add artboards shapes to updates when RenderOpacity has dirt

Fixes nested artboards not applying inherited opacity to their backgrounds
Issue #5887

Diffs=
0dcbdade4 add artboards shapes to updates when RenderOpacity has dirt (#5971)

Co-authored-by: hernan <hernantorrisi@gmail.com>

.rive_head

@@ -1 +1 @@
-85b2b6ed1965d66f5f268993e54f5f89f30a2e29
+0dcbdade49885fcae4de304972ae37f6283f19d1

include/rive/shapes/shape_paint_container.hpp

@@ -38,6 +38,10 @@ class ShapePaintContainer
     std::unique_ptr<CommandPath> makeCommandPath(PathSpace space);
 
     void propagateOpacity(float opacity);
+
+    #ifdef TESTING
+    const std::vector<ShapePaint*>& shapePaints() const { return m_ShapePaints; }
+    #endif
 };
 } // namespace rive
 

src/artboard.cpp

@@ -427,6 +427,10 @@ void Artboard::update(ComponentDirt value)
         m_ClipPath = factory()->makeRenderPath(clip);
         m_BackgroundPath = factory()->makeRenderPath(bg);
     }
+    if (hasDirt(value, ComponentDirt::RenderOpacity))
+    {
+        propagateOpacity(childOpacity());
+    }
 }
 
 bool Artboard::updateComponents()

test/nested_artboard_opacity_test.cpp

@@ -0,0 +1,26 @@
+#include <rive/file.hpp>
+#include <rive/node.hpp>
+#include <rive/nested_artboard.hpp>
+#include <rive/shapes/paint/shape_paint.hpp>
+#include "rive_file_reader.hpp"
+
+TEST_CASE("Nested artboard background renders with opacity", "[file]")
+{
+    auto file = ReadRiveFile("../../test/assets/nested_artboard_opacity.riv");
+
+    auto mainArtboard = file->artboard()->instance();
+    REQUIRE(mainArtboard->find("Parent Artboard") != nullptr);
+    auto artboard = mainArtboard->find<rive::Artboard>("Parent Artboard");  
+    artboard->updateComponents();
+    REQUIRE(artboard->is<rive::Artboard>());
+    REQUIRE(artboard->find("Nested artboard container") != nullptr);
+    auto nestedArtboardContainer = artboard->find<rive::NestedArtboard>("Nested artboard container");
+    REQUIRE(nestedArtboardContainer->artboard() != nullptr);
+    auto nestedArtboard = nestedArtboardContainer->artboard();
+    nestedArtboard->updateComponents();
+    auto paints = nestedArtboard->shapePaints();
+    REQUIRE(paints.size() == 1);
+    auto paint = paints[0];
+    REQUIRE(paint->is<rive::ShapePaint>());
+    REQUIRE(paint->renderOpacity() == 0.3275f);
+}