fix: replace magic number 4 with channels field in PixelDataResult

Author: NorbertKlockiewicz

packages/react-native-executorch/common/rnexecutorch/host_objects/JsiConversions.h

@@ -575,7 +575,7 @@ getJsiValue(const models::style_transfer::PixelDataResult &result,
   auto sizesArray = jsi::Array(runtime, 3);
   sizesArray.setValueAtIndex(runtime, 0, jsi::Value(result.height));
   sizesArray.setValueAtIndex(runtime, 1, jsi::Value(result.width));
-  sizesArray.setValueAtIndex(runtime, 2, jsi::Value(4));
+  sizesArray.setValueAtIndex(runtime, 2, jsi::Value(result.channels));
   obj.setProperty(runtime, "sizes", sizesArray);
 
   obj.setProperty(runtime, "scalarType",

packages/react-native-executorch/common/rnexecutorch/models/style_transfer/StyleTransfer.cpp

@@ -61,7 +61,7 @@ PixelDataResult toPixelDataResult(const cv::Mat &bgrMat) {
   cv::cvtColor(bgrMat, rgba, cv::COLOR_BGR2RGBA);
   std::size_t dataSize = static_cast<std::size_t>(size.width) * size.height * 4;
   auto pixelBuffer = std::make_shared<OwningArrayBuffer>(rgba.data, dataSize);
-  return PixelDataResult{pixelBuffer, size.width, size.height};
+  return PixelDataResult{pixelBuffer, size.width, size.height, rgba.channels()};
 }
 
 StyleTransferResult StyleTransfer::generateFromString(std::string imageSource,

packages/react-native-executorch/common/rnexecutorch/models/style_transfer/Types.h

@@ -11,6 +11,7 @@ struct PixelDataResult {
   std::shared_ptr<OwningArrayBuffer> dataPtr;
   int width;
   int height;
+  int channels;
 };
 
 using StyleTransferResult = std::variant<PixelDataResult, std::string>;