/// <summary>
/// Adds an EXIF property to an image.
/// </summary>
/// <param name="image"></param>
/// <param name="property"></param>
public static void AddExifData(Image image, ExifProperty property)
{
if (image == null)
{
throw new ArgumentNullException("image");
}
if (property == null)
{
return;
}
PropertyItem propertyItem;
// The .NET interface for GDI+ does not allow instantiation of the
// PropertyItem class. Therefore one must be stolen off the Image
// and repurposed. GDI+ uses PropertyItem by value so there is no
// side effect when changing the values and reassigning to the image.
if (image.PropertyItems == null || image.PropertyItems.Length < 1)
{
propertyItem = ExifWriter.CreatePropertyItem();
}
else
{
propertyItem = image.PropertyItems[0];
}
propertyItem.Id = (int)property.Tag;
propertyItem.Type = (short)property.Type;
Type dataType = ExifDataTypeAttribute.GetDataType(property.Tag);
propertyItem.Value = ExifEncoder.ConvertData(dataType, property.Type, property.Value);
propertyItem.Len = propertyItem.Value.Length;
// This appears to not be necessary
ExifWriter.RemoveExifData(image, property.Tag);
image.SetPropertyItem(propertyItem);
}
/// <summary>
/// Converts a property item to an object or array of objects.
/// </summary>
/// <param name="propertyItem">the property item to convert</param>
/// <returns>the property value</returns>
public static object FromPropertyItem(PropertyItem propertyItem)
{
if (propertyItem == null)
{
return(null);
}
object data = null;
ExifTag tag = ExifTag.Unknown;
Type dataType = null;
if (Enum.IsDefined(typeof(ExifTag), propertyItem.Id))
{
tag = (ExifTag)propertyItem.Id;
dataType = ExifDataTypeAttribute.GetDataType(tag);
}
ExifType type = (ExifType)propertyItem.Type;
switch (type)
{
case ExifType.Ascii:
{
// The value represents an array of chars terminated with null ('\0') char
data = Encoding.ASCII.GetString(propertyItem.Value).TrimEnd('\0');
break;
}
case ExifType.Byte:
{
switch (tag)
{
case ExifTag.MSTitle:
case ExifTag.MSSubject:
case ExifTag.MSAuthor:
case ExifTag.MSKeywords:
case ExifTag.MSComments:
{
// The value represents an array of unicode bytes terminated with null ('\0') char
data = Encoding.Unicode.GetString(propertyItem.Value).TrimEnd('\0');
break;
}
default:
{
// The value represents an array of bytes
data = propertyItem.Value;
break;
}
}
break;
}
case ExifType.Raw:
{
// The value represents an array of bytes
data = propertyItem.Value;
break;
}
case ExifType.UInt16:
{
// The value represents an array of unsigned 16-bit integers.
int count = propertyItem.Len / UInt16Size;
ushort[] result = new ushort[count];
for (int i = 0; i < count; i++)
{
result[i] = ReadUInt16(propertyItem.Value, i * UInt16Size);
}
data = result;
break;
}
case ExifType.Int32:
{
// The value represents an array of signed 32-bit integers.
int count = propertyItem.Len / Int32Size;
int[] result = new int[count];
for (int i = 0; i < count; i++)
{
result[i] = ReadInt32(propertyItem.Value, i * Int32Size);
}
data = result;
break;
}
case ExifType.UInt32:
{
// The value represents an array of unsigned 32-bit integers.
int count = propertyItem.Len / UInt32Size;
uint[] result = new uint[count];
for (int i = 0; i < count; i++)
{
result[i] = ReadUInt32(propertyItem.Value, i * UInt32Size);
}
data = result;
break;
}
case ExifType.Rational:
{
// The value represents an array of signed rational numbers
// Numerator is an Int32 value, denominator a UInt32 value.
int count = propertyItem.Len / RationalSize;
Rational <int>[] result = new Rational <int> [count];
for (int i = 0; i < count; i++)
{
result[i] = new Rational <int>(
ReadInt32(propertyItem.Value, i * RationalSize),
ReadInt32(propertyItem.Value, i * RationalSize + Int32Size));
}
data = result;
break;
}
case ExifType.URational:
{
// The value represents an array of signed rational numbers
// Numerator and denominator are UInt32 values.
int count = propertyItem.Len / URationalSize;
Rational <uint>[] result = new Rational <uint> [count];
for (int i = 0; i < count; i++)
{
result[i] = new Rational <uint>(
ReadUInt32(propertyItem.Value, i * URationalSize),
ReadUInt32(propertyItem.Value, i * URationalSize + UInt32Size));
}
data = result;
break;
}
default:
{
data = propertyItem.Value;
break;
}
}
return(ExifDecoder.ConvertData(dataType, data));
}
