1. 程式人生 > >input type=file 上傳圖片前預覽 親測支援 ie8 chrome ff android及ios瀏覽器(將網上的版本整合一下)

input type=file 上傳圖片前預覽 親測支援 ie8 chrome ff android及ios瀏覽器(將網上的版本整合一下)

<!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>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Firefox3,IE6,IE7,IE8上傳圖片預覽</title>
    <style type="text/css">#preview_wrapper{ display:inline-block; width:100px; height:100px; background-color:#CCC; } #preview_fake{ /* 該物件使用者在IE下顯示預覽圖片 */ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale); } #preview_size_fake{ /* 該物件只用來在IE下獲得圖片的原始尺寸,無其它用途 */ filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image); visibility:hidden; } #preview{ /* 該物件使用者在FF下顯示預覽圖片 */ width:100px; height:100px; }</style>
    <script type="text/javascript">function onUploadImgChange(sender) {
        if (!sender.value.match(/.jpg|.jpeg|.png/i)) {
          alert('圖片格式無效!');
          return false;
        }

        var objPreview = document.getElementById('preview');
        var objPreviewFake = document.getElementById('preview_fake');
        var objPreviewSizeFake = document.getElementById('preview_size_fake');

        if (sender.files && sender.files[0]) {
          objPreview.style.display = 'block';
          objPreview.style.width = 'auto';
          objPreview.style.height = 'auto';

          // Firefox 因安全性問題已無法直接通過 input[file].value 獲取完整的檔案路徑
          if (window.createObjectURL != undefined) { // basic
            objPreview.src = window.createObjectURL(sender.files[0]);
          } else if (window.URL != undefined) { // mozilla(firefox)
            objPreview.src = window.URL.createObjectURL(sender.files[0]);
          } else if (window.webkitURL != undefined) { // webkit or chrome
            objPreview.src = window.webkitURL.createObjectURL(sender.files[0]);
          }
        } else if (objPreviewFake.filters) {
          // IE7,IE8 在設定本地圖片地址為 img.src 時出現莫名其妙的後果     
          //(相同環境有時能顯示,有時不顯示),因此只能用濾鏡來解決     
          // IE7, IE8因安全性問題已無法直接通過 input[file].value 獲取完整的檔案路徑     
          sender.select();
          var imgSrc = document.selection.createRange().text;

          objPreviewFake.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;
          objPreviewSizeFake.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;

          autoSizePreview(objPreviewFake, objPreviewSizeFake.offsetWidth, objPreviewSizeFake.offsetHeight);
          objPreview.style.display = 'none';
        }
      }

      function onPreviewLoad(sender) {
        autoSizePreview(sender, sender.offsetWidth, sender.offsetHeight);
      }

      function autoSizePreview(objPre, originalWidth, originalHeight) {
        var zoomParam = clacImgZoomParam(100, 100, originalWidth, originalHeight);
        objPre.style.width = zoomParam.width + 'px';
        objPre.style.height = zoomParam.height + 'px';
        objPre.style.marginTop = zoomParam.top + 'px';
        objPre.style.marginLeft = zoomParam.left + 'px';
      }

      function clacImgZoomParam(maxWidth, maxHeight, width, height) {
        var param = {
          width: width,
          height: height,
          top: 0,
          left: 0
        };

        if (width > maxWidth || height > maxHeight) {
          rateWidth = width / maxWidth;
          rateHeight = height / maxHeight;

          if (rateWidth > rateHeight) {
            param.width = maxWidth;
            param.height = height / rateWidth;
          } else {
            param.width = width / rateHeight;
            param.height = maxHeight;
          }
        }

        param.left = (maxWidth - param.width) / 2;
        param.top = (maxHeight - param.height) / 2;

        return param;
      }
    </script>
  </head>
  
  <body>
    <div id="preview_wrapper">
      <div id="preview_fake">
        <img id="preview" onload="onPreviewLoad(this)" /></div>
    </div>
    <br/>
    <input id="upload_img" type="file" onchange="onUploadImgChange(this)" />
    <br/>
    <img id="preview_size_fake" />
  </body>

</html>