/// <summary>
/// Create a standard <see cref="PageReadRequest"/> for a specified <see cref="IPagedDataProvider{T}"/>
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="provider"></param>
/// <param name="offset"></param>
/// <returns></returns>
public static PageReadRequest CreateReadRequest <T>(this IPagedDataProvider <T> provider, int offset)
{
var alignedOffset = provider.PageAlignedOffset(offset);
return(new PageReadRequest()
{
Offset = alignedOffset, Take = provider.MaxPageSize
});
}
protected PagedSourceListViewModelBase(IScarletCommandBuilder commandBuilder, SynchronizationContext synchronizationContext, Func <TViewModel, string> selector, IPagedDataProvider <TViewModel> pagedDataProvider)
: base(synchronizationContext, selector)
{
CommandBuilder = commandBuilder ?? throw new ArgumentNullException(nameof(commandBuilder));
Dispatcher = commandBuilder.Dispatcher ?? throw new ArgumentNullException(nameof(IScarletCommandBuilder.Dispatcher));
CommandManager = commandBuilder.CommandManager ?? throw new ArgumentNullException(nameof(IScarletCommandBuilder.CommandManager));
_pagedDataProvider = pagedDataProvider ?? throw new ArgumentNullException(nameof(pagedDataProvider));
SelectedItems = new ObservableCollection <TViewModel>();
BusyStack = new ObservableBusyStack((hasItems) => IsBusy = hasItems);
PageSize = 50;
_loadCommand = commandBuilder
.Create(Load, CanLoad)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
_refreshCommand = commandBuilder
.Create(Refresh, CanRefresh)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
_unloadCommand = commandBuilder
.Create(Unload, CanUnload)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
NextCommand = commandBuilder
.Create(Next, CanNext)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
PreviousCommand = commandBuilder
.Create(Previous, CanPrevious)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
FirstCommand = commandBuilder
.Create(First, CanFirst)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
LastCommand = commandBuilder
.Create(Last, CanLast)
.WithSingleExecution()
.WithBusyNotification(BusyStack)
.WithAsyncCancellation()
.Build();
}
/// <summary>
/// Utility function to calculate a page aligned offset for a <see cref="IPagedDataProvider{T}"/>
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="provider"></param>
/// <param name="offset"></param>
/// <returns></returns>
public static int PageAlignedOffset <T>(this IPagedDataProvider <T> provider, int offset)
{
var chunkSize = provider.MaxPageSize;
return((int)Math.Floor(((float)offset) / chunkSize) * chunkSize);
}