public IFDEntry(ushort tag, ExifValueType type, uint count, uint offset)
{
Tag = tag;
Type = type;
Count = count;
Offset = offset;
}
/// <summary>
/// Determines whether the values fit in the offset field.
/// </summary>
/// <param name="type">The type.</param>
/// <param name="count">The count.</param>
/// <returns>
/// <see langword="true"/> if the values fit in the offset field; otherwise, <see langword="false"/>.
/// </returns>
public static bool ValueFitsInOffsetField(ExifValueType type, uint count)
{
switch (type)
{
case ExifValueType.Byte:
case ExifValueType.Ascii:
case ExifValueType.Undefined:
case (ExifValueType)6: // SByte
return(count <= 4);
case ExifValueType.Short:
case ExifValueType.SShort:
return(count <= 2);
case ExifValueType.Long:
case ExifValueType.SLong:
case ExifValueType.Float:
case (ExifValueType)13: // IFD
return(count <= 1);
case ExifValueType.Rational:
case ExifValueType.SRational:
case ExifValueType.Double:
default:
return(false);
}
}
/// <summary>
/// Gets the size in bytes of a <see cref="TagDataType"/> value.
/// </summary>
/// <param name="type">The tag type.</param>
/// <returns>
/// The size of the value in bytes.
/// </returns>
public static int GetSizeInBytes(ExifValueType type)
{
switch (type)
{
case ExifValueType.Byte:
case ExifValueType.Ascii:
case ExifValueType.Undefined:
case (ExifValueType)6: // SByte
return(1);
case ExifValueType.Short:
case ExifValueType.SShort:
return(2);
case ExifValueType.Long:
case ExifValueType.SLong:
case ExifValueType.Float:
case (ExifValueType)13: // IFD
return(4);
case ExifValueType.Rational:
case ExifValueType.SRational:
case ExifValueType.Double:
return(8);
default:
return(0);
}
}
private string GetValueStringFromOffset()
{
string valueString;
ExifValueType type = entry.Type;
uint count = entry.Count;
uint offset = entry.Offset;
if (count == 0)
{
return(string.Empty);
}
int typeSizeInBytes = ExifValueTypeUtil.GetSizeInBytes(type);
if (typeSizeInBytes == 1)
{
byte[] bytes = new byte[count];
if (offsetIsBigEndian)
{
switch (count)
{
case 1:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
break;
case 2:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
break;
case 3:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
bytes[2] = (byte)((offset >> 8) & 0x000000ff);
break;
case 4:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
bytes[2] = (byte)((offset >> 8) & 0x000000ff);
bytes[3] = (byte)(offset & 0x000000ff);
break;
}
}
else
{
switch (count)
{
case 1:
bytes[0] = (byte)(offset & 0x000000ff);
break;
case 2:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
break;
case 3:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
bytes[2] = (byte)((offset >> 16) & 0x000000ff);
break;
case 4:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
bytes[2] = (byte)((offset >> 16) & 0x000000ff);
bytes[3] = (byte)((offset >> 24) & 0x000000ff);
break;
}
}
if (type == ExifValueType.Ascii)
{
valueString = Encoding.UTF8.GetString(bytes).TrimEnd('\0');
}
else if (count == 1)
{
valueString = bytes[0].ToString(CultureInfo.InvariantCulture);
}
else
{
StringBuilder builder = new();
uint lastItemIndex = count - 1;
for (int i = 0; i < count; i++)
{
builder.Append(bytes[i].ToString(CultureInfo.InvariantCulture));
if (i < lastItemIndex)
{
builder.Append(',');
}
}
valueString = builder.ToString();
}
}
else if (typeSizeInBytes == 2)
{
ushort[] values = new ushort[count];
