public OnControlScrollChangedListener(
AndroidHorizontalListViewRenderer nativeView,
HorizontalListView element)
{
_weakNativeView = new WeakReference <AndroidHorizontalListViewRenderer>(nativeView);
_element = element;
}
private async Task UpdateCurrentIndexAsync(
AndroidHorizontalListViewRenderer nativeView,
CancellationToken token)
{
await Task.Delay(500);
if (token.IsCancellationRequested)
{
return;
}
if (nativeView?.LinearLayoutManager == null || _element == null)
{
return;
}
nativeView._isCurrentIndexUpdateBackfire = true;
try
{
_element.CurrentIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
_element.ScrollBeganCommand?.Execute(null);
InternalLogger.Info($"CurrentIndex: {_element.CurrentIndex}");
}
finally
{
nativeView._isCurrentIndexUpdateBackfire = false;
}
}
private void UpdateCurrentIndex(
AndroidHorizontalListViewRenderer nativeView,
CancellationToken token)
{
if (token.IsCancellationRequested)
{
return;
}
if (nativeView?.LinearLayoutManager == null || _element == null)
{
return;
}
nativeView._isCurrentIndexUpdateBackfire = true;
try
{
_element.CurrentIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
InternalLogger.Info($"CurrentIndex: {_element.CurrentIndex}");
}
finally
{
nativeView._isCurrentIndexUpdateBackfire = false;
}
}
private void UpdateCurrentIndex(
AndroidHorizontalListViewRenderer nativeView,
CancellationToken token)
{
if (token.IsCancellationRequested)
{
return;
}
if (nativeView?.LinearLayoutManager == null || _element == null)
{
return;
}
nativeView._isCurrentIndexUpdateBackfire = true;
try
{
int newIndex = -1;
if (_element.SnapStyle != SnapStyle.None)
{
newIndex = nativeView.CurrentSnapIndex;
}
else
{
newIndex = nativeView.LinearLayoutManager.FindFirstCompletelyVisibleItemPosition();
if (newIndex == -1)
{
newIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
}
}
if (newIndex == -1)
{
InternalLogger.Warn(
"Failed to find the current index: UpdateCurrentIndex returns nothing");
return;
}
_element.CurrentIndex = newIndex;
InternalLogger.Info($"CurrentIndex: {_element.CurrentIndex}");
}
finally
{
nativeView._isCurrentIndexUpdateBackfire = false;
}
}
private async Task UpdateCurrentIndexAsync(
AndroidHorizontalListViewRenderer nativeView,
CancellationToken token)
{
await Task.Delay(500);
if (token.IsCancellationRequested)
{
return;
}
nativeView._isCurrentIndexUpdateBackfire = true;
try
{
_element.CurrentIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
_element.ScrollBeganCommand?.Execute(null);
// System.Diagnostics.Debug.WriteLine($"DEBUG_SCROLL: CurrentIndex: {_element.CurrentIndex}");
}
finally
{
nativeView._isCurrentIndexUpdateBackfire = false;
}
}
private void UpdateCurrentIndex(
AndroidHorizontalListViewRenderer nativeView,
CancellationToken token)
{
if (token.IsCancellationRequested)
{
return;
}
if (nativeView?.LinearLayoutManager == null || _element == null)
{
return;
}
nativeView._isCurrentIndexUpdateBackfire = true;
try
{
int newIndex = -1;
if (_element.SnapStyle == SnapStyle.Center)
{
int firstIndex = nativeView.LinearLayoutManager.FindFirstCompletelyVisibleItemPosition();
if (firstIndex == 0)
{
// Check if first item is fully visible, if true don't snap.
newIndex = 0;
}
int lastIndex = nativeView.LinearLayoutManager.FindLastCompletelyVisibleItemPosition();
if (lastIndex == nativeView.Control.GetAdapter().ItemCount - 1)
{
// Check if first item is fully visible, if true don't snap.
newIndex = lastIndex;
}
if (newIndex == -1)
{
int firstItemIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
int lastItemIndex = nativeView.LinearLayoutManager.FindLastVisibleItemPosition();
newIndex = firstItemIndex + (lastItemIndex - firstItemIndex) / 2;
}
}
else
{
newIndex = nativeView.LinearLayoutManager.FindFirstVisibleItemPosition();
}
if (newIndex == -1)
{
InternalLogger.Warn(
"Failed to find the current index: UpdateCurrentIndex returns nothing");
return;
}
_element.CurrentIndex = newIndex;
InternalLogger.Info($"CurrentIndex: {_element.CurrentIndex}");
}
finally
{
nativeView._isCurrentIndexUpdateBackfire = false;
}
}
public StartSnapHelper(AndroidHorizontalListViewRenderer nativeView)
: base(nativeView)
{
}
public CenterSnapHelper(AndroidHorizontalListViewRenderer nativeView)
{
WeakNativeView = new WeakReference <AndroidHorizontalListViewRenderer>(nativeView);
}
