From 2c73b0fb449899aca62f9e7233ae48e5594092cb Mon Sep 17 00:00:00 2001
From: Antoine Vandecreme <ant.vand@gmail.com>
Date: Fri, 9 Oct 2015 14:15:54 -0400
Subject: [PATCH] Use Math.round instead of Math.floor and Math.ceil for
 overlay placement.

---
 changelog.txt            |  1 +
 src/overlay.js           |  4 ++--
 test/modules/overlays.js | 20 ++++++++++----------
 3 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/changelog.txt b/changelog.txt
index bfab2bad..25685ca1 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -29,6 +29,7 @@ OPENSEADRAGON CHANGELOG
 * Fix for Chrome (v45) issue that key is sometimes undefined outside of the for-in loop (#730)
 * World.removeAll now cancels any in-flight image loads; same for Viewer.open and Viewer.close (#734)
 * Optimized adding large numbers of items to the world with collectionMode (#735)
+* Fix overlays position (use rounding instead of flooring and ceiling)
 
 2.0.0:
 
diff --git a/src/overlay.js b/src/overlay.js
index 0484ead6..2fe72413 100644
--- a/src/overlay.js
+++ b/src/overlay.js
@@ -250,8 +250,8 @@
 
             this.adjust( position, size );
 
-            position = position.apply( Math.floor );
-            size     = size.apply( Math.ceil );
+            position = position.apply( Math.round );
+            size     = size.apply( Math.round );
 
             // rotate the position of the overlay
             // TODO only rotate overlays if in canvas mode
diff --git a/test/modules/overlays.js b/test/modules/overlays.js
index 00341ce8..3e26b4c4 100644
--- a/test/modules/overlays.js
+++ b/test/modules/overlays.js
@@ -241,20 +241,20 @@
             var viewport = viewer.viewport;
 
             var expPosition = viewport.imageToViewerElementCoordinates(
-                new OpenSeadragon.Point( 13, 120 ) ).apply( Math.floor );
+                new OpenSeadragon.Point( 13, 120 ) ).apply( Math.round );
             var actPosition = $( "#overlay" ).position();
             equal( actPosition.left, expPosition.x, "X position mismatch " + contextMessage );
             equal( actPosition.top, expPosition.y, "Y position mismatch " + contextMessage );
 
             var zoom = viewport.viewportToImageZoom( viewport.getZoom( true ) );
-            var expectedWidth = Math.ceil( 124 * zoom );
-            var expectedHeight = Math.ceil( 132 * zoom );
+            var expectedWidth = Math.round( 124 * zoom );
+            var expectedHeight = Math.round( 132 * zoom );
             equal( $( "#overlay" ).width(), expectedWidth, "Width mismatch " + contextMessage );
             equal( $( "#overlay" ).height( ), expectedHeight, "Height mismatch " + contextMessage );
 
 
             expPosition = viewport.imageToViewerElementCoordinates(
-                new OpenSeadragon.Point( 400, 500 ) ).apply( Math.floor );
+                new OpenSeadragon.Point( 400, 500 ) ).apply( Math.round );
             actPosition = $( "#fixed-overlay" ).position();
             equal( actPosition.left, expPosition.x, "Fixed overlay X position mismatch " + contextMessage );
             equal( actPosition.top, expPosition.y, "Fixed overlay Y position mismatch " + contextMessage );
@@ -305,7 +305,7 @@
             var viewport = viewer.viewport;
 
             var expPosition = viewport.viewportToViewerElementCoordinates(
-                new OpenSeadragon.Point( 0.2, 0.1 ) ).apply( Math.floor );
+                new OpenSeadragon.Point( 0.2, 0.1 ) ).apply( Math.round );
             var actPosition = $( "#overlay" ).position();
             equal( actPosition.left, expPosition.x, "X position mismatch " + contextMessage );
             equal( actPosition.top, expPosition.y, "Y position mismatch " + contextMessage );
@@ -317,7 +317,7 @@
 
 
             expPosition = viewport.viewportToViewerElementCoordinates(
-                new OpenSeadragon.Point( 0.5, 0.6 ) ).apply( Math.floor );
+                new OpenSeadragon.Point( 0.5, 0.6 ) ).apply( Math.round );
             actPosition = $( "#fixed-overlay" ).position();
             equal( actPosition.left, expPosition.x, "Fixed overlay X position mismatch " + contextMessage );
             equal( actPosition.top, expPosition.y, "Fixed overlay Y position mismatch " + contextMessage );
@@ -373,7 +373,7 @@
             var viewport = viewer.viewport;
 
             var expPosition = viewport.viewportToViewerElementCoordinates(
-                new OpenSeadragon.Point( 0.2, 0.1 ) ).apply( Math.floor );
+                new OpenSeadragon.Point( 0.2, 0.1 ) ).apply( Math.round );
             var actPosition = $( "#overlay" ).position();
             equal( actPosition.left, expPosition.x, "X position mismatch " + contextMessage );
             equal( actPosition.top, expPosition.y, "Y position mismatch " + contextMessage );
@@ -384,7 +384,7 @@
 
             var expPosition = viewport.viewportToViewerElementCoordinates(
                 new OpenSeadragon.Point( 0.5, 0.6 ) )
-                .apply( Math.floor )
+                .apply( Math.round )
                 .plus( expectedOffset );
             var actPosition = $( "#fixed-overlay" ).position();
             equal( actPosition.left, expPosition.x, "Fixed overlay X position mismatch " + contextMessage );
@@ -447,7 +447,7 @@
 
             var expPosition = viewport.viewportToViewerElementCoordinates(
                 new OpenSeadragon.Point( 0.5, 0.6 ) )
-                .apply( Math.floor )
+                .apply( Math.round )
                 .plus( expectedOffset );
             var actPosition = $( "#fixed-overlay" ).position();
             equal( actPosition.left, expPosition.x, "Fixed overlay X position mismatch " + contextMessage );
@@ -501,7 +501,7 @@
 
             var expPosition = viewport.viewportToViewerElementCoordinates(
                 new OpenSeadragon.Point( 0.5, 0.6 ) )
-                .apply( Math.floor )
+                .apply( Math.round )
                 .plus( expectedOffset );
             var actPosition = $( "#fixed-overlay" ).position();
             equal( actPosition.left, expPosition.x, "Fixed overlay X position mismatch " + contextMessage );