编辑:刚刚发现下面的项目在GitHub上:
https://github.com/jquery/jquery-mousewheel
我尝试了演示,它是能够报告我的触摸板和鼠标的滚动速度。它也能够停止滚动没有任何位置固定的黑客:D
我会看看在接下来的几天,看我是否可以写任何报道滚动速度,方向,速度,设备等希望我'能够制作一些可以覆盖所有滚动交互的jquery插件。
当我已经有了关于这个问题的详细信息我会更新这个帖子。
这是不可能预测鼠标滚动将结束。
,另一方面触屏/触摸板刷卡有一定的速度,用户停止刷卡,就像一辆汽车,得到了一推,之后开始减缓之后将放缓。
可悲的是每一个浏览器/操作系统/驱动器/触摸屏/触摸板/等都有它自己的实现对于减缓,因此,我们无法预测。
但是,我们当然可以写我们自己的实现。
我们得到了3个实现,可以作出:
A.方向
B.方向和速度
C.方向,速度和速度
iCalender可能使用实现A.
执行一个:
输出滚动方向到控制台,用户能够滚动+/- 1px的被检测的方向 之前。
Demo on JSFiddle
Demo with animation on JSFiddle
(function iDirection() {
var preventLoop = true;
var currentScroll = scrollTop();
function scroll() {
if(preventLoop) {
//Get new scroll position
var newScroll = scrollTop();
//Stop scrolling
preventLoop = false;
freeze(newScroll);
//Check direction
if(newScroll > currentScroll) {
console.log("scrolling down");
//scroll down animation here
} else {
console.log("scrolling up");
//scroll up animation here
}
/*
Time in milliseconds the scrolling is disabled,
in most cases this is equal to the time the animation takes
*/
setTimeout(function() {
//Update scroll position
currentScroll = newScroll;
//Enable scrolling
unfreeze();
/*
Wait 100ms before enabling the direction function again
(to prevent a loop from occuring).
*/
setTimeout(function() {
preventLoop = true;
}, 100);
}, 1000);
}
}
$(window).on("scroll", scroll);
})();
实现B:
输出滚动方向,距离和平均速度到控制台,用户能够滚动distance
变量中设置的像素数量。
如果用户快速滚动,他们可能会滚动几个像素。
Demo on JSFiddle
(function iDirectionSpeed() {
var distance = 50; //pixels to scroll to determine speed
var preventLoop = true;
var currentScroll = scrollTop();
var currentDate = false;
function scroll() {
if(preventLoop) {
//Set date on scroll
if(!currentDate) {
currentDate = new Date();
}
//Get new scroll position
var newScroll = scrollTop();
var scrolledDistance = Math.abs(currentScroll - newScroll);
//User scrolled `distance` px or scrolled to the top/bottom
if(scrolledDistance >= distance || !newScroll || newScroll == scrollHeight()) {
//Stop scrolling
preventLoop = false;
freeze(newScroll);
//Get new date
var newDate = new Date();
//Calculate time
var time = newDate.getTime() - currentDate.getTime();
//Output speed
console.log("average speed: "+scrolledDistance+"px in "+time+"ms");
/*
To calculate the animation duration in ms:
x: time
y: scrolledDistance
z: distance you're going to animate
animation duration = z/y * x
*/
//Check direction
if(newScroll > currentScroll) {
console.log("scrolling down");
//scroll down animation here
} else {
console.log("scrolling up");
//scroll up animation here
}
/*
Time in milliseconds the scrolling is disabled,
in most cases this is equal to the time the animation takes
*/
setTimeout(function() {
//Update scroll position
currentScroll = newScroll;
//Unset date
currentDate = false;
//Enable scrolling
unfreeze();
/*
Wait 100ms before enabling the direction function again
(to prevent a loop from occuring).
