WIP: LineWrapper change events cover all screen lines.

Because the editor only repaints entire lines at a time, the loss of
precision shouldn't matter.

spec/atom/line-wrapper-spec.coffee

@@ -39,6 +39,47 @@ describe "LineWrapper", ->
       changeHandler = jasmine.createSpy('changeHandler')
       wrapper.on 'change', changeHandler
 
+    fdescribe "when a single buffer line is updated", ->
+      describe "when the number of screen lines remains the same for the changed buffer line", ->
+        it "re-wraps the existing lines and emits a change event for all its screen lines", ->
+          buffer.insert([6, 28], '1234567')
+          expect(tokensText(wrapper.tokensForScreenRow(7))).toBe '      current < pivot ? left1234567.push(current) '
+          expect(tokensText(wrapper.tokensForScreenRow(8))).toBe ': right.push(current);'
+          expect(tokensText(wrapper.tokensForScreenRow(9))).toBe '    }'
+
+          expect(changeHandler).toHaveBeenCalled()
+          [event] = changeHandler.argsForCall[0]
+          expect(event.oldRange).toEqual([[7, 0], [8, 20]])
+          expect(event.newRange).toEqual([[7, 0], [8, 22]])
+
+      describe "when the number of screen lines increases for the changed buffer line", ->
+        it "re-wraps and adds an additional screen line and emits a change event for all screen lines", ->
+          buffer.insert([6, 28], '1234567890')
+          expect(tokensText(wrapper.tokensForScreenRow(7))).toBe '      current < pivot ? '
+          expect(tokensText(wrapper.tokensForScreenRow(8))).toBe 'left1234567890.push(current) : '
+          expect(tokensText(wrapper.tokensForScreenRow(9))).toBe 'right.push(current);'
+          expect(tokensText(wrapper.tokensForScreenRow(10))).toBe '    }'
+
+          expect(changeHandler).toHaveBeenCalled()
+          [event] = changeHandler.argsForCall[0]
+          expect(event.oldRange).toEqual([[7, 0], [8, 20]])
+          expect(event.newRange).toEqual([[7, 0], [9, 20]])
+
+      describe "when the number of screen lines decreases for the changed buffer line", ->
+        it "re-wraps and removes a screen line and emits a change event for all screen lines", ->
+          buffer.change(new Range([6, 24], [6, 42]), '')
+          expect(tokensText(wrapper.tokensForScreenRow(7))).toBe '      current < pivot ?  : right.push(current);'
+          expect(tokensText(wrapper.tokensForScreenRow(8))).toBe '    }'
+
+          expect(changeHandler).toHaveBeenCalled()
+          [event] = changeHandler.argsForCall[0]
+          expect(event.oldRange).toEqual([[7, 0], [8, 20]])
+          expect(event.newRange).toEqual([[7, 0], [7, 47]])
+
+    describe "when buffer lines are inserted", ->
+
+    describe "when buffer lines are removed", ->
+
     describe "when an unwrapped line is updated", ->
       describe "when the update does not cause the line to wrap", ->
         it "updates tokens for the corresponding screen line and emits a change event", ->
@@ -88,7 +129,7 @@ describe "LineWrapper", ->
     describe "when a wrapped line is updated", ->
       describe "when the old text spans multiple screen lines", ->
         describe "when the new text spans fewer screen lines than the old text", ->
-          fit "updates tokens for the corresponding screen lines and emits a change event", ->
+          it "updates tokens for the corresponding screen lines and emits a change event", ->
             wrapper.setMaxLength(15)
 
             range = new Range([3, 8], [3, 47])

src/atom/line-wrapper.coffee

@@ -9,19 +9,27 @@ class LineWrapper
     @buffer = @highlighter.buffer
     @buildWrappedLines()
     @highlighter.on 'change', (e) =>
-      oldRange = @screenRangeFromBufferRange(e.oldRange)
-      oldCount = @wrappedLines[e.oldRange.start.row].screenLines.length
+      oldRange = new Range
+
+      bufferRow = e.oldRange.start.row
+      oldRange.start.row = @firstScreenRowForBufferRow(bufferRow)
+      oldRange.end.row = @lastScreenRowForBufferRow(bufferRow)
+      oldRange.end.column = _.last(@wrappedLines[bufferRow].screenLines).textLength
+
       @wrappedLines[e.oldRange.start.row] = @buildWrappedLineForBufferRow(e.newRange.start.row)
-      newCount = @wrappedLines[e.oldRange.start.row].screenLines.length
 
-      newRange = @screenRangeFromBufferRange(e.newRange)
-
-      if newCount > oldCount
-        newRange.end.row = newRange.start.row + (newCount - 1)
-        newRange.end.column = @tokensForScreenRow(newRange.end.row).textLength
+      newRange = oldRange.copy()
+      newRange.end.row = @lastScreenRowForBufferRow(bufferRow)
+      newRange.end.column = _.last(@wrappedLines[bufferRow].screenLines).textLength
 
       @trigger 'change', { oldRange, newRange }
 
+  firstScreenRowForBufferRow: (bufferRow) ->
+    @screenPositionFromBufferPosition([bufferRow, 0]).row
+
+  lastScreenRowForBufferRow: (bufferRow) ->
+    @screenPositionFromBufferPosition([bufferRow, @buffer.getLine(bufferRow).length]).row
+
   setMaxLength: (@maxLength) ->
     @buildWrappedLines()
 

src/atom/range.coffee

@@ -3,7 +3,7 @@ _ = require 'underscore'
 
 module.exports =
 class Range
-  constructor: (pointA, pointB) ->
+  constructor: (pointA = new Point(0, 0), pointB = new Point(0, 0)) ->
     pointA = Point.fromObject(pointA)
     pointB = Point.fromObject(pointB)