private static IExifValue GetOffsetValue(List <IExifValue> ifdValues, List <IExifValue> values, ExifTag offset)
{
int index = -1;
for (int i = 0; i < ifdValues.Count; i++)
{
if (ifdValues[i].Tag == offset)
{
index = i;
}
}
if (values.Count > 0)
{
if (index != -1)
{
return(ifdValues[index]);
}
ExifValue result = ExifValues.Create(offset);
ifdValues.Add(result);
return(result);
}
else if (index != -1)
{
ifdValues.RemoveAt(index);
}
return(null);
}
/// <summary>
/// Sets the value of the specified tag.
/// </summary>
/// <param name="tag">The tag of the exif value.</param>
/// <param name="value">The value.</param>
internal void SetValueInternal(ExifTag tag, object value)
{
foreach (IExifValue exifValue in this.Values)
{
if (exifValue.Tag == tag)
{
exifValue.TrySetValue(value);
return;
}
}
ExifValue newExifValue = ExifValues.Create(tag);
if (newExifValue is null)
{
throw new NotSupportedException();
}
newExifValue.TrySetValue(value);
this.values.Add(newExifValue);
}
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);
}