From 3e5609244530943da9a7ae559950affa4f7628fc Mon Sep 17 00:00:00 2001
From: Antoine Vandecreme <ant.vand@gmail.com>
Date: Tue, 26 Jan 2016 15:59:10 -0500
Subject: [PATCH] Fix tests.

---
 src/tile.js | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/tile.js b/src/tile.js
index 4adb7a1d..f8861cd7 100644
--- a/src/tile.js
+++ b/src/tile.js
@@ -351,10 +351,13 @@ $.Tile.prototype = /** @lends OpenSeadragon.Tile.prototype */{
      * @return {OpenSeadragon.Point}
      */
     getTranslationForEdgeSmoothing: function(scale, canvasSize, sketchCanvasSize) {
-        var sketchCanvasDelta = new $.Point(
-            Math.ceil((sketchCanvasSize.x - canvasSize.x) / 2),
-            Math.ceil((sketchCanvasSize.y - canvasSize.y) / 2));
-        return sketchCanvasDelta.minus(
+        // The translation vector must have positive values, otherwise the image goes a bit off
+        // the sketch canvas to the top and left and we must use negative coordinates to repaint it
+        // to the main canvas. In that case, some browsers throw:
+        // INDEX_SIZE_ERR: DOM Exception 1: Index or size was negative, or greater than the allowed value.
+        var x = Math.max(1, Math.ceil((sketchCanvasSize.x - canvasSize.x) / 2));
+        var y = Math.max(1, Math.ceil((sketchCanvasSize.y - canvasSize.y) / 2));
+        return new $.Point(x, y).minus(
             this.position
                 .times($.pixelDensityRatio)
                 .times(scale || 1)