jquery - 如何制作自定义滚动条 jQuery 插件

Question

我正在考虑制作自定义滚动条 jQuery 插件，有很多可用的插件，但我想制作自己的插件，问题是我没有得到如何通过移动其他 div 元素(滚动条)来移动内容的概念)以及我应该如何使用鼠标滚轮移动内容？

请帮助我理解这一点。

谢谢

Answer 1

滚动条逻辑

(onInit, onResize) thumbSize = viewportSize * viewportSize / areaSize
(onThumbDrag)      viewportScrollPos = areaSize / viewportSize * thumbPos
(onViewportScroll) thumbPos = viewportScrollPos / viewportSize * thumbSize

最简单的概念是使用 jQuery UI 可拖动并将 .draggable() 方法附加到 .scrollbar

var $scrollable  = $(".scrollable"),
    $scrollbar   = $(".scrollbar"),
    height       = $scrollable.outerHeight(true),    // visible height
    scrollHeight = $scrollable.prop("scrollHeight"), // total height
    barHeight    = height * height / scrollHeight;   // Scrollbar height!

// Scrollbar drag:
$scrollbar.height( barHeight ).draggable({
  axis : "y",
  containment : "parent", 
  drag: function(e, ui) {
    $scrollable.scrollTop( scrollHeight / height * ui.position.top  );
  }
}); 

// Element scroll:
$scrollable.on("scroll", function() {
  $scrollbar.css({top: $scrollable.scrollTop() / height * barHeight });
});

.parent{
  position:relative;
  overflow:hidden;
  height:200px;
  width:180px;
  background:#ddd;
}
.scrollable{
  overflow-y:scroll;
  position:absolute;
  padding:0 17px 0 0;
  width: 180px;
  height:100%;
}
.scrollbar{
  cursor:n-resize;
  position:absolute;
  overflow:auto;
  top:0px;
  right:0px;
  z-index:2;
  background:#444;
  width:17px;
  border-radius:8px;
}

<script src="//code.jquery.com/jquery-1.11.0.min.js"></script>
<script src="//code.jquery.com/ui/1.11.0/jquery-ui.min.js"></script>

<div class="parent">
  <div class="scrollbar"></div>
  <div class="scrollable">
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras non nunc eget sapien molestie mollis. Proin vestibulum vehicula varius. Duis a nunc ac risus facilisis consectetur.
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras non nunc eget sapien molestie mollis. Proin vestibulum vehicula varius. Duis a nunc ac risus facilisis consectetur.
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras non nunc eget sapien molestie mollis. Proin vestibulum vehicula varius. Duis a nunc ac risus facilisis consectetur.
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras non nunc eget sapien molestie mollis. Proin vestibulum vehicula varius. Duis a nunc ac risus facilisis consectetur.       
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras non nunc eget sapien molestie mollis. Proin vestibulum vehicula varius. Duis a nunc ac risus facilisis consectetur.
  </div>
</div>

以上只是一个示例，涉及所需的逻辑和数学，
它错过了“隐藏滚动条”，只是为了保持简单。我将让您添加所有需要的调整、插件。