Resize filter should include canvas zoom and group zoom

src/filters/resize_filter.class.js

@@ -30,6 +30,8 @@
 
     /**
      * Resize type
+     * for webgl resizyType is just lanczos, for canvas2d can be:
+     * bilinear, hermite, sliceHacl, lanczos.
      * @param {String} resizeType
      * @default
      */
@@ -50,7 +52,7 @@
     scaleY: 0,
 
     /**
-     * LanczosLobes parameter for lanczos filter
+     * LanczosLobes parameter for lanczos filter, valid for resizeType lanczos
      * @param {Number} lanczosLobes
      * @default
      */

src/shapes/image.class.js

@@ -385,10 +385,10 @@
 
     applyResizeFilters: function() {
       var filter = this.resizeFilter,
-          retinaScaling = this.canvas ? this.canvas.getRetinaScaling() : 1,
           minimumScale = this.minimumScaleTrigger,
-          scaleX = this.scaleX * retinaScaling,
-          scaleY = this.scaleY * retinaScaling,
+          objectScale = this.getTotalObjectScaling(),
+          scaleX = objectScale.scaleX,
+          scaleY = objectScale.scaleY,
           elementToFilter = this._filteredEl || this._originalElement;
       if (this.group) {
         this.set('dirty', true);
@@ -397,6 +397,8 @@
         this._element = elementToFilter;
         this._filterScalingX = 1;
         this._filterScalingY = 1;
+        this._lastScaleX = 1;
+        this._lastScaleY = 1;
         return;
       }
       if (!fabric.filterBackend) {
@@ -408,8 +410,8 @@
       canvasEl.width = sourceWidth;
       canvasEl.height = sourceHeight;
       this._element = canvasEl;
-      filter.scaleX = scaleX;
-      filter.scaleY = scaleY;
+      this._lastScaleX = filter.scaleX = scaleX;
+      this._lastScaleY = filter.scaleY = scaleY;
       fabric.filterBackend.applyFilters(
         [filter], elementToFilter, sourceWidth, sourceHeight, this._element, cacheKey);
       this._filterScalingX = canvasEl.width / this._originalElement.width;
@@ -473,9 +475,7 @@
      * @param {CanvasRenderingContext2D} ctx Context to render on
      */
     _render: function(ctx) {
-      if (this.isMoving === false && this.resizeFilter && this._needsResize()) {
-        this._lastScaleX = this.scaleX;
-        this._lastScaleY = this.scaleY;
+      if (this.isMoving !== true && this.resizeFilter && this._needsResize()) {
         this.applyResizeFilters();
       }
       this._stroke(ctx);
@@ -497,7 +497,8 @@
      * @private, needed to check if image needs resize
      */
     _needsResize: function() {
-      return (this.scaleX !== this._lastScaleX || this.scaleY !== this._lastScaleY);
+      var scale = this.getTotalObjectScaling();
+      return (scale.scaleX !== this._lastScaleX || scale.scaleY !== this._lastScaleY);
     },
 
     /**

src/shapes/object.class.js

@@ -678,12 +678,10 @@
      * @return {Object}.zoomY zoomY zoom value to unscale the canvas before drawing cache
      */
     _getCacheCanvasDimensions: function() {
-      var zoom = this.canvas && this.canvas.getZoom() || 1,
-          objectScale = this.getObjectScaling(),
-          retina = this.canvas && this.canvas._isRetinaScaling() ? fabric.devicePixelRatio : 1,
+      var objectScale = this.getTotalObjectScaling(),
           dim = this._getNonTransformedDimensions(),
-          zoomX = objectScale.scaleX * zoom * retina,
-          zoomY = objectScale.scaleY * zoom * retina,
+          zoomX = objectScale.scaleX,
+          zoomY = objectScale.scaleY,
           width = dim.x * zoomX,
           height = dim.y * zoomY;
       return {
@@ -890,6 +888,21 @@
       return { scaleX: scaleX, scaleY: scaleY };
     },
 
