48 lines
1.5 KiB
JavaScript
48 lines
1.5 KiB
JavaScript
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// Copyright 2015, 2016 Ethcore (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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export function scrollTo (element, to, duration) {
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let start = element.scrollTop;
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let change = to - start;
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let increment = 50;
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let animateScroll = elapsedTime => {
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elapsedTime += increment;
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let position = easeInOut(elapsedTime, start, change, duration);
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element.scrollTop = position;
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if (elapsedTime < duration) {
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setTimeout(() => {
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// stop if user scrolled
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if (element.scrollTop !== parseInt(position, 10)) {
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return;
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}
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animateScroll(elapsedTime);
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}, increment);
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}
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};
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animateScroll(0);
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}
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export function easeInOut (currentTime, start, change, duration) {
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currentTime /= duration / 2;
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if (currentTime < 1) {
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return change / 2 * currentTime * currentTime + start;
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}
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currentTime -= 1;
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return -change / 2 * (currentTime * (currentTime - 2) - 1) + start;
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}
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