using MediaBrowser.Common.Logging; using System; using System.Collections.Generic; using System.Drawing; using System.IO; using System.Linq; namespace MediaBrowser.Controller.Drawing { /// /// Taken from http://stackoverflow.com/questions/111345/getting-image-dimensions-without-reading-the-entire-file/111349 /// http://www.codeproject.com/Articles/35978/Reading-Image-Headers-to-Get-Width-and-Height /// Minor improvements including supporting unsigned 16-bit integers when decoding Jfif and added logic /// to load the image using new Bitmap if reading the headers fails /// public static class ImageHeader { /// /// The error message /// const string errorMessage = "Could not recognize image format."; /// /// The image format decoders /// private static readonly Dictionary> imageFormatDecoders = new Dictionary> { { new byte[] { 0x42, 0x4D }, DecodeBitmap }, { new byte[] { 0x47, 0x49, 0x46, 0x38, 0x37, 0x61 }, DecodeGif }, { new byte[] { 0x47, 0x49, 0x46, 0x38, 0x39, 0x61 }, DecodeGif }, { new byte[] { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A }, DecodePng }, { new byte[] { 0xff, 0xd8 }, DecodeJfif }, }; /// /// Gets the dimensions of an image. /// /// The path of the image to get the dimensions of. /// The dimensions of the specified image. /// The image was of an unrecognised format. public static Size GetDimensions(string path) { try { using (var fs = File.OpenRead(path)) { using (var binaryReader = new BinaryReader(fs)) { return GetDimensions(binaryReader); } } } catch { Logger.LogInfo("Failed to read image header for {0}. Doing it the slow way.", path); using (var fs = File.OpenRead(path)) { // Co it the old fashioned way using (var b = Image.FromStream(fs, true, false)) { return b.Size; } } } } /// /// Gets the dimensions of an image. /// /// The binary reader. /// Size. /// binaryReader /// The image was of an unrecognized format. private static Size GetDimensions(BinaryReader binaryReader) { int maxMagicBytesLength = imageFormatDecoders.Keys.OrderByDescending(x => x.Length).First().Length; var magicBytes = new byte[maxMagicBytesLength]; for (int i = 0; i < maxMagicBytesLength; i += 1) { magicBytes[i] = binaryReader.ReadByte(); foreach (var kvPair in imageFormatDecoders) { if (StartsWith(magicBytes, kvPair.Key)) { return kvPair.Value(binaryReader); } } } throw new ArgumentException(errorMessage, "binaryReader"); } /// /// Startses the with. /// /// The this bytes. /// The that bytes. /// true if XXXX, false otherwise private static bool StartsWith(byte[] thisBytes, byte[] thatBytes) { for (int i = 0; i < thatBytes.Length; i += 1) { if (thisBytes[i] != thatBytes[i]) { return false; } } return true; } /// /// Reads the little endian int16. /// /// The binary reader. /// System.Int16. private static short ReadLittleEndianInt16(BinaryReader binaryReader) { var bytes = new byte[sizeof(short)]; for (int i = 0; i < sizeof(short); i += 1) { bytes[sizeof(short) - 1 - i] = binaryReader.ReadByte(); } return BitConverter.ToInt16(bytes, 0); } /// /// Reads the little endian int32. /// /// The binary reader. /// System.Int32. private static int ReadLittleEndianInt32(BinaryReader binaryReader) { var bytes = new byte[sizeof(int)]; for (int i = 0; i < sizeof(int); i += 1) { bytes[sizeof(int) - 1 - i] = binaryReader.ReadByte(); } return BitConverter.ToInt32(bytes, 0); } /// /// Decodes the bitmap. /// /// The binary reader. /// Size. private static Size DecodeBitmap(BinaryReader binaryReader) { binaryReader.ReadBytes(16); int width = binaryReader.ReadInt32(); int height = binaryReader.ReadInt32(); return new Size(width, height); } /// /// Decodes the GIF. /// /// The binary reader. /// Size. private static Size DecodeGif(BinaryReader binaryReader) { int width = binaryReader.ReadInt16(); int height = binaryReader.ReadInt16(); return new Size(width, height); } /// /// Decodes the PNG. /// /// The binary reader. /// Size. private static Size DecodePng(BinaryReader binaryReader) { binaryReader.ReadBytes(8); int width = ReadLittleEndianInt32(binaryReader); int height = ReadLittleEndianInt32(binaryReader); return new Size(width, height); } /// /// Decodes the jfif. /// /// The binary reader. /// Size. /// private static Size DecodeJfif(BinaryReader binaryReader) { while (binaryReader.ReadByte() == 0xff) { byte marker = binaryReader.ReadByte(); short chunkLength = ReadLittleEndianInt16(binaryReader); if (marker == 0xc0) { binaryReader.ReadByte(); int height = ReadLittleEndianInt16(binaryReader); int width = ReadLittleEndianInt16(binaryReader); return new Size(width, height); } if (chunkLength < 0) { var uchunkLength = (ushort)chunkLength; binaryReader.ReadBytes(uchunkLength - 2); } else { binaryReader.ReadBytes(chunkLength - 2); } } throw new ArgumentException(errorMessage); } } }