From c7cc404c4232256542a42b792cb22e6d97804dc9 Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Fri, 28 Aug 2015 13:39:14 -0600
Subject: [PATCH] Simplify page-up/page-down
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We simply move the cursor up or down by the number of whole lines that
fit on screen, allowing autoscroll to adjust the scroll position. This
causes there to be a margin under the location to which we move the
cursor, but I think it’s better to provide context and keep the
autoscroll experience consistent when using the keyboard.
---
 spec/text-editor-spec.coffee | 13 +------------
 src/text-editor.coffee       |  6 +-----
 2 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/spec/text-editor-spec.coffee b/spec/text-editor-spec.coffee
index 739e3a3c4..7d9e17dc2 100644
--- a/spec/text-editor-spec.coffee
+++ b/spec/text-editor-spec.coffee
@@ -4535,26 +4535,21 @@ describe "TextEditor", ->
       expect(editor.getScrollBottom()).toBe (9 + editor.getVerticalScrollMargin()) * 10
 
   describe ".pageUp/Down()", ->
-    it "scrolls one screen height up or down and moves the cursor one page length", ->
+    it "moves the cursor down one page length", ->
       editor.setLineHeightInPixels(10)
       editor.setHeight(50)
-      expect(editor.getScrollHeight()).toBe 130
       expect(editor.getCursorBufferPosition().row).toBe 0
 
       editor.pageDown()
-      expect(editor.getScrollTop()).toBe 50
       expect(editor.getCursorBufferPosition().row).toBe 5
 
       editor.pageDown()
-      expect(editor.getScrollTop()).toBe 80
       expect(editor.getCursorBufferPosition().row).toBe 10
 
       editor.pageUp()
-      expect(editor.getScrollTop()).toBe 30
       expect(editor.getCursorBufferPosition().row).toBe 5
 
       editor.pageUp()
-      expect(editor.getScrollTop()).toBe 0
       expect(editor.getCursorBufferPosition().row).toBe 0
 
   describe ".selectPageUp/Down()", ->
@@ -4565,28 +4560,22 @@ describe "TextEditor", ->
       expect(editor.getCursorBufferPosition().row).toBe 0
 
       editor.selectPageDown()
-      expect(editor.getScrollTop()).toBe 30
       expect(editor.getSelectedBufferRanges()).toEqual [[[0, 0], [5, 0]]]
 
       editor.selectPageDown()
-      expect(editor.getScrollTop()).toBe 80
       expect(editor.getSelectedBufferRanges()).toEqual [[[0, 0], [10, 0]]]
 
       editor.selectPageDown()
-      expect(editor.getScrollTop()).toBe 80
       expect(editor.getSelectedBufferRanges()).toEqual [[[0, 0], [12, 2]]]
 
       editor.moveToBottom()
       editor.selectPageUp()
-      expect(editor.getScrollTop()).toBe 50
       expect(editor.getSelectedBufferRanges()).toEqual [[[7, 0], [12, 2]]]
 
       editor.selectPageUp()
-      expect(editor.getScrollTop()).toBe 0
       expect(editor.getSelectedBufferRanges()).toEqual [[[2, 0], [12, 2]]]
 
       editor.selectPageUp()
-      expect(editor.getScrollTop()).toBe 0
       expect(editor.getSelectedBufferRanges()).toEqual [[[0, 0], [12, 2]]]
 
   describe '.get/setPlaceholderText()', ->
diff --git a/src/text-editor.coffee b/src/text-editor.coffee
index b8c2a76fb..1f5cc6363 100644
--- a/src/text-editor.coffee
+++ b/src/text-editor.coffee
@@ -2898,14 +2898,10 @@ class TextEditor extends Model
   setVerticalScrollbarWidth: (width) -> @displayBuffer.setVerticalScrollbarWidth(width)
 
   pageUp: ->
-    newScrollTop = @getScrollTop() - @getHeight()
     @moveUp(@getRowsPerPage())
-    @setScrollTop(newScrollTop)
 
   pageDown: ->
-    newScrollTop = @getScrollTop() + @getHeight()
     @moveDown(@getRowsPerPage())
-    @setScrollTop(newScrollTop)
 
   selectPageUp: ->
     @selectUp(@getRowsPerPage())
@@ -2915,7 +2911,7 @@ class TextEditor extends Model
 
   # Returns the number of rows per page
   getRowsPerPage: ->
-    Math.max(1, Math.ceil(@getHeight() / @getLineHeightInPixels()))
+    Math.max(1, Math.floor(@getHeight() / @getLineHeightInPixels()))
 
   ###
   Section: Config