function previewImage(obj)
{
if (checkFiles(obj.value)){
var file= obj;
var MAXWIDTH = 155;
var MAXHEIGHT = 95;
var parent = obj.parentNode;
var divpreviewid = parent.getElementsByTagName("div")[0].id;
var imghead = divpreviewid+imghead;
var div = document.getElementById(divpreviewid);
if (file.files && file.files[0])
{
div.innerHTML = '<img id='+imghead+'>';
var img = document.getElementById(imghead);
img.onload = function(){
var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
//alert("寬度:"+img.width+" 高度:"+img.height);
img.width = rect.width;
img.height = rect.height;
img.style.marginLeft = rect.left+'px';
img.style.marginTop = rect.top+'px';
}
var reader = new FileReader();
reader.onload = function(evt){img.src = evt.target.result;}
reader.readAsDataURL(file.files[0]);
}
else
{
var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
file.select();
var src = document.selection.createRange().text;
div.innerHTML = '<img id='+imghead+'>';
var img = document.getElementById(imghead);
img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
status =('rect:'+rect.top+','+rect.left+','+rect.width+','+rect.height);
div.innerHTML = "<div id="+imghead+" style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;margin-left:"+rect.left+"px;"+sFilter+src+"\"'></div>";
}
}
else{
var parent = obj.parentNode;
//alert(parent.getElementsByTagName("input")[0].id);
parent.getElementsByTagName("input")[0].value="";
}
}
function clacImgZoomParam( maxWidth, maxHeight, width, height ){
var param = {top:0, left:0, width:width, height:height};
if( width>maxWidth || height>maxHeight )
{
rateWidth = width / maxWidth;
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;
}
function checkFiles(str, exStr) {
if (typeof (exStr) == 'undefined')
exStr = ".jpg|.png|.gif|.jpeg";
var strRegex = "(" + exStr + ")$"; //用於驗證圖片擴展名的正則表達式
var re = new RegExp(strRegex);
if (re.test(str.toLowerCase())) {
return true;
}
else {
alert("文件名不合法,文件的擴展名必須爲" + exStr + "格式");
return false;
}
}
js實現本地圖片預覽
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