private async Task FetchingPageSizeTask()
{
// Call the deriving class to get the information
DataListPageResult <T> pageInfo = await FetchPageSizeAsync();
Update(pageInfo);
}
private async Task FetchingPageTask(int pageNumber)
{
// Call the deriving class to get the information
DataListPageResult <T> pageInfo = await FetchPageAsync(pageNumber);
Update(pageInfo);
// Remove the fetching page task from the internal list so subsequent requests are reperformed
fetchingPageTasks[pageNumber - 1] = null;
}
private void Update(DataListPageResult <T> pageInfo)
{
// Update the total item count
// TODO : Handle situation if the total item count has changed between calls! (raise collection changed & update internals?)
if (pageInfo.TotalItemCount != null && count != pageInfo.TotalItemCount)
{
count = pageInfo.TotalItemCount;
}
// Update the items per page
if (pageInfo.ItemsPerPage != null)
{
itemsPerPage = pageInfo.ItemsPerPage.Value;
}
// If we know both the item count and the items per page then...
if (count != null && itemsPerPage != null)
{
// (a) Update the PageVirtualizingList with this information
////////////InternalList.UpdateCount(count.Value, itemsPerPage.Value);
// (b) If the number of pages has changed then update the array for fetching page tasks
int pageCount = (count.Value - 1) / itemsPerPage.Value + 1;
if (fetchingPageTasks.Length < pageCount)
{
Task[] newPageFetchingTasks = new Task[pageCount];
fetchingPageTasks.CopyTo(newPageFetchingTasks, 0);
fetchingPageTasks = newPageFetchingTasks;
}
}
// Update the page information
if (pageInfo.PageNumber != null)
{
int startIndex = itemsPerPage.Value * (pageInfo.PageNumber.Value - 1);
for (int i = 0; i < pageInfo.Page.Count; i++)
{
InternalList[startIndex + i] = pageInfo.Page[i];
}
}
}