const int ktagMinVp = 0x7f000000; // copied from VwCacheDa.h, mimimum value for assigned virtual props.
/// <summary>
/// We implement this to record modify times.
/// </summary>
/// <param name="hvo"></param>
/// <param name="tag"></param>
/// <param name="ivMin"></param>
/// <param name="cvIns"></param>
/// <param name="cvDel"></param>
public void PropChanged(int hvo, int tag, int ivMin, int cvIns, int cvDel)
{
CheckDisposed();
if (m_fModifyChangeInProgress) // ignore PropChanged on the DateModified property!
{
return;
}
// Typically an Undo will restore the modify time to what it was before the
// main change. We don't want to reverse that by recording the time of the Undo!
// Note that there is one pathological scenario:
// t1: make a change.
// t2: undo the change.
// t3: export all changed records (since before t1).
// t4: redo the change. Record appears to have been modified at time t2.
// t5: export all changed records (since t3).
// If this was the only change to the record, it is not part of either export,
// and the change might be lost.
// To prevent this, I think the 'export changed records' function should clear
// the Undo stack.
if (m_cache.ActionHandlerAccessor != null && m_cache.ActionHandlerAccessor.IsUndoOrRedoInProgress)
{
return;
}
if (tag < 0 || tag >= ktagMinVp)
{
return; // phony or virtual properties, not real changes (e.g., different filter applied, or selection moving in browse).
}
try
{
DateTime dtNow = DateTime.Now;
int hvoMajor = 0; // hvo of the 'major' object that has the DateModified property.
if (SameMinute(dtNow, m_currentMinute))
{
// We can use our Dictionary
if (m_recentMods.ContainsKey(hvo))
{
hvoMajor = m_recentMods[hvo];
}
}
else
{
ResetDelay();
}
int flidModify = 0;
if (hvoMajor == 0)
{
for (int hvoCandidate = hvo; hvoCandidate != 0;
hvoCandidate = m_cache.GetOwnerOfObject(hvoCandidate))
{
// We assume that this is a dummy object at this point and GetClassOfObject
// only accepts real objects. Since it's a dummy object, changes should never
// affect the modify time of a real object. Maybe at some point we can get an
// interface method to check for dummy objects.
if (hvoCandidate < 0)
{
return;
}
int clid = m_cache.GetClassOfObject(hvoCandidate);
if (clid == 0)
{
return; // maybe a deleted object, no good to us, we can't record modify time.
}
flidModify = (int)m_mdc.GetFieldId2((uint)clid, "DateModified", true);
if (flidModify != 0)
{
hvoMajor = hvoCandidate;
break;
}
}
if (hvoMajor == 0)
{
return; // found no owner with DateCreated property.
}
m_recentMods[hvo] = hvoMajor; // lets us find it fast if modified again soon.
}
else
{
// We need to set flidModify!
int clid = m_cache.GetClassOfObject(hvoMajor);
if (clid != 0)
{
flidModify = (int)m_mdc.GetFieldId2((uint)clid, "DateModified", true);
}
}
if (flidModify == 0)
{
return; // can't set the time prop without a field...
}
DateTime oldModifyTime = m_cache.GetTimeProperty(hvoMajor, flidModify);
// If we already noted a modify time in the current minute, don't do it again.
// This is intended to keep down the overhead of recording modify times for frequently
// modified objects.
if (SameMinute(oldModifyTime, dtNow))
{
//Trace.TraceInformation("New Modify Time ({0}) for {1} is same minute as the old ({2}).\n",
// dtNow, hvoMajor, oldModifyTime);
return;
}
// if (m_currentMinute != null &&
// m_currentMinute.Date == dtNow.Date && m_currentMinute.Hour = dtNow.Hour && m_currentMinute.Minute == dtNow.Minute)
// return;
// Set the modify time. If possible tack this on to the last Undo task (or the current one, if a
// transaction is open).
if (m_cache.ActionHandlerAccessor != null && m_cache.VwOleDbDaAccessor != null &&
((m_cache.DatabaseAccessor != null && m_cache.DatabaseAccessor.IsTransactionOpen()) ||
m_cache.CanUndo))
{
m_cache.ContinueUndoTask();
m_cache.SetTimeProperty(hvoMajor, flidModify, dtNow);
m_cache.EndUndoTask();
}
else
{
// We don't have an Undo task to append to, so somehow a Save has occurred
// in the midst of the operation that caused the time stamp modification.
// If we make an empty undo task, the user will typically have no idea what
// could be undone, and will be confused. Best to make it impossible to
// undo the timestamp change also.
using (new SuppressSubTasks(m_cache))
{
m_cache.SetTimeProperty(hvoMajor, flidModify, dtNow);
}
}
//Trace.TraceInformation("Setting new Modify Time ({0}) for {1}\n",
// dtNow, hvoMajor);
}
finally
{
m_fModifyChangeInProgress = false;
}
}