+    /**
+     * Return the object scale factor counting also the group scaling, zoom and retina
+     * @return {Object} object with scaleX and scaleY properties
+     */
+    getTotalObjectScaling: function() {
+      var scale = this.getObjectScaling(), scaleX = scale.scaleX, scaleY = scale.scaleY;
+      if (this.canvas) {
+        var zoom = this.canvas.getZoom();
+        var retina = this.canvas.getRetinaScaling();
+        scaleX *= zoom * retina;
+        scaleY *= zoom * retina;
+      }
+      return { scaleX: scaleX, scaleY: scaleY };
+    },
+
     /**
      * Return the object opacity counting also the group property
      * @return {Number}

test/unit/object.js

@@ -52,6 +52,9 @@
       fabric.perfLimitSizeTotal = 2097152;
       fabric.maxCacheSideLimit = 4096;
       fabric.minCacheSideLimit = 256;
+      fabric.devicePixelRatio = 1;
+      canvas.enableRetinaScaling = false;
+      canvas.setZoom(1);
       canvas.clear();
       canvas.backgroundColor = fabric.Canvas.prototype.backgroundColor;
       canvas.calcOffset();
@@ -989,13 +992,30 @@
     assert.equal(typeof deserializedObject.clipTo, 'function');
   });
 
-  QUnit.test('getObjectScale', function(assert) {
+  QUnit.test('getTotalObjectScaling with zoom', function(assert) {
+    var object = new fabric.Object({ scaleX: 3, scaleY: 2});
+    canvas.setZoom(3);
+    canvas.add(object);
+    var objectScale = object.getTotalObjectScaling();
+    assert.deepEqual(objectScale, { scaleX: object.scaleX * 3, scaleY: object.scaleY * 3 });
+  });
+
+  QUnit.test('getTotalObjectScaling with retina', function(assert) {
+    var object = new fabric.Object({ scaleX: 3, scaleY: 2});
+    canvas.enableRetinaScaling = true;
+    fabric.devicePixelRatio = 4;
+    canvas.add(object);
+    var objectScale = object.getTotalObjectScaling();
+    assert.deepEqual(objectScale, { scaleX: object.scaleX * 4, scaleY: object.scaleY * 4 });
+  });
+
+  QUnit.test('getObjectScaling', function(assert) {
     var object = new fabric.Object({ scaleX: 3, scaleY: 2});
     var objectScale = object.getObjectScaling();
     assert.deepEqual(objectScale, {scaleX: object.scaleX, scaleY: object.scaleY});
   });
 
-  QUnit.test('getObjectScale in group', function(assert) {
+  QUnit.test('getObjectScaling in group', function(assert) {
     var object = new fabric.Object({ scaleX: 3, scaleY: 2});
     var group = new fabric.Group();
     group.scaleX = 2;

