AssetRipper_AssetRipper/Source/AssetRipper.Export.Modules.Textures/CrunchHandler.cs

using AssetRipper.Import.Logging;
using AssetRipper.SourceGenerated.Enums;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;

namespace AssetRipper.Export.UnityProjects.Textures;

internal static partial class CrunchHandler
{
	public static bool DecompressCrunch(TextureFormat textureFormat, UnityVersion unityVersion, ReadOnlySpan<byte> data, [NotNullWhen(true)] out byte[]? uncompressedBytes)
	{
		if (OperatingSystem.IsWindows())
		{
			return DecompressCrunchWithUtinyDecoder(textureFormat, unityVersion, data, out uncompressedBytes);
		}
		else
		{
			return DecompressCrunchWithStudioDecoder(textureFormat, unityVersion, data, out uncompressedBytes);
		}
	}

	private static bool IsUseUnityCrunch(UnityVersion version, TextureFormat format)
	{
		if (version.GreaterThanOrEquals(2017, 3))
		{
			return true;
		}
		return format is TextureFormat.ETC_RGB4Crunched or TextureFormat.ETC2_RGBA8Crunched;
	}

	[SupportedOSPlatform("windows")]
	[LibraryImport("crunch")]
	[UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
	[return: MarshalAs(UnmanagedType.Bool)]
	private static partial bool DecompressCRN(ReadOnlySpan<byte> pSrcFileData, int srcFileSize, out IntPtr uncompressedData, out int uncompressedSize);

	[SupportedOSPlatform("windows")]
	[LibraryImport("crunchunity")]
	[UnmanagedCallConv(CallConvs = new Type[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
	[return: MarshalAs(UnmanagedType.Bool)]
	private static partial bool DecompressUnityCRN(ReadOnlySpan<byte> pSrcFileData, int srcFileSize, out IntPtr uncompressedData, out int uncompressedSize);

	[SupportedOSPlatform("windows")]
	private static bool DecompressCrunchWithUtinyDecoder(TextureFormat textureFormat, UnityVersion unityVersion, ReadOnlySpan<byte> data, [NotNullWhen(true)] out byte[]? uncompressedBytes)
	{
		IntPtr uncompressedData = default;
		try
		{
			bool result = IsUseUnityCrunch(unityVersion, textureFormat)
				? DecompressUnityCRN(data, data.Length, out uncompressedData, out int uncompressedSize)
				: DecompressCRN(data, data.Length, out uncompressedData, out uncompressedSize);

			if (result && uncompressedSize > 0 && uncompressedData != default)
			{
				uncompressedBytes = new byte[uncompressedSize];
				Marshal.Copy(uncompressedData, uncompressedBytes, 0, uncompressedSize);
				return true;
			}
			else
			{
				uncompressedBytes = null;
				return false;
			}
		}
		finally
		{
			if (uncompressedData != default)
			{
				Marshal.FreeHGlobal(uncompressedData);
			}
		}
	}

	private static bool DecompressCrunchWithStudioDecoder(TextureFormat textureFormat, UnityVersion unityVersion, ReadOnlySpan<byte> data, [NotNullWhen(true)] out byte[]? uncompressedBytes)
	{
		return IsUseUnityCrunch(unityVersion, textureFormat)
			? DecompressUnityCrunchWithStudioDecoder(data, out uncompressedBytes)
			: DecompressNormalCrunchWithStudioDecoder(data, out uncompressedBytes);
	}

	private static bool DecompressNormalCrunchWithStudioDecoder(ReadOnlySpan<byte> data, [NotNullWhen(true)] out byte[]? uncompressedBytes)
	{
		if (data.Length <= 0)
		{
			throw new ArgumentException(null, nameof(data));
		}

		Logger.Info("About to unpack normal crunch...");
		uncompressedBytes = Texture2DDecoder.TextureDecoder.UnpackCrunch(data);
		return uncompressedBytes is { Length: > 0 };
	}

	private static bool DecompressUnityCrunchWithStudioDecoder(ReadOnlySpan<byte> data, [NotNullWhen(true)] out byte[]? uncompressedBytes)
	{
		if (data.Length <= 0)
		{
			throw new ArgumentException(null, nameof(data));
		}

		Logger.Info("About to unpack unity crunch...");
		uncompressedBytes = Texture2DDecoder.TextureDecoder.UnpackUnityCrunch(data);
		return uncompressedBytes is { Length: > 0 };
	}
}