<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
</HEAD>
<script>
var maxH = 768;
var maxW = 1024;
function DrawImage(ImgD){
var preW = 300;
var preH = 400 ;
var image=new Image();
image.src=ImgD.src;
if(image.width > maxW || image.height > maxH){
alert("图片尺寸过大,请选择" + maxW + "*" + maxH + "的图片!");
return;
}
if(image.width>0 && image.height>0){
flag=true;
if(image.width/image.height>= preW/preH){
if(image.width>preW){
ImgD.width=preW;
ImgD.height=(image.height*preW)/image.width;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
else{
if(image.height>preH){
ImgD.height=preH;
ImgD.width=(image.width*preH)/image.height;
}else{
ImgD.width=image.width;
ImgD.height=image.height;
}
ImgD.alt=image.width+"×"+image.height;
}
}
}
function checkFormat(filePath) {
var i = filePath.lastIndexOf('.');
var len = filePath.length;
var str = filePath.substring(len,i+1);
var extName = "JPG,GIF,PNG,JPEG,BMP";
if(extName.indexOf(str.toUpperCase()) < 0) {
alert("请选择正确的图片文件!");
return false;
}
return true;
}
function FileChange(Value){
if(checkFormat(Value)){
flag=false;
document.getElementById("uploadimage").width=10;
document.getElementById("uploadimage").height=10;
document.getElementById("uploadimage").alt="";
document.getElementById("uploadimage").src=Value;
}
}
</script>
<BODY>
<input type="file" size="30" name="picaddress" onChange="javascript:FileChange(this.value);">
<br><IMG id=uploadimage height=0 width=0 src="" onload="javascript:DrawImage(this);" >
</BODY>
</HTML>
参考资料:http://www.baidu.com