From eae80ca46daeefc683291e1e19720f41dd993468 Mon Sep 17 00:00:00 2001
From: Ben Ogle <ogle.ben@gmail.com>
Date: Wed, 12 Nov 2014 11:50:22 -0800
Subject: [PATCH] Add a check for negative bounds when translating the overlay

---
 spec/text-editor-component-spec.coffee | 51 ++++++++++++++++++++++++++
 src/overlay-manager.coffee             |  6 ++-
 2 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/spec/text-editor-component-spec.coffee b/spec/text-editor-component-spec.coffee
index 41eaafece..ba95f371c 100644
--- a/spec/text-editor-component-spec.coffee
+++ b/spec/text-editor-component-spec.coffee
@@ -1319,6 +1319,57 @@ describe "TextEditorComponent", ->
         expect(overlay.style.left).toBe position.left + 'px'
         expect(overlay.style.top).toBe position.top - itemHeight + 'px'
 
+      describe "when the editor is very small", ->
+        beforeEach ->
+          gutterWidth = componentNode.querySelector('.gutter').offsetWidth
+          windowWidth = gutterWidth + 6 * editor.getDefaultCharWidth()
+          windowHeight = 6 * editor.getLineHeightInPixels()
+
+          wrapperNode.style.width = windowWidth + 'px'
+          wrapperNode.style.height = windowHeight + 'px'
+
+          component.measureHeightAndWidth()
+          nextAnimationFrame()
+
+        it "does not flip horizontally and force the overlay to have a negative left", ->
+          marker = editor.displayBuffer.markBufferRange([[0, 2], [0, 2]], invalidate: 'never')
+          decoration = editor.decorateMarker(marker, {type: 'overlay', item})
+          nextAnimationFrame()
+
+          position = editor.pixelPositionForBufferPosition([0, 2])
+
+          overlay = component.getTopmostDOMNode().querySelector('atom-overlay')
+          expect(overlay.style.left).toBe position.left + 'px'
+          expect(overlay.style.top).toBe position.top + editor.getLineHeightInPixels() + 'px'
+
+          editor.insertText('a')
+          nextAnimationFrame()
+
+          position = editor.pixelPositionForBufferPosition([0, 3])
+
+          expect(overlay.style.left).toBe position.left + 'px'
+          expect(overlay.style.top).toBe position.top + editor.getLineHeightInPixels() + 'px'
+
+        it "does not flip vertically and force the overlay to have a negative top", ->
+          marker = editor.displayBuffer.markBufferRange([[1, 0], [1, 0]], invalidate: 'never')
+          decoration = editor.decorateMarker(marker, {type: 'overlay', item})
+          nextAnimationFrame()
+
+          position = editor.pixelPositionForBufferPosition([1, 0])
+
+          overlay = component.getTopmostDOMNode().querySelector('atom-overlay')
+          expect(overlay.style.left).toBe position.left + 'px'
+          expect(overlay.style.top).toBe position.top + editor.getLineHeightInPixels() + 'px'
+
+          editor.insertNewline()
+          nextAnimationFrame()
+
+          position = editor.pixelPositionForBufferPosition([2, 0])
+
+          expect(overlay.style.left).toBe position.left + 'px'
+          expect(overlay.style.top).toBe position.top + editor.getLineHeightInPixels() + 'px'
+
+
       describe "when editor scroll position is not 0", ->
         it "flips horizontally when near the right edge", ->
           editor.setScrollLeft(2 * editor.getDefaultCharWidth())
diff --git a/src/overlay-manager.coffee b/src/overlay-manager.coffee
index 62b4780e4..aee83008d 100644
--- a/src/overlay-manager.coffee
+++ b/src/overlay-manager.coffee
@@ -36,10 +36,12 @@ class OverlayManager
     itemHeight = item.offsetHeight
 
     left = pixelPosition.left
-    left -= itemWidth if left + itemWidth - editor.getScrollLeft() > editor.getWidth()
+    if left + itemWidth - editor.getScrollLeft() > editor.getWidth() and left - itemWidth >= editor.getScrollLeft()
+      left -= itemWidth
 
     top = pixelPosition.top + lineHeightInPixels
-    top -= itemHeight + lineHeightInPixels if top + itemHeight - editor.getScrollTop() > editor.getHeight()
+    if top + itemHeight - editor.getScrollTop() > editor.getHeight() and top - itemHeight - lineHeightInPixels >= editor.getScrollTop()
+      top -= itemHeight + lineHeightInPixels
 
     overlay.style.top = top + 'px'
     overlay.style.left = left + 'px'