From 2dd8a65e632dab7aaf0da4710a341de83551a8c2 Mon Sep 17 00:00:00 2001
From: Jonathan Lake <jonathan.lake@uphs.upenn.edu>
Date: Tue, 21 Aug 2018 17:39:46 -0400
Subject: [PATCH] Adds option to set rotation increment for nav buttons and
 keyboard; Issue 1518

---
 src/openseadragon.js |  4 ++++
 src/viewer.js        | 27 ++++++++++-----------------
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/openseadragon.js b/src/openseadragon.js
index 77616346..74851e94 100644
--- a/src/openseadragon.js
+++ b/src/openseadragon.js
@@ -271,6 +271,9 @@
   *     events between different devices, causing the faster devices to slow down enough to make the zoom control
   *     more manageable.
   *
+  * @property {Number} [rotationIncrement=90]
+  *     The number of degrees to rotate right or left when the rotate buttons or keyboard shortcuts are activated.
+  *
   * @property {Number} [pixelsPerWheelLine=40]
   *     For pixel-resolution scrolling devices, the number of pixels equal to one scroll line.
   *
@@ -1137,6 +1140,7 @@ function OpenSeadragon( options ){
             autoResize:             true,
             preserveImageSizeOnResize: false, // requires autoResize=true
             minScrollDeltaTime:     50,
+            rotationIncrement:      90,
 
             //DEFAULT CONTROL SETTINGS
             showSequenceControl:     true,  //SEQUENCE
diff --git a/src/viewer.js b/src/viewer.js
index b91cfd7b..2adf8bb1 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -2640,19 +2640,19 @@ function onCanvasKeyPress( event ) {
                   this.viewport.applyConstraints();
                 }
                 return false;
-            case 114: //r - 90 degrees clockwise rotation
+            case 114: //r - clockwise rotation
               if(this.viewport.flipped){
-                this.viewport.setRotation(this.viewport.degrees - 90);
+                this.viewport.setRotation($.positiveModulo(this.viewport.degrees - this.rotationIncrement, 360));
               } else{
-                this.viewport.setRotation(this.viewport.degrees + 90);
+                this.viewport.setRotation($.positiveModulo(this.viewport.degrees + this.rotationIncrement, 360));
               }
               this.viewport.applyConstraints();
               return false;
-            case 82: //R - 90 degrees counterclockwise  rotation
+            case 82: //R - counterclockwise  rotation
               if(this.viewport.flipped){
-                this.viewport.setRotation(this.viewport.degrees + 90);
+                this.viewport.setRotation($.positiveModulo(this.viewport.degrees + this.rotationIncrement, 360));
               } else{
-                this.viewport.setRotation(this.viewport.degrees - 90);
+                this.viewport.setRotation($.positiveModulo(this.viewport.degrees - this.rotationIncrement, 360));
               }
               this.viewport.applyConstraints();
               return false;
@@ -3490,38 +3490,31 @@ function onFullScreen() {
     }
 }
 
-/**
- * Note: The current rotation feature is limited to 90 degree turns.
- */
 function onRotateLeft() {
     if ( this.viewport ) {
         var currRotation = this.viewport.getRotation();
 
         if ( this.viewport.flipped ){
-          currRotation = $.positiveModulo(currRotation + 90, 360);
+          currRotation = $.positiveModulo(currRotation + this.rotationIncrement, 360);
         } else {
-          currRotation = $.positiveModulo(currRotation - 90, 360);
+          currRotation = $.positiveModulo(currRotation - this.rotationIncrement, 360);
         }
         this.viewport.setRotation(currRotation);
     }
 }
 
-/**
- * Note: The current rotation feature is limited to 90 degree turns.
- */
 function onRotateRight() {
     if ( this.viewport ) {
         var currRotation = this.viewport.getRotation();
 
         if ( this.viewport.flipped ){
-          currRotation = $.positiveModulo(currRotation - 90, 360);
+          currRotation = $.positiveModulo(currRotation - this.rotationIncrement, 360);
         } else {
-          currRotation = $.positiveModulo(currRotation + 90, 360);
+          currRotation = $.positiveModulo(currRotation + this.rotationIncrement, 360);
         }
         this.viewport.setRotation(currRotation);
     }
 }
-
 /**
  * Note: When pressed flip control button
  */