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Copy pathday1030-custom-scrollbar.html
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day1030-custom-scrollbar.html
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<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta content="width=device-width, initial-scale=1.0" name="viewport">
<title>Scratch</title>
<style>
* {
padding: 0;
margin: 0;
box-sizing: border-box;
}
html,
body {
height: 100%;
background-color: #888;
}
li {
list-style: none;
}
body {
display: flex;
justify-content: center;
padding-top: 100px;
}
main {
display: flex;
padding: 0 20px;
height: 21em;
overflow: hidden;
max-width: 600px;
}
main > .content {
position: relative;
flex-grow: 1;
padding-right: 10px;
height: fit-content;
}
main > .scroll {
flex-shrink: 0;
position: relative;
width: 28px;
background-color: #333;
}
.scroll > .scroll--thumb {
position: absolute;
background-color: #ddd;
height: 50%;
width: 100%;
cursor: move;
}
.scroll > .scroll--thumb:active {
transform: scaleX(1.2);
}
</style>
<script>
function listenEvent(elem, event, callback, ...args) {
let removeListener;
if (elem.addEventListener) {
elem.addEventListener(event, callback, ...args);
removeListener = function () {
elem.removeEventListener(event, callback);
};
} else {
// IE 9
elem.attachEvent("on" + event);
removeListener = function () {
elem.detachEvent("on" + event, callback);
};
}
return removeListener;
}
</script>
</head>
<body>
<main class="container">
<section class="content">
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Alias, animi, atque blanditiis consectetur
consequatur dolore doloremque eius fugiat incidunt, laboriosam mollitia natus nobis nostrum quia quo quos sit
velit veritatis!</p>
</section>
<section class="scroll">
<div class="scroll--thumb"></div>
</section>
</main>
<script>
function DraggableManager() {
function Draggable(elem, cbDragStart, cbDragEnd, cbDragMove) {
this.elem = elem;
this.cbDragStart = cbDragStart;
this.cbDragEnd = cbDragEnd;
this.cbDragMove = cbDragMove;
this.dragging = false;
this.lastMousePos = { x: 0, y: 0 };
this.dragKey = NaN;
this.onDragStart = function (e) {
if (!isNaN(this.dragKey) && e.button !== this.dragKey) {
return;
}
if (this.dragging) {
return;
}
this.dragKey = e.button;
this.dragging = true;
this.elem.dataset.dgDragging = this.dragging;
this.lastMousePos.x = e.clientX;
this.lastMousePos.y = e.clientY;
this.cbDragStart && this.cbDragStart();
};
this.onDragMove = function (e) {
if (!this.dragging) {
return;
}
const posDiff = {
x: e.clientX - this.lastMousePos.x,
y: e.clientY - this.lastMousePos.y,
};
this.lastMousePos.x = e.clientX;
this.lastMousePos.y = e.clientY;
const oldPos = {
x: this.elem.offsetLeft,
y: this.elem.offsetTop,
};
let newPos = { ...oldPos };
newPos.x += posDiff.x;
newPos.y += posDiff.y;
if (this.cbDragMove) {
newPos = this.cbDragMove(oldPos, newPos) ?? newPos;
}
this.elem.style.top = newPos.y + "px";
this.elem.style.left = newPos.x + "px";
};
this.onDragEnd = function (e) {
if (!isNaN(this.dragKey) && e.button !== this.dragKey) {
return;
}
if (!this.dragging) {
return;
}
this.dragKey = NaN;
this.dragging = false;
this.elem.dataset.dgDragging = this.dragging;
this.cbDragEnd && this.cbDragEnd();
};
listenEvent(elem, "mousedown", this.onDragStart.bind(this));
listenEvent(document, "mousemove", this.onDragMove.bind(this), { passive: true });
listenEvent(document, "mouseup", this.onDragEnd.bind(this));
}
this.draggableList = [];
this.addDraggable = function (...args) {
this.draggableList.push(new Draggable(...args));
};
}
</script>
<script>
const dragMgr = new DraggableManager();
const oContent = document.querySelector(".content");
oContent.innerHTML = new Array(10).fill(oContent.innerHTML).join("");
const oScrollThumb = document.querySelector(".scroll > .scroll--thumb");
const viewH = document.querySelector(".container").offsetHeight;
const scrollBarH = oScrollThumb.parentElement.offsetHeight;
const scrollThumbH = scrollBarH * viewH / oContent.offsetHeight;
const scrollThumbMaxDeltaY = scrollBarH - scrollThumbH;
oScrollThumb.style.height = `${scrollThumbH}px`;
function pipe(...fnList) {
return (...args) => fnList.reduce((returnV, fn) => fn(...args) ?? returnV, undefined);
}
function moveOnlyY(oldPos, newPos) {
return { x: oldPos.x, y: newPos.y };
}
function clamp(v, min, max) {
return Math.max(min, Math.min(max, v));
}
function boundedY(oldPos, newPos) {
return { x: oldPos.x, y: clamp(newPos.y, 0, scrollThumbMaxDeltaY) };
}
function scrollContent() {
oContent.style.top = `-${(oContent.offsetHeight - viewH) * oScrollThumb.offsetTop / scrollThumbMaxDeltaY}px`;
}
dragMgr.addDraggable(oScrollThumb, null, null, pipe(moveOnlyY, boundedY, scrollContent));
listenEvent(oContent, "wheel", (e) => {
oScrollThumb.style.top = `${clamp(oScrollThumb.offsetTop + e.deltaY * 0.2, 0, scrollThumbMaxDeltaY)}px`;
scrollContent();
}, { passive: true });
</script>
</body>
</html>