UI updates and preroll buffer to 8 frames

apps/LoopThroughWithOpenGLCompositing/OpenGLComposite.cpp

@@ -63,6 +63,7 @@ constexpr GLuint kDecodedVideoTextureUnit = 1;
 constexpr GLuint kSourceHistoryTextureUnitBase = 2;
 constexpr GLuint kPackedVideoTextureUnit = 2;
 constexpr GLuint kGlobalParamsBindingPoint = 0;
+constexpr unsigned kPrerollFrameCount = 8;
 const char* kVertexShaderSource =
 	"#version 430 core\n"
 	"out vec2 vTexCoord;\n"
@@ -1233,7 +1234,7 @@ bool OpenGLComposite::Start()
 	mTotalPlayoutFrames = 0;
 
 	// Preroll frames
-	for (unsigned i = 0; i < 5; i++)
+	for (unsigned i = 0; i < kPrerollFrameCount; i++)
 	{
 		// Take each video frame from the front of the queue and move it to the back
 		IDeckLinkMutableVideoFrame* outputVideoFrame = mDLOutputVideoFrameQueue.front();

apps/LoopThroughWithOpenGLCompositing/RuntimeHost.cpp

@@ -53,6 +53,25 @@ bool MatchesControlKey(const std::string& candidate, const std::string& key)
 	return candidate == key || SimplifyControlKey(candidate) == SimplifyControlKey(key);
 }
 
+bool TryParseLayerIdNumber(const std::string& layerId, uint64_t& number)
+{
+	const std::string prefix = "layer-";
+	if (layerId.rfind(prefix, 0) != 0 || layerId.size() == prefix.size())
+		return false;
+
+	uint64_t parsed = 0;
+	for (std::size_t index = prefix.size(); index < layerId.size(); ++index)
+	{
+		const unsigned char ch = static_cast<unsigned char>(layerId[index]);
+		if (!std::isdigit(ch))
+			return false;
+		parsed = parsed * 10 + static_cast<uint64_t>(ch - '0');
+	}
+
+	number = parsed;
+	return true;
+}
+
 std::vector<double> JsonArrayToNumbers(const JsonValue& value)
 {
 	std::vector<double> numbers;
@@ -583,6 +602,7 @@ bool RuntimeHost::Initialize(std::string& error)
 			return false;
 		if (!ScanShaderPackages(error))
 			return false;
+		NormalizePersistentLayerIdsLocked();
 
 		for (LayerPersistentState& layer : mPersistentState.layers)
 		{
@@ -1469,15 +1489,31 @@ bool RuntimeHost::WriteTextFile(const std::filesystem::path& path, const std::st
 	std::error_code fsError;
 	std::filesystem::create_directories(path.parent_path(), fsError);
 
-	std::ofstream output(path, std::ios::binary);
+	const std::filesystem::path temporaryPath = path.string() + ".tmp";
+	std::ofstream output(temporaryPath, std::ios::binary | std::ios::trunc);
 	if (!output)
 	{
-		error = "Could not write file: " + path.string();
+		error = "Could not write file: " + temporaryPath.string();
 		return false;
 	}
 
 	output << contents;
-	return output.good();
+	output.close();
+	if (!output.good())
+	{
+		error = "Could not finish writing file: " + temporaryPath.string();
+		return false;
+	}
+
+	if (!MoveFileExA(temporaryPath.string().c_str(), path.string().c_str(), MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH))
+	{
+		const DWORD lastError = GetLastError();
+		std::filesystem::remove(temporaryPath, fsError);
+		error = "Could not replace file: " + path.string() + " (Win32 error " + std::to_string(lastError) + ")";
+		return false;
+	}
+
+	return true;
 }
 
 bool RuntimeHost::ResolvePaths(std::string& error)
@@ -1728,6 +1764,38 @@ bool RuntimeHost::DeserializeLayerStackLocked(const JsonValue& layersValue, std:
 	return true;
 }
 
+void RuntimeHost::NormalizePersistentLayerIdsLocked()
+{
+	std::set<std::string> usedIds;
+	uint64_t maxLayerNumber = mNextLayerId;
+
+	for (LayerPersistentState& layer : mPersistentState.layers)
+	{
+		uint64_t layerNumber = 0;
+		const bool hasReusableId = !layer.id.empty() &&
+			usedIds.find(layer.id) == usedIds.end() &&
+			TryParseLayerIdNumber(layer.id, layerNumber);
+
+		if (hasReusableId)
+		{
+			usedIds.insert(layer.id);
+			maxLayerNumber = std::max(maxLayerNumber, layerNumber);
+			continue;
+		}
+
+		do
+		{
+			++maxLayerNumber;
+			layer.id = "layer-" + std::to_string(maxLayerNumber);
+		}
+		while (usedIds.find(layer.id) != usedIds.end());
+
+		usedIds.insert(layer.id);
+	}
+
+	mNextLayerId = maxLayerNumber;
+}
+
 std::vector<std::string> RuntimeHost::GetStackPresetNamesLocked() const
 {
 	std::vector<std::string> presetNames;

apps/LoopThroughWithOpenGLCompositing/RuntimeHost.h

@@ -112,6 +112,7 @@ private:
 	JsonValue BuildStateValue() const;
 	JsonValue SerializeLayerStackLocked() const;
 	bool DeserializeLayerStackLocked(const JsonValue& layersValue, std::vector<LayerPersistentState>& layers, std::string& error);
+	void NormalizePersistentLayerIdsLocked();
 	std::vector<std::string> GetStackPresetNamesLocked() const;
 	std::string MakeSafePresetFileStem(const std::string& presetName) const;
 	JsonValue SerializeParameterValue(const ShaderParameterDefinition& definition, const ShaderParameterValue& value) const;