iron-overlay-manager.html
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<!--
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->
<link rel="import" href="../polymer/polymer.html">
<script>
Polymer.IronOverlayManager = (function() {
var overlays = [];
var DEFAULT_Z = 10;
var backdrops = [];
// track overlays for z-index and focus managemant
function addOverlay(overlay) {
var z0 = currentOverlayZ();
overlays.push(overlay);
var z1 = currentOverlayZ();
if (z1 <= z0) {
applyOverlayZ(overlay, z0);
}
}
function removeOverlay(overlay) {
var i = overlays.indexOf(overlay);
if (i >= 0) {
overlays.splice(i, 1);
setZ(overlay, '');
}
}
function applyOverlayZ(overlay, aboveZ) {
setZ(overlay, aboveZ + 2);
}
function setZ(element, z) {
element.style.zIndex = z;
}
function currentOverlay() {
var i = overlays.length - 1;
while (overlays[i] && !overlays[i].opened) {
--i;
}
return overlays[i];
}
function currentOverlayZ() {
var z;
var current = currentOverlay();
if (current) {
var z1 = window.getComputedStyle(current).zIndex;
if (!isNaN(z1)) {
z = Number(z1);
}
}
return z || DEFAULT_Z;
}
function focusOverlay() {
var current = currentOverlay();
// We have to be careful to focus the next overlay _after_ any current
// transitions are complete (due to the state being toggled prior to the
// transition). Otherwise, we risk infinite recursion when a transitioning
// (closed) overlay becomes the current overlay.
//
// NOTE: We make the assumption that any overlay that completes a transition
// will call into focusOverlay to kick the process back off. Currently:
// transitionend -> _applyFocus -> focusOverlay.
if (current && !current.transitioning) {
current._applyFocus();
}
}
function trackBackdrop(element) {
// backdrops contains the overlays with a backdrop that are currently
// visible
if (element.opened) {
backdrops.push(element);
} else {
var index = backdrops.indexOf(element);
if (index >= 0) {
backdrops.splice(index, 1);
}
}
}
function getBackdrops() {
return backdrops;
}
return {
addOverlay: addOverlay,
removeOverlay: removeOverlay,
currentOverlay: currentOverlay,
currentOverlayZ: currentOverlayZ,
focusOverlay: focusOverlay,
trackBackdrop: trackBackdrop,
getBackdrops: getBackdrops
};
})();
</script>