jQuery Gallery下一个/上一个按钮

Question

I made a jquery gallery a half year ago (SO community helped me alot cause I'm not familiar enough with js/jquery) and now I'd like to add next/previous buttons to this gallery. I tried combine it with other galleries but nothing worked properly.

here is js:

<script type="text/javascript">
function showPic (whichpic) {
if (document.getElementById) {
$('#actimg').fadeOut(170);
setTimeout(function() {
document.getElementById('actimg').src = whichpic.href; 
$('#actimg').fadeIn(170);
}, 170);
return false; 
} else {
return true;
 } 
}
</script>

and html:

<img id="actimg" src="" width="600" height="400" alt="main" />

<a onclick="return showPic(this)" href="example_1.jpg">
<img height="39px" width="58px" src="example_1.jpg" alt="thumbnail" />
</a>

<a onclick="return showPic(this)" href="example_2.jpg">
<img height="39px" width="58px" src="example_2.jpg" alt="thumbnail" />
</a>

<a onclick="return showPic(this)" href="example_3.jpg">
<img height="39px" width="58px" src="example_3.jpg" alt="thumbnail" />
</a>

gallery looks like http://www.rafsimons.com/collections/aw-11/ but it's not flash and there are no next/prev buttons which I want to make now. Thanks in advance for help.

Answer 1

First add a class attribute to all your thumbs ( <a> tags) so they can be easily referred to from jQuery:

<a class="gallery_item" onclick="return showPic(this)" href="example_1.jpg">
<img height="39px" width="58px" src="example_1.jpg" alt="thumbnail" />
</a>
...

We need a way to know which one is the current image. We can store that information in a custom attribute in your <a> tag itself. For this modify your showPic function like:

function showPic (whichpic) {
  if (document.getElementById) {
    $('.gallery_item').removeAttr('current'); // <- remove 'current' attribute from all thumbs
    $('#actimg').fadeOut(170);
    setTimeout(function() {
      document.getElementById('actimg').src = whichpic.href; 
      $('#actimg').fadeIn(170);
      $(whichpic).attr('current', '1'); // <- set this one as current
    }, 170);
    return false; 
  } else {
    return true;
  }
}

Now add 2 links for next/prev buttons and place them where appropriate. Give their ids as 'next' and 'prev'

<a href="#" id="prev" onclick="return nextPic()">Prev</a>

<a href="#" id="next" onclick="return prevPic()">Next</a>

Now add 2 js functions nextPic() and prevPic() like:

function nextPic() {
  var current = null;
  $('.gallery_item').each(function() {
    if($(this).attr('current')=='1') {
    current = $(this);
    return false;
    }
  });
  if(current!=null) {
    if(current.parent().next().length!=0) {
    showPic(current.parent().next().find('.gallery_item')[0]); // <- show next pic
    }
    else {
    showPic($('.gallery_item:first')[0]); // if no next pic, show first pic
    }
  }
  return false;
}

function prevPic() {
  var current = null;
  $('.gallery_item').each(function() {
    if($(this).attr('current')=='1') {
    current = $(this);
    return false;
    }
  });
  if(current!=null) {
    if(current.parent().prev().length!=0) {
    showPic(current.parent().prev().find('.gallery_item')[0]); // <- show next pic
    }
    else {
    showPic($('.gallery_item:last')[0]); // if no next pic, show first pic
    }
  }
  return false;
}

Add this too, to initialize the first image as current by default.

$().ready(function() {
  $('.gallery_item:first').attr('current', '1');
});