When you do ng-click
you can pass the click event $event
to your function.
<button class="btn btn-{{ (gesture.area_id == '0') && 'primary' || 'default' }}"
type="button"
value="0"
ng-click="changeArea(gesture.area_id,gesture.id,$event)">
</button>
Then in your $scope.changeArea
you can do this:
$scope.changeArea = function (param1, param2, e)
From there you should be able to grab the elements values.