/// <summary>
/// Reads a custom directory from the arbitrary offset within file/stream.
/// </summary>
/// <param name="offset">The directory offset.</param>
/// <param name="info">The array of <see cref="TiffFieldInfo"/> objects to merge to
/// existing field information.</param>
/// <param name="count">The number of items to use from
/// the <paramref name="info"/> array.</param>
/// <returns><c>true</c> if a custom directory was read successfully;
/// otherwise, <c>false</c></returns>
public bool ReadCustomDirectory(long offset, TiffFieldInfo[] info, int count)
{
const string module = "ReadCustomDirectory";
setupFieldInfo(info, count);
uint dummyNextDirOff;
TiffDirEntry[] dir;
short dircount = fetchDirectory((uint)offset, out dir, out dummyNextDirOff);
if (dircount == 0)
{
ErrorExt(this, m_clientdata, module,
"{0}: Failed to read custom directory at offset {1}", m_name, offset);
return false;
}
FreeDirectory();
m_dir = new TiffDirectory();
int fix = 0;
for (short i = 0; i < dircount; i++)
{
if ((m_flags & TiffFlags.Swab) == TiffFlags.Swab)
{
short temp = (short)dir[i].tdir_tag;
SwabShort(ref temp);
dir[i].tdir_tag = (TiffTag)(ushort)temp;
temp = (short)dir[i].tdir_type;
SwabShort(ref temp);
dir[i].tdir_type = (TiffType)temp;
SwabLong(ref dir[i].tdir_count);
SwabUInt(ref dir[i].tdir_offset);
}
if (fix >= m_nfields || dir[i].tdir_tag == TiffTag.Ignore)
continue;
while (fix < m_nfields && m_fieldinfo[fix].Tag < dir[i].tdir_tag)
fix++;
if (fix >= m_nfields || m_fieldinfo[fix].Tag != dir[i].tdir_tag)
{
WarningExt(this, m_clientdata, module,
"{0}: unknown field with tag {1} (0x{2:x}) encountered",
m_name, (ushort)dir[i].tdir_tag, (ushort)dir[i].tdir_tag);
TiffFieldInfo[] arr = new TiffFieldInfo[1];
arr[0] = createAnonFieldInfo(dir[i].tdir_tag, dir[i].tdir_type);
MergeFieldInfo(arr, 1);
fix = 0;
while (fix < m_nfields && m_fieldinfo[fix].Tag < dir[i].tdir_tag)
fix++;
}
// null out old tags that we ignore.
if (m_fieldinfo[fix].Bit == FieldBit.Ignore)
{
dir[i].tdir_tag = TiffTag.Ignore;
continue;
}
// Check data type.
TiffFieldInfo fip = m_fieldinfo[fix];
while (dir[i].tdir_type != fip.Type && fix < m_nfields)
{
if (fip.Type == TiffType.Any)
{
// wildcard
break;
}
fip = m_fieldinfo[++fix];
if (fix >= m_nfields || fip.Tag != dir[i].tdir_tag)
{
WarningExt(this, m_clientdata, module,
"{0}: wrong data type {1} for \"{2}\"; tag ignored",
m_name, dir[i].tdir_type, m_fieldinfo[fix - 1].Name);
dir[i].tdir_tag = TiffTag.Ignore;
continue;
}
}
// Check count if known in advance.
if (fip.ReadCount != TiffFieldInfo.Variable &&
fip.ReadCount != TiffFieldInfo.Variable2)
{
int expected = fip.ReadCount;
if (fip.ReadCount == TiffFieldInfo.Spp)
expected = m_dir.td_samplesperpixel;
if (!checkDirCount(dir[i], expected))
{
dir[i].tdir_tag = TiffTag.Ignore;
continue;
}
}
// EXIF tags which need to be specifically processed.
switch (dir[i].tdir_tag)
{
case TiffTag.EXIF_SUBJECTDISTANCE:
fetchSubjectDistance(dir[i]);
break;
default:
fetchNormalTag(dir[i]);
break;
}
}
return true;
}
/// <summary>
/// Releases storage associated with current directory.
/// </summary>
public void FreeDirectory()
{
if (m_dir != null)
{
clearFieldBit(FieldBit.YCbCrSubsampling);
clearFieldBit(FieldBit.YCbCrPositioning);
m_dir = null;
}
}
private static void defaultRefBlackWhite(TiffDirectory td)
{
td.td_refblackwhite = new float[6];
if (td.td_photometric == Photometric.YCBCR)
{
// YCbCr (Class Y) images must have the ReferenceBlackWhite tag set. Fix the
// broken images, which lacks that tag.
