From f1276f59ded8ae5356dd0dff2bed5b1dc808e3c3 Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Tue, 1 Sep 2015 10:43:45 -0600
Subject: [PATCH] Autoscroll when mouse gets close to the edge of the editor
 scroll view

Previously, we required the cursor to exceed the bounds of the editor,
but that makes it impossible to scroll when the window is maximized.
---
 spec/text-editor-component-spec.coffee | 19 ++++++++++---------
 src/text-editor-component.coffee       | 22 +++++++++++++---------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/spec/text-editor-component-spec.coffee b/spec/text-editor-component-spec.coffee
index 3feb70da7..7e1b2fd64 100644
--- a/spec/text-editor-component-spec.coffee
+++ b/spec/text-editor-component-spec.coffee
@@ -1850,7 +1850,7 @@ describe "TextEditorComponent", ->
         nextAnimationFrame()
         expect(editor.getSelectedScreenRange()).toEqual [[2, 4], [10, 0]]
 
-      it "autoscrolls when the cursor exceeds the boundaries of the editor", ->
+      it "autoscrolls when the cursor approaches the boundaries of the editor", ->
         wrapperNode.style.height = '100px'
         wrapperNode.style.width = '100px'
         component.measureDimensions()
@@ -1860,26 +1860,26 @@ describe "TextEditorComponent", ->
         expect(editor.getScrollLeft()).toBe(0)
 
         linesNode.dispatchEvent(buildMouseEvent('mousedown', {clientX: 0, clientY: 0}, which: 1))
-        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 150, clientY: 50}, which: 1))
+        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 100, clientY: 50}, which: 1))
         nextAnimationFrame()
 
         expect(editor.getScrollTop()).toBe(0)
         expect(editor.getScrollLeft()).toBeGreaterThan(0)
 
-        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 150, clientY: 150}, which: 1))
+        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 100, clientY: 100}, which: 1))
         nextAnimationFrame()
         expect(editor.getScrollTop()).toBeGreaterThan(0)
 
         previousScrollTop = editor.getScrollTop()
         previousScrollLeft = editor.getScrollLeft()
 
-        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: -20, clientY: 50}, which: 1))
+        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 10, clientY: 50}, which: 1))
         nextAnimationFrame()
 
         expect(editor.getScrollTop()).toBe(previousScrollTop)
         expect(editor.getScrollLeft()).toBeLessThan(previousScrollLeft)
 
-        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: -20, clientY: -20}, which: 1))
+        linesNode.dispatchEvent(buildMouseEvent('mousemove', {clientX: 10, clientY: 10}, which: 1))
         nextAnimationFrame()
 
         expect(editor.getScrollTop()).toBeLessThan(previousScrollTop)
@@ -1995,7 +1995,7 @@ describe "TextEditorComponent", ->
 
         linesNode.dispatchEvent(buildMouseEvent('mousemove', clientCoordinatesForScreenPosition([8, 4]), which: 1))
         nextAnimationFrame()
-        expect(editor.getSelectedScreenRange()).toEqual [[5, 0], [9, 0]]
+        expect(editor.getSelectedScreenRange()).toEqual [[5, 0], [8, 0]]
         expect(editor.getScrollTop()).toBe maximalScrollTop # does not autoscroll upward (regression)
 
         linesNode.dispatchEvent(buildMouseEvent('mouseup', clientCoordinatesForScreenPosition([9, 3]), which: 1))
@@ -2086,7 +2086,7 @@ describe "TextEditorComponent", ->
         nextAnimationFrame()
         expect(editor.getLastSelection().isReversed()).toBe false
 
-      it "autoscrolls when the cursor exceeds the top or bottom of the editor", ->
+      it "autoscrolls when the cursor approaches the top or bottom of the editor", ->
         wrapperNode.style.height = 6 * lineHeightInPixels + 'px'
         component.measureDimensions()
         nextAnimationFrame()
@@ -2100,11 +2100,12 @@ describe "TextEditorComponent", ->
         expect(editor.getScrollTop()).toBeGreaterThan 0
         maxScrollTop = editor.getScrollTop()
 
-        gutterNode.dispatchEvent(buildMouseEvent('mousemove', clientCoordinatesForScreenRowInGutter(5)))
+
+        gutterNode.dispatchEvent(buildMouseEvent('mousemove', clientCoordinatesForScreenRowInGutter(10)))
         nextAnimationFrame()
         expect(editor.getScrollTop()).toBe maxScrollTop
 
-        gutterNode.dispatchEvent(buildMouseEvent('mousemove', clientCoordinatesForScreenRowInGutter(2)))
+        gutterNode.dispatchEvent(buildMouseEvent('mousemove', clientCoordinatesForScreenRowInGutter(7)))
         nextAnimationFrame()
         expect(editor.getScrollTop()).toBeLessThan maxScrollTop
 
diff --git a/src/text-editor-component.coffee b/src/text-editor-component.coffee
index fce46f35c..8ff7a0d77 100644
--- a/src/text-editor-component.coffee
+++ b/src/text-editor-component.coffee
@@ -545,20 +545,24 @@ class TextEditorComponent
       disposables.dispose()
 
     autoscroll = (mouseClientPosition) =>
-      editorClientRect = @domNode.getBoundingClientRect()
+      {top, bottom, left, right} = @scrollViewNode.getBoundingClientRect()
+      top += 30
+      bottom -= 30
+      left += 30
+      right -= 30
 
-      if mouseClientPosition.clientY < editorClientRect.top
-        mouseYDelta = editorClientRect.top - mouseClientPosition.clientY
+      if mouseClientPosition.clientY < top
+        mouseYDelta = top - mouseClientPosition.clientY
         yDirection = -1
-      else if mouseClientPosition.clientY > editorClientRect.bottom
-        mouseYDelta = mouseClientPosition.clientY - editorClientRect.bottom
+      else if mouseClientPosition.clientY > bottom
+        mouseYDelta = mouseClientPosition.clientY - bottom
         yDirection = 1
 
-      if mouseClientPosition.clientX < editorClientRect.left
-        mouseXDelta = editorClientRect.left - mouseClientPosition.clientX
+      if mouseClientPosition.clientX < left
+        mouseXDelta = left - mouseClientPosition.clientX
         xDirection = -1
-      else if mouseClientPosition.clientX > editorClientRect.right
-        mouseXDelta = mouseClientPosition.clientX - editorClientRect.right
+      else if mouseClientPosition.clientX > right
+        mouseXDelta = mouseClientPosition.clientX - right
         xDirection = 1
 
       if mouseYDelta?