From d7ba07f139e3be3c2f4d4c98f569600b10906c04 Mon Sep 17 00:00:00 2001
From: Eric Mannes <emannes@gmail.com>
Date: Mon, 3 Aug 2015 07:33:39 -0700
Subject: [PATCH] Scrolls to cursor if not visible after enter/delete/backspace
 pressed, fixing issue #433

---
 src/core/editor.coffee       | 13 +++++++++++++
 src/modules/keyboard.coffee  |  2 ++
 test/unit/core/editor.coffee | 29 +++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)

diff --git a/src/core/editor.coffee b/src/core/editor.coffee
index 6736f61a64..7cfcf3f4f4 100644
--- a/src/core/editor.coffee
+++ b/src/core/editor.coffee
@@ -109,6 +109,19 @@ class Editor
       top: bounds.top - containerBounds.top
     }
 
+  scrollCursorIntoView: () ->
+    return unless @selection.range
+    startBounds = this.getBounds(@selection.range.start)
+    endBounds = this.getBounds(@selection.range.end)
+    containerBounds = @root.parentNode.getBoundingClientRect()
+    containerHeight = containerBounds.bottom - containerBounds.top
+    if containerHeight < endBounds.top + endBounds.height
+      [line, offset] = @doc.findLineAt(@selection.range.end)
+      line.node.scrollIntoView(false)
+    else if startBounds.top < 0
+      [line, offset] = @doc.findLineAt(@selection.range.start)
+      line.node.scrollIntoView()
+
   _deleteAt: (index, length) ->
     return if length <= 0
     @selection.shiftAfter(index, -1 * length, =>
diff --git a/src/modules/keyboard.coffee b/src/modules/keyboard.coffee
index 8118d80f99..980c4cee5d 100644
--- a/src/modules/keyboard.coffee
+++ b/src/modules/keyboard.coffee
@@ -60,6 +60,7 @@ class Keyboard
         @toolbar.setActive(format, value) if @toolbar?
         return
       )
+      @quill.editor.scrollCursorIntoView()
       return false
     )
 
@@ -78,6 +79,7 @@ class Keyboard
               @quill.deleteText(range.start - 1, range.start, Quill.sources.USER)
           else if range.start < @quill.getLength() - 1
             @quill.deleteText(range.start, range.start + 1, Quill.sources.USER)
+      @quill.editor.scrollCursorIntoView()
       return false
     )
 
diff --git a/test/unit/core/editor.coffee b/test/unit/core/editor.coffee
index 825b0b271c..f111a8615e 100644
--- a/test/unit/core/editor.coffee
+++ b/test/unit/core/editor.coffee
@@ -395,4 +395,33 @@ describe('Editor', ->
       )
     )
   )
+
+  describe('scrollCursorIntoView()', ->
+    beforeEach( ->
+      @editor.root.style.height = "50px"
+      @editor.root.style.overflow = "auto"
+      @editor.root.innerHTML = '<div><span style="font-size: 32px;">a<br>b<br>c<br>d</span></div>'
+    )
+
+    it('scrolls down when cursor too low', ->
+      bounds = @editor.getBounds(7)
+      expect(bounds.top).toBeGreaterThan(100)
+      @editor.selection.setRange(new Quill.Lib.Range(7, 7))
+      @editor.scrollCursorIntoView()
+      bounds = @editor.getBounds(7)
+      expect(bounds.top).not.toBeLessThan(0)
+      expect(bounds.top + bounds.height).not.toBeGreaterThan(100)
+    )
+
+    it('scrolls up when cursor too high', ->
+      @editor.root.scrollTop = 50
+      bounds = @editor.getBounds(1)
+      expect(bounds.top + bounds.height).toBeLessThan(0)
+      @editor.selection.setRange(new Quill.Lib.Range(1, 1))
+      @editor.scrollCursorIntoView()
+      bounds = @editor.getBounds(1)
+      expect(bounds.top).not.toBeLessThan(0)
+      expect(bounds.top + bounds.height).not.toBeGreaterThan(100)
+    )
+  )
 )