private async Task InitialiseObserver()
{
var elementReference = this.IntersectionObserverContext?.Ref?.Current;
if (elementReference == null || Equals(elementReference, default(ElementReference)))
{
throw new Exception(NO_ELEMENT_MESSAGE);
}
this.Observer = await this.ObserverService.Observe(elementReference.Value, this.OnIntersectUpdate, this.Options);
}
public async ValueTask DisposeAsync()
{
var observer = this.Observer;
if (observer == null)
{
return;
}
this.Observer = null;
await observer.Dispose();
await this.OnDisposed.InvokeAsync();
}
protected override async Task OnAfterRenderAsync(bool firstRender)
{
if (!firstRender)
{
return;
}
var parent = await Parent.ToInteropElement();
var last = await Last.ToInteropElement();
var observer = new IntersectionObserver(
new ActionCallback <IntersectionObserverEntry[], IntersectionObserver>(
(entries, other) =>
{
var intersectedEntries = entries.Where(a => a.isIntersecting);
foreach (var intersectedEntry in intersectedEntries)
{
Console.WriteLine(intersectedEntry.target.id, intersectedEntry.intersectionRatio);
last.innerHTML = intersectedEntry.target.id + " : " + intersectedEntry.intersectionRatio;
}
return(Task.CompletedTask);
}
),
new IntersectionObserverInitCachedEntity
{
root = parent
}
);
for (var i = 1; i <= 100; i++)
{
var child = EventHorizonBlazorInterop.FuncClass <Element>(
entity => new Element(entity),
new string[] { "document", "createElement" },
"div"
); // document.createElement('div');
child.id = i.ToString();
child.innerHTML = child.id;
parent.appendChild(child);
observer.observe(child);
}
}
private async void OnIntersectUpdate(IList <IntersectionObserverEntry> entries)
{
var entry = entries?.FirstOrDefault();
if (entry == null)
{
return;
}
await this.IsIntersectingChanged.InvokeAsync(entry.IsIntersecting);
await this.OnChange.InvokeAsync(entry);
this.IntersectionObserverContext.Entry = entry;
this.StateHasChanged();
if (this.Once && entry.IsIntersecting)
{
await this.Observer.Dispose();
this.Observer = null;
}
}
private async Task InitialiseObserver()
{
this.Observer = await this.ObserverService.Observe(this.Element, this.OnIntersectUpdate, this.Options);
}
