实现圆弧拖动<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
/* reset */
*, *::before, *::after {
margin: 0;
padding: 0;
box-sizing: border-box;
}
/* Variables */
/* content */
#app {
height: 100%;
display: flex;
justify-content: center;
align-items: center;
background-color: #264653;
}
.circle-container {
width: 320px;
height: 320px;
position: relative;
}
.circle-container .circle {
position: absolute;
z-index: 10;
left: 0;
top: 0;
width: 320px;
height: 320px;
border-radius: 50%;
border: 10px solid #ffffff;
display: flex;
justify-content: center;
align-items: center;
color: #ffffff;
font-size: 3rem;
-webkit-user-select: none;
}
.circle-container .circle-bar {
position: absolute;
z-index: 20;
left: 145px;
top: -10px;
width: 30px;
height: 30px;
border-radius: 50%;
background-color: #e76f51;
cursor: pointer;
box-shadow: 0 0 1px 1px #777777;
}
/*# sourceMappingURL=main.css.map */
</style>
</head>
<body>
<div id="app">
<div class="circle-container">
<div class="circle">0</div>
<div class="circle-bar"></div>
</div>
</div>
<script>
const $bar = document.querySelector('.circle-bar')
const $circle = document.querySelector('.circle')
const $container = document.querySelector('.circle-container')
const circle_r = 320 / 2 // 圆形半径
const circle_b = 10 // 圆形边距(border-width)
const bar_r = 15 // 小球半径
function init() {
let isDrag = false
let mouse_offset = { x: 0, y: 0 }
$bar.addEventListener('mousedown', (e) => {
isDrag = true
mouse_offset = getMouseOffset(e)
})
window.addEventListener('mousemove', (e) => {
if (!isDrag) return
const event_offset_x = (e.clientX
- mouse_offset.x
- $container.offsetLeft
- circle_r)
const event_offset_y = -(e.clientY
- mouse_offset.y
- $container.offsetTop
- circle_r)
const radian = Math.atan2(event_offset_y, event_offset_x)
const x = Math.cos(radian) * (circle_r - circle_b / 2)
const y = Math.sin(radian) * (circle_r - circle_b / 2)
$bar.style.left = x - bar_r + circle_r + 'px'
$bar.style.top = circle_r - (y + bar_r) + 'px'
updateContent(radian)
})
window.addEventListener('mouseup', (e) => {
isDrag = false
})
}
function updateContent(radian) {
let angle = radian * (180 / Math.PI) // -180 ~ 180
if (angle >= -180 && angle <= 90) {
angle = 90 - angle
} else {
angle = 360 - (angle - 90)
}
// 0 ~ 360
$circle.textContent = Math.floor(angle)
}
function getMouseOffset(e) {
const mouse_offset_x = (e.clientX
- $container.offsetLeft
- e.currentTarget.offsetLeft
- bar_r)
const mouse_offset_y = -(e.clientY
- $container.offsetTop
- e.currentTarget.offsetTop
- bar_r)
console.log(e.clientX, $container.offsetLeft, e.currentTarget.offsetLeft,mouse_offset_x,$container)
return {
x: mouse_offset_x,
y: mouse_offset_y
}
}
init()
</script>
</body>
</html>
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