private static Size DecodeWebP(BinaryReader binaryReader)
{
// 'RIFF' already read
binaryReader.ReadBytes(4);
if (ByteHelper.ReadInt32LE(binaryReader) != 1346520407)// 1346520407 : 'WEBP'
{
return(Size.Empty);
}
switch (ByteHelper.ReadInt32LE(binaryReader))
{
case 540561494: // 'VP8 ' : lossy
// skip stuff we don't need
binaryReader.ReadBytes(7);
if (ByteHelper.ReadInt24LE(binaryReader) != 2752925) // invalid webp file
{
return(Size.Empty);
}
return(new Size(ByteHelper.ReadInt16LE(binaryReader), ByteHelper.ReadInt16LE(binaryReader)));
case 1278758998: // 'VP8L' : lossless
// skip stuff we don't need
binaryReader.ReadBytes(4);
if (binaryReader.ReadByte() != 47) // 0x2f : 47 1 byte signature
{
return(Size.Empty);
}
byte[] b = binaryReader.ReadBytes(4);
return(new Size(
1 + (((b[1] & 0x3F) << 8) | b[0]),
1 + ((b[3] << 10) | (b[2] << 2) | ((b[1] & 0xC0) >> 6))));
// if something breaks put in the '& 0xF' but & oxf should do nothing in theory
// because inclusive & with 1111 will leave the binary untouched
// 1 + (((wh[3] & 0xF) << 10) | (wh[2] << 2) | ((wh[1] & 0xC0) >> 6))
case 1480085590: // 'VP8X' : extended
// skip stuff we don't need
binaryReader.ReadBytes(8);
return(new Size(1 + ByteHelper.ReadInt24LE(binaryReader), 1 + ByteHelper.ReadInt24LE(binaryReader)));
}
return(Size.Empty);
}
private static Size DecodeTiffLE(BinaryReader binaryReader)
{
if (binaryReader.ReadByte() != 0)
{
return(Size.Empty);
}
int idfStart = ByteHelper.ReadInt32LE(binaryReader);
binaryReader.BaseStream.Seek(idfStart, SeekOrigin.Begin);
int numberOfIDF = ByteHelper.ReadInt16LE(binaryReader);
int width = -1;
int height = -1;
for (int i = 0; i < numberOfIDF; i++)
{
short field = ByteHelper.ReadInt16LE(binaryReader);
switch (field)
{
// https://www.awaresystems.be/imaging/tiff/tifftags/baseline.html
default:
binaryReader.ReadBytes(10);
break;
case 256: // image width
binaryReader.ReadBytes(6);
width = ByteHelper.ReadInt32LE(binaryReader);
break;
case 257: // image length
binaryReader.ReadBytes(6);
height = ByteHelper.ReadInt32LE(binaryReader);
break;
}
if (width != -1 && height != -1)
{
return(new Size(width, height));
}
}
return(Size.Empty);
}
