public static string Virtualise(this string source, TextScrollInfo scroll)
{
if (scroll == null || scroll.TotalChars == 0)
{
return(source);
}
return(new string(source.Skip(scroll.FirstIndex).Take(scroll.TotalChars).ToArray()));
}
public static IEnumerable <DisplayText> Virtualise(this IEnumerable <DisplayText> source, TextScrollInfo scroll)
{
var items = source.AsArray();
if (scroll == null || scroll.TotalChars == 0)
{
return(items);
}
// var list = new List<DisplayText>(items.Length);
int lastIndex = scroll.FirstIndex + scroll.TotalChars;
var displayBounds = items.Aggregate(new List <DisplayWithIndex>(), (state, latest) =>
{
if (state.Count == 0)
{
state.Add(new DisplayWithIndex(latest, 0));
}
else
{
var last = state.Last();
state.Add(new DisplayWithIndex(latest, last.StartIndex + last.Text.Length));
}
return(state);
}).ToArray();
var result = displayBounds
.Select(item =>
{
if (item.Inbounds(scroll.FirstIndex, lastIndex))
{
//clip it and yield
return(item.Clip(scroll.FirstIndex, lastIndex));
}
return(null);
}).Where(item => item != null)
.ToArray();
return(result);
}
