From a685f3dc374401f0170a8eb7663eb973a1d21053 Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Tue, 3 Feb 2015 21:02:33 -0700
Subject: [PATCH] Prevent updates for off-screen line decoration markers on
 change

When there were lots of off-screen markers, we were performing lots of
redundant updates when off-screen markers changed. Now we only perform
updates if they intersect the visible row range.

@maxbrunsfeld this should improve the situation for folding/unfolding
when there are lots of others folds. Let me know.
---
 src/text-editor-presenter.coffee | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/text-editor-presenter.coffee b/src/text-editor-presenter.coffee
index 7eb29b6b0..aeff452a5 100644
--- a/src/text-editor-presenter.coffee
+++ b/src/text-editor-presenter.coffee
@@ -563,12 +563,27 @@ class TextEditorPresenter
 
   decorationMarkerDidChange: (decoration, change) ->
     if decoration.isType('line') or decoration.isType('line-number')
-      @removeFromLineDecorationCaches(decoration, new Range(change.oldTailScreenPosition, change.oldHeadScreenPosition))
-      @addToLineDecorationCaches(decoration, new Range(change.newTailScreenPosition, change.newHeadScreenPosition))
-      @updateLinesState() if decoration.isType('line')
-      @updateLineNumbersState() if decoration.isType('line-number')
+      intersectsVisibleRowRange = false
+      startRow = @computeStartRow()
+      endRow = @computeEndRow()
+      oldRange = new Range(change.oldTailScreenPosition, change.oldHeadScreenPosition)
+      newRange = new Range(change.newTailScreenPosition, change.newHeadScreenPosition)
+
+      if oldRange.intersectsRowRange(startRow, endRow - 1)
+        @removeFromLineDecorationCaches(decoration, oldRange)
+        intersectsVisibleRowRange = true
+
+      if newRange.intersectsRowRange(startRow, endRow - 1)
+        @addToLineDecorationCaches(decoration, newRange)
+        intersectsVisibleRowRange = true
+
+      if intersectsVisibleRowRange
+        @updateLinesState() if decoration.isType('line')
+        @updateLineNumbersState() if decoration.isType('line-number')
+
     if decoration.isType('highlight')
       @updateHighlightState(decoration)
+
     if decoration.isType('overlay')
       @updateOverlaysState()