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comparison .cms/lib/codemirror/src/display/scroll_events.js @ 0:78edf6b517a0 draft

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24.10
author Coffee CMS <info@coffee-cms.ru>
date Fri, 11 Oct 2024 22:40:23 +0000
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1 import { chrome, chrome_version, gecko, ie, mac, presto, safari, webkit } from "../util/browser.js"
2 import { e_preventDefault } from "../util/event.js"
3
4 import { updateDisplaySimple } from "./update_display.js"
5 import { setScrollLeft, updateScrollTop } from "./scrolling.js"
6
7 // Since the delta values reported on mouse wheel events are
8 // unstandardized between browsers and even browser versions, and
9 // generally horribly unpredictable, this code starts by measuring
10 // the scroll effect that the first few mouse wheel events have,
11 // and, from that, detects the way it can convert deltas to pixel
12 // offsets afterwards.
13 //
14 // The reason we want to know the amount a wheel event will scroll
15 // is that it gives us a chance to update the display before the
16 // actual scrolling happens, reducing flickering.
17
18 let wheelSamples = 0, wheelPixelsPerUnit = null
19 // Fill in a browser-detected starting value on browsers where we
20 // know one. These don't have to be accurate -- the result of them
21 // being wrong would just be a slight flicker on the first wheel
22 // scroll (if it is large enough).
23 if (ie) wheelPixelsPerUnit = -.53
24 else if (gecko) wheelPixelsPerUnit = 15
25 else if (chrome) wheelPixelsPerUnit = -.7
26 else if (safari) wheelPixelsPerUnit = -1/3
27
28 function wheelEventDelta(e) {
29 let dx = e.wheelDeltaX, dy = e.wheelDeltaY
30 if (dx == null && e.detail && e.axis == e.HORIZONTAL_AXIS) dx = e.detail
31 if (dy == null && e.detail && e.axis == e.VERTICAL_AXIS) dy = e.detail
32 else if (dy == null) dy = e.wheelDelta
33 return {x: dx, y: dy}
34 }
35 export function wheelEventPixels(e) {
36 let delta = wheelEventDelta(e)
37 delta.x *= wheelPixelsPerUnit
38 delta.y *= wheelPixelsPerUnit
39 return delta
40 }
41
42 export function onScrollWheel(cm, e) {
43 // On Chrome 102, viewport updates somehow stop wheel-based
44 // scrolling. Turning off pointer events during the scroll seems
45 // to avoid the issue.
46 if (chrome && chrome_version == 102) {
47 if (cm.display.chromeScrollHack == null) cm.display.sizer.style.pointerEvents = "none"
48 else clearTimeout(cm.display.chromeScrollHack)
49 cm.display.chromeScrollHack = setTimeout(() => {
50 cm.display.chromeScrollHack = null
51 cm.display.sizer.style.pointerEvents = ""
52 }, 100)
53 }
54 let delta = wheelEventDelta(e), dx = delta.x, dy = delta.y
55 let pixelsPerUnit = wheelPixelsPerUnit
56 if (e.deltaMode === 0) {
57 dx = e.deltaX
58 dy = e.deltaY
59 pixelsPerUnit = 1
60 }
61
62 let display = cm.display, scroll = display.scroller
63 // Quit if there's nothing to scroll here
64 let canScrollX = scroll.scrollWidth > scroll.clientWidth
65 let canScrollY = scroll.scrollHeight > scroll.clientHeight
66 if (!(dx && canScrollX || dy && canScrollY)) return
67
68 // Webkit browsers on OS X abort momentum scrolls when the target
69 // of the scroll event is removed from the scrollable element.
70 // This hack (see related code in patchDisplay) makes sure the
71 // element is kept around.
72 if (dy && mac && webkit) {
73 outer: for (let cur = e.target, view = display.view; cur != scroll; cur = cur.parentNode) {
74 for (let i = 0; i < view.length; i++) {
75 if (view[i].node == cur) {
76 cm.display.currentWheelTarget = cur
77 break outer
78 }
79 }
80 }
81 }
82
83 // On some browsers, horizontal scrolling will cause redraws to
84 // happen before the gutter has been realigned, causing it to
85 // wriggle around in a most unseemly way. When we have an
86 // estimated pixels/delta value, we just handle horizontal
87 // scrolling entirely here. It'll be slightly off from native, but
88 // better than glitching out.
89 if (dx && !gecko && !presto && pixelsPerUnit != null) {
90 if (dy && canScrollY)
91 updateScrollTop(cm, Math.max(0, scroll.scrollTop + dy * pixelsPerUnit))
92 setScrollLeft(cm, Math.max(0, scroll.scrollLeft + dx * pixelsPerUnit))
93 // Only prevent default scrolling if vertical scrolling is
94 // actually possible. Otherwise, it causes vertical scroll
95 // jitter on OSX trackpads when deltaX is small and deltaY
96 // is large (issue #3579)
97 if (!dy || (dy && canScrollY))
98 e_preventDefault(e)
99 display.wheelStartX = null // Abort measurement, if in progress
100 return
101 }
102
103 // 'Project' the visible viewport to cover the area that is being
104 // scrolled into view (if we know enough to estimate it).
105 if (dy && pixelsPerUnit != null) {
106 let pixels = dy * pixelsPerUnit
107 let top = cm.doc.scrollTop, bot = top + display.wrapper.clientHeight
108 if (pixels < 0) top = Math.max(0, top + pixels - 50)
109 else bot = Math.min(cm.doc.height, bot + pixels + 50)
110 updateDisplaySimple(cm, {top: top, bottom: bot})
111 }
112
113 if (wheelSamples < 20 && e.deltaMode !== 0) {
114 if (display.wheelStartX == null) {
115 display.wheelStartX = scroll.scrollLeft; display.wheelStartY = scroll.scrollTop
116 display.wheelDX = dx; display.wheelDY = dy
117 setTimeout(() => {
118 if (display.wheelStartX == null) return
119 let movedX = scroll.scrollLeft - display.wheelStartX
120 let movedY = scroll.scrollTop - display.wheelStartY
121 let sample = (movedY && display.wheelDY && movedY / display.wheelDY) ||
122 (movedX && display.wheelDX && movedX / display.wheelDX)
123 display.wheelStartX = display.wheelStartY = null
124 if (!sample) return
125 wheelPixelsPerUnit = (wheelPixelsPerUnit * wheelSamples + sample) / (wheelSamples + 1)
126 ++wheelSamples
127 }, 200)
128 } else {
129 display.wheelDX += dx; display.wheelDY += dy
130 }
131 }
132 }