fix canvas drawer when viewport is flipped and tiled image is rotated. fix webgl drawer debug info when viewport is flipped.

src/canvasdrawer.js

@@ -80,6 +80,7 @@ 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");
@@ -115,7 +116,10 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
      */
     draw(tiledImages) {
         this._prepareNewFrame(); // prepare to draw a new frame
-
+        if(this.viewer.viewport.getFlip() !== this._viewportFlipped){
+            this._flip();
+            this._viewportFlipped = !this._viewportFlipped;
+        }
         for(const tiledImage of tiledImages){
             if (tiledImage.opacity !== 0) {
                 this._drawTiles(tiledImage);
@@ -300,13 +304,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
                     tiledImage.getClippedBounds(true))
                     .getIntegerBoundingBox();
 
-                if(this.viewer.viewport.getFlip()) {
-                    if (this.viewport.getRotation(true) % 360 !== 0 ||
-                        tiledImage.getRotation(true) % 360 !== 0) {
-                        bounds.x = this.viewer.container.clientWidth - (bounds.x + bounds.width);
-                    }
-                }
-
                 bounds = bounds.times($.pixelDensityRatio);
             }
             this._clear(true, bounds);
@@ -315,27 +312,7 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         // When scaling, we must rotate only when blending the sketch canvas to
         // avoid interpolation
         if (!sketchScale) {
-            if (this.viewport.getRotation(true) % 360 !== 0) {
+            this._setRotations(tiledImage, useSketch);
-                this._offsetForRotation({
-                    degrees: this.viewport.getRotation(true),
-                    useSketch: useSketch
-                });
-            }
-            if (tiledImage.getRotation(true) % 360 !== 0) {
-                this._offsetForRotation({
-                    degrees: tiledImage.getRotation(true),
-                    point: this.viewport.pixelFromPointNoRotate(
-                        tiledImage._getRotationPoint(true), true),
-                    useSketch: useSketch
-                });
-            }
-
-            if (this.viewport.getRotation(true) % 360 === 0 &&
-                tiledImage.getRotation(true) % 360 === 0) {
-                if(this.viewer.viewport.getFlip()) {
-                    this._flip();
-                }
-            }
         }
 
         var usedClip = false;
@@ -456,20 +433,7 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
 
         if (useSketch) {
             if (sketchScale) {
-                if (this.viewport.getRotation(true) % 360 !== 0) {
+                this._setRotations(tiledImage);
-                    this._offsetForRotation({
-                        degrees: this.viewport.getRotation(true),
-                        useSketch: false
-                    });
-                }
-                if (tiledImage.getRotation(true) % 360 !== 0) {
-                    this._offsetForRotation({
-                        degrees: tiledImage.getRotation(true),
-                        point: this.viewport.pixelFromPointNoRotate(
-                            tiledImage._getRotationPoint(true), true),
-                        useSketch: false
-                    });
-                }
             }
             this.blendSketch({
                 opacity: tiledImage.opacity,
@@ -488,15 +452,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
             }
         }
 
-        if (!sketchScale) {
-            if (this.viewport.getRotation(true) % 360 === 0 &&
-                tiledImage.getRotation(true) % 360 === 0) {
-                if(this.viewer.viewport.getFlip()) {
-                    this._flip();
-                }
-            }
-        }
-
         this._drawDebugInfo( tiledImage, lastDrawn );
 
         // Fire tiled-image-drawn event.
@@ -607,7 +562,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         }
 
         context.save();
-        // context.globalAlpha = this.options.opacity; // this was deprecated previously and should not be applied as it is set per TiledImage
 
         if (typeof scale === 'number' && scale !== 1) {
             // draw tile at a different scale
@@ -853,21 +807,10 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.strokeStyle = this.debugGridColor[colorIndex];
         context.fillStyle = this.debugGridColor[colorIndex];
 
-        if (this.viewport.getRotation(true) % 360 !== 0 ) {
+        this._setRotations(tiledImage);
-            this._offsetForRotation({degrees: this.viewport.getRotation(true)});
+
-        }
+        if(this._viewportFlipped){
-        if (tiledImage.getRotation(true) % 360 !== 0) {
+            this._flip({point: tile.position.plus(tile.size.divide(2))});
-            this._offsetForRotation({
-                degrees: tiledImage.getRotation(true),
-                point: tiledImage.viewport.pixelFromPointNoRotate(
-                    tiledImage._getRotationPoint(true), true)
-            });
-        }
-        if (tiledImage.viewport.getRotation(true) % 360 === 0 &&
-            tiledImage.getRotation(true) % 360 === 0) {
-            if(tiledImage._drawer.viewer.viewport.getFlip()) {
-                tiledImage._drawer._flip();
-            }
         }
 
         context.strokeRect(
@@ -882,7 +825,8 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
 
