126 lines
4.3 KiB
C#
126 lines
4.3 KiB
C#
using System.Drawing;
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namespace File_Folder_Helper.Helpers.Exif;
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internal static class Dimensions
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{
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#pragma warning disable IDE0230
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private static readonly Dictionary<byte[], Func<BinaryReader, Size?>> _ImageFormatDecoders = new()
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{
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{ new byte[] { 0x42, 0x4D }, DecodeBitmap },
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{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif },
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{ new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif },
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{ new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng },
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{ new byte[] { 0xff, 0xd8 }, DecodeJfif },
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{ new byte[] { 0x52, 0x49, 0x46, 0x46 }, DecodeWebP },
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};
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#pragma warning restore IDE0230
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private static bool StartsWith(byte[] thisBytes, byte[] thatBytes)
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{
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for (int i = 0; i < thatBytes.Length; i += 1)
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{
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if (thisBytes[i] == thatBytes[i])
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continue;
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return false;
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}
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return true;
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}
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private static short ReadLittleEndianInt16(BinaryReader binaryReader)
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{
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byte[] bytes = new byte[sizeof(short)];
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for (int i = 0; i < sizeof(short); i += 1)
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bytes[sizeof(short) - 1 - i] = binaryReader.ReadByte();
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return BitConverter.ToInt16(bytes, 0);
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}
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private static int ReadLittleEndianInt32(BinaryReader binaryReader)
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{
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byte[] bytes = new byte[sizeof(int)];
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for (int i = 0; i < sizeof(int); i += 1)
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bytes[sizeof(int) - 1 - i] = binaryReader.ReadByte();
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return BitConverter.ToInt32(bytes, 0);
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}
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private static Size? DecodeBitmap(BinaryReader binaryReader)
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{
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_ = binaryReader.ReadBytes(16);
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int width = binaryReader.ReadInt32();
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int height = binaryReader.ReadInt32();
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return new Size(width, height);
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}
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private static Size? DecodeGif(BinaryReader binaryReader)
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{
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int width = binaryReader.ReadInt16();
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int height = binaryReader.ReadInt16();
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return new Size(width, height);
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}
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private static Size? DecodePng(BinaryReader binaryReader)
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{
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_ = binaryReader.ReadBytes(8);
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int width = ReadLittleEndianInt32(binaryReader);
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int height = ReadLittleEndianInt32(binaryReader);
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return new Size(width, height);
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}
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private static Size? DecodeJfif(BinaryReader binaryReader)
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{
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while (binaryReader.ReadByte() == 0xff)
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{
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byte marker = binaryReader.ReadByte();
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short chunkLength = ReadLittleEndianInt16(binaryReader);
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if (marker == 0xc0)
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{
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_ = binaryReader.ReadByte();
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int height = ReadLittleEndianInt16(binaryReader);
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int width = ReadLittleEndianInt16(binaryReader);
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return new Size(width, height);
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}
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if (chunkLength >= 0)
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_ = binaryReader.ReadBytes(chunkLength - 2);
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else
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{
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ushort uChunkLength = (ushort)chunkLength;
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_ = binaryReader.ReadBytes(uChunkLength - 2);
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}
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}
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return null;
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}
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private static Size? DecodeWebP(BinaryReader binaryReader)
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{
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_ = binaryReader.ReadUInt32(); // Size
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_ = binaryReader.ReadBytes(15); // WEBP, VP8 + more
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_ = binaryReader.ReadBytes(3); // SYNC
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int width = binaryReader.ReadUInt16() & 0b00_11111111111111; // 14 bits width
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int height = binaryReader.ReadUInt16() & 0b00_11111111111111; // 14 bits height
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return new Size(width, height);
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}
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internal static Size? GetDimensions(BinaryReader binaryReader)
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{
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int maxMagicBytesLength = _ImageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length;
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byte[] magicBytes = new byte[maxMagicBytesLength];
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for (int i = 0; i < maxMagicBytesLength; i += 1)
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{
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magicBytes[i] = binaryReader.ReadByte();
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foreach (KeyValuePair<byte[], Func<BinaryReader, Size?>> kvPair in _ImageFormatDecoders)
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{
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if (StartsWith(magicBytes, kvPair.Key))
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return kvPair.Value(binaryReader);
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}
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}
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return null;
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}
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internal static Size? GetDimensions(string path)
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{
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using BinaryReader binaryReader = new(File.OpenRead(path));
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return GetDimensions(binaryReader);
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}
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} |