*/
setTimeout(function() {
preventLoop = true;
}, 100);
}, 1000);
}
}
}
$(window).on("scroll", scroll);
})();
实现C:
输出滚动方向,距离和速度到控制台,用户能够滚动的像素中所设定的量distance
变量。
如果用户快速滚动,他们可能会滚动几个像素。在上述实现使用
Demo on JSFiddle
(function iDirectionSpeedVelocity() {
var distance = 100; //pixels to scroll to determine speed
var preventLoop = true;
var currentScroll = [];
var currentDate = [];
function scroll() {
if(preventLoop) {
//Set date on scroll
currentDate.push(new Date());
//Set scrollTop on scroll
currentScroll.push(scrollTop());
var lastDate = currentDate[currentDate.length - 1];
var lastScroll = currentScroll[currentScroll.length - 1];
//User scrolled `distance` px or scrolled to the top/bottom
if(Math.abs(currentScroll[0] - lastScroll) >= distance || !lastScroll || lastScroll == scrollHeight()) {
//Stop scrolling
preventLoop = false;
freeze(currentScroll[currentScroll.length - 1]);
//Total time
console.log("Time: "+(lastDate.getTime() - currentDate[0].getTime())+"ms");
//Total distance
console.log("Distance: "+Math.abs(lastScroll - currentScroll[0])+"px");
/*
Calculate speeds between every registered scroll
(speed is described in milliseconds per pixel)
*/
var speeds = [];
for(var x = 0; x < currentScroll.length - 1; x++) {
var time = currentDate[x + 1].getTime() - currentDate[x].getTime();
var offset = Math.abs(currentScroll[x - 1] - currentScroll[x]);
if(offset) {
var speed = time/offset;
speeds.push(speed);
}
}
//Output array of registered speeds (milliseconds per pixel)
console.log("speeds (milliseconds per pixel):");
console.log(speeds);
/*
We can use the array of speeds to check if the speed is increasing
or decreasing between the first and last half as example
*/
var half = Math.round(speeds.length/2);
var equal = half == speeds.length ? 0 : 1;
var firstHalfSpeed = 0;
for(var x = 0; x < half; x++) {
firstHalfSpeed += speeds[x];
}
firstHalfSpeed /= half;
var secondHalfSpeed = 0;
for(var x = half - equal; x < speeds.length; x++) {
secondHalfSpeed += speeds[x];
}
secondHalfSpeed /= half;
console.log("average first half speed: "+firstHalfSpeed+"ms per px");
console.log("average second half speed: "+secondHalfSpeed+"ms per px");
if(firstHalfSpeed < secondHalfSpeed) {
console.log("conclusion: speed is decreasing");
} else {
console.log("conclusion: speed is increasing");
}
//Check direction
if(lastScroll > currentScroll[0]) {
console.log("scrolling down");
//scroll down animation here
} else {
console.log("scrolling up");
//scroll up animation here
}
/*
Time in milliseconds the scrolling is disabled,
in most cases this is equal to the time the animation takes
*/
setTimeout(function() {
//Unset scroll positions
currentScroll = [];
//Unset dates
currentDate = [];
//Enable scrolling
unfreeze();
/*
Wait 100ms before enabling the direction function again
(to prevent a loop from occuring).
*/
setTimeout(function() {
preventLoop = true;
}, 100);
}, 2000);
}
}
}
$(window).on("scroll", scroll);
})();
辅助功能:
//Source: https://github.com/seahorsepip/jPopup
function freeze(top) {
if(window.innerWidth > document.documentElement.clientWidth) {
$("html").css("overflow-y", "scroll");
}
$("html").css({"width": "100%", "height": "100%", "position": "fixed", "top": -top});
}
function unfreeze() {
$("html").css("position", "static");
$("html, body").scrollTop(-parseInt($("html").css("top")));
$("html").css({"position": "", "width": "", "height": "", "top": "", "overflow-y": ""});
}
function scrollTop() {
return $("html").scrollTop() ? $("html").scrollTop() : $("body").scrollTop();
}
function scrollHeight() {
return $("html")[0].scrollHeight ? $("html")[0].scrollHeight : $("body")[0].scrollHeight;
}
只是看了一眼在评论中提到scrollify,这是10KB并需要在每一个简单的事件钩:触摸,鼠标滚动,键盘按钮等。
这似乎不是很有前途的证据,谁知道什么可能的用户交互可以导致未来的滚动?
另一方面,onscroll事件将始终在页面滚动时触发,因此我们只需将动画代码挂钩即可,无需担心任何输入设备交互。
你会如何知道用户何时会停止提前时间? – epascarello
@epascarello我基本上是指1个手势。即使我们的滚动显示为连续的,它们也是由具有特定滚动值的一系列离散手势组成的。不同的硬件以不同的方式对待这些手势,但是计算机的某处知道滚动将会有多远。 – Robert
您可能想要提到您指的是惯性/动量滚动,而不是正常的鼠标滚动。我不知道有什么办法可以做到这一点。 –