openrat-cms

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feature_detection.js (2994B)

      1 import { elt, range, removeChildren, removeChildrenAndAdd } from "./dom.js"
      2 import { ie, ie_version } from "./browser.js"
      3 
      4 // Detect drag-and-drop
      5 export let dragAndDrop = function() {
      6   // There is *some* kind of drag-and-drop support in IE6-8, but I
      7   // couldn't get it to work yet.
      8   if (ie && ie_version < 9) return false
      9   let div = elt('div')
     10   return "draggable" in div || "dragDrop" in div
     11 }()
     12 
     13 let zwspSupported
     14 export function zeroWidthElement(measure) {
     15   if (zwspSupported == null) {
     16     let test = elt("span", "\u200b")
     17     removeChildrenAndAdd(measure, elt("span", [test, document.createTextNode("x")]))
     18     if (measure.firstChild.offsetHeight != 0)
     19       zwspSupported = test.offsetWidth <= 1 && test.offsetHeight > 2 && !(ie && ie_version < 8)
     20   }
     21   let node = zwspSupported ? elt("span", "\u200b") :
     22     elt("span", "\u00a0", null, "display: inline-block; width: 1px; margin-right: -1px")
     23   node.setAttribute("cm-text", "")
     24   return node
     25 }
     26 
     27 // Feature-detect IE's crummy client rect reporting for bidi text
     28 let badBidiRects
     29 export function hasBadBidiRects(measure) {
     30   if (badBidiRects != null) return badBidiRects
     31   let txt = removeChildrenAndAdd(measure, document.createTextNode("A\u062eA"))
     32   let r0 = range(txt, 0, 1).getBoundingClientRect()
     33   let r1 = range(txt, 1, 2).getBoundingClientRect()
     34   removeChildren(measure)
     35   if (!r0 || r0.left == r0.right) return false // Safari returns null in some cases (#2780)
     36   return badBidiRects = (r1.right - r0.right < 3)
     37 }
     38 
     39 // See if "".split is the broken IE version, if so, provide an
     40 // alternative way to split lines.
     41 export let splitLinesAuto = "\n\nb".split(/\n/).length != 3 ? string => {
     42   let pos = 0, result = [], l = string.length
     43   while (pos <= l) {
     44     let nl = string.indexOf("\n", pos)
     45     if (nl == -1) nl = string.length
     46     let line = string.slice(pos, string.charAt(nl - 1) == "\r" ? nl - 1 : nl)
     47     let rt = line.indexOf("\r")
     48     if (rt != -1) {
     49       result.push(line.slice(0, rt))
     50       pos += rt + 1
     51     } else {
     52       result.push(line)
     53       pos = nl + 1
     54     }
     55   }
     56   return result
     57 } : string => string.split(/\r\n?|\n/)
     58 
     59 export let hasSelection = window.getSelection ? te => {
     60   try { return te.selectionStart != te.selectionEnd }
     61   catch(e) { return false }
     62 } : te => {
     63   let range
     64   try {range = te.ownerDocument.selection.createRange()}
     65   catch(e) {}
     66   if (!range || range.parentElement() != te) return false
     67   return range.compareEndPoints("StartToEnd", range) != 0
     68 }
     69 
     70 export let hasCopyEvent = (() => {
     71   let e = elt("div")
     72   if ("oncopy" in e) return true
     73   e.setAttribute("oncopy", "return;")
     74   return typeof e.oncopy == "function"
     75 })()
     76 
     77 let badZoomedRects = null
     78 export function hasBadZoomedRects(measure) {
     79   if (badZoomedRects != null) return badZoomedRects
     80   let node = removeChildrenAndAdd(measure, elt("span", "x"))
     81   let normal = node.getBoundingClientRect()
     82   let fromRange = range(node, 0, 1).getBoundingClientRect()
     83   return badZoomedRects = Math.abs(normal.left - fromRange.left) > 1
     84 }