Changed GetDimensions to handle a stream at the end and one exit

This commit is contained in:
2025-06-15 07:22:20 -07:00
parent 9a51d995cc
commit 66f366e9cf

View File

@ -8,16 +8,16 @@ internal static class Dimensions
#pragma warning disable IDE0230 #pragma warning disable IDE0230
private static readonly Dictionary<byte[], Func<BinaryReader, Size?>> _ImageFormatDecoders = new() private static readonly Dictionary<byte[], Func<BinaryReader, Size?>> _ImageFormatDecoders = new()
{ {
{ new byte[] { 0xff, 0xd8 }, DecodeJfif },
{ new byte[] { 0x42, 0x4D }, DecodeBitmap }, { new byte[] { 0x42, 0x4D }, DecodeBitmap },
{ new byte[] { 0x52, 0x49, 0x46, 0x46 }, DecodeWebP },
{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif }, { new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif }, { new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
{ new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng }, { new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
{ new byte[] { 0xff, 0xd8 }, DecodeJfif },
{ new byte[] { 0x52, 0x49, 0x46, 0x46 }, DecodeWebP },
}; };
#pragma warning restore IDE0230 #pragma warning restore IDE0230
private static bool StartsWith(byte[] thisBytes, byte[] thatBytes) private static bool StartsWith(List<byte> thisBytes, byte[] thatBytes)
{ {
for (int i = 0; i < thatBytes.Length; i += 1) for (int i = 0; i < thatBytes.Length; i += 1)
{ {
@ -103,30 +103,49 @@ internal static class Dimensions
internal static Size? GetDimensions(BinaryReader binaryReader) internal static Size? GetDimensions(BinaryReader binaryReader)
{ {
int maxMagicBytesLength = _ImageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length; Size? result;
byte[] magicBytes = new byte[maxMagicBytesLength]; List<byte> magicBytes = [];
for (int i = 0; i < maxMagicBytesLength; i += 1) int[] magicBytesLengths = (from l in _ImageFormatDecoders.Keys where l.Length <= binaryReader.BaseStream.Length orderby l.Length descending select l.Length).ToArray();
if (magicBytesLengths.Length == 0)
result = null;
else
{ {
magicBytes[i] = binaryReader.ReadByte(); result = null;
foreach (KeyValuePair<byte[], Func<BinaryReader, Size?>> kvPair in _ImageFormatDecoders) if (binaryReader.BaseStream.Length == binaryReader.BaseStream.Position)
_ = binaryReader.BaseStream.Seek(0, SeekOrigin.Begin);
for (int i = 0; i < magicBytesLengths[0]; i++)
{ {
if (StartsWith(magicBytes, kvPair.Key)) magicBytes.Add(binaryReader.ReadByte());
return kvPair.Value(binaryReader); foreach (KeyValuePair<byte[], Func<BinaryReader, Size?>> kvPair in _ImageFormatDecoders)
{
if (StartsWith(magicBytes, kvPair.Key))
{
result = kvPair.Value(binaryReader);
break;
}
}
if (result is not null)
break;
} }
} }
return null; return result;
} }
internal static Size? GetDimensions(string path) internal static Size? GetDimensions(string path)
{ {
using BinaryReader binaryReader = new(File.OpenRead(path)); Size? result;
return GetDimensions(binaryReader); using FileStream fileStream = File.OpenRead(path);
using BinaryReader binaryReader = new(fileStream);
result = GetDimensions(binaryReader);
return result;
} }
internal static Size? GetDimensions(Stream stream) internal static Size? GetDimensions(Stream stream)
{ {
Size? result;
using BinaryReader binaryReader = new(stream); using BinaryReader binaryReader = new(stream);
return GetDimensions(binaryReader); result = GetDimensions(binaryReader);
return result;
} }
} }