phonegap讨教,该如何解决

phonegap讨教
function dump_pic(data)
  {
  var viewport = document.getElementById('viewport');
  console.log(data);
  viewport.style.display = "";
  viewport.style.position = "absolute";
  viewport.style.top = "10px";
  viewport.style.left = "10px";
  document.getElementById("test_img").src = "data:image/jpeg;base64," + data;
  }

详细说明一下这个函数，谢谢

------解决方案--------------------
就像这样的
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA
AAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO
9TXL0Y4OHwAAAABJRU5ErkJggg==" />