解决Extjs上传图片无法预览的解决方法

{ 
width: 450, 
fileUpload: true, 
fieldLabel: '选择图片', 
items: [{ 
xtype: 'textfield', 
id: 'up_forth', 
name: 'up_forth', 
inputType: 'file', 
width: 300 
}] 
}

预览box

{ 
columnWidth: .18, 
bodyStyle: ' margin:4px 10px 10px 5px', 
layout: 'form', 
items: [{ 
xtype: 'box', 
autoEl: { 
width: 150, height: 150, 
tag: 'div', 
id: 'browser_up_forth' 
} 
}] 
}

myfrom表示上传控件外围的FormPanel,, contril_id表示上传控件的ID，只要在程序上预览注册该方法就可以，preview (myfrom,'up_forth' );

var preview = function (myform, control_id) { 
var img_reg = /\.([jJ][pP][gG]){1}$|\.([jJ][pP][eE][gG]){1}$|\.([gG][iI][fF]){1}$|\.([pP][nN][gG]){1}$|\.([bB][mM][pP]){1}$/ 
myform.on('render', function (f) { 
myform.form.findField(control_id).on('render', function () { 
Ext.get(control_id).on('change', function (field, newValue, oldValue) { 
var obj = Ext.get(control_id).dom; 
var url = getFullPath(obj); 
if (img_reg.test(url)) { 
var newPreview = Ext.get('browser_' + control_id).dom; 
var showPic = Ext.get("showPic_" + control_id); 
if (showPic != null) { 
showPic.remove();//删除原来的图片 
} 
var imgDiv = document.createElement("div"); 
imgDiv.id = "showPic_" + control_id; 
document.body.appendChild(imgDiv); 
imgDiv.style.width = "150px"; 
imgDiv.style.height = "150px"; 
imgDiv.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod = scale)"; 
imgDiv.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = url; 
newPreview.appendChild(imgDiv); 
} 
}, this); 
}, this); 
}, this); 
} //得到图片地址 
function getFullPath(obj) { 
if (obj) { 
// ie 
if (window.navigator.userAgent.indexOf("MSIE") >= 1) { 
obj.select(); 
return document.selection.createRange().text; 
} 
// firefox 
else if (window.navigator.userAgent.indexOf("Firefox") >= 1) { 
if (obj.files) { 
return obj.files.item(0).getAsDataURL(); 
} 
return obj.value; 
} 
return obj.value; 
} 
}