test/visual/resize_filter.js

@@ -0,0 +1,173 @@
+(function() {
+  fabric.enableGLFiltering = false;
+  var _pixelMatch = pixelmatch;
+  if (fabric.isLikelyNode) {
+    var fs = global.fs;
+    _pixelMatch = global.pixelmatch;
+  }
+  var fabricCanvas = this.canvas = new fabric.Canvas(null, {enableRetinaScaling: false, renderOnAddRemove: false});
+  var pixelmatchOptions = {
+    includeAA: false,
+    threshold: 0.095
+  };
+  fabric.Object.prototype.objectCaching = false;
+
+  function getAbsolutePath(path) {
+    var isAbsolute = /^https?:/.test(path);
+    if (isAbsolute) { return path; };
+    var imgEl = fabric.document.createElement('img');
+    imgEl.src = path;
+    var src = imgEl.src;
+    imgEl = null;
+    return src;
+  }
+
+  function getFixtureName(filename) {
+    var finalName = '/../fixtures/' + filename;
+    return fabric.isLikelyNode ? (__dirname + finalName) : getAbsolutePath('test/fixtures/' + filename);
+  }
+
+  function getGoldeName(filename) {
+    var finalName = '/golden/' + filename;
+    return fabric.isLikelyNode ? (__dirname + finalName) : getAbsolutePath('test/visual/golden/' + filename);
+  }
+
+  function getImage(filename, original, callback) {
+    if (fabric.isLikelyNode && original) {
+      try {
+        fs.statSync(filename);
+      }
+      catch (err) {
+        var dataUrl = original.toDataURL().split(',')[1];
+        console.log('creating original for ', filename);
+        fs.writeFileSync(filename, dataUrl, { encoding: 'base64' });
+      }
+    }
+    var img = fabric.document.createElement('img');
+    img.onload = function() {
+      callback(img);
+    };
+    img.onerror = function(err) {
+      console.log('Image loading errored', err);
+    };
+    img.src = filename;
+  }
+
+  QUnit.module('Image resize filter test', {
+    afterEach: function() {
+      fabricCanvas.setZoom(1);
+      fabricCanvas.setDimensions({
+        width: 300,
+        height: 150,
+      });
+      fabricCanvas.clear();
+      fabricCanvas.renderAll();
+    }
+  });
+
+  var tests = [];
+
+  function imageResizeTest(canvas, callback) {
+    getImage(getFixtureName('parrot.png'), false, function(img) {
+      canvas.setDimensions({
+        width: 200,
+        height: 200,
+      });
+      var zoom = 8;
+      var image = new fabric.Image(img);
+      image.resizeFilter = new fabric.Image.filters.Resize({ resizeType: 'lanczos' });
+      canvas.setZoom(zoom);
+      image.scaleToWidth(canvas.width / zoom);
+      canvas.add(image);
+      canvas.renderAll();
+      callback(canvas.lowerCanvasEl);
+    });
+  }
+
+  tests.push({
+    test: 'Image resize with canvas zoom',
+    code: imageResizeTest,
+    golden: 'parrot.png',
+    percentage: 0.06,
+  });
+
+  function imageResizeTestNoZoom(canvas, callback) {
+    getImage(getFixtureName('parrot.png'), false, function(img) {
+      canvas.setDimensions({
+        width: 200,
+        height: 200,
+      });
+      var image = new fabric.Image(img);
+      image.resizeFilter = new fabric.Image.filters.Resize({ resizeType: 'lanczos' });
+      image.scaleToWidth(canvas.width);
+      canvas.add(image);
+      canvas.renderAll();
+      callback(canvas.lowerCanvasEl);
+    });
+  }
+
+  tests.push({
+    test: 'Image resize without zoom',
+    code: imageResizeTestNoZoom,
+    golden: 'parrot.png',
+    percentage: 0.06,
+  });
+
+  function imageResizeTestGroup(canvas, callback) {
+    getImage(getFixtureName('parrot.png'), false, function(img) {
+      canvas.setDimensions({
+        width: 200,
+        height: 200,
+      });
+      var image = new fabric.Image(img, { strokeWidth: 0 });
+      image.resizeFilter = new fabric.Image.filters.Resize({ resizeType: 'lanczos' });
+      var group = new fabric.Group([image]);
+      group.strokeWidth = 0;
+      group.scaleToWidth(canvas.width);
+      canvas.add(group);
+      canvas.renderAll();
+      callback(canvas.lowerCanvasEl);
+    });
+  }
+
+  tests.push({
+    test: 'Image resize with scaled group',
+    code: imageResizeTestGroup,
+    golden: 'parrot.png',
+    percentage: 0.06,
+  });
+
+  tests.forEach(function(testObj) {
+    var testName = testObj.test;
+    var code = testObj.code;
+    var percentage = testObj.percentage;
+    var golden = testObj.golden;
+    QUnit.test(testName, function(assert) {
+      var done = assert.async();
+      code(fabricCanvas, function(renderedCanvas) {
+        var width = renderedCanvas.width;
+        var height = renderedCanvas.height;
+        var totalPixels = width * height;
+        var imageDataCanvas = renderedCanvas.getContext('2d').getImageData(0, 0, width, height).data;
+        var canvas = fabric.document.createElement('canvas');
+        canvas.width = width;
+        canvas.height = height;
+        var ctx = canvas.getContext('2d');
+        var output = ctx.getImageData(0, 0, width, height).data;
+        getImage(getGoldeName(golden), renderedCanvas, function(golden) {
+          ctx.drawImage(golden, 0, 0);
+          var imageDataGolden = ctx.getImageData(0, 0, width, height).data;
+          var differentPixels = _pixelMatch(imageDataCanvas, imageDataGolden, output, width, height, pixelmatchOptions);
+          var percDiff = differentPixels / totalPixels * 100;
+          var okDiff = totalPixels * percentage;
+          assert.ok(
+            differentPixels < okDiff,
+            testName + ' has too many different pixels ' + differentPixels + '(' + okDiff + ') representing ' + percDiff + '%'
+          );
+          console.log('Different pixels:', differentPixels, '/', totalPixels, ' diff:', percDiff.toFixed(3), '%');
+          done();
+        });
+      });
+    });
+  });
+})();