[sksg] Simplify TrimEffect

Move the Lottie-specific bits to Skottie and keep TrimEffect as a thin
SkTrimPathEffect wrapper.

TBR=

Change-Id: Iecc6624d01ba61eb96a2056ef8e9e24e731f8979
Reviewed-on: https://skia-review.googlesource.com/115923
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

5 files changed, 69 insertions, 30 deletions

diff --git a/experimental/skottie/Skottie.cpp b/experimental/skottie/Skottie.cpp
index a7b6b23817..5a04e5a719 100644
--- a/experimental/skottie/Skottie.cpp
+++ b/experimental/skottie/Skottie.cpp
@@ -427,19 +427,21 @@ std::vector<sk_sp<sksg::GeometryNode>> AttachTrimGeometryEffect(
     std::vector<sk_sp<sksg::GeometryNode>> trimmed;
     trimmed.reserve(inputs.size());
     for (const auto& i : inputs) {
-        const auto trim = sksg::TrimEffect::Make(i);
-        trimmed.push_back(trim);
+        const auto trimEffect = sksg::TrimEffect::Make(i);
+        trimmed.push_back(trimEffect);
+
+        const auto trimComposite = sk_make_sp<CompositeTrimEffect>(std::move(trimEffect));
         BindProperty<ScalarValue>(jtrim["s"], &ctx->fAnimators,
-            [trim](const ScalarValue& s) {
-                trim->setStart(s * 0.01f);
+            [trimComposite](const ScalarValue& s) {
+                trimComposite->setStart(s);
             });
         BindProperty<ScalarValue>(jtrim["e"], &ctx->fAnimators,
-            [trim](const ScalarValue& e) {
-                trim->setEnd(e * 0.01f);
+            [trimComposite](const ScalarValue& e) {
+                trimComposite->setEnd(e);
             });
         BindProperty<ScalarValue>(jtrim["o"], &ctx->fAnimators,
-            [trim](const ScalarValue& o) {
-                trim->setOffset(o / 360);
+            [trimComposite](const ScalarValue& o) {
+                trimComposite->setOffset(o);
             });
     }
 
diff --git a/experimental/skottie/SkottieProperties.cpp b/experimental/skottie/SkottieProperties.cpp
index 0816e15bca..a774217a8c 100644
--- a/experimental/skottie/SkottieProperties.cpp
+++ b/experimental/skottie/SkottieProperties.cpp
@@ -15,6 +15,7 @@
 #include "SkSGPath.h"
 #include "SkSGRect.h"
 #include "SkSGTransform.h"
+#include "SkSGTrimEffect.h"
 
 #include <cmath>
 
@@ -190,4 +191,37 @@ void CompositeRadialGradient::onApply() {
     grad->setEndRadius(SkPoint::Distance(this->startPoint(), this->endPoint()));
 }
 
+CompositeTrimEffect::CompositeTrimEffect(sk_sp<sksg::TrimEffect> trimEffect)
+    : fTrimEffect(std::move(trimEffect)) {
+    SkASSERT(fTrimEffect);
+}
+
+void CompositeTrimEffect::apply() {
+    // BM semantics: start/end are percentages, offset is "degrees" (?!).
+    const auto  start = fStart  / 100,
+                  end = fEnd    / 100,
+               offset = fOffset / 360;
+
+    auto startT = SkTMin(start, end) + offset,
+          stopT = SkTMax(start, end) + offset;
+    auto   mode = SkTrimPathEffect::Mode::kNormal;
+
+    if (stopT - startT < 1) {
+        startT -= SkScalarFloorToScalar(startT);
+        stopT  -= SkScalarFloorToScalar(stopT);
+
+        if (startT > stopT) {
+            SkTSwap(startT, stopT);
+            mode = SkTrimPathEffect::Mode::kInverted;
+        }
+    } else {
+        startT = 0;
+        stopT  = 1;
+    }
+
+    fTrimEffect->setStart(startT);
+    fTrimEffect->setStop(stopT);
+    fTrimEffect->setMode(mode);
+}
+
 } // namespace skottie
diff --git a/experimental/skottie/SkottieProperties.h b/experimental/skottie/SkottieProperties.h
index 8ca026eaeb..5e3fad0d9a 100644
--- a/experimental/skottie/SkottieProperties.h
+++ b/experimental/skottie/SkottieProperties.h
@@ -28,6 +28,7 @@ class Path;
 class RadialGradient;
 class RRect;
 class RenderNode;;
+class TrimEffect;
 }
 
 namespace Json { class Value; }
@@ -161,6 +162,22 @@ private:
     using INHERITED = CompositeGradient;
 };
 
