getNeighborIds: add scope, add automatic prefetch for articles under mouse

functions.js

@@ -1477,9 +1477,11 @@ function explainError(code) {
 }
 
 // this only searches loaded headlines list, not in CDM
-function getRelativePostIds(id) {
+function getRelativePostIds(id, limit) {
 
-	debug("getRelativePostIds: " + id);
+	if (!limit) limit = 3;
+
+	debug("getRelativePostIds: " + id + " limit=" + limit);
 
 	var ids = new Array();
 	var container = document.getElementById("headlinesList");
@@ -1491,13 +1493,23 @@ function getRelativePostIds(id) {
 			var r_id = rows[i].id.replace("RROW-", "");
 
 			if (r_id == id) {
-				if (i > 0) ids.push(rows[i-1].id.replace("RROW-", ""));
+/*				if (i > 0) ids.push(rows[i-1].id.replace("RROW-", ""));
 				if (i > 1) ids.push(rows[i-2].id.replace("RROW-", ""));
 				if (i > 2) ids.push(rows[i-3].id.replace("RROW-", ""));
 
 				if (i < rows.length-1) ids.push(rows[i+1].id.replace("RROW-", ""));
 				if (i < rows.length-2) ids.push(rows[i+2].id.replace("RROW-", ""));
-				if (i < rows.length-3) ids.push(rows[i+3].id.replace("RROW-", ""));
+				if (i < rows.length-3) ids.push(rows[i+3].id.replace("RROW-", "")); */
+
+				for (var k = 1; k <= limit; k++) {
+					var nid = false;
+
+					if (i > k-1) var nid = rows[i-k].id.replace("RROW-", "");
+					if (nid) ids.push(nid);
+
+					if (i < rows.length-k) nid = rows[i+k].id.replace("RROW-", "");
+					if (nid) ids.push(nid);
+				}
 
 				return ids;
 			}

modules/backend-rpc.php

@@ -414,6 +414,21 @@
 
 		}
 
+		if ($subop == "getArticles") {
+			$ids = split(",", db_escape_string($_REQUEST["ids"]));
+
+			print "<rpc-reply>";
+
+			foreach ($ids as $id) {
+				if ($id) {
+					outputArticleXML($link, $id, 0, false);
+				}
+			}
+			print "</rpc-reply>";
+
+			return;
+		}
+
 		print "<rpc-reply><error>Unknown method: $subop</error></rpc-reply>";
 	}
 ?>

viewfeed.js

@@ -1604,9 +1604,66 @@ function cdmClicked(elem) {
 	} 
 }
 
+function preload_article_callback(transport) {
+	try {
+		if (transport.responseXML) {
+			var articles = transport.responseXML.getElementsByTagName("article");
+
+			for (var i = 0; i < articles.length; i++) {
+				var id = articles[i].getAttribute("id");
+				if (!cache_find(id)) {
+					cache_inject(id, articles[i].firstChild.nodeValue);				
+					debug("preloaded article: " + id);
+				}
+			}
+		}
+	} catch (e) {
+		exception_error("preload_article_callback", e);
+	}
+}
+
+function preloadArticleUnderPointer(id) {
+	try {
+		if (post_under_pointer == id && !cache_find(id)) {
+
+			debug("trying to preload article " + id);
+
+			var neighbor_ids = getRelativePostIds(id, 1);
+
+			/* only request uncached articles */
+
+			var cids_to_request = Array();
+
+			for (var i = 0; i < neighbor_ids.length; i++) {
+				if (!cache_check(neighbor_ids[i])) {
+					cids_to_request.push(neighbor_ids[i]);
+				}
+			}
+			debug("additional ids: " + cids_to_request.toString());
+
+			cids_to_request.push(id);
+
+			var query = "backend.php?op=rpc&subop=getArticles&ids=" + 
+				cids_to_request.toString();
+			new Ajax.Request(query, {
+				onComplete: function(transport) { 
+					preload_article_callback(transport);
+			} });
+		}
+	} catch (e) {
+		exception_error("preloadArticleUnderPointer", e);
+	}
+}
+
 function postMouseIn(id) {
 	try {
-		post_under_pointer = id;
+		if (post_under_pointer != id) {
+			post_under_pointer = id;
+			if (!isCdmMode()) {
+				window.setTimeout("preloadArticleUnderPointer(" + id + ")", 250);
+			}
+		}
+
 	} catch (e) {
 		exception_error("postMouseIn", e);
 	}