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feat($anchorScroll): support a configurable vertical scroll offset
Add support for a configurable vertical scroll offset to `$anchorScroll`. The offset can be defined by a specific number of pixels, a callback function that returns the number of pixels on demand or a jqLite/JQuery wrapped DOM element whose height and position are used if it has fixed position. The offset algorithm takes into account items that are near the bottom of the page preventing over-zealous offset correction. Closes #9368 Closes #2070 Closes #9360
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‎src/ng/anchorScroll.js

+211-53
Original file line numberDiff line numberDiff line change
@@ -1,66 +1,174 @@
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'use strict';
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/**
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* @ngdoc service
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* @name $anchorScroll
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* @kind function
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* @requires $window
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* @requires $location
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* @requires $rootScope
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* @ngdoc provider
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* @name $anchorScrollProvider
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*
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* @description
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* When called, it checks current value of `$location.hash()` and scrolls to the related element,
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* according to rules specified in
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* [Html5 spec](http://dev.w3.org/html5/spec/Overview.html#the-indicated-part-of-the-document).
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*
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* It also watches the `$location.hash()` and scrolls whenever it changes to match any anchor.
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* This can be disabled by calling `$anchorScrollProvider.disableAutoScrolling()`.
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*
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* @example
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<example module="anchorScrollExample">
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<file name="index.html">
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<div id="scrollArea" ng-controller="ScrollController">
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<a ng-click="gotoBottom()">Go to bottom</a>
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<a id="bottom"></a> You're at the bottom!
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</div>
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</file>
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<file name="script.js">
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angular.module('anchorScrollExample', [])
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.controller('ScrollController', ['$scope', '$location', '$anchorScroll',
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function ($scope, $location, $anchorScroll) {
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$scope.gotoBottom = function() {
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// set the location.hash to the id of
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// the element you wish to scroll to.
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$location.hash('bottom');
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// call $anchorScroll()
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$anchorScroll();
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};
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}]);
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</file>
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<file name="style.css">
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#scrollArea {
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height: 350px;
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overflow: auto;
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}
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#bottom {
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display: block;
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margin-top: 2000px;
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}
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</file>
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</example>
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* Use `$anchorScrollProvider` to disable automatic scrolling whenever
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* {@link ng.$location#hash $location.hash()} changes.
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*/
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function $AnchorScrollProvider() {
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var autoScrollingEnabled = true;
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/**
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* @ngdoc method
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* @name $anchorScrollProvider#disableAutoScrolling
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*
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* @description
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* By default, {@link ng.$anchorScroll $anchorScroll()} will automatically will detect changes to
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* {@link ng.$location#hash $location.hash()} and scroll to the element matching the new hash.<br />
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* Use this method to disable automatic scrolling.
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*
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* If automatic scrolling is disabled, one must explicitly call
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* {@link ng.$anchorScroll $anchorScroll()} in order to scroll to the element related to the
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* current hash.
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*/
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this.disableAutoScrolling = function() {
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autoScrollingEnabled = false;
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};
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/**
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* @ngdoc service
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* @name $anchorScroll
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* @kind function
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* @requires $window
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* @requires $location
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* @requires $rootScope
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*
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* @description
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* When called, it checks the current value of {@link ng.$location#hash $location.hash()} and
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* scrolls to the related element, according to the rules specified in the
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* [Html5 spec](http://dev.w3.org/html5/spec/Overview.html#the-indicated-part-of-the-document).
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*
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* It also watches the {@link ng.$location#hash $location.hash()} and automatically scrolls to
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* match any anchor whenever it changes. This can be disabled by calling
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* {@link ng.$anchorScrollProvider#disableAutoScrolling $anchorScrollProvider.disableAutoScrolling()}.
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*
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* Additionally, you can use its {@link ng.$anchorScroll#yOffset yOffset} property to specify a
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* vertical scroll-offset (either fixed or dynamic).
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*
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* @property {(number|function|jqLite)} yOffset
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* If set, specifies a vertical scroll-offset. This is often useful when there are fixed
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* positioned elements at the top of the page, such as navbars, headers etc.
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*
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* `yOffset` can be specified in various ways:
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* - **number**: A fixed number of pixels to be used as offset.<br /><br />
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* - **function**: A getter function called everytime `$anchorScroll()` is executed. Must return
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* a number representing the offset (in pixels).<br /><br />
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* - **jqLite**: A jqLite/jQuery element to be used for specifying the offset. The distance from
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* the top of the page to the element's bottom will be used as offset.<br />
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* **Note**: The element will be taken into account only as long as its `position` is set to
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* `fixed`. This option is useful, when dealing with responsive navbars/headers that adjust
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* their height and/or positioning according to the viewport's size.
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*
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* <br />
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* <div class="alert alert-warning">
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* In order for `yOffset` to work properly, scrolling should take place on the document's root and
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* not some child element.
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* </div>
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*
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* @example
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<example module="anchorScrollExample">
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<file name="index.html">
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<div id="scrollArea" ng-controller="ScrollController">
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<a ng-click="gotoBottom()">Go to bottom</a>
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<a id="bottom"></a> You're at the bottom!
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</div>
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</file>
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<file name="script.js">
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angular.module('anchorScrollExample', [])
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.controller('ScrollController', ['$scope', '$location', '$anchorScroll',
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function ($scope, $location, $anchorScroll) {
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$scope.gotoBottom = function() {
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// set the location.hash to the id of
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// the element you wish to scroll to.
