问题描述
我正在尝试制作图像滑块/转盘。差不多完成了,只是最后一个问题。因此,该旋转木马中的项目在拖动时会移动。他们获得动力并逐渐停止。因此,如果我再次拖动,而它们仍在移动,则曾经发生的事情是-它们将停止,然后根据新的阻力进行移动。我真正想要的是-如果拖动方向与当前运动方向相同,则更高的速度(从当前运动速度和新的拖动速度)应该是新速度。基本上,我正在尝试模拟移动滚动。没什么大不了的,我写了代码以获得后一个结果,但是它并没有按预期工作。结果很奇怪。动画会更快,更突然地停止。完全不同。由于mouseDown事件处理程序中的第45行/最后一行(将速度重置为0),因此该项目按以前的方式工作(即新速度基于最新拖动)。如果您在第45行添加注释,则会弹出该问题。 Without line 45 With line 45 编辑:刚刚意识到,当速度达到特定阈值时,即使第二个也表现出不同的行为。
var projectContainer = document.querySelector(".project-container")
var projects = document.querySelectorAll(".project")
// exProject is declared so that every project has same transalte to refer to instead of referring to their individual transalations
var exProject = projects[0]
var style = window.getComputedStyle(exProject)
exProject.currentTranslationX = (new WebKitCSSMatrix(style.webkitTransform)).m41
// after dragging,do not add force if mouse has not been moved for pauseTime milliseconds
pauseTime = 40
lastMousePositions = []
//this will set margin to 80,i thought this is better than hardcoding
elementAOffset = projects[0].offsetLeft;
elementBOffset = projects[1].offsetLeft;
elementAWidth = parseInt(getComputedStyle(projects[0]).width)
margin = (elementBOffset - (elementAOffset + elementAWidth))
//projects will teleport to other side if they hit either of the boundary
LeftSideBoundary = -(elementAWidth)
RightSideBoundary = (elementAWidth * (projects.length)) + (margin * (projects.length))
RightSidePosition = RightSideBoundary - elementAWidth;
//how often to update speed (in milliseconds)
intervalTime = 15
//how much speed is lost at every interTime milliseconds
frictionPerMilliseconds = (20 / 1000);
frictionPerMilliseconds *= intervalTime * 5;
mouseInitialPosition = 0;
mouseIsDown = false
startTime = 0;
speed = 0;
mousemoving = false
projectContainer.addEventListener("mousedown",e => {
mouseInitialPosition = e.clientX
mouseIsDown = true;
startDate = new Date();
startTime = startDate.getTime();
lastMousePositions.push(e.clientX)
// speed = 0
})
projectContainer.addEventListener("mousemove",e => {
if (!mouseIsDown) return;
distanceTravelled = e.clientX - mouseInitialPosition
if (speed === 0) {
projects.forEach(project => {
project.style.transform = 'translateX(' + ((exProject.currentTranslationX) + ((distanceTravelled))) + 'px)';
shiftPosition(project,distanceTravelled)
})
}
if ((new Date()).getTime() - lastMousePositions[lastMousePositions.length - 1][1] > 50) {
lastMousePositions = []
}
pushToMousePositions(e.clientX)
})
projectContainer.addEventListener("mouseup",e => {
dragEnd(e);
})
projectContainer.addEventListener("mouseleave",e => {
dragEnd(e);
})
function dragEnd(e) {
finalPosition = e.clientX;
distanceTravelled = finalPosition - mouseInitialPosition
endDate = new Date();
endTime = endDate.getTime();
timeElapsed = (endTime - startTime) / 1000
mouseIsDown = false;
tempSpeed = distanceTravelled / timeElapsed
tempSpeed = (tempSpeed / 1000) * 15
if (tempSpeed < 0 && speed < 0) {
if (tempSpeed < speed) {
speed = tempSpeed
}
} else if (tempSpeed > 0 && speed > 0) {
if (tempSpeed > speed) {
speed = tempSpeed
}
} else {
speed = tempSpeed
}
if (lastMousePositions.length === 0) {
console.log("error gonna pop up")
}
if (endTime - (lastMousePositions[lastMousePositions.length - 1])[1] >= pauseTime) {
speed = 0
}
mouseExit(e)
intervalFunction = setInterval(move,intervalTime)
}
function mouseExit(e) {
mouseIsDown = false
lastMousePositions = []
var style = window.getComputedStyle(exProject)
exProject.currentTranslationX = (new WebKitCSSMatrix(style.webkitTransform)).m41
projects.forEach(project => {
project.style.transform = 'translateX(' + (exProject.currentTranslationX) + 'px)'
shiftPosition(project,0)
})
}
function move() {
if (speed === 0) {
clearInterval(intervalFunction)
} else if (Math.abs(speed) <= frictionPerMilliseconds) {
style = window.getComputedStyle(exProject)
exProject.currentTranslationX = (new WebKitCSSMatrix(style.webkitTransform)).m41
projects.forEach(project => {
project.style.transform = 'translateX(' + ((exProject.currentTranslationX) + (speed)) + 'px)'
shiftPosition(project,0)
})
speed = 0
} else {
style = window.getComputedStyle(exProject)
exProject.currentTranslationX = (new WebKitCSSMatrix(style.webkitTransform)).m41
projects.forEach(project => {
project.style.transform = 'translateX(' + ((exProject.currentTranslationX) + (speed)) + 'px)'
shiftPosition(project,0)
})
speed < 0 ? speed += frictionPerMilliseconds : speed -= frictionPerMilliseconds;
}
}
function pushToMousePositions(positionToPush) {
if (lastMousePositions.length < 50) {
lastMousePositions.push([positionToPush,(new Date()).getTime()])
} else {
lastMousePositions.shift();
lastMousePositions.push([positionToPush,(new Date()).getTime()])
}
}
function shiftPosition(project,mouseMovement) {
//projectVisualPosition is relative to the left border of container div
projectVisualPosition = project.offsetLeft + (exProject.currentTranslationX + mouseMovement)
tempStyle = window.getComputedStyle(project)
if (projectVisualPosition < LeftSideBoundary) {
project.style.left = ((parseInt(tempStyle.left) + RightSidePosition + 350) + 'px')
}
if (projectVisualPosition > RightSidePosition) {
project.style.left = ((parseInt(tempStyle.left)) - (RightSidePosition + elementAWidth)) + 'px'
}
}
*,*::before,*::after{
margin:0px;
padding:0px;
box-sizing: border-box;
font-size:0px;
user-select: none;
font-size:0;
}
body{
position: relative;
}
.project-container{
font-size: 0px;
position: relative;
width:1500px;
height:400px;
background-color: rgb(15,207,224);
margin:auto;
margin-top:60px;
white-space: nowrap;
overflow: hidden;
padding-left:40px;
padding-right:40px;
}
.project{
font-size:100px;
margin:40px;
display: inline-block;
height:300px;
width:350px;
background-color:red;
border: black 3px solid;
user-select: none;
position: relative;
}
<div class="project-container">
<div class="project">1</div>
<div class="project">2</div>
<div class="project">3</div>
<div class="project">4</div>
<div class="project">5</div>
<div class="project">6</div>
<div class="project">7</div>
<div class="project">8</div>
</div>
解决方法
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