List

See the ListDemo.cs.

using Gridrand.RimGui.Manual;
using System.Collections.Generic;

namespace Gridrand.RimGui.Extensions.Manual
{
    /// <summary>
    /// Demonstrates a list view with both non-scrolling and scrolling items.
    /// </summary>
    class ListDemo : ManualBase, IManual
    {
        readonly ListSet nonScrollList = new();
        readonly ListSet fixedScrollList = new();

        public ListDemo(ManualBaseResource p) : base(p)
        {
        }

        public void Draw()
        {
            // Display non-scrolling list view
            Gui.Heading("NonScroll");
            DrawNonScroll(nonScrollList);

            // Display scrolling list view
            Gui.Heading("Scroll");
            DrawFixedScroll(fixedScrollList);
        }

        void DrawNonScroll(ListSet listSet)
        {
            using (Style.Frame.Paddings.Begin(new(1, 1, 1, 1)))
            using (Gui.BeginFrame())
            {
                // Set vertical spacing between items to 0.
                using var s = Style.SpacingYs.Begin(0f);

                // Iterate and draw each item in the list.
                for (int i = 0; i < listSet.Items.Count; i++)
                {
                    DrawItem(listSet, listSet.Items[i]);
                    // Handle item selection based on user input.
                    listSet.SelectedItems.HandlePress(Input, listSet.Items[i], Ctx.WasLastPressedThisFrame());
                }
            }
        }

        void DrawFixedScroll(ListSet listSet)
        {
            using (Style.Frame.Paddings.Begin(new(1, 1, 1, 1)))
            using (Gui.BeginFrame())
            using (Style.SpacingYs.Begin(0f))
            using (Gui.NextHeight(100f).BeginFixedScroll(listSet.Items.Count))
            {
                // Loop while there are more items to draw within the fixed scroll view.
                while (Ctx.AdvanceFixedScrollItem())
                {
                    // Get the current item to draw based on the scroll index.
                    var node = listSet.Items[Ctx.GetFixedScrollIndex()];
                    DrawItem(listSet, node);
                    // Handle item selection based on user input.
                    listSet.SelectedItems.HandlePress(Input, node, Ctx.WasLastPressedThisFrame());
                }
            }
            // Get the rectangle of the last drawn scroll area and set it as a deselection area.
            var scrollRect = Ctx.GetLastWidgetRect();
            Gui.NextRect(scrollRect).DeselectionArea(listSet.SelectedItems);
        }

        /// <summary>
        /// Draws a list item with a checkbox and an index label.
        /// </summary>
        /// <param name="listSet"></param>
        /// <param name="item"></param>
        void DrawItem(ListSet listSet, Item item)
        {
            using var s = Ctx.PushId(item.GetHashCode());
            var nodeRect = Ctx.AllocateRect();

            using (Ctx.BeginDeferredBuilding())
            {
                var paddedRect = nodeRect.Shrink(Style.InteractiveItem.Paddings.Get());

                // note:Unscaled because the scale has already been taken into account.
                using var rects = Ctx.LayoutBuilder
                    .FixedUnscaled(paddedRect.height)
                    .Fit(1)
                    .BuildHorizontal(paddedRect);

                var isChecked = item.IsChecked;

                // Draws a checkbox, updating item state if changed
                if (Gui.NextRect(rects.R0).CheckBox(ref isChecked))
                {
                    item.IsChecked = isChecked;
                }

                Gui.NextRect(rects.R1).Text(item.Name);
            }

            Gui.NextRect(nodeRect)
                .InteractiveItem(listSet.SelectedItems.IsSelected(item));
        }

        /// <summary>
        /// Represents an item in the list.
        /// </summary>
        class Item
        {
            public string Name { get; }
            public bool IsChecked { get; set; }

            public Item(string name)
            {
                Name = name;
            }
        }

        /// <summary>
        /// Manages a collection of <see cref="Item"/> objects and their selection state.
        /// </summary>
        class ListSet
        {
            public List<Item> Items { get; } = new();
            // Manages item selection
            public ItemSelection<Item> SelectedItems { get; } = new();

            public ListSet()
            {
                for (int i = 0; i < 10; i++)
                {
                    Items.Add(new Item(i.ToString()));
                }

                SelectedItems.Select(Items[1]);
                SelectedItems.Select(Items[3]);
                SelectedItems.Select(Items[4]);
            }
        }
    }
}