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$location.hash('bottom');
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// call $anchorScroll()
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$anchorScroll();
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};
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}]);
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</file>
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<file name="style.css">
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#scrollArea {
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height: 280px;
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overflow: auto;
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}
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#bottom {
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display: block;
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margin-top: 2000px;
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}
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</file>
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</example>
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*
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* <hr />
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* The example below illustrates the use of a vertical scroll-offset (specified as a fixed value).
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* See {@link ng.$anchorScroll#yOffset $anchorScroll.yOffset} for more details.
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*
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* @example
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<example module="anchorScrollOffsetExample">
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<file name="index.html">
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<div class="fixed-header" ng-controller="headerCtrl">
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<a href="" ng-click="gotoAnchor(x)" ng-repeat="x in [1,2,3,4,5]">
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Go to anchor {{x}}
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</a>
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</div>
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<div id="anchor{{x}}" class="anchor" ng-repeat="x in [1,2,3,4,5]">
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Anchor {{x}} of 5
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</div>
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</file>
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<file name="script.js">
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angular.module('anchorScrollOffsetExample', [])
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.run(['$anchorScroll', function($anchorScroll) {
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$anchorScroll.yOffset = 50; // always scroll by 50 extra pixels
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}])
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.controller('headerCtrl', ['$anchorScroll', '$location', '$scope',
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function ($anchorScroll, $location, $scope) {
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$scope.gotoAnchor = function(x) {
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var newHash = 'anchor' + x;
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if ($location.hash() !== newHash) {
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// set the $location.hash to `newHash` and
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// $anchorScroll will automatically scroll to it
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$location.hash('anchor' + x);
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} else {
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// call $anchorScroll() explicitly,
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// since $location.hash hasn't changed
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$anchorScroll();
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}
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};
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}
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]);
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</file>
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<file name="style.css">
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body {
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padding-top: 50px;
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}
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.anchor {
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border: 2px dashed DarkOrchid;
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padding: 10px 10px 200px 10px;
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}
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.fixed-header {
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background-color: rgba(0, 0, 0, 0.2);
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height: 50px;
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position: fixed;
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top: 0; left: 0; right: 0;
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}
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.fixed-header > a {
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display: inline-block;
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margin: 5px 15px;
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}
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</file>
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</example>
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*/
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this.$get = ['$window', '$location', '$rootScope', function($window, $location, $rootScope) {
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var document = $window.document;
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var scrollScheduled = false;
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// Helper function to get first anchor from a NodeList
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// (using `Array#some()` instead of `angular#forEach()` since it's more performant
@@ -76,20 +184,69 @@ function $AnchorScrollProvider() {
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return result;
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}
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function getYOffset() {
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var offset = scroll.yOffset;
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if (isFunction(offset)) {
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offset = offset();
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} else if (isElement(offset)) {
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var elem = offset[0];
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var style = $window.getComputedStyle(elem);
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if (style.position !== 'fixed') {
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offset = 0;
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} else {
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offset = elem.getBoundingClientRect().bottom;
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}
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} else if (!isNumber(offset)) {
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offset = 0;
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}
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return offset;
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}
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function scrollTo(elem) {
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if (elem) {
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elem.scrollIntoView();
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var offset = getYOffset();
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if (offset) {
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// `offset` is the number of pixels we should scroll UP in order to align `elem` properly.
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// This is true ONLY if the call to `elem.scrollIntoView()` initially aligns `elem` at the
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// top of the viewport.
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//
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// IF the number of pixels from the top of `elem` to the end of the page's content is less
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// than the height of the viewport, then `elem.scrollIntoView()` will align the `elem` some
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// way down the page.
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//
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// This is often the case for elements near the bottom of the page.
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//
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// In such cases we do not need to scroll the whole `offset` up, just the difference between
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// the top of the element and the offset, which is enough to align the top of `elem` at the
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// desired position.
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var elemTop = elem.getBoundingClientRect().top;
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$window.scrollBy(0, elemTop - offset);
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}
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} else {
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$window.scrollTo(0, 0);
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}
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}
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function scroll() {
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var hash = $location.hash(), elm;
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// empty hash, scroll to the top of the page
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if (!hash) $window.scrollTo(0, 0);
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if (!hash) scrollTo(null);
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// element with given id
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else if ((elm = document.getElementById(hash))) elm.scrollIntoView();
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else if ((elm = document.getElementById(hash))) scrollTo(elm);
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// first anchor with given name :-D
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else if ((elm = getFirstAnchor(document.getElementsByName(hash)))) elm.scrollIntoView();
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else if ((elm = getFirstAnchor(document.getElementsByName(hash)))) scrollTo(elm);
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// no element and hash == 'top', scroll to the top of the page
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else if (hash === 'top') $window.scrollTo(0, 0);
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else if (hash === 'top') scrollTo(null);
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}
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// does not scroll when user clicks on anchor link that is currently on
@@ -100,11 +257,12 @@ function $AnchorScrollProvider() {
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// skip the initial scroll if $location.hash is empty
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if (newVal === oldVal && newVal === '') return;
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$rootScope.$evalAsync(scroll);
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jqLiteDocumentLoaded(function() {
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$rootScope.$evalAsync(scroll);
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});
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});
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}
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return scroll;
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}];
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}
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