How to check image dimension on upload?

Question

Building a custom module and would like to have this option implemented so user will not be able to upload image if the width and height is not as specified. :P

Found this example:

public function validateUploadFile($filePath) {
    $testsize[] = getimagesize($filePath);
    if (!(getimagesize($filePath)) || ($testsize[0][0] < 900) || ($testsize[0][1] < 900)) {
    Mage::throwException($this->__('Image size must be same or greater than 900px * 900px .'));
}
    $_processor = new Varien_Image($filePath);
    return $_processor->getMimeType() !== null;
}

but not sure if it works (not tested yet). If anyone know how to and where to add this code .... should I rewrite image upload function or ....

Sorry guys, I should mention that I'm talking about admin not customer side.

Answer 1

it is possible with jQuery :

      $(document).ready(function(){

     var _URL = window.URL || window.webkitURL;

     $('#file').change(function () {
      var file = $(this)[0].files[0];

      img = new Image();
      var imgwidth = 0;
      var imgheight = 0;
      var maxwidth = 640;
      var maxheight = 640;

      img.src = _URL.createObjectURL(file);
      img.onload = function() {
       imgwidth = this.width;
       imgheight = this.height;

       $("#width").text(imgwidth);
       $("#height").text(imgheight);
       if(imgwidth <= maxwidth && imgheight <= maxheight){

        var formData = new FormData();
        formData.append('fileToUpload', $('#file')[0].files[0]);

        $.ajax({
          url: 'upload_image.php',
          type: 'POST',
          data: formData,
          processData: false,
          contentType: false,
          dataType: 'json',
          success: function (response) {
            if(response.status == 1){
              $("#prev_img").attr("src","upload/"+response.returnText);
              $("#prev_img").show();
              $("#response").text("Upload successfully");
            }else{
              $("#response").text(response.returnText);
            } 
          }
       });
      }else{
       $("#response").text("Image size must be "+maxwidth+"X"+maxheight);
      }
     };
     img.onerror = function() {

      $("#response").text("not a valid file: " + file.type);
     }

 });
});