snapdrop/app/elements/file-sharing/file-drop-behavior.html

<link rel="import" href="file-selection-behavior.html">
<script>
'use strict';
window.Chat = window.Chat || {};
Chat.FileDropBehaviorImpl = {
    attached: function() {
        var dropZone = this;

        dropZone.addEventListener('dragover', function(e) {
            e.stopPropagation();
            e.preventDefault();
            e.dataTransfer.dropEffect = 'copy';
            dropZone.style.transform = 'scale(1.2)';
        }, false);

        var dragEnd = function() {
            dropZone.style.transform = 'scale(1)';
        };

        dropZone.addEventListener('dragleave', dragEnd, false);
        dropZone.addEventListener('dragexit', dragEnd, false);
        dropZone.addEventListener('dragend', dragEnd, false);

        // Get file data on drop
        dropZone.addEventListener('drop', function(event) {
            event.stopPropagation();
            event.preventDefault();
            
            //call dragend
            dragEnd();

            // Get files
            var files = event.dataTransfer.files;
            // Notify Selection
            this.notifyFilesSelection(files);
        });
    }
};
Chat.FileDropBehavior = [Chat.FileDropBehaviorImpl, Chat.FileSelectionBehavior];
</script>