[skottie] Initial mask support

TBR=

Change-Id: Ibf4baeb17f98e1ed359f04deefe2f1c09414540d
Reviewed-on: https://skia-review.googlesource.com/98840
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

4 files changed, 74 insertions, 9 deletions

diff --git a/experimental/skottie/Skottie.cpp b/experimental/skottie/Skottie.cpp
index 73818d0035..2199f51f2a 100644
--- a/experimental/skottie/Skottie.cpp
+++ b/experimental/skottie/Skottie.cpp
@@ -173,17 +173,18 @@ sk_sp<sksg::RenderNode> AttachOpacity(const Json::Value& jtransform, AttachConte
 
 sk_sp<sksg::RenderNode> AttachComposition(const Json::Value&, AttachContext* ctx);
 
-sk_sp<sksg::GeometryNode> AttachPathGeometry(const Json::Value& jpath, AttachContext* ctx) {
-    SkASSERT(jpath.isObject());
-
+sk_sp<sksg::Path> AttachPath(const Json::Value& jpath, AttachContext* ctx) {
     auto path_node = sksg::Path::Make();
-    auto path_attached = BindProperty<ShapeValue>(jpath["ks"], ctx, path_node,
-        [](sksg::Path* node, const ShapeValue& p) { node->setPath(p); });
+    return BindProperty<ShapeValue>(jpath, ctx, path_node,
+                                    [](sksg::Path* node, const ShapeValue& p) { node->setPath(p); })
+        ? path_node
+        : nullptr;
+}
 
-    if (path_attached)
-        LOG("** Attached path geometry - verbs: %d\n", path_node->getPath().countVerbs());
+sk_sp<sksg::GeometryNode> AttachPathGeometry(const Json::Value& jpath, AttachContext* ctx) {
+    SkASSERT(jpath.isObject());
 
-    return path_attached ? path_node : nullptr;
+    return AttachPath(jpath["ks"], ctx);
 }
 
 sk_sp<sksg::GeometryNode> AttachRRectGeometry(const Json::Value& jrect, AttachContext* ctx) {
@@ -881,6 +882,62 @@ struct AttachLayerContext {
     }
 };
 
+SkBlendMode MaskBlendMode(char mode) {
+    switch (mode) {
+    case 'a': return SkBlendMode::kSrcOver;    // Additive
+    case 's': return SkBlendMode::kExclusion;  // Subtract
+    case 'i': return SkBlendMode::kDstIn;      // Intersect
+    case 'l': return SkBlendMode::kLighten;    // Lighten
+    case 'd': return SkBlendMode::kDarken;     // Darken
+    case 'f': return SkBlendMode::kDifference; // Difference
+    default: break;
+    }
+
+    return SkBlendMode::kSrcOver;
+}
+
+sk_sp<sksg::RenderNode> AttachMask(const Json::Value& jmask,
+                                   AttachContext* ctx,
+                                   sk_sp<sksg::RenderNode> childNode) {
+    if (!jmask.isArray())
+        return childNode;
+
+    auto mask_group = sksg::Group::Make();
+
+    for (const auto& m : jmask) {
+        if (!m.isObject())
+            continue;
+
+        const auto inverted = ParseBool(m["inv"], false);
+        // TODO
+        if (inverted) {
+            LogFail(m, "Unsupported inverse mask");
+            continue;
+        }
+
+        auto mask_path = AttachPath(m["pt"], ctx);
+        if (!mask_path) {
+            LogFail(m, "Could not parse mask path");
+            continue;
+        }
+
+        auto mode = ParseString(m["mode"], "");
+        if (mode.size() != 1 || !strcmp(mode.c_str(), "n")) // "None" masks have no effect.
+            continue;
+
+        auto mask_paint = sksg::Color::Make(SK_ColorBLACK);
+        mask_paint->setBlendMode(MaskBlendMode(mode.c_str()[0]));
+        BindProperty<ScalarValue>(m["o"], ctx, mask_paint,
+            [](sksg::Color* node, const ScalarValue& o) { node->setOpacity(o * 0.01f); });
+
+        mask_group->addChild(sksg::Draw::Make(std::move(mask_path), std::move(mask_paint)));
+    }
+
+    return mask_group->empty()
+        ? childNode
+        : sksg::MaskEffect::Make(std::move(childNode), std::move(mask_group));
+}
+
 sk_sp<sksg::RenderNode> AttachLayer(const Json::Value& jlayer,
                                     AttachLayerContext* layerCtx) {
     if (!jlayer.isObject())
@@ -903,8 +960,10 @@ sk_sp<sksg::RenderNode> AttachLayer(const Json::Value& jlayer,
 
