Fix faulty position regression in Item#rasterize()

Closes #1905

Author: lehni

.nvmrc

@@ -1 +1 @@
-13
+14

src/item/Item.js

@@ -1796,21 +1796,23 @@ new function() { // Injection scope for various item event handlers
             resolution = arg0;
             insert = arg1;
         }
-        if (!raster) {
+        if (raster) {
+            raster.matrix.reset(true);
+        } else {
             raster = new Raster(Item.NO_INSERT);
         }
-        // TODO: Switch to options object for more descriptive call signature.
         var bounds = this.getStrokeBounds(),
             scale = (resolution || this.getView().getResolution()) / 72,
             // Floor top-left corner and ceil bottom-right corner, to never
             // blur or cut pixels.
             topLeft = bounds.getTopLeft().floor(),
             bottomRight = bounds.getBottomRight().ceil(),
-            size = new Size(bottomRight.subtract(topLeft)).multiply(scale);
+            boundsSize = new Size(bottomRight.subtract(topLeft)),
+            rasterSize = boundsSize.multiply(scale);
         // Pass `true` for clear, so reused rasters don't draw over old pixels.
-        raster.setSize(size, true);
+        raster.setSize(rasterSize, true);
 
-        if (!size.isZero()) {
+        if (!rasterSize.isZero()) {
             var ctx = raster.getContext(true),
                 matrix = new Matrix().scale(scale).translate(topLeft.negate());
             ctx.save();
@@ -1819,11 +1821,15 @@ new function() { // Injection scope for various item event handlers
             this.draw(ctx, new Base({ matrices: [matrix] }));
             ctx.restore();
         }
-        raster.transform(new Matrix().translate(topLeft.add(size.divide(2)))
+        raster.transform(
+            new Matrix()
+                .translate(topLeft.add(boundsSize.divide(2)))
                 // Take resolution into account and scale back to original size.
-                .scale(1 / scale));
-        if (insert === undefined || insert)
+                .scale(1 / scale)
+        );
+        if (insert === undefined || insert) {
             raster.insertAbove(this);
+        }
         return raster;
     },
 

test/tests/Item.js

@@ -1025,10 +1025,39 @@ test('Children global matrices are cleared after parent transformation', functio
 
 test('Item#rasterize() with empty bounds', function() {
     new Path.Line([0, 0], [100, 0]).rasterize();
-    view.update();
+    view.update(); // This should not throw
     expect(0);
 });
 
+test('Item#rasterize() bounds', function() {
+    var circle = new Path.Circle({
+        center: [50, 50],
+        radius: 5,
+        fillColor: 'red'
+    });
+    equals(function() {
+        return circle.bounds;
+    }, new Rectangle({ x: 45, y: 45, width: 10, height: 10 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 72 }).bounds;
+    }, new Rectangle({ x: 45, y: 45, width: 10, height: 10 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 144 }).bounds;
+    }, new Rectangle({ x: 45, y: 45, width: 10, height: 10 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 200 }).bounds;
+    }, new Rectangle({ x: 45.14, y: 45.14, width: 9.72, height: 9.72 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 400 }).bounds;
+    }, new Rectangle({ x: 45.05, y: 45.05, width: 9.9, height: 9.9 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 600 }).bounds;
+    }, new Rectangle({ x: 45.02, y: 45.02, width: 9.96, height: 9.96 }));
+    equals(function() {
+        return circle.rasterize({ resolution: 1000 }).bounds;
+    }, new Rectangle({ x: 45.032, y: 45.032, width: 9.936, height: 9.936 }));
+});
+
 test('Item#draw() with CompoundPath as clip item', function() {
     function createdClippedGroup(invertedOrder) {
         var compound = new CompoundPath({