+class CompositeTrimEffect final : public SkRefCnt {
+public:
+    explicit CompositeTrimEffect(sk_sp<sksg::TrimEffect>);
+
+    COMPOSITE_PROPERTY(Start , SkScalar,   0)
+    COMPOSITE_PROPERTY(End   , SkScalar, 100)
+    COMPOSITE_PROPERTY(Offset, SkScalar,   0)
+
+private:
+    void apply();
+
+    sk_sp<sksg::TrimEffect> fTrimEffect;
+
+    using INHERITED = SkRefCnt;
+};
+
 #undef COMPOSITE_PROPERTY
 
 } // namespace skottie
diff --git a/experimental/sksg/geometry/SkSGTrimEffect.cpp b/experimental/sksg/geometry/SkSGTrimEffect.cpp
index fea8249161..b8c59bcfe8 100644
--- a/experimental/sksg/geometry/SkSGTrimEffect.cpp
+++ b/experimental/sksg/geometry/SkSGTrimEffect.cpp
@@ -42,22 +42,7 @@ SkRect TrimEffect::onRevalidate(InvalidationController* ic, const SkMatrix& ctm)
     const auto childbounds = fChild->revalidate(ic, ctm);
     const auto path        = fChild->asPath();
 
-    // TODO: relocate these funky semantics to a Skottie composite helper,
-    //       and refactor TrimEffect as a thin SkTrimpPathEffect wrapper.
-    auto start = SkTMin(fStart, fEnd) + fOffset,
-         stop  = SkTMax(fStart, fEnd) + fOffset;
-
-    sk_sp<SkPathEffect> trim;
-    if (stop - start < 1) {
-        start -= SkScalarFloorToScalar(start);
-        stop  -= SkScalarFloorToScalar(stop);
-
-        trim = start <= stop
-            ? SkTrimPathEffect::Make(start, stop, SkTrimPathEffect::Mode::kNormal)
-            : SkTrimPathEffect::Make(stop, start, SkTrimPathEffect::Mode::kInverted);
-    }
-
-    if (trim) {
+    if (auto trim = SkTrimPathEffect::Make(fStart, fStop, fMode)) {
         fTrimmedPath.reset();
         SkStrokeRec rec(SkStrokeRec::kHairline_InitStyle);
         SkAssertResult(trim->filterPath(&fTrimmedPath, path, &rec, &childbounds));
diff --git a/experimental/sksg/geometry/SkSGTrimEffect.h b/experimental/sksg/geometry/SkSGTrimEffect.h
index 4e950a7ade..18f15921e7 100644
--- a/experimental/sksg/geometry/SkSGTrimEffect.h
+++ b/experimental/sksg/geometry/SkSGTrimEffect.h
@@ -11,6 +11,7 @@
 #include "SkSGGeometryNode.h"
 
 #include "SkPath.h"
+#include "SkTrimPathEffect.h"
 
 class SkCanvas;
 class SkPaint;
@@ -28,9 +29,9 @@ public:
 
     ~TrimEffect() override;
 
-    SG_ATTRIBUTE(Start , SkScalar, fStart )
-    SG_ATTRIBUTE(End   , SkScalar, fEnd   )
-    SG_ATTRIBUTE(Offset, SkScalar, fOffset)
+    SG_ATTRIBUTE(Start , SkScalar              , fStart )
+    SG_ATTRIBUTE(Stop  , SkScalar              , fStop  )
+    SG_ATTRIBUTE(Mode  , SkTrimPathEffect::Mode, fMode  )
 
 protected:
     void onClip(SkCanvas*, bool antiAlias) const override;
@@ -45,9 +46,9 @@ private:
     const sk_sp<GeometryNode> fChild;
 
     SkPath                    fTrimmedPath;
-    SkScalar                  fStart  = 0, // starting t
-                              fEnd    = 1, // ending t
-                              fOffset = 0; // t offset
+    SkScalar                  fStart = 0,
+                              fStop  = 1;
+    SkTrimPathEffect::Mode    fMode  = SkTrimPathEffect::Mode::kNormal;
 
     using INHERITED = GeometryNode;
 };