ExtJS上传图片预览功能

{
                    columnWidth: .9,
                    layout: 'form',
                    border: false,
                    items : [{
                            inputType : "file",
                            fieldLabel: '上传图片',
                            name: 'imageupload',
                            id:'imageupload',                           
                            xtype: 'textfield',
                            anchor: '40%'
                         
                            }]
            
                   },
                   {
                    columnWidth: .5,
                    layout: 'form',
                    border: false,
                    items : [
                            {
                                 xtype: 'box',
                                id : 'browseImage',
                                fieldLabel : "预览图片",
                                autoEl : {
                                    width : 100,
                                    height : 150,
                                    tag : 'img',
                                    //type : 'image',
                                    src : Ext.BLANK_IMAGE_URL,
                                    style : 'filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);',
                                    complete:'off',
                                    id : 'imageBrowse'
                                    }
                            }
                            
                             ]           
            
                   }