| 1 | /*
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| 2 | * Copyright 2020 Adobe. All rights reserved.
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| 3 | * This file is licensed to you under the Apache License, Version 2.0 (the "License");
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| 4 | * you may not use this file except in compliance with the License. You may obtain a copy
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| 5 | * of the License at http://www.apache.org/licenses/LICENSE-2.0
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| 6 | *
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| 7 | * Unless required by applicable law or agreed to in writing, software distributed under
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| 8 | * the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR REPRESENTATIONS
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| 9 | * OF ANY KIND, either express or implied. See the License for the specific language
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| 10 | * governing permissions and limitations under the License.
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| 11 | */
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| 12 |
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| 13 | import {getScrollParents} from './getScrollParents';
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| 14 |
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| 15 | interface ScrollIntoViewportOpts {
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| 16 | /** The optional containing element of the target to be centered in the viewport. */
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| 17 | containingElement?: Element
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| 18 | }
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| 19 |
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| 20 | /**
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| 21 | * Scrolls `scrollView` so that `element` is visible.
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| 22 | * Similar to `element.scrollIntoView({block: 'nearest'})` (not supported in Edge),
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| 23 | * but doesn't affect parents above `scrollView`.
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| 24 | */
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| 25 | export function scrollIntoView(scrollView: HTMLElement, element: HTMLElement) {
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| 26 | let offsetX = relativeOffset(scrollView, element, 'left');
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| 27 | let offsetY = relativeOffset(scrollView, element, 'top');
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| 28 | let width = element.offsetWidth;
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| 29 | let height = element.offsetHeight;
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| 30 | let x = scrollView.scrollLeft;
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| 31 | let y = scrollView.scrollTop;
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| 32 |
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| 33 | // Account for top/left border offsetting the scroll top/Left
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| 34 | let {borderTopWidth, borderLeftWidth} = getComputedStyle(scrollView);
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| 35 | let borderAdjustedX = scrollView.scrollLeft + parseInt(borderLeftWidth, 10);
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| 36 | let borderAdjustedY = scrollView.scrollTop + parseInt(borderTopWidth, 10);
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| 37 | // Ignore end/bottom border via clientHeight/Width instead of offsetHeight/Width
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| 38 | let maxX = borderAdjustedX + scrollView.clientWidth;
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| 39 | let maxY = borderAdjustedY + scrollView.clientHeight;
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| 40 |
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| 41 | if (offsetX <= x) {
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| 42 | x = offsetX - parseInt(borderLeftWidth, 10);
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| 43 | } else if (offsetX + width > maxX) {
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| 44 | x += offsetX + width - maxX;
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| 45 | }
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| 46 | if (offsetY <= borderAdjustedY) {
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| 47 | y = offsetY - parseInt(borderTopWidth, 10);
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| 48 | } else if (offsetY + height > maxY) {
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| 49 | y += offsetY + height - maxY;
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| 50 | }
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| 51 | scrollView.scrollLeft = x;
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| 52 | scrollView.scrollTop = y;
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| 53 | }
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| 54 |
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| 55 | /**
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| 56 | * Computes the offset left or top from child to ancestor by accumulating
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| 57 | * offsetLeft or offsetTop through intervening offsetParents.
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| 58 | */
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| 59 | function relativeOffset(ancestor: HTMLElement, child: HTMLElement, axis: 'left'|'top') {
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| 60 | const prop = axis === 'left' ? 'offsetLeft' : 'offsetTop';
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| 61 | let sum = 0;
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| 62 | while (child.offsetParent) {
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| 63 | sum += child[prop];
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| 64 | if (child.offsetParent === ancestor) {
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| 65 | // Stop once we have found the ancestor we are interested in.
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| 66 | break;
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| 67 | } else if (child.offsetParent.contains(ancestor)) {
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| 68 | // If the ancestor is not `position:relative`, then we stop at
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| 69 | // _its_ offset parent, and we subtract off _its_ offset, so that
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| 70 | // we end up with the proper offset from child to ancestor.
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| 71 | sum -= ancestor[prop];
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| 72 | break;
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| 73 | }
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| 74 | child = child.offsetParent as HTMLElement;
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| 75 | }
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| 76 | return sum;
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| 77 | }
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| 78 |
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| 79 | /**
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| 80 | * Scrolls the `targetElement` so it is visible in the viewport. Accepts an optional `opts.containingElement`
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| 81 | * that will be centered in the viewport prior to scrolling the targetElement into view. If scrolling is prevented on
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| 82 | * the body (e.g. targetElement is in a popover), this will only scroll the scroll parents of the targetElement up to but not including the body itself.
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| 83 | */
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| 84 | export function scrollIntoViewport(targetElement: Element, opts?: ScrollIntoViewportOpts) {
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| 85 | if (document.contains(targetElement)) {
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| 86 | let root = document.scrollingElement || document.documentElement;
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| 87 | let isScrollPrevented = window.getComputedStyle(root).overflow === 'hidden';
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| 88 | // If scrolling is not currently prevented then we aren’t in a overlay nor is a overlay open, just use element.scrollIntoView to bring the element into view
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| 89 | if (!isScrollPrevented) {
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| 90 | let {left: originalLeft, top: originalTop} = targetElement.getBoundingClientRect();
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| 91 |
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| 92 | // use scrollIntoView({block: 'nearest'}) instead of .focus to check if the element is fully in view or not since .focus()
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| 93 | // won't cause a scroll if the element is already focused and doesn't behave consistently when an element is partially out of view horizontally vs vertically
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| 94 | targetElement?.scrollIntoView?.({block: 'nearest'});
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| 95 | let {left: newLeft, top: newTop} = targetElement.getBoundingClientRect();
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| 96 | // Account for sub pixel differences from rounding
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| 97 | if ((Math.abs(originalLeft - newLeft) > 1) || (Math.abs(originalTop - newTop) > 1)) {
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| 98 | opts?.containingElement?.scrollIntoView?.({block: 'center', inline: 'center'});
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| 99 | targetElement.scrollIntoView?.({block: 'nearest'});
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| 100 | }
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| 101 | } else {
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| 102 | let scrollParents = getScrollParents(targetElement);
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| 103 | // If scrolling is prevented, we don't want to scroll the body since it might move the overlay partially offscreen and the user can't scroll it back into view.
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| 104 | for (let scrollParent of scrollParents) {
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| 105 | scrollIntoView(scrollParent as HTMLElement, targetElement as HTMLElement);
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| 106 | }
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| 107 | }
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| 108 | }
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| 109 | }
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