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File: editor/codemirror/src/display/scroll_events.js

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  Classes of Cedric Maenetja   Custom PHP HTML Parser   editor/codemirror/src/display/scroll_events.js   Download  
File: editor/codemirror/src/display/scroll_events.js
Role: Auxiliary data
Content type: text/plain
Description: Auxiliary data
Class: Custom PHP HTML Parser
Process HTML to replace it with parameter values
Author: By
Last change:
Date: 1 year ago
Size: 5,478 bytes
 

Contents

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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 } } }