JavaScript 图片上传预览效果(15)

该文档说了怎么在页面做图片预览, 一步一步的

//滤镜显示

_filterShow: function() {

this._filterPreload();

var preload = this._preload,

data = this._data.replace(/[)'"%]/g, function(s){ return escape(escape(s)); }); try{

preload.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = data; }catch(e){ this._error("filter error"); return; }

//设置滤镜并显示

this.img.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src=\"" + data + "\")";

this._imgShow( ImagePreview.TRANSPARENT, preload.offsetWidth, preload.offsetHeight ); },

//显示预览

_imgShow: function(src, width, height) {

var img = this.img, style = img.style,

ratio = Math.max( 0, this.ratio ) || Math.min( 1,

Math.max( 0, this.maxWidth ) / width || 1,

Math.max( 0, this.maxHeight ) / height || 1

);

//设置预览尺寸

style.width = Math.round( width * ratio ) + "px";

style.height = Math.round( height * ratio ) + "px";

//设置src

img.src = src;

this.onShow();

},

//销毁程序

dispose: function() {

//销毁上传文件对象

if ( this._upload ) {

this._upload.dispose(); this._upload = null;

}

//销毁预载图片对象

if ( this._preload ) {

var preload = this._preload, parent = preload.parentNode;

this._preload = preload.onload = preload.onerror = null;

parent && parent.removeChild(preload);

}

//销毁相关对象

this.file = this.img = null;