osu-framework/osu.Framework/Graphics/Containers/OverlayContainer.cs

// 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.

using System.Collections.Generic;
using osu.Framework.Input;
using osu.Framework.Input.Events;

namespace osu.Framework.Graphics.Containers
{
    /// <summary>
    /// An element which starts hidden and can be toggled to visible.
    /// </summary>
    public abstract partial class OverlayContainer : VisibilityContainer
    {
        /// <summary>
        /// Whether we should block any positional input from interacting with things behind us.
        /// </summary>
        protected virtual bool BlockPositionalInput => true;

        /// <summary>
        /// Scroll events are sometimes required to be handled differently to general positional input.
        /// This covers whether scroll events that occur within this overlay's bounds are blocked or not.
        /// Defaults to the same value as <see cref="BlockPositionalInput"/>
        /// </summary>
        protected virtual bool BlockScrollInput => BlockPositionalInput;

        /// <summary>
        /// Whether we should block any non-positional input from interacting with things behind us.
        /// </summary>
        protected virtual bool BlockNonPositionalInput => false;

        internal override bool BuildNonPositionalInputQueue(List<Drawable> queue, bool allowBlocking = true)
        {
            if (PropagateNonPositionalInputSubTree && HandleNonPositionalInput && BlockNonPositionalInput)
            {
                // when blocking non-positional input behind us, we still want to make sure the global handlers receive events
                // but we don't want other drawables behind us handling them.
                queue.RemoveAll(d => !(d is IHandleGlobalKeyboardInput));
            }

            return base.BuildNonPositionalInputQueue(queue, allowBlocking);
        }

        public override bool DragBlocksClick => false;

        protected override bool OnHover(HoverEvent e) => BlockPositionalInput;
        protected override bool OnMouseDown(MouseDownEvent e) => BlockPositionalInput;
        protected override bool OnMouseMove(MouseMoveEvent e) => BlockPositionalInput;
        protected override bool OnScroll(ScrollEvent e) => BlockScrollInput && base.ReceivePositionalInputAt(e.ScreenSpaceMousePosition);
    }
}