         // Rotate the text the right way around.
         context.translate( tileCenterX, tileCenterY );
-        context.rotate( Math.PI / 180 * -this.viewport.getRotation(true) );
+        const angleInDegrees = this.viewport.getRotation(true);
+        context.rotate( Math.PI / 180 * -angleInDegrees );
         context.translate( -tileCenterX, -tileCenterY );
 
         if( tile.x === 0 && tile.y === 0 ){
@@ -935,13 +879,6 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
             this._restoreRotationChanges();
         }
 
-        if (tiledImage.viewport.getRotation(true) % 360 === 0 &&
-            tiledImage.getRotation(true) % 360 === 0) {
-            if(tiledImage._drawer.viewer.viewport.getFlip()) {
-                tiledImage._drawer._flip();
-            }
-        }
-
         context.restore();
     }
 
@@ -972,6 +909,33 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         return new $.Point(this.canvas.width / 2, this.canvas.height / 2);
     }
 
+    /**
+     * Set rotations for viewport & tiledImage
+     * @private
+     * @param {OpenSeadragon.TiledImage} tiledImage
+     * @param {Boolean} [useSketch=false]
+     */
+    _setRotations(tiledImage, useSketch = false) {
+        var saveContext = false;
+        if (this.viewport.getRotation(true) % 360 !== 0) {
+            this._offsetForRotation({
+                degrees: this.viewport.getRotation(true),
+                useSketch: useSketch,
+                saveContext: saveContext
+            });
+            saveContext = false;
+        }
+        if (tiledImage.getRotation(true) % 360 !== 0) {
+            this._offsetForRotation({
+                degrees: tiledImage.getRotation(true),
+                point: this.viewport.pixelFromPointNoRotate(
+                    tiledImage._getRotationPoint(true), true),
+                useSketch: useSketch,
+                saveContext: saveContext
+            });
+        }
+    }
+
     // private
     _offsetForRotation(options) {
         var point = options.point ?
@@ -982,12 +946,7 @@ class CanvasDrawer extends OpenSeadragon.DrawerBase{
         context.save();
 
         context.translate(point.x, point.y);
-        if(this.viewer.viewport.flipped){
-          context.rotate(Math.PI / 180 * -options.degrees);
-          context.scale(-1, 1);
-        } else{
         context.rotate(Math.PI / 180 * options.degrees);
-        }
         context.translate(-point.x, -point.y);
     }
 

src/webgldrawer.js

@@ -529,10 +529,14 @@
             }
             this._outputContext.restore();
             if(tiledImage.debugMode){
-                let colorIndex = this.viewer.world.getIndexOfItem(tiledImage) % this.debugGridColor.length;
+                const flipped = this.viewer.viewport.getFlip();
-                let strokeStyle = this.debugGridColor[colorIndex];
+                if(flipped){
-                let fillStyle = this.debugGridColor[colorIndex];
+                    this._flip();
-                this._drawDebugInfo(tilesToDraw, tiledImage, strokeStyle, fillStyle);
+                }
+                this._drawDebugInfo(tilesToDraw, tiledImage, flipped);
+                if(flipped){
+                    this._flip();
+                }
             }
 
 
@@ -1067,32 +1071,64 @@
             this._clippingContext.restore();
         }
 
+            /**
+         * Set rotations for viewport & tiledImage
+         * @private
+         * @param {OpenSeadragon.TiledImage} tiledImage
+         */
+        _setRotations(tiledImage) {
+            var saveContext = false;
+            if (this.viewport.getRotation(true) % 360 !== 0) {
+                this._offsetForRotation({
+                    degrees: this.viewport.getRotation(true),
+                    saveContext: saveContext
+                });
+                saveContext = false;
+            }
+            if (tiledImage.getRotation(true) % 360 !== 0) {
+                this._offsetForRotation({
+                    degrees: tiledImage.getRotation(true),
+                    point: this.viewport.pixelFromPointNoRotate(
+                        tiledImage._getRotationPoint(true), true),
+                    saveContext: saveContext
+                });
+            }
+        }
+
         // private
         _offsetForRotation(options) {
             var point = options.point ?
                 options.point.times($.pixelDensityRatio) :
-                new $.Point(this._outputCanvas.width / 2, this._outputCanvas.height / 2);
+                this._getCanvasCenter();
 
             var context = this._outputContext;
             context.save();
 
             context.translate(point.x, point.y);
-            if(this.viewport.flipped){
-                context.rotate(Math.PI / 180 * -options.degrees);
-                context.scale(-1, 1);
-            } else{
             context.rotate(Math.PI / 180 * options.degrees);
-            }
             context.translate(-point.x, -point.y);
         }
 
