third_party/polymer/v1_0/components/iron-overlay-behavior/iron-overlay-manager.html

   1 <!--
   2 @license
   3 Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
   4 This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   5 The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   6 The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   7 Code distributed by Google as part of the polymer project is also
   8 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   9 -->
  10
  11 <link rel="import" href="../polymer/polymer.html">
  12
  13 <script>
  14
  15   Polymer.IronOverlayManager = (function() {
  16
  17     var overlays = [];
  18     var DEFAULT_Z = 10;
  19     var backdrops = [];
  20
  21     // track overlays for z-index and focus managemant
  22     function addOverlay(overlay) {
  23       var z0 = currentOverlayZ();
  24       overlays.push(overlay);
  25       var z1 = currentOverlayZ();
  26       if (z1 <= z0) {
  27         applyOverlayZ(overlay, z0);
  28       }
  29     }
  30
  31     function removeOverlay(overlay) {
  32       var i = overlays.indexOf(overlay);
  33       if (i >= 0) {
  34         overlays.splice(i, 1);
  35         setZ(overlay, '');
  36       }
  37     }
  38
  39     function applyOverlayZ(overlay, aboveZ) {
  40       setZ(overlay, aboveZ + 2);
  41     }
  42
  43     function setZ(element, z) {
  44       element.style.zIndex = z;
  45     }
  46
  47     function currentOverlay() {
  48       return overlays[overlays.length-1];
  49     }
  50
  51     function currentOverlayZ() {
  52       var z;
  53       var current = currentOverlay();
  54       if (current) {
  55         var z1 = window.getComputedStyle(current).zIndex;
  56         if (!isNaN(z1)) {
  57           z = Number(z1);
  58         }
  59       }
  60       return z || DEFAULT_Z;
  61     }
  62
  63     function focusOverlay() {
  64       var current = currentOverlay();
  65       // We have to be careful to focus the next overlay _after_ any current
  66       // transitions are complete (due to the state being toggled prior to the
  67       // transition). Otherwise, we risk infinite recursion when a transitioning
  68       // (closed) overlay becomes the current overlay.
  69       //
  70       // NOTE: We make the assumption that any overlay that completes a transition
  71       // will call into focusOverlay to kick the process back off. Currently:
  72       // transitionend -> _applyFocus -> focusOverlay.
  73       if (current && !current.transitioning) {
  74         current._applyFocus();
  75       }
  76     }
  77
  78     function trackBackdrop(element) {
  79       // backdrops contains the overlays with a backdrop that are currently
  80       // visible
  81       if (element.opened) {
  82         backdrops.push(element);
  83       } else {
  84         var index = backdrops.indexOf(element);
  85         if (index >= 0) {
  86           backdrops.splice(index, 1);
  87         }
  88       }
  89     }
  90
  91     function getBackdrops() {
  92       return backdrops;
  93     }
  94
  95     return {
  96       addOverlay: addOverlay,
  97       removeOverlay: removeOverlay,
  98       currentOverlay: currentOverlay,
  99       currentOverlayZ: currentOverlayZ,
 100       focusOverlay: focusOverlay,
 101       trackBackdrop: trackBackdrop,
 102       getBackdrops: getBackdrops
 103     };
 104
 105   })();
 106
 107 </script>