From d042d15a5097ed4ae6672c9730ef2b4dc7a835ca Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Mon, 7 Jul 2014 15:21:48 -0600
Subject: [PATCH] Autoscroll to cursor on undo

Fixes #2815

This commit changes our autoscroll strategy for cursors significantly.

Originally, we were autoscrolling whenever the cursor's marker changed
positions. This worked well, except we didn't end up autoscrolling when
the user *attempted* to move the cursor to an invalid position, such as
moving down at the end of the buffer, due to the fact that the marker
wouldn't change.

Then, we moved to always requesting an autoscroll whenever a position
change was requested via Cursor::changePosition. This missed out on
moving the cursor when inserting text, so we then also added an explicit
autoscroll call when inserting text.

This had the problem of not autoscrolling due to undo. So finally, this
solution combines explicit autoscroll in ::changePosition to capture
intent, as well as implicit autoscrolling whenever the cursor's marker
position changes due to a textual change in the buffer. This captures
undo/redo correctly.
---
 spec/editor-spec.coffee | 6 ++++++
 src/cursor.coffee       | 1 +
 src/selection.coffee    | 2 --
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/spec/editor-spec.coffee b/spec/editor-spec.coffee
index 290710df7..f6b4b78dd 100644
--- a/spec/editor-spec.coffee
+++ b/spec/editor-spec.coffee
@@ -792,6 +792,12 @@ describe "Editor", ->
         editor.insertNewline()
         expect(editor.getScrollBottom()).toBe 15 * 10
 
+      it "autoscrolls to the cursor when it moves due to undo", ->
+        editor.insertText('abc')
+        editor.setScrollTop(Infinity)
+        editor.undo()
+        expect(editor.getScrollTop()).toBe 0
+
   describe "selection", ->
     selection = null
 
diff --git a/src/cursor.coffee b/src/cursor.coffee
index 7ab62ae81..58bf31395 100644
--- a/src/cursor.coffee
+++ b/src/cursor.coffee
@@ -28,6 +28,7 @@ class Cursor extends Model
 
       # Supports old editor view
       @needsAutoscroll ?= @isLastCursor() and !textChanged
+      @autoscroll() if @editor.manageScrollPosition and @isLastCursor() and textChanged
 
       @goalColumn = null
 
diff --git a/src/selection.coffee b/src/selection.coffee
index 93bebbe7c..c34374299 100644
--- a/src/selection.coffee
+++ b/src/selection.coffee
@@ -326,8 +326,6 @@ class Selection extends Model
 
     newBufferRange = @editor.buffer.setTextInRange(oldBufferRange, text, pick(options, 'undo'))
 
-    @cursor.autoscroll() if @editor.manageScrollPosition and @cursor.isLastCursor()
-
     if options.select
       @setBufferRange(newBufferRange, reversed: wasReversed)
     else