? parseInt(htmlColNumber) : colNumber;
rowNumber = htmlRowNumber ? parseInt(htmlRowNumber) : rowNumber;
var htmlWidth = $('#LXXUploadPic').attr('LXXWidth');
var htmlHeight = $('#LXXUploadPic').attr('LXXHeight');
width = width ? parseInt(htmlWidth) : width;
height = height ? parseInt(htmlHeight) : height;
//开始搭建UI
var html = "<table class='LXXUploadPic'>";
for(var i = 0; i<rowNumber; i++){
html += "<tr>";
for(var j = 0; j<colNumber; j++){
html += "<td><input type='file' name='file[]' id=img"+j+" /></td>";
html += "<td class="+"displaynone"+"></td>";
}
html += "</tr>";
}
html += "</table>";
$('#LXXUploadPic').html(html);
//$('.LXXUploadPic tr td').css('width', width).css('height', height);
}
/**
根据input[file]对象获取添加的图片url
*/
function getObjectURL(file) {
var url = null;
if (window.createObjectURL != undefined) {
url = window.createObjectURL(file)
} else if (window.URL != undefined) {
url = window.URL.createObjectURL(file)
} else if (window.webkitURL != undefined) {
url = window.webkitURL.createObjectURL(file)
}
return url
};
/**
选中图片将图片显示出来
*/
function changeToShow(){
$('input[type="file"]').change(function(){
//根据input[file]对象获取添加的图片url
var src = getObjectURL(this.files[0]);
$(this).parent().css('background', 'url(' + src + ') no-repeat center center').css('background-size', '100% 100%');
});
}
$(document).ready(function(){
//根据配置项搭建UI
makeUI();
//选中图片将图片显示出来
changeToShow();
});
</script>
</body>
</html>php接收：
<?php
//打印三维数组$_FILES中的内容，查看一下存储上传文件的结构
print_r($_FILES);
echo "<br/>";
echo "<br/>";
echo "<br/>";
var_dump($_POST);
echo "<br/>";
echo "<br/>";
echo "<br/>";
$dest_folder = "images/";
if(!file_exists($dest_folder)){
if(mkdir($dest_folder)){
}else{
echo"创建文件夹失败<br/>";
}
}
foreach ($_FILES["file"]["error"] as $key => $error ){
if ($error == UPLOAD_ERR_OK)
{
$tmp_name = $_FILES["file"]["tmp_name"][$key];
$name = time().$key.$_FILES["file"]["name"][$key];
$uploadfile = $dest_folder.$name;
//$filepath="/images/";
//$filepath=$filepath.$uploadfile;
move_uploaded_file($tmp_name, $uploadfile);
$php_self = $_SERVER['PHP_SELF'];
$php_dir = dirname($php_self);
//$url = 'http://'.$_SERVER['HTTP_HOST'].$php_dir.'/'.$uploadfile;
$arr = array(
'id' => $key,
//'url' => $url
'url' => $name
);
echo json_encode($arr);
}
}
?>
网上找的压缩函数：
// 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;
}
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
这也叫压缩……这不就是把图片缩小了嘛。
要上传的话，去学习一下表单的操作，以及 Ajax 你也应该用得上。