<!DOCTYPE html>
<html>
<head>
<!--by 0o晓月メ http://www.cnblogs.com/final-elysion/p/6092675.html-->
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no, width=device-width">
<title>compress pic to base64</title>
<script type="text/javascript">
function uploadBtnClick(){
var scope = this;
// change pic to base64
if(window.File && window.FileReader && window.FileList && window.Blob){
//For Ext :
//var filefield = me.down('filefield'),
// file = filefield.fileInputEl.dom.files[0];
var filefield = document.getElementById('fileToUpload'),
file = filefield.files[0];
var compressValue = document.getElementById('compressValue');
processfile(file,compressValue,uploadCompressFile,scope);
}else{
alert("Upload picture is not fully supported in this browser");
}
}
function processfile(file,compressValue,uploadCompressFile,scope) {
var reader = new FileReader();
reader.onload = function (event) {
var blob = new Blob([event.target.result]);
window.URL = window.URL || window.webkitURL;
var blobURL = window.URL.createObjectURL(blob);
var image = new Image();
image.src = blobURL;
image.onload = function() {
var resized = resizeMe(image);
compressValue.value = resized;
uploadCompressFile.apply(scope);
}
};
reader.readAsArrayBuffer(file);
}
function resizeMe(img) {
//压缩的大小
var max_width =1024;
var max_height =768;
var canvas = document.createElement('canvas');
var width = img.width;
var height = img.height;
if(width > height) {
if(width > max_width) {
height = Math.round(height *= max_width / width);
width = max_width;
}
}
else{
if(height > max_height) {
width = Math.round(width *= max_height / height);
height = max_height;
}
}
canvas.width = width;
canvas.height = height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, width, height);
//压缩率
return canvas.toDataURL("image/jpeg",0.7);
}
// call back
function uploadCompressFile(){
//do ajax upload
document.getElementById('displayValue').innerHTML = document.getElementById('compressValue').value;
}
</script>
</head>
<body >
<input type="file" name="fileToUpload" id="fileToUpload"/> <br />
<input type="text" name="compressValue" id="compressValue" style="display:none;" /><br/>
<input type="button" onclick="uploadBtnClick()" value="上存" /><br/>
<div id='displayValue' style="word-spacing: normal;word-wrap: break-word;"></div>
</body>
</html>
