Cover art handling: significantly reduce memory usage. fixes #93

src/libs/subsonic/impl/ParameterParsing.hpp

@@ -55,7 +55,7 @@ namespace API::Subsonic
 	{
 		std::vector<T> res {getMultiParametersAs<T>(parameterMap, param)};
 		if (res.empty())
-			throw RequiredParameterMissingError {};
+			throw RequiredParameterMissingError {param};
 
 		return res;
 	}
@@ -78,7 +78,7 @@ namespace API::Subsonic
 	{
 		auto res {getParameterAs<T>(parameterMap, param)};
 		if (!res)
-			throw RequiredParameterMissingError {};
+			throw RequiredParameterMissingError {param};
 
 		return *res;
 	}

src/libs/subsonic/impl/SubsonicResource.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Emeric Poupon
+ * copyright (c) 2019 emeric poupon
  *
  * This file is part of LMS.
  *
@@ -546,7 +546,7 @@ handleCreatePlaylistRequest(RequestContext& context)
 		throw BadParameterGenericError {"songId"};
 
 	if (!name && !id)
-		throw RequiredParameterMissingError {};
+		throw RequiredParameterMissingError {"name or id"};
 
 	auto transaction {context.dbSession.createUniqueTransaction()};
 
@@ -1746,21 +1746,21 @@ handleGetCoverArt(RequestContext& context, const Wt::Http::Request& /*request*/,
 	std::size_t size {getParameterAs<std::size_t>(context.parameters, "size").value_or(256)};
 	size = clamp(size, std::size_t {32}, std::size_t {1024});
 
-	std::vector<unsigned char> data;
+	std::unique_ptr<CoverArt::ICoverArt> cover;
 	switch (id.type)
 	{
 		case Id::Type::Track:
-			data = Service<CoverArt::IGrabber>::get()->getFromTrack(context.dbSession, id.value, CoverArt::Format::JPEG, size);
+			cover = Service<CoverArt::IGrabber>::get()->getFromTrack(context.dbSession, id.value, size);
 			break;
 		case Id::Type::Release:
-			data = Service<CoverArt::IGrabber>::get()->getFromRelease(context.dbSession, id.value, CoverArt::Format::JPEG, size);
+			cover = Service<CoverArt::IGrabber>::get()->getFromRelease(context.dbSession, id.value, size);
 			break;
 		default:
 			throw BadParameterGenericError {"id"};
 	}
 
-	response.out().write(reinterpret_cast<const char*>(&data[0]), data.size());
-	response.setMimeType(CoverArt::formatToMimeType(CoverArt::Format::JPEG));
+	response.out().write(reinterpret_cast<const char*>(cover->getData()), cover->getDataSize());
+	response.setMimeType(std::string {cover->getMimeType()});
 }
 
 using RequestHandlerFunc = std::function<Response(RequestContext& context)>;

src/libs/subsonic/impl/SubsonicResponse.hpp

@@ -73,9 +73,14 @@ class GenericError : public Error
 class RequiredParameterMissingError : public Error
 {
 	public:
-		RequiredParameterMissingError() : Error {Code::RequiredParameterMissing} {}
+		RequiredParameterMissingError(std::string_view param)
+			: Error {Code::RequiredParameterMissing}
+			, _param {param}
+			{}
+
 	private:
-		std::string getMessage() const override { return "Required parameter is missing."; }
+		std::string getMessage() const override { return "Required parameter '" + _param + "' is missing."; }
+		std::string _param;
 };
 
 class ClientMustUpgradeError : public Error