[skotty, sksg] Add layer transform inheritance support

Split the matrix component of sksg::Transform into its own, free-floating,
chainable node.

Update the composite transform animator to target matrix nodes instead of
transform nodes.

Update the layer transform attachment logic to follow "parent" references,
and build matrix inheritance chains on the fly.

TBR=
Change-Id: I017e5e462274c2cc210730e057b3ea2e7de5c0cb
Reviewed-on: https://skia-review.googlesource.com/90803
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

1 files changed, 45 insertions, 6 deletions

diff --git a/experimental/sksg/effects/SkSGTransform.cpp b/experimental/sksg/effects/SkSGTransform.cpp
index dc31623db2..1ea1e619a8 100644
--- a/experimental/sksg/effects/SkSGTransform.cpp
+++ b/experimental/sksg/effects/SkSGTransform.cpp
@@ -11,21 +11,60 @@
 
 namespace sksg {
 
-Transform::Transform(sk_sp<RenderNode> child, const SkMatrix& matrix)
+Matrix::Matrix(const SkMatrix& m, sk_sp<Matrix> parent)
+    : fParent(std::move(parent))
+    , fLocalMatrix(m) {
+    if (fParent) {
+        fParent->addInvalReceiver(this);
+    }
+}
+
+Matrix::~Matrix() {
+    if (fParent) {
+        fParent->removeInvalReceiver(this);
+    }
+}
+
+Node::RevalidationResult Matrix::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
+    fTotalMatrix = fLocalMatrix;
+
+    if (fParent) {
+        fParent->revalidate(ic, ctm);
+        fTotalMatrix.postConcat(fParent->getTotalMatrix());
+    }
+
+    // A free-floating matrix contributes no damage.
+    return { SkRect::MakeEmpty(), Damage::kBlockSelf };
+}
+
+Transform::Transform(sk_sp<RenderNode> child, sk_sp<Matrix> matrix)
     : INHERITED(std::move(child))
-    , fMatrix(matrix) {}
+    , fMatrix(std::move(matrix)) {
+    fMatrix->addInvalReceiver(this);
+}
+
+Transform::~Transform() {
+    fMatrix->removeInvalReceiver(this);
+}
 
 void Transform::onRender(SkCanvas* canvas) const {
-    SkAutoCanvasRestore acr(canvas, !fMatrix.isIdentity());
-    canvas->concat(fMatrix);
+    const auto& m = fMatrix->getTotalMatrix();
+    SkAutoCanvasRestore acr(canvas, !m.isIdentity());
+    canvas->concat(m);
     this->INHERITED::onRender(canvas);
 }
 
 Node::RevalidationResult Transform::onRevalidate(InvalidationController* ic, const SkMatrix& ctm) {
     SkASSERT(this->hasInval());
 
-    auto result = this->INHERITED::onRevalidate(ic, SkMatrix::Concat(ctm, fMatrix));
-    fMatrix.mapRect(&result.fBounds);
+    // We don't care about matrix reval results, but we do care whether it was invalidated.
+    const auto localDamage = fMatrix->hasInval() ? Damage::kForceSelf : Damage::kDefault;
+    fMatrix->revalidate(ic, ctm);
+
+    const auto& m = fMatrix->getTotalMatrix();
+    auto result = this->INHERITED::onRevalidate(ic, SkMatrix::Concat(ctm, m));
+    m.mapRect(&result.fBounds);
+    result.fDamage = localDamage;
 
     return result;
 }