private static TDataType[] ToArray <TDataType>(ExifDataType dataType, ReadOnlySpan <byte> data, ConverterMethod <TDataType> converter)
{
int dataTypeSize = (int)ExifDataTypes.GetSize(dataType);
int length = data.Length / dataTypeSize;
var result = new TDataType[length];
for (int i = 0; i < length; i++)
{
ReadOnlySpan <byte> buffer = data.Slice(i * dataTypeSize, dataTypeSize);
result.SetValue(converter(buffer), i);
}
return(result);
}
private static uint GetLength(IExifValue value) => GetNumberOfComponents(value) * ExifDataTypes.GetSize(value.DataType);
private bool TryReadValue(out ExifValue exifValue)
{
exifValue = default;
// 2 | 2 | 4 | 4
// tag | type | count | value offset
if (this.RemainingLength < 12)
{
return(false);
}
var tag = (ExifTagValue)this.ReadUInt16();
ExifDataType dataType = EnumUtils.Parse(this.ReadUInt16(), ExifDataType.Unknown);
// Ensure that the data type is valid
if (dataType == ExifDataType.Unknown)
{
return(false);
}
uint numberOfComponents = this.ReadUInt32();
// Issue #132: ExifDataType == Undefined is treated like a byte array.
// If numberOfComponents == 0 this value can only be handled as an inline value and must fallback to 4 (bytes)
if (dataType == ExifDataType.Undefined && numberOfComponents == 0)
{
numberOfComponents = 4;
}
uint size = numberOfComponents * ExifDataTypes.GetSize(dataType);
this.TryReadSpan(4, out ReadOnlySpan <byte> offsetBuffer);
object value;
if (size > 4)
{
int oldIndex = this.position;
uint newIndex = this.ConvertToUInt32(offsetBuffer);
// Ensure that the new index does not overrun the data
if (newIndex > int.MaxValue)
{
this.AddInvalidTag(new UnkownExifTag(tag));
return(false);
}
this.position = (int)newIndex;
if (this.RemainingLength < size)
{
this.AddInvalidTag(new UnkownExifTag(tag));
this.position = oldIndex;
return(false);
}
this.TryReadSpan((int)size, out ReadOnlySpan <byte> dataBuffer);
value = this.ConvertValue(dataType, dataBuffer, numberOfComponents);
this.position = oldIndex;
}
else
{
value = this.ConvertValue(dataType, offsetBuffer, numberOfComponents);
}
exifValue = ExifValues.Create(tag) ?? ExifValues.Create(tag, dataType, numberOfComponents);
if (exifValue is null)
{
this.AddInvalidTag(new UnkownExifTag(tag));
return(false);
}
if (!exifValue.TrySetValue(value))
{
return(false);
}
return(true);
}