if (offsetIsBigEndian)
{
switch (count)
{
case 1:
values[0] = (ushort)((offset >> 16) & 0x0000ffff);
break;
case 2:
values[0] = (ushort)((offset >> 16) & 0x0000ffff);
values[1] = (ushort)(offset & 0x0000ffff);
break;
}
}
else
{
switch (count)
{
case 1:
values[0] = (ushort)(offset & 0x0000ffff);
break;
case 2:
values[0] = (ushort)(offset & 0x0000ffff);
values[1] = (ushort)((offset >> 16) & 0x0000ffff);
break;
}
}
if (count == 1)
{
switch (type)
{
case ExifValueType.SShort:
valueString = ((short)values[0]).ToString(CultureInfo.InvariantCulture);
break;
case ExifValueType.Short:
default:
valueString = values[0].ToString(CultureInfo.InvariantCulture);
break;
}
}
else
{
switch (type)
{
case ExifValueType.SShort:
valueString = ((short)values[0]).ToString(CultureInfo.InvariantCulture) + "," +
((short)values[1]).ToString(CultureInfo.InvariantCulture);
break;
case ExifValueType.Short:
default:
valueString = values[0].ToString(CultureInfo.InvariantCulture) + "," +
values[1].ToString(CultureInfo.InvariantCulture);
break;
}
}
}
else
{
valueString = offset.ToString(CultureInfo.InvariantCulture);
}
return(valueString);
}
public unsafe byte[] GetValueBytesFromOffset()
{
if (!OffsetFieldContainsValue)
{
return(null);
}
ExifValueType type = entry.Type;
uint count = entry.Count;
uint offset = entry.Offset;
if (count == 0)
{
return(Array.Empty <byte>());
}
// Paint.NET always stores data in little-endian byte order.
byte[] bytes;
if (type == ExifValueType.Byte ||
type == ExifValueType.Ascii ||
type == (ExifValueType)6 || // SByte
type == ExifValueType.Undefined)
{
bytes = new byte[count];
if (offsetIsBigEndian)
{
switch (count)
{
case 1:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
break;
case 2:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
break;
case 3:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
bytes[2] = (byte)((offset >> 8) & 0x000000ff);
break;
case 4:
bytes[0] = (byte)((offset >> 24) & 0x000000ff);
bytes[1] = (byte)((offset >> 16) & 0x000000ff);
bytes[2] = (byte)((offset >> 8) & 0x000000ff);
bytes[3] = (byte)(offset & 0x000000ff);
break;
}
}
else
{
switch (count)
{
case 1:
bytes[0] = (byte)(offset & 0x000000ff);
break;
case 2:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
break;
case 3:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
bytes[2] = (byte)((offset >> 16) & 0x000000ff);
break;
case 4:
bytes[0] = (byte)(offset & 0x000000ff);
bytes[1] = (byte)((offset >> 8) & 0x000000ff);
bytes[2] = (byte)((offset >> 16) & 0x000000ff);
bytes[3] = (byte)((offset >> 24) & 0x000000ff);
break;
}
}
}
else if (type == ExifValueType.Short || type == ExifValueType.SShort)
{
int byteArrayLength = unchecked ((int)count) * sizeof(ushort);
bytes = new byte[byteArrayLength];
fixed(byte *ptr = bytes)
{
ushort *ushortPtr = (ushort *)ptr;
if (offsetIsBigEndian)
{
switch (count)
{
case 1:
ushortPtr[0] = (ushort)((offset >> 16) & 0x0000ffff);
break;
case 2:
ushortPtr[0] = (ushort)((offset >> 16) & 0x0000ffff);
ushortPtr[1] = (ushort)(offset & 0x0000ffff);
break;
}
}
else
{
switch (count)
{
case 1:
ushortPtr[0] = (ushort)(offset & 0x0000ffff);
break;
case 2:
ushortPtr[0] = (ushort)(offset & 0x0000ffff);
ushortPtr[1] = (ushort)((offset >> 16) & 0x0000ffff);
break;
}
}
}
}
else
{
bytes = new byte[4];
fixed(byte *ptr = bytes)
{
// The offset is stored as little-endian in memory.
*(uint *)ptr = offset;
}
}
return(bytes);
}
