1 files changed, 44 insertions, 6 deletions
diff --git a/experimental/sksg/effects/SkSGTransform.h b/experimental/sksg/effects/SkSGTransform.h
index 8a97a679ed..0d11739f30 100644
--- a/experimental/sksg/effects/SkSGTransform.h
+++ b/experimental/sksg/effects/SkSGTransform.h
@@ -15,25 +15,63 @@
 namespace sksg {
 
 /**
- * Concrete Effect node, wrapping an SkMatrix.
+ * Concrete node, wrapping an SkMatrix, with an optional parent Matrix (to allow chaining):
+ *
+ *    M' = parent x M
+ */
+class Matrix : public Node {
+public:
+    static sk_sp<Matrix> Make(const SkMatrix& m, sk_sp<Matrix> parent = nullptr) {
+        return sk_sp<Matrix>(new Matrix(m, std::move(parent)));
+    }
+
+    ~Matrix() override;
+
+    SG_ATTRIBUTE(Matrix, SkMatrix, fLocalMatrix)
+
+    const SkMatrix& getTotalMatrix() const { return fTotalMatrix; }
+
+protected:
+    explicit Matrix(const SkMatrix&, sk_sp<Matrix>);
+
+    RevalidationResult onRevalidate(InvalidationController*, const SkMatrix&) override;
+
+private:
+    sk_sp<Matrix> fParent;
+    SkMatrix      fLocalMatrix,
+                  fTotalMatrix; // cached during revalidation
+
+    typedef Node INHERITED;
+};
+
+/**
+ * Concrete Effect node, binding a Matrix to a RenderNode.
  */
 class Transform : public EffectNode {
 public:
-    static sk_sp<Transform> Make(sk_sp<RenderNode> child, const SkMatrix& matrix) {
-        return sk_sp<Transform>(new Transform(std::move(child), matrix));
+    static sk_sp<Transform> Make(sk_sp<RenderNode> child, sk_sp<Matrix> matrix) {
+        return child && matrix
+            ? sk_sp<Transform>(new Transform(std::move(child), std::move(matrix)))
+            : nullptr;
     }
 
-    SG_ATTRIBUTE(Matrix, SkMatrix, fMatrix)
+    static sk_sp<Transform> Make(sk_sp<RenderNode> child, const SkMatrix& m) {
+        return Make(std::move(child), Matrix::Make(m));
+    }
+
+    ~Transform() override;
+
+    const sk_sp<Matrix>& getMatrix() const { return fMatrix; }
 
 protected:
-    Transform(sk_sp<RenderNode>, const SkMatrix&);
+    Transform(sk_sp<RenderNode>, sk_sp<Matrix>);
 
     void onRender(SkCanvas*) const override;
 
     RevalidationResult onRevalidate(InvalidationController*, const SkMatrix&) override;
 
 private:
-    SkMatrix fMatrix;
+    sk_sp<Matrix> fMatrix;
 
     typedef EffectNode INHERITED;
 };