third_party/polymer/v1_0/components-chromium/iron-overlay-behavior/iron-overlay-manager-extracted.js

   1 Polymer.IronOverlayManager = (function() {
   2
   3     var overlays = [];
   4     var DEFAULT_Z = 10;
   5     var backdrops = [];
   6
   7     // track overlays for z-index and focus managemant
   8     function addOverlay(overlay) {
   9       var z0 = currentOverlayZ();
  10       overlays.push(overlay);
  11       var z1 = currentOverlayZ();
  12       if (z1 <= z0) {
  13         applyOverlayZ(overlay, z0);
  14       }
  15     }
  16
  17     function removeOverlay(overlay) {
  18       var i = overlays.indexOf(overlay);
  19       if (i >= 0) {
  20         overlays.splice(i, 1);
  21         setZ(overlay, '');
  22       }
  23     }
  24
  25     function applyOverlayZ(overlay, aboveZ) {
  26       setZ(overlay, aboveZ + 2);
  27     }
  28
  29     function setZ(element, z) {
  30       element.style.zIndex = z;
  31     }
  32
  33     function currentOverlay() {
  34       var i = overlays.length - 1;
  35       while (overlays[i] && !overlays[i].opened) {
  36         --i;
  37       }
  38       return overlays[i];
  39     }
  40
  41     function currentOverlayZ() {
  42       var z;
  43       var current = currentOverlay();
  44       if (current) {
  45         var z1 = window.getComputedStyle(current).zIndex;
  46         if (!isNaN(z1)) {
  47           z = Number(z1);
  48         }
  49       }
  50       return z || DEFAULT_Z;
  51     }
  52
  53     function focusOverlay() {
  54       var current = currentOverlay();
  55       // We have to be careful to focus the next overlay _after_ any current
  56       // transitions are complete (due to the state being toggled prior to the
  57       // transition). Otherwise, we risk infinite recursion when a transitioning
  58       // (closed) overlay becomes the current overlay.
  59       //
  60       // NOTE: We make the assumption that any overlay that completes a transition
  61       // will call into focusOverlay to kick the process back off. Currently:
  62       // transitionend -> _applyFocus -> focusOverlay.
  63       if (current && !current.transitioning) {
  64         current._applyFocus();
  65       }
  66     }
  67
  68     function trackBackdrop(element) {
  69       // backdrops contains the overlays with a backdrop that are currently
  70       // visible
  71       if (element.opened) {
  72         backdrops.push(element);
  73       } else {
  74         var index = backdrops.indexOf(element);
  75         if (index >= 0) {
  76           backdrops.splice(index, 1);
  77         }
  78       }
  79     }
  80
  81     function getBackdrops() {
  82       return backdrops;
  83     }
  84
  85     return {
  86       addOverlay: addOverlay,
  87       removeOverlay: removeOverlay,
  88       currentOverlay: currentOverlay,
  89       currentOverlayZ: currentOverlayZ,
  90       focusOverlay: focusOverlay,
  91       trackBackdrop: trackBackdrop,
  92       getBackdrops: getBackdrops
  93     };
  94
  95   })();