Merge pull request #945 from edemaine/pointarray-transform

Add PointArray.transform by analogy to Point.transform

2 files changed, 45 insertions, 0 deletions

diff --git a/spec/spec/pointarray.js b/spec/spec/pointarray.js
new file mode 100644
index 0000000..f50f981
--- /dev/null
+++ b/spec/spec/pointarray.js
@@ -0,0 +1,28 @@
+describe('PointArray', function() {
+  const squareString = '0,0 1,0 1,1 0,1';
+  const square = new SVG.PointArray(squareString)
+
+  describe('toString()', function() {
+    it('round trips with string', () => {
+      expect(square.toString()).toEqual(squareString)
+    })
+  })
+
+  describe('transform()', function() {
+    it('translates correctly', () => {
+      const translation = new SVG.Matrix().translate(2,1)
+      const newSquare = square.transform(translation)
+      expect(newSquare.toString()).toEqual('2,1 3,1 3,2 2,2')
+    })
+
+    it('transforms like Point', () => {
+      const matrix = new SVG.Matrix(1, 2, 3, 4, 5, 6)
+      const newSquare = square.transform(matrix)
+      for (let i = 0; i < square.length; i++) {
+        const squarePoint = new SVG.Point(square[i])
+        const newSquarePoint = new SVG.Point(newSquare[i])
+        expect(squarePoint.transform(matrix)).toEqual(newSquarePoint)
+      }
+    })
+  })
+})
diff --git a/src/types/PointArray.js b/src/types/PointArray.js
index 9e7406d..2246bbd 100644
--- a/src/types/PointArray.js
+++ b/src/types/PointArray.js
@@ -71,6 +71,23 @@ extend(PointArray, {
     return points
   },
 
+  // transform points with matrix (similar to Point.transform)
+  transform (m) {
+    const points = []
+
+    for (let i = 0; i < this.length; i++) {
+      const point = this[i]
+      // Perform the matrix multiplication
+      points.push([
+        m.a * point[0] + m.c * point[1] + m.e,
+        m.b * point[0] + m.d * point[1] + m.f
+      ])
+    }
+
+    // Return the required point
+    return new PointArray(points)
+  },
+
   // Move point string
   move (x, y) {
     var box = this.bbox()