/// <summary>
/// Limpa uma página.
/// </summary>
/// <param name="data"></param>
protected virtual void ClearPage(VirtualListLoaderResult <T> data)
{
if (data == null)
{
throw new InvalidOperationException("LoadResult cannot be null.");
}
if ((data.UpdateCount && (_count == 0 || _count != data.NewCount)) || !InstanceInitialized)
{
_count = data.NewCount;
int numberSessions = PageSize == 0 || _count == 0 ? 1 : (int)Math.Ceiling(_count / (double)PageSize);
if (Sessions != null)
{
for (int i = 0; i < Sessions.Length; i++)
{
if (Sessions[i] != null)
{
Sessions[i].Dispose();
Sessions[i] = null;
}
}
}
Sessions = new IDataPage <T> [numberSessions];
_version++;
RaisePropertyChanged("Count");
RaiseCollectionReset();
}
}
/// <summary>
/// Método assíncrono que faz a carga da contagem.
/// </summary>
/// <param name="args"></param>
private void LoadCountWork(object args)
{
var loaderArgs = (VirtualListLoaderEventArgs)args;
VirtualListLoaderResult <DataWrapper <T> > result = null;
if (Loader != null)
{
try
{
result = Loader.Load(this, loaderArgs.StartRow, loaderArgs.PageSize, loaderArgs.NeedItemsCount, loaderArgs.ReferenceObject);
}
catch (Exception ex)
{
result = new VirtualListLoaderResult <DataWrapper <T> >(ex);
}
}
else
{
result = new VirtualListLoaderResult <DataWrapper <T> >(new DataWrapper <T> [0], 0);
}
if (_synchronizationContext != null)
{
_synchronizationContext.Send(LoadCountCompleted, new object[] {
loaderArgs,
result
});
}
if (result.Error != null)
{
OnAsyncVirtualListError(result.Error);
}
}
/// <summary>
/// Define a contagem inicial.
/// </summary>
/// <param name="count"></param>
internal void SetInitialCount(int count)
{
var result = new VirtualListLoaderResult <DataWrapper <T> >(null, count);
ClearPage(result);
InstanceInitialized = true;
RaiseCollectionReset();
RaisePropertyChanged("Count");
}
/// <summary>
/// Popula uma página.
/// </summary>
/// <param name="data">Dados a se popular.</param>
/// <param name="index">Índice da página.</param>
protected virtual void PopulatePage(VirtualListLoaderResult <T> data, int index)
{
ClearPage(data);
int sessionIndex = PageSize == 0 ? 0 : (int)Math.Floor(index / (double)PageSize);
var page = CreateDataPage(sessionIndex);
page.Populate(data.Items);
Sessions[sessionIndex] = page;
OnDataPageLoaded(new DataPageLoadedEventArgs <T>(page));
}