helpers.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
The complete set of authors may be found at http://polymer.github.io/AUTHORS
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS
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
-->
<script>
function findElementInList(container, selector) {
var i = 0;
var children = container._children;
var ms = Polymer.DomApi.matchesSelector;
for (; i < children.length; i++) {
if (children[i].nodeType === Node.ELEMENT_NODE && ms.call(children[i], selector)) {
return children[i];
}
}
return null;
}
function buildItem(index) {
return {
index: index
};
}
function buildDataSet(size) {
var data = [];
while (data.length < size) {
data.push(buildItem(data.length));
}
return data;
}
function simulateScroll(config, fn) {
var list = config.list;
var target = config.target;
var delay = config.delay || 1;
var contribution = config.contribution || 10;
function scroll(dir, prevVal) {
if ((dir > 0 && list.scrollTop >= target) ||
(dir < 0 && list.scrollTop <= target) ||
list.scrollTop === prevVal
){
list.scrollTop = target;
setTimeout(fn.bind(null, list.scrollTop), 100);
return;
}
prevVal = list.scrollTop;
list.scrollTop = list.scrollTop + dir;
setTimeout(scroll.bind(null, dir, prevVal), delay);
}
if (list.scrollTop < target) {
scroll(Math.abs(contribution), -1);
} else if (list.scrollTop > target) {
scroll(-Math.abs(contribution), -1);
}
}
function getFirstItemFromList(list) {
var listRect = list.getBoundingClientRect();
return document.elementFromPoint(listRect.left + 1, listRect.top + 1);
}
function getLastItemFromList(list) {
var listRect = list.getBoundingClientRect();
return document.elementFromPoint(listRect.left + 1, listRect.top + listRect.height - 1);
}
</script>