public object GetField(int n)
{
object res;
ImageFieldData fi = GetFieldInfo(n);
int count = fi.Count;
int offset = GetFieldOffset(n);;
Object o;
int len;
SafePointer sp = m_pHeader + offset;
if (fi.VarLen)
{
// this assumes we can not have varlen arrays of headers
count = GetFieldSize(n) / fi.GetTypeLen();
}
if (count == 1)
{
return(sp.SafePointerToType(fi));
}
// if a negative count is provided we tread it as an offset of
// the field where to find the real count
if (count < 0)
{
count = Convert.ToInt32(GetField(n + count));
}
res = new object[count];
for (int i = 0; i < count; i++)
{
o = sp.SafePointerToType(fi);
((object[])res)[i] = o;
if (o is ImageHeader)
{
len = ((ImageHeader)o).Size;
}
else
{
len = fi.GetTypeLen();
}
sp = sp + len;
}
return(res);
}
public int GetFieldSize(int n)
{
ImageFieldData fi = GetFieldInfo(n);
int count = fi.Count;
int padding = fi.PadTo;
int size;
int len;
if (fi.VarLen)
{
SafePointer field_start = m_pHeader + GetFieldOffset(n);
SafePointer field_end = field_start;
while ((byte)field_end != fi.TrailingByte)
{
field_end++;
}
// if we have a VarLen and a PadTo specified we will make sure
// we only skip up to PadTo trailing bytes
if (padding != 0)
{
padding = padding - (field_end.Address - m_pHeader.Address) % padding;
}
else
{
padding = -1;
}
while (((byte)field_end == fi.TrailingByte) && (padding-- != 0))
{
field_end++;
}
return(field_end - field_start);
}
if (fi.Type == Type.HEADER)
{
object o = GetField(n);
if (o is Array)
{
len = ((ImageHeader)((object[])o)[0]).Size;
}
else
{
len = ((ImageHeader)o).Size;
}
}
else
{
len = fi.GetTypeLen();
}
if (count == 1)
{
return(len);
}
// if a negative count is provided we tread it as an offset of
// the field where to find the real count
if (count < 0)
{
count = Convert.ToInt32(GetField(n + count));
}
size = len * count;
// We don't pad is the size is already a multiple of padding
if ((padding != 0) && (size % padding != 0))
{
size += padding - (size % padding);
}
return(size);
}