/// <summary>
/// Loads the next LayerInfo record.
/// </summary>
/// <param name="reader">The file reader</param>
/// <param name="psdFile">The PSD file.</param>
/// <param name="globalLayerInfo">True if the LayerInfo record is being
/// loaded from the end of the Layer and Mask Information section;
/// false if it is being loaded from the end of a Layer record.</param>
public static LayerInfo Load(PsdBinaryReader reader, PsdFile psdFile,
bool globalLayerInfo, long fileEndPos)
{
Util.DebugMessage(reader.BaseStream, "Load, Begin, LayerInfo");
// Some keys use a signature of 8B64, but the identity of these keys
// is undocumented. We will therefore accept either signature.
var signature = reader.ReadAsciiChars(4);
if ((signature != "8BIM") && (signature != "8B64"))
{
throw new PsdInvalidException(
"LayerInfo signature invalid, must be 8BIM or 8B64.");
}
var key = reader.ReadAsciiChars(4);
var hasLongLength = LayerInfoUtil.HasLongLength(key, psdFile.IsLargeDocument);
LayerInfo result = new RawLayerInfo("dummy");
bool breakFromLoop = false;
while (!breakFromLoop)
{
var baseStartPosition = reader.BaseStream.Position;
var length = hasLongLength
? reader.ReadInt64()
: reader.ReadInt32();
var startPosition = reader.BaseStream.Position;
switch (key)
{
case "Layr":
case "Lr16":
case "Lr32":
result = new InfoLayers(reader, psdFile, key, length);
break;
case "lsct":
case "lsdk":
result = new LayerSectionInfo(reader, key, (int)length);
break;
case "luni":
result = new LayerUnicodeName(reader);
break;
case "lyid":
result = new LayerId(reader, key, length);
break;
default:
result = new RawLayerInfo(reader, signature, key, length);
break;
}
// May have additional padding applied.
var endPosition = startPosition + length;
if (reader.BaseStream.Position < endPosition)
{
reader.BaseStream.Position = endPosition;
}
// Documentation states that the length is even-padded. Actually:
// 1. Most keys have 4-padded lengths.
// 2. However, some keys (LMsk) have even-padded lengths.
// 3. Other keys (Txt2, Lr16, Lr32) have unpadded lengths.
//
// Photoshop writes data that is always 4-padded, even when the stated
// length is not a multiple of 4. The length mismatch seems to occur
// only on global layer info. We do not read extra padding in other
// cases because third-party programs are likely to follow the spec.
if (globalLayerInfo)
{
reader.ReadPadding(startPosition, 4);
}
//try if we can read the next signature
if (reader.BaseStream.Position < fileEndPos)
{
var nowPosition = reader.BaseStream.Position;
signature = reader.ReadAsciiChars(4);
if ((signature != "8BIM") && (signature != "8B64"))
{
hasLongLength = true;
reader.BaseStream.Position = baseStartPosition;
}
else
{
reader.BaseStream.Position = nowPosition;
breakFromLoop = true;
}
}
else
{
breakFromLoop = true;
}
}
Util.DebugMessage(reader.BaseStream, "Load, End, LayerInfo, {0}, {1}",
result.Signature, result.Key);
return(result);
}
/// <summary>
/// Loads the next LayerInfo record.
/// </summary>
/// <param name="reader">The file reader</param>
/// <param name="psdFile">The PSD file.</param>
/// <param name="globalLayerInfo">True if the LayerInfo record is being
/// loaded from the end of the Layer and Mask Information section;
/// false if it is being loaded from the end of a Layer record.</param>
/// <returns>LayerInfo object if it was successfully read, or null if
/// padding was found.</returns>
private static LayerInfo Load(PsdBinaryReader reader, PsdFile psdFile,
bool globalLayerInfo)
{
Util.DebugMessage(reader.BaseStream, "Load, Begin, LayerInfo");
// Most keys have undocumented signatures, so we always accept either one.
var signature = reader.ReadAsciiChars(4);
if ((signature != "8BIM") && (signature != "8B64"))
{
throw new PsdInvalidException(
$"{nameof(LayerInfo)} signature invalid, must be 8BIM or 8B64.");
}
var key = reader.ReadAsciiChars(4);
var hasLongLength = LayerInfoUtil.HasLongLength(signature, key, psdFile.IsLargeDocument);
var length = hasLongLength
? reader.ReadInt64()
: reader.ReadInt32();
var startPosition = reader.BaseStream.Position;
LayerInfo result;
switch (key)
{
case "Layr":
case "Lr16":
case "Lr32":
result = new InfoLayers(reader, psdFile, key, length);
break;
case "lsct":
case "lsdk":
result = new LayerSectionInfo(reader, key, (int)length);
break;
case "luni":
result = new LayerUnicodeName(reader);
break;
default:
result = new RawLayerInfo(reader, signature, key, length);
break;
}
// May have additional padding applied.
var endPosition = startPosition + length;
if (reader.BaseStream.Position < endPosition)
{
reader.BaseStream.Position = endPosition;
}
// Documentation states that the length is even-padded. Actually:
// 1. Most keys have 4-padded lengths.
// 2. However, some keys (LMsk) have even-padded lengths.
// 3. Other keys (Txt2, Lr16, Lr32) have unpadded lengths.
//
// Photoshop writes data that is always 4-padded, even when the stated
// length is not a multiple of 4. The length mismatch seems to occur
// only on global layer info. We do not read extra padding in other
// cases because third-party programs are likely to follow the spec.
if (globalLayerInfo)
{
reader.ReadPadding(startPosition, 4);
}
Util.DebugMessage(reader.BaseStream,
$"Load, End, LayerInfo, {result.Signature}, {result.Key}");
return(result);
}