diff --git a/src/drawer.js b/src/drawer.js
index 6d989efd..32c0c3d5 100644
--- a/src/drawer.js
+++ b/src/drawer.js
@@ -232,6 +232,22 @@ $.Drawer.prototype = /** @lends OpenSeadragon.Drawer.prototype */{
         }
     },
 
+    /**
+     * Translates from OpenSeadragon viewer rectangle to drawer rectangle.
+     * @param {OpenSeadragon.Rect} rectangle - The rectangle in viewport coordinate system.
+     */
+    viewportToDrawerRectangle: function(rectangle) {
+        var topLeft = this.viewport.pixelFromPoint(rectangle.getTopLeft(), true);
+        var size = this.viewport.deltaPixelsFromPoints(rectangle.getSize(), true);
+
+        return new $.Rect(
+            topLeft.x * $.pixelDensityRatio,
+            topLeft.y * $.pixelDensityRatio,
+            size.x    * $.pixelDensityRatio,
+            size.y    * $.pixelDensityRatio
+        );
+    },
+
     /**
      * Draws the given tile.
      * @param {OpenSeadragon.Tile} tile - The tile to draw.