Merge pull request #8558 from atom/ns-simplify-page-up-down

Simplify page-up/page-down

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()', ->

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