From aa8c14de62965cab091557ebc26ea51800c1b3dd Mon Sep 17 00:00:00 2001
From: Fabian Jakobs <fabian.jakobs@web.de>
Date: Fri, 1 Oct 2010 10:43:36 +0200
Subject: [PATCH] slow down background tokenizer if line is below the editor's
 last visible line

---
 src/ace/BackgroundTokenizer.js | 7 +++++--
 src/ace/Editor.js              | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/ace/BackgroundTokenizer.js b/src/ace/BackgroundTokenizer.js
index 72d20db3..6a05b8b8 100644
--- a/src/ace/BackgroundTokenizer.js
+++ b/src/ace/BackgroundTokenizer.js
@@ -7,7 +7,7 @@
  */
 require.def("ace/BackgroundTokenizer", ["ace/lib/oop", "ace/MEventEmitter"], function(oop, MEventEmitter) {
 
-var BackgroundTokenizer = function(tokenizer) {
+var BackgroundTokenizer = function(tokenizer, editor) {
     this.running = false;
     this.textLines = [];
     this.lines = [];
@@ -24,6 +24,7 @@ var BackgroundTokenizer = function(tokenizer) {
         var textLines = self.textLines;
 
         var processedLines = 0;
+        var lastVisibleRow = editor.getLastVisibleRow();
 
         while (self.currentLine < textLines.length) {
             self.lines[self.currentLine] = self.$tokenizeRows(self.currentLine, self.currentLine)[0];
@@ -33,7 +34,9 @@ var BackgroundTokenizer = function(tokenizer) {
             processedLines += 1;
             if ((processedLines % 5 == 0) && (new Date() - workerStart) > 20) {
                 self.fireUpdateEvent(startLine, self.currentLine-1);
-                self.running = setTimeout(self.$worker, 30);
+                
+                var timeout = self.currentLine < lastVisibleRow ? 20 : 100;
+                self.running = setTimeout(self.$worker, timeout);
                 return;
             }
         }
diff --git a/src/ace/Editor.js b/src/ace/Editor.js
index 47bf334e..2d5eabc7 100644
--- a/src/ace/Editor.js
+++ b/src/ace/Editor.js
@@ -254,7 +254,7 @@ var Editor = function(renderer, doc) {
 
         if (!this.bgTokenizer) {
             var onUpdate = ace.bind(this.onTokenizerUpdate, this);
-            this.bgTokenizer = new BackgroundTokenizer(tokenizer);
+            this.bgTokenizer = new BackgroundTokenizer(tokenizer, this);
             this.bgTokenizer.addEventListener("update", onUpdate);
         } else {
             this.bgTokenizer.setTokenizer(tokenizer);