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Fix scroll box elastic scrolling #1024

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Merged
merged 3 commits into from
Jun 27, 2022
Merged

Fix scroll box elastic scrolling #1024

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52f4343
maint(pat scroll box): Document that scroll-down and scroll-up classe…
thet Jun 27, 2022
61fa3d8
maint(pat scroll box): Improve demo styles.
thet Jun 27, 2022
596fd06
fix(pat scroll box): Fix issue where elastic scrolling on Safari woul…
thet Jun 27, 2022
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6 changes: 4 additions & 2 deletions src/pat/scroll-box/documentation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,9 @@ Ho(horizontal scrolling is not yet supported.

The classes are:

- `scroll-up`: when scrolling upwards,
- `scroll-down`: when scrolling downwards,
- `scroll-up`: when scrolling upwards - the class is kept even after scrolling has stopped,
- `scroll-down`: when scrolling downwards - the class is kept even after scrolling has stopped,
- `scrolling-up`: when scrolling upwards - this class is removed after scrolling has stopped,
- `scrolling-down`: when scrolling downwards - this class is removed after scrolling has stopped,
- `scroll-position-top`: when the scrolling container is scrolled to the top,
- `scroll-position-bottom`: when the scrolling container is scrolled to the bottom.
13 changes: 12 additions & 1 deletion src/pat/scroll-box/index.html
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Expand Up @@ -15,6 +15,15 @@
height: 200vh;
}

.container {
/**
* trick to espatblish a relative containing block
* for position:fixed
* See: https://developer.mozilla.org/en-US/docs/Web/CSS/position#fixed
*/
transform: rotate(0);
}

body .pat-scroll-box {
overflow-y: auto;
border: 1px solid black;
Expand Down Expand Up @@ -49,8 +58,10 @@
</style>
</head>
<body class="pat-scroll-box">
<div class="container">
<div class="pat-scroll-box">
<div class="pat-scroll-box--inner">hello.</div>
<div class="pat-scroll-box--inner">hello.</div>
</div>
</div>
</body>
</html>
5 changes: 3 additions & 2 deletions src/pat/scroll-box/scroll-box.js
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Expand Up @@ -62,15 +62,14 @@ export default Base.extend({
const to_add = [];

if (scroll_pos < this.last_known_scroll_position) {
to_add.push("scroll-up");
to_add.push("scroll-up");
to_add.push("scrolling-up");
} else if (this.last_known_scroll_position < scroll_pos) {
to_add.push("scroll-down");
to_add.push("scrolling-down");
}

if (scroll_pos === 0) {
if (scroll_pos <= 0) {
to_add.push("scroll-position-top");
} else if (
this.scroll_listener === window &&
Expand Down Expand Up @@ -101,6 +100,8 @@ export default Base.extend({
},

clear_scrolling_classes() {
// Remove ``scrolling-up`` and ``scrolling-down``
// but keep ``scroll-up`` and ``scroll-down``.
this.el.classList.remove("scrolling-up", "scrolling-down");
},

Expand Down
22 changes: 22 additions & 0 deletions src/pat/scroll-box/scroll-box.test.js
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Expand Up @@ -69,6 +69,16 @@ describe("pat-scroll-box", function () {
expect(el.classList).not.toContain("scrolling-up");
expect(el.classList).toContain("scrolling-down");

el.scrollTop = 250; // overscrolling / elastic scrolling in Safari
el.dispatchEvent(events.scroll_event());
await utils.animation_frame();
expect(el.classList).not.toContain("scroll-position-top");
expect(el.classList).toContain("scroll-position-bottom");
expect(el.classList).not.toContain("scroll-up");
expect(el.classList).toContain("scroll-down");
expect(el.classList).not.toContain("scrolling-up");
expect(el.classList).toContain("scrolling-down");

el.scrollTop = 0;
el.dispatchEvent(events.scroll_event());
await utils.animation_frame();
Expand All @@ -79,7 +89,19 @@ describe("pat-scroll-box", function () {
expect(el.classList).toContain("scrolling-up");
expect(el.classList).not.toContain("scrolling-down");

el.scrollTop = -50; // overscrolling / elastic scrolling in Safari
el.dispatchEvent(events.scroll_event());
await utils.animation_frame();
expect(el.classList).toContain("scroll-position-top");
expect(el.classList).not.toContain("scroll-position-bottom");
expect(el.classList).toContain("scroll-up");
expect(el.classList).not.toContain("scroll-down");
expect(el.classList).toContain("scrolling-up");
expect(el.classList).not.toContain("scrolling-down");

// Test for clearing the scrolling classes after a scroll stop
// scroll-up and scroll-down are not cleared.

// Still there...
await utils.timeout(custom_timeout / 2);
expect(el.classList).toContain("scrolling-up");
Expand Down