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Add comments and split out update steps into a more logical flow

This commit is contained in:
Dean Herbert 2020-10-13 13:44:32 +09:00
parent 20b54fb904
commit 06e84c8eb3

View File

@ -566,53 +566,56 @@ namespace osu.Game.Screens.Select
bool revalidateItems = !itemsCache.IsValid;
// First we iterate over all non-filtered carousel items and populate their
// vertical position data.
if (revalidateItems)
updateYPositions();
var (firstIndex, lastIndex) = getDisplayRange();
// This data is consumed to find the currently displayable range.
// This is the range we want to keep drawables for, and should exceed the visible range slightly to avoid drawable churn.
var newDisplayRange = getDisplayRange();
if (revalidateItems || firstIndex != displayedRange.first || lastIndex != displayedRange.last)
// If the filtered items or visible range has changed, pooling requirements need to be checked.
// This involves fetching new items from the pool, returning no-longer required items.
if (revalidateItems || newDisplayRange != displayedRange)
{
Logger.Log("revalidation requested");
// Remove all items that should no longer be on-screen
// TODO: figure out a more resilient way of doing this removal.
// scrollableContent.RemoveAll(p => p.Y + p.Item.TotalHeight < visibleUpperBound || p.Y > visibleBottomBound);
displayedRange = (firstIndex, lastIndex);
displayedRange = newDisplayRange;
// Add those items within the previously found index range that should be displayed.
for (int i = firstIndex; i < lastIndex; ++i)
for (int i = displayedRange.first; i < displayedRange.last; ++i)
{
var item = visibleItems[i];
var panel = scrollableContent.FirstOrDefault(c => c.Item == item);
if (scrollableContent.Any(c => c.Item == item)) continue;
if (panel == null)
{
Logger.Log($"getting panel for {item} from pool");
panel = setPool.Get(p => p.Item = item);
panel.Y = item.CarouselYPosition;
panel.Depth = i;
Logger.Log($"getting panel for {item} from pool");
var panel = setPool.Get(p => p.Item = item);
panel.Depth = i;
panel.Y = item.CarouselYPosition;
scrollableContent.Add(panel);
}
scrollableContent.Add(panel);
}
else
{
if (panel.IsPresent)
panel.MoveToY(item.CarouselYPosition, 800, Easing.OutQuint);
else
panel.Y = item.CarouselYPosition;
// Remove any items which are far out of the visible range.
}
scrollableContent.ChangeChildDepth(panel, i);
}
// Finally, if the filtered items have changed, animate drawables to their new locations.
// This is common if a selected/collapsed state has changed.
if (revalidateItems)
{
foreach (DrawableCarouselItem panel in scrollableContent.Children)
{
panel.MoveToY(panel.Item.CarouselYPosition, 800, Easing.OutQuint);
}
}
// Update externally controlled state of currently visible items
// (e.g. x-offset and opacity).
// Update externally controlled state of currently visible items (e.g. x-offset and opacity).
// This is a per-frame update on all drawable panels.
foreach (DrawableCarouselItem p in scrollableContent.Children)
{
updateItem(p);
}
}
private (int firstIndex, int lastIndex) getDisplayRange()