Angularjs在ng单击时添加加载微调器

如何在ng上使用loading.gif替换默认图像，然后在加载选定图像时显示该图像

HTML-部分

    <img ng-src="currentImg"> <!-- this is the default image  -->
         <!-- i need to swap current image with loading.gif and then display selected img from below --> 
         <!-- on click is changing currentImg (default image) var to ng-src -->
   <img ng-click="currentImg=item.imgSmall1" ng-src="{{item.imgSmall1}}">
   <img ng-click="currentImg=item.imgSmall2" ng-src="{{item.imgSmall2}}">
        ...

---

@伊万，对不起，我没听懂。你到底想做什么？

$scope.currentImg= "default img"; 
$scope.SETcurrentImg = function(...){
      currentImg="loading.gif";
      //when image is loaded display below img
      // ???
      currentImg="some selected img";
}