td.td_refblackwhite[0] = 0.0F;
td.td_refblackwhite[1] = td.td_refblackwhite[3] = td.td_refblackwhite[5] = 255.0F;
td.td_refblackwhite[2] = td.td_refblackwhite[4] = 128.0F;
}
else
{
// Assume RGB (Class R)
for (int i = 0; i < 3; i++)
{
td.td_refblackwhite[2 * i + 0] = 0;
td.td_refblackwhite[2 * i + 1] = (float)((1L << td.td_bitspersample) - 1L);
}
}
}
private static bool defaultTransferFunction(TiffDirectory td)
{
short[][] tf = td.td_transferfunction;
tf[0] = null;
tf[1] = null;
tf[2] = null;
if (td.td_bitspersample >= sizeof(int) * 8 - 2)
return false;
int n = 1 << td.td_bitspersample;
tf[0] = new short[n];
tf[0][0] = 0;
for (int i = 1; i < n; i++)
{
double t = (double)i / ((double)n - 1.0);
tf[0][i] = (short)Math.Floor(65535.0 * Math.Pow(t, 2.2) + 0.5);
}
if (td.td_samplesperpixel - td.td_extrasamples > 1)
{
tf[1] = new short[n];
Buffer.BlockCopy(tf[0], 0, tf[1], 0, tf[0].Length * sizeof(short));
tf[2] = new short[n];
Buffer.BlockCopy(tf[0], 0, tf[2], 0, tf[0].Length * sizeof(short));
}
return true;
}
/*
* Setup a default directory structure.
*/
private void setupDefaultDirectory()
{
int tiffFieldInfoCount;
TiffFieldInfo[] tiffFieldInfo = getFieldInfo(out tiffFieldInfoCount);
setupFieldInfo(tiffFieldInfo, tiffFieldInfoCount);
m_dir = new TiffDirectory();
m_postDecodeMethod = PostDecodeMethodType.pdmNone;
m_foundfield = null;
m_tagmethods = m_defaultTagMethods;
/*
* Give client code a chance to install their own
* tag extensions & methods, prior to compression overloads.
*/
if (m_extender != null)
m_extender(this);
SetField(TiffTag.Compression, Compression.None);
/*
* NB: The directory is marked dirty as a result of setting
* up the default compression scheme. However, this really
* isn't correct -- we want DirtyDirect to be set only
* if the user does something. We could just do the setup
* by hand, but it seems better to use the normal mechanism
* (i.e. SetField).
*/
m_flags &= ~TiffFlags.DirtyDirect;
/*
* we clear the IsTiled flag when setting up a new directory.
* Should we also be clearing stuff like InSubIFD?
*/
m_flags &= ~TiffFlags.IsTiled;
/*
* Clear other directory-specific fields.
*/
m_tilesize = -1;
m_scanlinesize = -1;
}
/// <summary>
/// Install extra samples information.
/// </summary>
private static bool setExtraSamples(TiffDirectory td, ref int v, FieldValue[] ap)
{
// XXX: Unassociated alpha data == 999 is a known Corel Draw bug, see below
const short EXTRASAMPLE_COREL_UNASSALPHA = 999;
v = ap[0].ToInt();
if (v > td.td_samplesperpixel)
return false;
byte[] va = ap[1].ToByteArray();
if (v > 0 && va == null)
{
// typically missing param
return false;
}
for (int i = 0; i < v; i++)
{
if ((ExtraSample)va[i] > ExtraSample.UnAssociatedAlpha)
{
// XXX: Corel Draw is known to produce incorrect
// ExtraSamples tags which must be patched here if we
// want to be able to open some of the damaged TIFF files:
if (i < v - 1)
{
short s = BitConverter.ToInt16(va, i);
if (s == EXTRASAMPLE_COREL_UNASSALPHA)
va[i] = (byte)ExtraSample.UnAssociatedAlpha;
}
else
return false;
}
}
td.td_extrasamples = (short)v;
td.td_sampleinfo = new ExtraSample[td.td_extrasamples];
for (int i = 0; i < td.td_extrasamples; i++)
td.td_sampleinfo[i] = (ExtraSample)va[i];
return true;
}
private bool byteCountLooksBad(TiffDirectory td)
{
/*
* Assume we have wrong StripByteCount value (in case of single strip) in
* following cases:
* - it is equal to zero along with StripOffset;
* - it is larger than file itself (in case of uncompressed image);
* - it is smaller than the size of the bytes per row multiplied on the
* number of rows. The last case should not be checked in the case of
* writing new image, because we may do not know the exact strip size
* until the whole image will be written and directory dumped out.
*/
return
(
(td.td_stripbytecount[0] == 0 && td.td_stripoffset[0] != 0) ||
(td.td_compression == Compression.None && td.td_stripbytecount[0] > getFileSize() - td.td_stripoffset[0]) ||
(m_mode == O_RDONLY && td.td_compression == Compression.None && td.td_stripbytecount[0] < ScanlineSize() * td.td_imagelength)
);
}