/// <summary>
/// Return whether it is OK to move the objects indicated by odi to the specified destination.
/// </summary>
/// <param name="hvoDstOwner"></param>
/// <param name="flidDst"></param>
/// <param name="ihvoDstStart"></param>
/// <param name="odi"></param>
/// <returns></returns>
public bool OkToMove(int hvoDstOwner, int flidDst, int ihvoDstStart, ObjectDragInfo odi)
{
CheckDisposed();
FDO.FdoCache cache = Slice.ContainingDataTree.Cache;
if (flidDst == odi.FlidSrc)
{
// Verify that it is not a no-operation.
if (hvoDstOwner == odi.HvoSrcOwner)
{
// Same property of same object. If it's a collection, disable.
FieldType fieldType = cache.GetFieldType(flidDst);
// We can't drag it to the position it's already at; that's no change. We also can't drag it
// to the position one greater: that amounts to trying to place it after itself, which (after
// removing it from before itself) amounts to a no-operation.
if (fieldType == FieldType.kcptOwningSequence &&
ihvoDstStart != odi.IhvoSrcStart && ihvoDstStart != odi.IhvoSrcStart + 1)
{
// It's a sequence and the target and source positions are different, so we can do it.
return(true);
}
}
else
{
// Different objects; need to verify no circular ownership involved.
for (int ihvo = odi.IhvoSrcStart; ihvo <= odi.IhvoSrcEnd; ihvo++)
{
int hvo = cache.GetVectorItem(odi.HvoSrcOwner, odi.FlidSrc, ihvo);
// See if hvoDstOwner is owned by hvo
int hvo2 = hvoDstOwner;
// loop from hvo2 to root owner of hvo2. If hvo2 or any of its owners is hvo,
// we have a problem.
while (hvo2 != 0)
{
if (hvo == hvo2)
{
return(false); // circular ownership, can't drop.
}
hvo2 = cache.GetOwnerOfObject(hvo2);
}
}
return(true);
}
}
else
{
// Different property, check signature.
IFwMetaDataCache mdc = cache.MetaDataCacheAccessor;
uint luclid = mdc.GetDstClsId((uint)flidDst);
for (int ihvo = odi.IhvoSrcStart; ihvo <= odi.IhvoSrcEnd; ihvo++)
{
int hvo = cache.GetVectorItem(odi.HvoSrcOwner, odi.FlidSrc, ihvo);
uint cls = (uint)cache.GetClassOfObject(hvo);
while (cls != 0 && cls != luclid)
{
cls = mdc.GetBaseClsId(cls);
}
if (cls == 0)
{
return(false); // wrong signature, can't drop.
}
}
// All sigs OK, allow drop.
return(true);
}
// If none of those cases is OK, can't do it.
return(false);
}
