fix #2495 editor freezes when setting scrollmargin and maxLines together

lib/ace/virtual_renderer.js

@@ -968,14 +968,15 @@ var VirtualRenderer = function(container, theme) {
             : 0;
         maxHeight += scrollPastEnd;
         
-        this.session.setScrollTop(Math.max(-this.scrollMargin.top,
+        var sm = this.scrollMargin;
-            Math.min(this.scrollTop, maxHeight - size.scrollerHeight + this.scrollMargin.bottom)));
+        this.session.setScrollTop(Math.max(-sm.top,
+            Math.min(this.scrollTop, maxHeight - size.scrollerHeight + sm.bottom)));
 
-        this.session.setScrollLeft(Math.max(-this.scrollMargin.left, Math.min(this.scrollLeft, 
+        this.session.setScrollLeft(Math.max(-sm.left, Math.min(this.scrollLeft, 
-            longestLine + 2 * this.$padding - size.scrollerWidth + this.scrollMargin.right)));
+            longestLine + 2 * this.$padding - size.scrollerWidth + sm.right)));
         
         var vScroll = !hideScrollbars && (this.$vScrollBarAlwaysVisible ||
-            size.scrollerHeight - maxHeight + scrollPastEnd < 0 || this.scrollTop);
+            size.scrollerHeight - maxHeight + scrollPastEnd < 0 || this.scrollTop > sm.top);
         var vScrollChanged = this.$vScroll !== vScroll;
         if (vScrollChanged) {
             this.$vScroll = vScroll;

lib/ace/virtual_renderer_test.js

@@ -36,26 +36,40 @@ if (typeof process !== "undefined") {
 define(function(require, exports, module) {
 "use strict";
 
+var Editor = require("./edit_session").Editor;
 var EditSession = require("./edit_session").EditSession;
 var VirtualRenderer = require("./virtual_renderer").VirtualRenderer;
 var assert = require("./test/assertions");
 
+var editor = null;
 module.exports = {
-    "test: screen2text the column should be rounded to the next character edge" : function() {
+    setUp: function() {
+        if (editor)
+            editor.destroy()
         var el = document.createElement("div");
-
         if (!el.getBoundingClientRect) {
             console.log("Skipping test: This test only runs in the browser");
             return;
         }
-
         el.style.left = "20px";
         el.style.top = "30px";
         el.style.width = "300px";
         el.style.height = "100px";
         document.body.appendChild(el);
-
         var renderer = new VirtualRenderer(el);
+        var editor = new Editor(renderer);
+        editor.on("destroy", function() {
+            document.body.removeChild(el);
+        });
+    },
+    tearDown: function() {
+        editor && editor.destroy();
+        editor = null;
+    },
+    "test: screen2text the column should be rounded to the next character edge" : function() {
+        if (!editor) return;
+        var renderer = editor.renderer;
+
         renderer.setPadding(0);
         renderer.setSession(new EditSession("1234"));
 
@@ -72,8 +86,24 @@ module.exports = {
         testPixelToText(9, 0, 0, 1);
         testPixelToText(10, 0, 0, 1);
         testPixelToText(14, 0, 0, 1);
-        testPixelToText(15, 0, 0, 2);
+        testPixelToText(15, 0, 0, 2);        
-        document.body.removeChild(el);
+    },
+    
+    "test scrollmargin + autosize": function(done) {
+        var editor = initAce();
+        if (!editor) return;
+        editor.setOptions({
+            maxLines: 100,
+            useWrapMode: true
+        });        
+        editor.renderer.setScrollMargin(10, 10);
+        editor.setValue("\n\n");
+        editor.setValue("\n\n\n\n");
+        editor.renderer.once("afterRender", function() {
+            setTimeout(function() {
+                done();
+            }, 0);
+        });
     }
 
     // change tab size after setDocument (for text layer)