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/*
* SonarQube
* Copyright (C) 2009-2018 SonarSource SA
* mailto:info AT sonarsource DOT com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
import { debounce } from 'lodash';
const SCROLLING_DURATION = 100;
const SCROLLING_INTERVAL = 10;
const SCROLLING_STEPS = SCROLLING_DURATION / SCROLLING_INTERVAL;
function isWindow(element: HTMLElement | Window): element is Window {
return element === window;
}
function getScrollPosition(element: HTMLElement | Window): number {
return isWindow(element) ? window.pageYOffset : element.scrollTop;
}
function scrollElement(element: HTMLElement | Window, position: number): void {
if (isWindow(element)) {
window.scrollTo(0, position);
} else {
element.scrollTop = position;
}
}
let smoothScrollTop = (y: number, parent: HTMLElement | Window) => {
let scrollTop = getScrollPosition(parent);
const scrollingDown = y > scrollTop;
const step = Math.ceil(Math.abs(y - scrollTop) / SCROLLING_STEPS);
let stepsDone = 0;
const interval = setInterval(() => {
if (scrollTop === y || SCROLLING_STEPS === stepsDone) {
clearInterval(interval);
} else {
let goal;
if (scrollingDown) {
goal = Math.min(y, scrollTop + step);
} else {
goal = Math.max(y, scrollTop - step);
}
stepsDone++;
scrollTop = goal;
scrollElement(parent, goal);
}
}, SCROLLING_INTERVAL);
};
smoothScrollTop = debounce(smoothScrollTop, SCROLLING_DURATION, { leading: true });
export function scrollToElement(
element: HTMLElement,
options: {
topOffset?: number;
bottomOffset?: number;
parent?: HTMLElement;
smooth?: boolean;
}
): void {
const opts = { topOffset: 0, bottomOffset: 0, parent: window, smooth: true, ...options };
const { parent } = opts;
const { top, bottom } = element.getBoundingClientRect();
const scrollTop = getScrollPosition(parent);
const height: number = isWindow(parent)
? window.innerHeight
: parent.getBoundingClientRect().height;
const parentTop = isWindow(parent) ? 0 : parent.getBoundingClientRect().top;
if (top - parentTop < opts.topOffset) {
const goal = scrollTop - opts.topOffset + top - parentTop;
if (opts.smooth) {
smoothScrollTop(goal, parent);
} else {
scrollElement(parent, goal);
}
}
if (bottom - parentTop > height - opts.bottomOffset) {
const goal = scrollTop + bottom - parentTop - height + opts.bottomOffset;
if (opts.smooth) {
smoothScrollTop(goal, parent);
} else {
scrollElement(parent, goal);
}
}
}
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