本地图片预览

// JavaScript Document
function previewImage(file,name)
{
  var MAXWIDTH  = 150;
  var MAXHEIGHT = 200;
  if (file.files && file.files[0])
  {
    var img = document.getElementById(name);
    img.onload = function(){
      var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
      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;
    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);
    $("#"+name).css("width","rect.width").css("height","rect.height").css("margin-top","rect.top").css("margin-left","rect.left");
  }
}
function clacImgZoomParam( maxWidth, maxHeight, width, height ){
    var param = {top:0, left:0, 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;
}