Add background color rendering support for blur background in RootLayer. (#1230)

Author: Hparty

src/layers/RootLayer.cpp

@@ -120,6 +120,9 @@ bool RootLayer::drawLayer(const DrawArgs& args, Canvas* canvas, float alpha, Ble
   auto color = _backgroundColor;
   color.alpha = color.alpha * alpha;
   canvas->drawColor(color, blendMode);
+  if (args.blurBackground) {
+    args.blurBackground->getCanvas()->drawColor(color, blendMode);
+  }
   return Layer::drawLayer(args, canvas, alpha, blendMode, transform3D);
 }
 

test/baseline/version.json

@@ -244,6 +244,7 @@
         "PassThoughAndNormal": "43cd416",
         "PassThrough_Test": "7fa7fcb8",
         "Preserve3DNestedLayers": "0b31d462",
+        "RootLayerBackgroundColorWithBlurBackground": "d15a4d35",
         "ShapeStyleWithMatrix": "0cfb8996",
         "StrokeOnTop_Off": "80c523ee",
         "StrokeOnTop_On": "80c523ee",

test/src/LayerTest.cpp

@@ -26,6 +26,7 @@
 #include "layers/OpaqueContext.h"
 #include "layers/DrawArgs.h"
 #include "layers/RootLayer.h"
+#include "layers/BackgroundContext.h"
 #include "layers/SubtreeCache.h"
 #include "layers/TileCache.h"
 #include "layers/compositing3d/Layer3DContext.h"
@@ -3137,4 +3138,48 @@ TGFX_TEST(LayerTest, Contour3DWithDropShadow) {
   EXPECT_TRUE(Baseline::Compare(surface, "LayerTest/Contour3DWithDropShadow"));
 }
 
+TGFX_TEST(LayerTest, RootLayerBackgroundColorWithBlurBackground) {
+  ContextScope scope;
+  auto context = scope.getContext();
+  EXPECT_TRUE(context != nullptr);
+  
+  auto surface = Surface::Make(context, 200, 200);
+  auto displayList = std::make_unique<DisplayList>();
+  
+  // Set background color on display list (which sets it on root layer)
+  auto backgroundColor = Color::FromRGBA(255, 0, 0, 128); // Semi-transparent red
+  displayList->setBackgroundColor(backgroundColor);
+  EXPECT_EQ(displayList->backgroundColor(), backgroundColor);
+  
+  // Add a bottom layer to provide content that will be blurred
+  auto bottomLayer = ShapeLayer::Make();
+  Path bottomPath = {};
+  bottomPath.addRect(Rect::MakeXYWH(60.0f, 60.0f, 80.0f, 80.0f));
+  bottomLayer->setPath(bottomPath);
+  bottomLayer->setFillStyle(ShapeStyle::Make(Color::FromRGBA(0, 0, 255, 255))); // Blue background content
+  displayList->root()->addChild(bottomLayer);
+  
+  // Add a shape layer with background blur to trigger the blurBackground code path
+  // Position it so part covers bottomLayer and part covers pure background
+  auto shapeLayer = ShapeLayer::Make();
+  Path path = {};
+  path.addRect(Rect::MakeXYWH(40.0f, 40.0f, 80.0f, 80.0f));
+  shapeLayer->setPath(path);
+  shapeLayer->setFillStyle(ShapeStyle::Make(Color::FromRGBA(255, 255, 255, 128))); // Semi-transparent white
+  
+  // Add background blur style to trigger the blur background rendering
+  auto backgroundBlur = BackgroundBlurStyle::Make(10.0f, 10.0f);
+  shapeLayer->setLayerStyles({backgroundBlur});
+  
+  displayList->root()->addChild(shapeLayer);
+  
+  // Render the display list - this will internally create BackgroundContext and call
+  // RootLayer::drawLayer with args.blurBackground set, testing our new code path
+  displayList->render(surface.get());
+  
+  // Compare with baseline to verify the background color is correctly drawn
+  // to both the main canvas and blur background canvas
+  EXPECT_TRUE(Baseline::Compare(surface, "LayerTest/RootLayerBackgroundColorWithBlurBackground"));
+}
+
 }  // namespace tgfx