Modx idx from zero

Question

How can I make it so that the code below starts from 0 instead of 1?

Call snippet:

<div class="bx-pager">
    [[!getImageList? 
        &tvname=`slider`
        &tpl=`@CODE:<a data-slide-index="[[+idx]]" href="#"><img src="[[+thumb]]"></a>
    `]]
</div>

Result:

<div class="bx-pager">
    <a data-slide-index="1" href="#" class="active"><img src="...."></a>
    <a data-slide-index="2" href="#"><img src="...."></a>
    <a data-slide-index="3" href="#"><img src="...."></a>
    <a data-slide-index="4" href="#"><img src="...."></a>
</div>

Desired result:

<div class="bx-pager">
    <a data-slide-index="0" href="#" class="active"><img src="...."></a>
    <a data-slide-index="1" href="#"><img src="...."></a>
    <a data-slide-index="2" href="#"><img src="...."></a>
    <a data-slide-index="3" href="#"><img src="...."></a>
</div>

Does anyone have any ideas how to obtain this?

Answer 1

I think you need to use an Output-Modifier, in this case 'decrement'. You apply it like this: [[+idx:decr]].

For more about Output-Modifiers, take a look here.