The only thing I could find online about scrolling is that Xlib gives you scrolling events as regular XButtonEvents (since, you know, we obviously need to track both scroll button presses and releases). However, this doesn't tell me anything about the amount the user wants to scroll with that button press, and it doesn't cover something like touchpad scrolling. Touchpad scrolling also seems especially horrid, since the user can “throw” the content with the touchpad, thus triggering page movement while not touching the pad. How am I supposed to handle all of this?

解决方案

Xlib将滚动事件表示为常规的 XButtonEvents（因为，你知道，我们显然需要跟踪滚轮按钮的按下和释放）。然而，这并不能告诉我用户在按下该按钮时希望滚动的距离，也没有涵盖像触控板滚动这样的情况。触控板滚动也显得格外糟糕，因为用户可以用触控板“抛掷”内容，从而在不触碰触控板时就触发页面移动。我应该如何处理这一切？

鼠标滚轮在系统中表现为额外的按钮，向上/向下对应4和5，向左/向右对应6和7。当你旋转滚轮时，它会生成一连串滚轮按钮的按下/释放事件。并且能够通过将滚轮向侧边推来实现横向滚动的鼠标，也会自动重复这些按钮按下事件。

因此，基于滚轮事件实现滚动的最简单方法，就是每次按钮按下时按固定距离移动。

如果你想实现平滑滚动和/或滚动效果，你应该改为测量滚轮按钮事件之间的时间间隔，并对其应用带衰减的滚动平均，将其转换为滚动速度。