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fix scroll problem when scrollbar on html element #1751

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merged 3 commits into from
May 8, 2021
Merged

fix scroll problem when scrollbar on html element #1751

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cc5c968
fix scroll problem when scrollbar on html element
Manfred-on-github May 7, 2021
01f3bb9
Merge remote-tracking branch 'origin/master' into issue-1745
Manfred-on-github May 7, 2021
763bc17
changes from review
Manfred-on-github May 7, 2021
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36 changes: 28 additions & 8 deletions spec/e2e/html/1727_resize_scroll_top.html
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,6 @@
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="../../../demo/demo.css"/>
<!-- <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/gridstack-h5.js"></script> -->
<script src="../../../dist/gridstack-h5.js"></script>
<style>
.topHeader {
Expand All @@ -30,16 +29,37 @@
width: 50px;
box-sizing: border-box;
}
.outer {
display: flex;
}
.main {
flex-grow: 1;
}
.bodyScroll {
height: 2000px;
width: 100px;
flex: 0 0 auto;
border: 3px solid blue;
}
</style>

</head>
<body>
<div class="topHeader">This is the header which brings an offset of 200 px</div>
<div class="row">
<div class="showDistance"></div>
<div class="willScroll">
<div class="grid-stack"></div>
</div>
<div class="outer">
<div class="main">
<div class="topHeader">
This page allows to test scrolling behavior when scroll element is not whole page (html element),
and when the scrolling element is not at the top of the page. Also effects of multiple
scrollbars can be tested, as the html element also can be scrolled.<br>
This is the header which brings an offset of 200 px</div>
<div class="row">
<div class="showDistance"></div>
<div class="willScroll">
<div class="grid-stack"></div>
</div>
</div>
</div>
<div class="bodyScroll">This causes the scrollbar on html element</div>
</div>

<script type="text/javascript">
Expand All @@ -48,7 +68,7 @@
{x: 0, y: 0, w: 2, h: 2, content: "resize-me - check scrolling starts only when in height of gray area, and you can scroll back up as well."},
{x: 3, y: 0, w: 2, h: 2, content: "this is here to have next item positioned way down"},
{x: 3, y: 2, w: 3, h: 2, content: "resize me - scroll will start immediately, but should not be extremely fast"},
{x: 6, y: 0, w: 2, h: 8, content: "this is here to have a scroll bar from the beginning"},
{x: 6, y: 0, w: 2, h: 8, content: "this is here to have a scroll bar on .main div from the beginning"},
];
grid.load(items);
</script>
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13 changes: 12 additions & 1 deletion src/utils.ts
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Expand Up @@ -351,7 +351,18 @@ export class Utils {
static updateScrollResize(event: MouseEvent, el: HTMLElement, distance: number): void {
const scrollEl = this.getScrollParent(el);
const height = scrollEl.clientHeight;
const offsetTop = scrollEl.getBoundingClientRect().top;
//when does pointer move out of visible area, which is then fixed by scrolling that element?
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not sure that first line help - also wrong syntax.
Also please change comments to '// ' (add space)

can we maybe rephrase this comment ? It's not helping me. I would document why we need offsetTop at all, THEN explain that document HTML is different due to returning viewport and not actual needed height. or something like that...

I have not looked into this so taking you word for it. Also add #1745 #1727 to your comment.

//property clientHeight returns height of element, but for 'html', it returns
//height of viewport. getBoundingClientRect() returns rect of element in client
//coordinates, for normal elements its height equals clientHeight, but for 'html'
//getBoundingClientRect() returns the location of the total page, height can be much larger
//than viewport height, and when scrolled, top is negative.
//So for 'html', we compare pointer position/height against viewport, for which top is 0,
//if some inner element is our scrollElement, we must compare it to the client position of that element.
let offsetTop = 0;
if (scrollEl != document.scrollingElement) {
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@adumesny adumesny May 7, 2021 •
edited
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!== please

also maybe use this.getScrollElement() (which I JUST RENAMED but changed to use document.scrollingElement 2 weeks ago from document.documentElement for Safari and being correct). This way there is only 1 place to change (if ever)

offsetTop = scrollEl.getBoundingClientRect().top;
}
const pointerPosY = event.clientY - offsetTop;
const top = pointerPosY < distance;
const bottom = pointerPosY > height - distance;
Expand Down