osu/osu.Game/Overlays/Chat/ChannelScrollContainer.cs

79 lines
2.7 KiB
C#

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
#nullable disable
using osu.Framework.Graphics;
using osu.Game.Graphics.Containers;
namespace osu.Game.Overlays.Chat
{
/// <summary>
/// An <see cref="OsuScrollContainer"/> with functionality to automatically scroll whenever the maximum scrollable distance increases.
/// </summary>
public partial class ChannelScrollContainer : OsuScrollContainer
{
/// <summary>
/// The chat will be automatically scrolled to end if and only if
/// the distance between the current scroll position and the end of the scroll
/// is less than this value.
/// </summary>
private const float auto_scroll_leniency = 10f;
/// <summary>
/// Whether to keep this container scrolled to end on new content.
/// </summary>
/// <remarks>
/// This is specifically controlled by whether the latest scroll operation made the container scrolled to end.
/// </remarks>
private bool trackNewContent = true;
protected override void UpdateAfterChildren()
{
base.UpdateAfterChildren();
if (trackNewContent && !IsScrolledToEnd())
ScrollToEnd();
}
private void updateTrackState() => trackNewContent = IsScrolledToEnd(auto_scroll_leniency);
// todo: we may eventually want this encapsulated in a "OnScrollChange" event handler method provided by ScrollContainer.
// important to note that this intentionally doesn't consider OffsetScrollPosition, but could make it do so with side changes.
#region Scroll handling
protected override void OnUserScroll(float value, bool animated = true, double? distanceDecay = null)
{
base.OnUserScroll(value, animated, distanceDecay);
updateTrackState();
}
public new void ScrollTo(float value, bool animated = true, double? distanceDecay = null)
{
base.ScrollTo(value, animated, distanceDecay);
updateTrackState();
}
public new void ScrollIntoView(Drawable d, bool animated = true)
{
base.ScrollIntoView(d, animated);
updateTrackState();
}
public new void ScrollToStart(bool animated = true, bool allowDuringDrag = false)
{
base.ScrollToStart(animated, allowDuringDrag);
updateTrackState();
}
public new void ScrollToEnd(bool animated = true, bool allowDuringDrag = false)
{
base.ScrollToEnd(animated, allowDuringDrag);
updateTrackState();
}
#endregion
}
}