From f2c8db5db0c2e5868437e634d12eae7b3c0df958 Mon Sep 17 00:00:00 2001
From: Tom <tmpearce@gmail.com>
Date: Sat, 27 Apr 2024 16:38:30 -0400
Subject: [PATCH 1/2] fix #2517

---
 src/canvasdrawer.js | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/canvasdrawer.js b/src/canvasdrawer.js
index e755c97b..1ec6a10b 100644
--- a/src/canvasdrawer.js
+++ b/src/canvasdrawer.js
@@ -80,8 +80,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         // Canvas default is "true", so this will only be changed if user specifies "false" in the options or via setImageSmoothinEnabled.
         this._imageSmoothingEnabled = true;
 
-        this._viewportFlipped = false;
-
         // Since the tile-drawn and tile-drawing events are fired by this drawer, make sure handlers can be added for them
         this.viewer.allowEventHandler("tile-drawn");
         this.viewer.allowEventHandler("tile-drawing");
@@ -118,8 +116,8 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         this._prepareNewFrame(); // prepare to draw a new frame
         if(this.viewer.viewport.getFlip() !== this._viewportFlipped){
             this._flip();
-            this._viewportFlipped = !this._viewportFlipped;
         }
+        console.log('draw', this._viewportFlipped);
         for(const tiledImage of tiledImages){
             if (tiledImage.opacity !== 0) {
                 this._drawTiles(tiledImage);
@@ -189,6 +187,10 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.restore();
     }
 
+    get _viewportFlipped(){
+        return this.context.getTransform().a < 0;
+    }
+
     /**
      * Fires the tile-drawing event.
      * @private
@@ -961,6 +963,7 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.translate(point.x, 0);
         context.scale(-1, 1);
         context.translate(-point.x, 0);
+        console.log('flipped');
     }
 
     // private

From 9d6a785aacc8158bb3a1b25391b32b650782db0e Mon Sep 17 00:00:00 2001
From: Tom <tmpearce@gmail.com>
Date: Sat, 27 Apr 2024 16:41:18 -0400
Subject: [PATCH 2/2] add comment; clean up console.log messages from testing

---
 src/canvasdrawer.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/canvasdrawer.js b/src/canvasdrawer.js
index 1ec6a10b..57525e37 100644
--- a/src/canvasdrawer.js
+++ b/src/canvasdrawer.js
@@ -117,7 +117,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         if(this.viewer.viewport.getFlip() !== this._viewportFlipped){
             this._flip();
         }
-        console.log('draw', this._viewportFlipped);
         for(const tiledImage of tiledImages){
             if (tiledImage.opacity !== 0) {
                 this._drawTiles(tiledImage);
@@ -187,6 +186,10 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.restore();
     }
 
+    /**
+     * Test whether the current context is flipped or not
+     * @private
+     */
     get _viewportFlipped(){
         return this.context.getTransform().a < 0;
     }
@@ -963,7 +966,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.translate(point.x, 0);
         context.scale(-1, 1);
         context.translate(-point.x, 0);
-        console.log('flipped');
     }
 
     // private