import { chrome, chrome_version, gecko, ie, mac, presto, safari, webkit } from "../util/browser.js"
import { e_preventDefault } from "../util/event.js"
import { updateDisplaySimple } from "./update_display.js"
import { setScrollLeft, updateScrollTop } from "./scrolling.js"
// Since the delta values reported on mouse wheel events are
// unstandardized between browsers and even browser versions, and
// generally horribly unpredictable, this code starts by measuring
// the scroll effect that the first few mouse wheel events have,
// and, from that, detects the way it can convert deltas to pixel
// offsets afterwards.
//
// The reason we want to know the amount a wheel event will scroll
// is that it gives us a chance to update the display before the
// actual scrolling happens, reducing flickering.
let wheelSamples = 0, wheelPixelsPerUnit = null
// Fill in a browser-detected starting value on browsers where we
// know one. These don't have to be accurate -- the result of them
// being wrong would just be a slight flicker on the first wheel
// scroll (if it is large enough).
if (ie) wheelPixelsPerUnit = -.53
else if (gecko) wheelPixelsPerUnit = 15
else if (chrome) wheelPixelsPerUnit = -.7
else if (safari) wheelPixelsPerUnit = -1/3
function wheelEventDelta(e) {
let dx = e.wheelDeltaX, dy = e.wheelDeltaY
if (dx == null && e.detail && e.axis == e.HORIZONTAL_AXIS) dx = e.detail
if (dy == null && e.detail && e.axis == e.VERTICAL_AXIS) dy = e.detail
else if (dy == null) dy = e.wheelDelta
return {x: dx, y: dy}
}
export function wheelEventPixels(e) {
let delta = wheelEventDelta(e)
delta.x *= wheelPixelsPerUnit
delta.y *= wheelPixelsPerUnit
return delta
}
export function onScrollWheel(cm, e) {
// On Chrome 102, viewport updates somehow stop wheel-based
// scrolling. Turning off pointer events during the scroll seems
// to avoid the issue.
if (chrome && chrome_version == 102) {
if (cm.display.chromeScrollHack == null) cm.display.sizer.style.pointerEvents = "none"
else clearTimeout(cm.display.chromeScrollHack)
cm.display.chromeScrollHack = setTimeout(() => {
cm.display.chromeScrollHack = null
cm.display.sizer.style.pointerEvents = ""
}, 100)
}
let delta = wheelEventDelta(e), dx = delta.x, dy = delta.y
let pixelsPerUnit = wheelPixelsPerUnit
if (e.deltaMode === 0) {
dx = e.deltaX
dy = e.deltaY
pixelsPerUnit = 1
}
let display = cm.display, scroll = display.scroller
// Quit if there's nothing to scroll here
let canScrollX = scroll.scrollWidth > scroll.clientWidth
let canScrollY = scroll.scrollHeight > scroll.clientHeight
if (!(dx && canScrollX || dy && canScrollY)) return
// Webkit browsers on OS X abort momentum scrolls when the target
// of the scroll event is removed from the scrollable element.
// This hack (see related code in patchDisplay) makes sure the
// element is kept around.
if (dy && mac && webkit) {
outer: for (let cur = e.target, view = display.view; cur != scroll; cur = cur.parentNode) {
for (let i = 0; i < view.length; i++) {
if (view[i].node == cur) {
cm.display.currentWheelTarget = cur
break outer
}
}
}
}
// On some browsers, horizontal scrolling will cause redraws to
// happen before the gutter has been realigned, causing it to
// wriggle around in a most unseemly way. When we have an
// estimated pixels/delta value, we just handle horizontal
// scrolling entirely here. It'll be slightly off from native, but
// better than glitching out.
if (dx && !gecko && !presto && pixelsPerUnit != null) {
if (dy && canScrollY)
updateScrollTop(cm, Math.max(0, scroll.scrollTop + dy * pixelsPerUnit))
setScrollLeft(cm, Math.max(0, scroll.scrollLeft + dx * pixelsPerUnit))
// Only prevent default scrolling if vertical scrolling is
// actually possible. Otherwise, it causes vertical scroll
// jitter on OSX trackpads when deltaX is small and deltaY
// is large (issue #3579)
if (!dy || (dy && canScrollY))
e_preventDefault(e)
display.wheelStartX = null // Abort measurement, if in progress
return
}
// 'Project' the visible viewport to cover the area that is being
// scrolled into view (if we know enough to estimate it).
if (dy && pixelsPerUnit != null) {
let pixels = dy * pixelsPerUnit
let top = cm.doc.scrollTop, bot = top + display.wrapper.clientHeight
if (pixels < 0) top = Math.max(0, top + pixels - 50)
else bot = Math.min(cm.doc.height, bot + pixels + 50)
updateDisplaySimple(cm, {top: top, bottom: bot})
}
if (wheelSamples < 20 && e.deltaMode !== 0) {
if (display.wheelStartX == null) {
display.wheelStartX = scroll.scrollLeft; display.wheelStartY = scroll.scrollTop
display.wheelDX = dx; display.wheelDY = dy
setTimeout(() => {
if (display.wheelStartX == null) return
let movedX = scroll.scrollLeft - display.wheelStartX
let movedY = scroll.scrollTop - display.wheelStartY
let sample = (movedY && display.wheelDY && movedY / display.wheelDY) ||
(movedX && display.wheelDX && movedX / display.wheelDX)
display.wheelStartX = display.wheelStartY = null
if (!sample) return
wheelPixelsPerUnit = (wheelPixelsPerUnit * wheelSamples + sample) / (wheelSamples + 1)
++wheelSamples
}, 200)
} else {
display.wheelDX += dx; display.wheelDY += dy
}
}
}
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