1 files changed, 143 insertions, 0 deletions
diff --git a/www/wiki/resources/src/mediawiki/page/image-pagination.js b/www/wiki/resources/src/mediawiki/page/image-pagination.js
new file mode 100644
index 00000000..06c34a50
--- /dev/null
+++ b/www/wiki/resources/src/mediawiki/page/image-pagination.js
@@ -0,0 +1,143 @@
+/*!
+ * Implement AJAX navigation for multi-page images so the user may browse without a full page reload.
+ */
+
+/* eslint-disable no-use-before-define */
+
+( function ( mw, $ ) {
+	var jqXhr, $multipageimage, $spinner,
+		cache = {},
+		cacheOrder = [];
+
+	/* Fetch the next page, caching up to 10 last-loaded pages.
+	 * @param {string} url
+	 * @return {jQuery.Promise}
+	 */
+	function fetchPageData( url ) {
+		if ( jqXhr && jqXhr.abort ) {
+			// Prevent race conditions and piling up pending requests
+			jqXhr.abort();
+		}
+		jqXhr = undefined;
+
+		// Try the cache
+		if ( cache[ url ] ) {
+			// Update access freshness
+			cacheOrder.splice( cacheOrder.indexOf( url ), 1 );
+			cacheOrder.push( url );
+			return $.Deferred().resolve( cache[ url ] ).promise();
+		}
+
+		// TODO Don't fetch the entire page. Ideally we'd only fetch the content portion or the data
+		// (thumbnail urls) and update the interface manually.
+		jqXhr = $.ajax( url ).then( function ( data ) {
+			return $( data ).find( 'table.multipageimage' ).contents();
+		} );
+
+		// Handle cache updates
+		jqXhr.done( function ( $contents ) {
+			jqXhr = undefined;
+
+			// Cache the newly loaded page
+			cache[ url ] = $contents;
+			cacheOrder.push( url );
+
+			// Remove the oldest entry if we're over the limit
+			if ( cacheOrder.length > 10 ) {
+				delete cache[ cacheOrder[ 0 ] ];
+				cacheOrder = cacheOrder.slice( 1 );
+			}
+		} );
+
+		return jqXhr.promise();
+	}
+
+	/* Fetch the next page and use jQuery to swap the table.multipageimage contents.
+	 * @param {string} url
+	 * @param {boolean} [hist=false] Whether this is a load triggered by history navigation (if
+	 *   true, this function won't push a new history state, for the browser did so already).
+	 */
+	function switchPage( url, hist ) {
+		var $tr, promise;
+
+		// Start fetching data (might be cached)
+		promise = fetchPageData( url );
+
+		// Add a new spinner if one doesn't already exist and the data is not already ready
+		if ( !$spinner && promise.state() !== 'resolved' ) {
+			$tr = $multipageimage.find( 'tr' );
+			$spinner = $.createSpinner( {
+				size: 'large',
+				type: 'block'
+			} )
+				// Copy the old content dimensions equal so that the current scroll position is not
+				// lost between emptying the table is and receiving the new contents.
+				.css( {
+					height: $tr.outerHeight(),
+					width: $tr.outerWidth()
+				} );
+
+			$multipageimage.empty().append( $spinner );
+		}
+
+		promise.done( function ( $contents ) {
+			$spinner = undefined;
+
+			// Replace table contents
+			$multipageimage.empty().append( $contents.clone() );
+
+			bindPageNavigation( $multipageimage );
+
+			// Fire hook because the page's content has changed
+			mw.hook( 'wikipage.content' ).fire( $multipageimage );
+
+			// Update browser history and address bar. But not if we came here from a history
+			// event, in which case the url is already updated by the browser.
+			if ( history.pushState && !hist ) {
+				history.pushState( { tag: 'mw-pagination' }, document.title, url );
+			}
+		} );
+	}
+
+	function bindPageNavigation( $container ) {
+		$container.find( '.multipageimagenavbox' ).one( 'click', 'a', function ( e ) {
+			var page, url;
+
+			// Generate the same URL on client side as the one generated in ImagePage::openShowImage.
+			// We avoid using the URL in the link directly since it could have been manipulated (T68608)
+			page = Number( mw.util.getParamValue( 'page', this.href ) );
+			url = mw.util.getUrl( mw.config.get( 'wgPageName' ), { page: page } );
+
+			switchPage( url );
+			e.preventDefault();
+		} );
+
+		$container.find( 'form[name="pageselector"]' ).one( 'change submit', function ( e ) {
+			switchPage( this.action + '?' + $( this ).serialize() );
+			e.preventDefault();
+		} );
+	}
+
+	$( function () {
+		if ( mw.config.get( 'wgCanonicalNamespace' ) !== 'File' ) {
+			return;
+		}
+		$multipageimage = $( 'table.multipageimage' );
+		if ( !$multipageimage.length ) {
+			return;
+		}
+
+		bindPageNavigation( $multipageimage );
+
+		// Update the url using the History API (if available)
+		if ( history.pushState && history.replaceState ) {
+			history.replaceState( { tag: 'mw-pagination' }, '' );
+			$( window ).on( 'popstate', function ( e ) {
+				var state = e.originalEvent.state;
+				if ( state && state.tag === 'mw-pagination' ) {
+					switchPage( location.href, true );
+				}
+			} );
+		}
+	} );
+}( mediaWiki, jQuery ) );