     // Layer content.
     auto layer = gLayerAttachers[type](jlayer, layerCtx->fCtx);
+    // Optional layer mask.
+    layer = AttachMask(jlayer["masksProperties"], layerCtx->fCtx, std::move(layer));
+    // Optional layer transform.
     if (auto layerMatrix = layerCtx->AttachLayerMatrix(jlayer)) {
-        // Optional layer transform.
         layer = sksg::Transform::Make(std::move(layer), std::move(layerMatrix));
     }
     // Optional layer opacity.
diff --git a/experimental/sksg/SkSGGroup.h b/experimental/sksg/SkSGGroup.h
index f9126ea37f..482f10db8c 100644
--- a/experimental/sksg/SkSGGroup.h
+++ b/experimental/sksg/SkSGGroup.h
@@ -26,6 +26,9 @@ public:
     void addChild(sk_sp<RenderNode>);
     void removeChild(const sk_sp<RenderNode>&);
 
+    size_t size() const { return SkTo<size_t>(fChildren.count()); }
+    bool  empty() const { return fChildren.empty(); }
+
 protected:
     Group();
     ~Group() override;
diff --git a/experimental/sksg/SkSGPaintNode.cpp b/experimental/sksg/SkSGPaintNode.cpp
index bb5b714030..9220b0f0af 100644
--- a/experimental/sksg/SkSGPaintNode.cpp
+++ b/experimental/sksg/SkSGPaintNode.cpp
@@ -23,6 +23,7 @@ SkRect PaintNode::onRevalidate(InvalidationController*, const SkMatrix&) {
 
     fPaint.reset();
     fPaint.setAntiAlias(fAntiAlias);
+    fPaint.setBlendMode(fBlendMode);
     fPaint.setStyle(fStyle);
     fPaint.setStrokeWidth(fStrokeWidth);
     fPaint.setStrokeMiter(fStrokeMiter);
diff --git a/experimental/sksg/SkSGPaintNode.h b/experimental/sksg/SkSGPaintNode.h
index 1085e27c0f..5c9563b3a6 100644
--- a/experimental/sksg/SkSGPaintNode.h
+++ b/experimental/sksg/SkSGPaintNode.h
@@ -26,6 +26,7 @@ public:
 
     SG_ATTRIBUTE(AntiAlias  , bool          , fAntiAlias  )
     SG_ATTRIBUTE(Opacity    , SkScalar      , fOpacity    )
+    SG_ATTRIBUTE(BlendMode  , SkBlendMode   , fBlendMode  )
     SG_ATTRIBUTE(StrokeWidth, SkScalar      , fStrokeWidth)
     SG_ATTRIBUTE(StrokeMiter, SkScalar      , fStrokeMiter)
     SG_ATTRIBUTE(Style      , SkPaint::Style, fStyle      )
@@ -46,6 +47,7 @@ private:
                    fStrokeWidth = 1,
                    fStrokeMiter = 4;
     bool           fAntiAlias   = false;
+    SkBlendMode    fBlendMode   = SkBlendMode::kSrcOver;
     SkPaint::Style fStyle       = SkPaint::kFill_Style;
     SkPaint::Join  fStrokeJoin  = SkPaint::kMiter_Join;
     SkPaint::Cap   fStrokeCap   = SkPaint::kButt_Cap;