自定义方法

$(function() {
    $('.zoomify').zoomify();

    $('.zoom').on('click', function() {
        $('.zoomify').zoomify('zoom');
    });
    $('.zoomIn').on('click', function() {
        $('.zoomify').zoomify('zoomIn');
    });
    $('.zoomOut').on('click', function() {
        $('.zoomify').zoomify('zoomOut');
    });
    $('.reposition').on('click', function() {
        $('.zoomify').zoomify('reposition');
    });
});

<div class="wrap">
    <img class="zoomify" src="images/img1.jpg" alt="">
</div>
<div class="btns">
    <a class="zoom" href="javascript:">放大/缩小</a>
    <a class="zoomIn" href="javascript:">放大</a>
    <a class="zoomOut" href="javascript:">缩小</a>
    <a class="reposition" href="javascript:">重新计算</a>
</div>