Scroll

See the ScrollDemo.cs.

using Gridrand.Contracts;
using Gridrand.RimGui.Manual.Utility;
namespace Gridrand.RimGui.Manual
{
    /// <summary>
    /// Demonstrates various scrolling behaviors.
    /// </summary>
    class ScrollDemo : ManualBase, IManual
    {
        int outerTextCount = 20;
        int textCountWithIterator = 20;

        float height = 100f;

        float outerHeight = 180f;
        float innerHeight = 100f;
        int innerTextCount = 10;

        // Flag to determine if the scroll should remain fixed at the bottom.
        bool shouldFixToBottom;

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

        public void Draw()
        {
            DrawSettings();
            using var scope = Style.ScrollBar.FixToBottom.Begin(shouldFixToBottom);
            DrawWithDynamic();
            DrawUsingHandler();
            DrawToBottomOfWindow();
        }

        void DrawSettings()
        {
            Gui.Heading("Settings");

            var rects = LayoutBuilder.AllocateMainAndToolTipRect();

            Gui.NextRect(rects.Main).LabelInput("FixToBottom", ref shouldFixToBottom);
            Gui.NextRect(rects.ToolTip).ToolTip("Keep the scroll fixed at the bottom even when new widgets are added.");
        }

        void DrawWithDynamic()
        {
            Gui.HeadingTooltip(
                "Dynamic",
                "A scroll that allows dynamic addition of widgets.\n" +
                "Suitable when the number of widgets is not large, as it processes all of them.");

            // Controls for modifying scroll properties.
            outerTextCount = Gui.LabelSliderNumeric("OuterTextCount", outerTextCount, 0, 100);
            innerTextCount = Gui.LabelSliderNumeric("innerTextCount", innerTextCount, 0, 100);
            outerHeight = Gui.LabelSliderNumeric("OuterHeight", outerHeight, 0, 300);
            innerHeight = Gui.LabelSliderNumeric("InnerHeight", innerHeight, 0, 300);

            // Set SpacingY to 0 within this scope.
            using var s = Style.SpacingYs.Begin(0f);
            using var p = Gui.BeginFramePadding1();
            Gui.NextHeight(Size.Fixed(outerHeight));
            // Outer scrollable area.
            if (Gui.BeginScroll())
            {
                using (Gui.BeginFramePadding1())
                {
                    // Inner scrollable area.
                    Gui.NextHeight(Size.Fixed(innerHeight));
                    if (Gui.BeginScroll())
                    {
                        for (int i = 0; i < innerTextCount; i++)
                        {
                            using (Ctx.PushId(i))
                                Gui.Text($"inner:{i}");
                        }
                        // Must be executed if BeginScroll() returns true.
                        Gui.EndScroll();
                    }
                }

                for (int i = 0; i < outerTextCount; i++)
                {
                    Gui.Text($"outer:{i}");
                }

                Gui.EndScroll();
            }
        }

        void DrawUsingHandler()
        {
            Gui.HeadingTooltip(
                "Fixed",
                "A scroll where the number and height of widgets must be determined before processing.\n" +
                "It only processes the displayed widgets, making it fast even when there are many.");

            // Controls for modifying fixed scroll properties.
            Gui.LabelInputNumeric("Height", ref height);
            textCountWithIterator = Gui.LabelSliderNumeric("TextCount", textCountWithIterator, 0, 100);

            using var p = Gui.BeginFramePadding1();
            // Create a scroll handler with fixed height and item count.
            var handler = Gui.CreateScrollHandler(height, textCountWithIterator, Style.StandardHeight, 0f);
            // Render only visible items based on the scroll handler.
            while (handler.Next())
            {
                Gui.Text($"{handler.CurrentIndex}");
            }
        }

        /// <summary>
        /// Shows how to display the scroll view at the very bottom of the window.
        /// </summary>
        void DrawToBottomOfWindow()
        {
            Gui.Heading("Fill to Bottom");
            using var p = Gui.BeginFramePadding1();

            Ctx.AddSpaceIfNeeded();
            // Create a scroll handler that fills the remaining height in the window.
            var handler = Gui.CreateScrollHandler(Ctx.GetRemainRect().height, 100, Style.StandardHeight, 0f);
            // Render only visible items based on the scroll handler.
            while (handler.Next())
            {
                Gui.Text(handler.CurrentIndex.ToString());
            }
        }
    }
}