From 7a82abcb189a98b06c7a2b97c50e320173599670 Mon Sep 17 00:00:00 2001
From: Georg Hagen <git.georg.hagen@madvoxel.com>
Date: Thu, 13 Feb 2025 23:26:50 +0100
Subject: [PATCH] Add JpegWithTagsWriter helper

---
 openVulkanoCpp/Image/JpegWithTagsWriter.hpp | 98 +++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 openVulkanoCpp/Image/JpegWithTagsWriter.hpp

diff --git a/openVulkanoCpp/Image/JpegWithTagsWriter.hpp b/openVulkanoCpp/Image/JpegWithTagsWriter.hpp
new file mode 100644
index 0000000..e7dffc3
--- /dev/null
+++ b/openVulkanoCpp/Image/JpegWithTagsWriter.hpp
@@ -0,0 +1,98 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include <algorithm>
+#include <filesystem>
+#include <span>
+#include <string_view>
+
+namespace OpenVulkano
+{
+	class JpegWithTagsWriter final
+	{
+		FILE* file;
+
+		template<typename T> static T EndianSwap(T value)
+		{
+			T result;
+
+			char* ptr = reinterpret_cast<char*>(&value);
+			std::reverse(ptr, ptr + sizeof(T));
+			result = value;
+
+			return result;
+		}
+
+		void Check() const
+		{
+			if (file == nullptr) throw std::runtime_error("Can't append to jpeg file, it has already been completed.");
+		}
+
+		// ReSharper disable once CppDFAConstantParameter
+		void WriteAppMarker(const int app = 1) const
+		{
+			// ReSharper disable once CppDFAConstantConditions
+			if (app > 0xF) [[unlikely]] throw std::runtime_error("App marker is out of range.");
+			fputc(0xFF, file);
+			fputc(0xE0 + app, file);
+		}
+
+		void Write16(uint16_t value) const
+		{
+			value = EndianSwap(value);
+			fwrite(&value, sizeof(value), 1, file);
+		}
+
+		void Write32(uint32_t value) const
+		{
+			value = EndianSwap(value);
+			fwrite(&value, sizeof(value), 1, file);
+		}
+
+	public:
+		JpegWithTagsWriter(const std::filesystem::path& filePath)
+		{
+			file = fopen(filePath.c_str(), "wb");
+			if (file == nullptr) throw std::runtime_error("Can't open file.");
+			// Write soi marker
+			fputc(0xFF, file);
+			fputc(0xD8, file);
+		}
+
+		void WriteExifTag(const std::span<uint8_t>& exifTag) const
+		{
+			WriteAppMarker();
+			Write16(exifTag.size() + 2); // 2 byte extra for the size value itself
+			fwrite(exifTag.data(), sizeof(uint8_t), exifTag.size(), file);
+		}
+
+		void WriteXmpTag(const std::string& xmpTag) const
+		{
+			constexpr std::string_view XMP_MARKER = "http://ns.adobe.com/xap/1.0/";
+			WriteAppMarker(1);
+			Write16(xmpTag.size() + XMP_MARKER.size() + 3); // 1 byte extra for null termination, 2 byte extra for the size value itself
+			fwrite(XMP_MARKER.data(), XMP_MARKER.size(), 1, file);
+			fputc(0, file); // Null terminate string
+			fwrite(xmpTag.c_str(), 1, xmpTag.size(), file);
+		}
+
+		// Must be called as last function, as this will finalize the image writing and will close the file
+		void WriteImageData(const std::span<uint8_t>& imageData)
+		{
+			Check();
+			// write image data and skip soi marker from og data
+			fwrite(imageData.data() + 2, sizeof(uint8_t), imageData.size() - 2, file);
+			fclose(file);
+			file = nullptr;
+		}
+
+		operator bool() const { return file != nullptr; }
+
+		bool IsOpen() const { return file != nullptr; }
+	};
+}