From 2394f25b92edaa0fa64bed856ccd87a339d2438e Mon Sep 17 00:00:00 2001
From: Ben Ogle <ogle.ben@gmail.com>
Date: Mon, 30 Sep 2013 14:33:06 -0700
Subject: [PATCH] Add the leftPixel cache back in

---
 spec/editor-spec.coffee | 26 +++++++++++++++++++++++++-
 src/editor.coffee       | 33 +++++++++++++++++++++------------
 2 files changed, 46 insertions(+), 13 deletions(-)

diff --git a/spec/editor-spec.coffee b/spec/editor-spec.coffee
index 1ad1c527c..f6b6d8a59 100644
--- a/spec/editor-spec.coffee
+++ b/spec/editor-spec.coffee
@@ -2199,10 +2199,34 @@ describe "Editor", ->
         expect(editor.pixelPositionForBufferPosition([2,7])).toEqual top: 0, left: 0
 
     describe "when the editor is attached and visible", ->
-      it "returns the top and left pixel positions", ->
+      beforeEach ->
         editor.attachToDom()
+
+      it "returns the top and left pixel positions", ->
         expect(editor.pixelPositionForBufferPosition([2,7])).toEqual top: 40, left: 70
 
+      it "caches the left position", ->
+        editor.renderedLines.css('font-size', '16px')
+        expect(editor.pixelPositionForBufferPosition([2,8])).toEqual top: 40, left: 80
+
+        # make characters smaller
+        editor.renderedLines.css('font-size', '15px')
+
+        expect(editor.pixelPositionForBufferPosition([2,8])).toEqual top: 40, left: 80
+
+      it "breaks left position cache when line is changed", ->
+        editor.renderedLines.css('font-size', '16px')
+        expect(editor.pixelPositionForBufferPosition([2,8])).toEqual top: 40, left: 80
+
+        editor.setCursorBufferPosition([2, 8])
+        editor.insertText("a")
+
+        # make characters smaller
+        editor.renderedLines.css('font-size', '15px')
+
+        expect(editor.pixelPositionForBufferPosition([2,8])).toEqual top: 40, left: 72
+
+
   describe "when clicking in the gutter", ->
     beforeEach ->
       editor.attachToDom()
diff --git a/src/editor.coffee b/src/editor.coffee
index a1791d1a6..ba18118a9 100644
--- a/src/editor.coffee
+++ b/src/editor.coffee
@@ -94,8 +94,7 @@ class Editor extends View
     @pendingChanges = []
     @newCursors = []
     @newSelections = []
-    @lineId = 0
-    @pixelLeftCache = {}
+    @pixelLeftCache = new WeakMap()
 
     if editSession?
       @edit(editSession)
@@ -1330,10 +1329,6 @@ class Editor extends View
 
   clearDirtyRanges: (intactRanges) ->
     renderedLines = @renderedLines[0]
-    killLine = (line) ->
-      next = line.nextSibling
-      renderedLines.removeChild(line)
-      next
 
     if intactRanges.length == 0
       @renderedLines.empty()
@@ -1341,13 +1336,19 @@ class Editor extends View
       domPosition = 0
       for intactRange in intactRanges
         while intactRange.domStart > domPosition
-          currentLine = killLine(currentLine)
+          currentLine = @clearLine(currentLine)
           domPosition++
         for i in [intactRange.start..intactRange.end]
           currentLine = currentLine.nextSibling
           domPosition++
       while currentLine
-        currentLine = killLine(currentLine)
+        currentLine = @clearLine(currentLine)
+
+  clearLine: (lineElement) ->
+    @pixelLeftCache.delete(lineElement)
+    next = lineElement.nextSibling
+    @renderedLines[0].removeChild(lineElement)
+    next
 
   fillDirtyRanges: (intactRanges, renderFrom, renderTo) ->
     renderedLines = @renderedLines[0]
@@ -1427,9 +1428,9 @@ class Editor extends View
   htmlForScreenLine: (screenLine, screenRow) ->
     { tokens, text, lineEnding, fold, isSoftWrapped } =  screenLine
     if fold
-      attributes = { class: 'fold line', 'fold-id': fold.id, 'line-id': @lineId++ }
+      attributes = { class: 'fold line', 'fold-id': fold.id }
     else
-      attributes = { class: 'line', 'line-id': @lineId++ }
+      attributes = { class: 'line' }
 
     invisibles = @invisibles if @showInvisibles
     eolInvisibles = @getEndOfLineInvisibles(screenLine)
@@ -1519,11 +1520,19 @@ class Editor extends View
       @renderedLines[0].removeChild(lineElement)
     { top: row * @lineHeight, left }
 
-  positionLeftForLineAndColumn: (lineElement, column) ->
-    chars = lineElement.find('.character')
+  positionLeftForLineAndColumn: (line, column) ->
+    lineCache = @pixelLeftCache.get(line[0])
+    @pixelLeftCache.set(line[0], lineCache = {}) unless lineCache?
+
+    return lineCache[column] if lineCache[column]?
+
+    chars = line.find('.character')
     left = 0
     for i in [0...column]
       left += chars[i].offsetWidth if chars[i]
+
+    lineCache[column] = left
+
     left
 
   pixelOffsetForScreenPosition: (position) ->