         // private
-        _drawDebugInfo( tilesToDraw, tiledImage, stroke, fill ) {
+        _flip(options) {
+            options = options || {};
+            var point = options.point ?
+            options.point.times($.pixelDensityRatio) :
+            this._getCanvasCenter();
+            var context = this._outputContext;
+
+            context.translate(point.x, 0);
+            context.scale(-1, 1);
+            context.translate(-point.x, 0);
+        }
+
+        // private
+        _drawDebugInfo( tilesToDraw, tiledImage, flipped ) {
 
             for ( var i = tilesToDraw.length - 1; i >= 0; i-- ) {
                 var tile = tilesToDraw[ i ].tile;
                 try {
-                    this._drawDebugInfoOnTile(tile, tilesToDraw.length, i, tiledImage, stroke, fill);
+                    this._drawDebugInfoOnTile(tile, tilesToDraw.length, i, tiledImage, flipped);
                 } catch(e) {
                     $.console.error(e);
                 }
@@ -1100,30 +1136,20 @@
         }
 
         // private
-        _drawDebugInfoOnTile(tile, count, i, tiledImage, stroke, fill) {
+        _drawDebugInfoOnTile(tile, count, i, tiledImage, flipped) {
 
-            var context = this._outputContext;
+            var colorIndex = this.viewer.world.getIndexOfItem(tiledImage) % this.debugGridColor.length;
+            var context = this.context;
             context.save();
             context.lineWidth = 2 * $.pixelDensityRatio;
             context.font = 'small-caps bold ' + (13 * $.pixelDensityRatio) + 'px arial';
-            context.strokeStyle = stroke;
+            context.strokeStyle = this.debugGridColor[colorIndex];
-            context.fillStyle = fill;
+            context.fillStyle = this.debugGridColor[colorIndex];
 
-            if (this.viewport.getRotation(true) % 360 !== 0 ) {
+            this._setRotations(tiledImage);
-                this._offsetForRotation({degrees: this.viewport.getRotation(true)});
+
-            }
+            if(flipped){
-            if (tiledImage.getRotation(true) % 360 !== 0) {
+                this._flip({point: tile.position.plus(tile.size.divide(2))});
-                this._offsetForRotation({
-                    degrees: tiledImage.getRotation(true),
-                    point: tiledImage.viewport.pixelFromPointNoRotate(
-                        tiledImage._getRotationPoint(true), true)
-                });
-            }
-            if (tiledImage.viewport.getRotation(true) % 360 === 0 &&
-                tiledImage.getRotation(true) % 360 === 0) {
-                if(tiledImage._drawer.viewer.viewport.getFlip()) {
-                    tiledImage._drawer._flip();
-                }
             }
 
             context.strokeRect(
@@ -1138,7 +1164,8 @@
 
             // Rotate the text the right way around.
             context.translate( tileCenterX, tileCenterY );
-            context.rotate( Math.PI / 180 * -this.viewport.getRotation(true) );
+            const angleInDegrees = this.viewport.getRotation(true);
+            context.rotate( Math.PI / 180 * -angleInDegrees );
             context.translate( -tileCenterX, -tileCenterY );
 
             if( tile.x === 0 && tile.y === 0 ){
@@ -1191,13 +1218,6 @@
                 this._restoreRotationChanges();
             }
 
-            if (tiledImage.viewport.getRotation(true) % 360 === 0 &&
-                tiledImage.getRotation(true) % 360 === 0) {
-                if(tiledImage._drawer.viewer.viewport.getFlip()) {
-                    tiledImage._drawer._flip();
-                }
-            }
-
             context.restore();
         }
 
@@ -1225,6 +1245,16 @@
 
         }
 
+        /**
+         * Get the canvas center
+         * @private
+         * @param {Boolean} sketch If set to true return the center point of the sketch canvas
+         * @returns {OpenSeadragon.Point} The center point of the canvas
+         */
+        _getCanvasCenter() {
+            return new $.Point(this.canvas.width / 2, this.canvas.height / 2);
+        }
+
         // private
         _restoreRotationChanges() {
             var context = this._outputContext;