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jquery implements the method of previewing images before uploading

  • 2020-07-21 06:55:49
  • OfStack

This article illustrates jquery's approach to preview images before uploading. Share to everybody for everybody reference. Specific implementation methods are as follows: 


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script src="jquery-1.8.1.min.js" type="text/javascript"></script>
<script>
/*
* Parameters that : Img: The picture ID;Width: Preview the width ;Height: Preview the height ;ImgType: Supported file types ;Callback: Select the file display image callback method ;
* Method of use : 
<div>
<img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
 Put the need to preview IMG Outside the label   Set of 1 a DIV  Then give the upload control ID To give uploadPreview The event 
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120, ImgType: ["gif", "jpeg", "jpg", "bmp", "png"], Callback: function () { }});
*/
jQuery.fn.extend({
  uploadPreview: function (opts) {
    var _self = this,
      _this = $(this);
    opts = jQuery.extend({
      Img: "ImgPr",
      Width: 100,
      Height: 100,
      ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],
      Callback: function () {}
    }, opts || {});
    _self.getObjectURL = function (file) {
      var url = null;
      if (window.createObjectURL != undefined) {
        url = window.createObjectURL(file)
      } else if (window.URL != undefined) {
        url = window.URL.createObjectURL(file)
      } else if (window.webkitURL != undefined) {
        url = window.webkitURL.createObjectURL(file)
      }
      return url
    };
    _this.change(function () {
      if (this.value) {
        if (!RegExp("\.(" + opts.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {
          alert(" File selection error , The image type must be " + opts.ImgType.join(" . ") + " In the 1 Kind of ");
          this.value = "";
          return false
        }
        if ($.browser.msie) {
          try {
            $("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
          } catch (e) {
            var src = "";
            var obj = $("#" + opts.Img);
            var div = obj.parent("div")[0];
            _self.select();
            if (top != self) {
              window.parent.document.body.focus()
            } else {
              _self.blur()
            }
            src = document.selection.createRange().text;
            document.selection.empty();
            obj.hide();
            obj.parent("div").css({
              'filter': 'progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)',
              'width': opts.Width + 'px',
              'height': opts.Height + 'px'
            });
            div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src
          }
        } else {
          $("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
        }
        opts.Callback()
      }
    })
  }
});
$(function () {
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120 });
});
</script>
</head>
<body>
<div style="width:500px;margin:0px auto;"><h2> Photo upload preview demo </h2>
<div><img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
</div>
</body>
</html>

Hopefully, this article has been helpful in your jquery programming.

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