Craftimizer/Craftimizer/ImGuiUtils.cs

using ImGuiNET;
using System;
using System.Collections.Generic;
using System.Numerics;

namespace Craftimizer.Plugin;

internal static class ImGuiUtils
{
    private static readonly Stack<(Vector2 Min, Vector2 Max)> GroupPanelLabelStack = new();

    // Adapted from https://github.com/ocornut/imgui/issues/1496#issuecomment-655048353
    public static void BeginGroupPanel(float width = -1, bool addPadding = true)
    {
        ImGui.BeginGroup();

        var itemSpacing = ImGui.GetStyle().ItemSpacing;
        ImGui.PushStyleVar(ImGuiStyleVar.FramePadding, Vector2.Zero);
        ImGui.PushStyleVar(ImGuiStyleVar.ItemSpacing, Vector2.Zero);

        var frameHeight = ImGui.GetFrameHeight();

        ImGui.BeginGroup();
        ImGui.Dummy(new Vector2(width < 0 ? ImGui.GetContentRegionAvail().X : width, 0));
        ImGui.Dummy(new Vector2(frameHeight * 0.5f, 0));
        ImGui.SameLine(0, 0);

        ImGui.BeginGroup();
        ImGui.Dummy(new Vector2(frameHeight * 0.5f, 0));
        GroupPanelLabelStack.Push((ImGui.GetItemRectMin(), ImGui.GetItemRectMax()));
        ImGui.SameLine(0, 0);
        ImGui.Dummy(new Vector2(0f, frameHeight * (addPadding ? 1 : .5f) + itemSpacing.Y));

        ImGui.BeginGroup();

        ImGui.PopStyleVar(2);

        ImGui.PushItemWidth(MathF.Max(0, ImGui.CalcItemWidth() - frameHeight));
    }

    public static void BeginGroupPanel(string name, float width = -1, bool addPadding = true)
    {
        ImGui.BeginGroup();

        var itemSpacing = ImGui.GetStyle().ItemSpacing;
        ImGui.PushStyleVar(ImGuiStyleVar.FramePadding, Vector2.Zero);
        ImGui.PushStyleVar(ImGuiStyleVar.ItemSpacing, Vector2.Zero);

        var frameHeight = ImGui.GetFrameHeight();

        ImGui.BeginGroup();
        ImGui.Dummy(new Vector2(width < 0 ? ImGui.GetContentRegionAvail().X : width, 0));
        ImGui.Dummy(new Vector2(frameHeight * 0.5f, 0));
        ImGui.SameLine(0, 0);

        ImGui.BeginGroup();
        ImGui.Dummy(new Vector2(frameHeight * 0.5f, 0));
        ImGui.SameLine(0, 0);
        ImGui.TextUnformatted(name);
        GroupPanelLabelStack.Push((ImGui.GetItemRectMin(), ImGui.GetItemRectMax()));
        ImGui.SameLine(0, 0);
        ImGui.Dummy(new Vector2(0f, frameHeight * (addPadding ? 1 : .5f) + itemSpacing.Y));

        ImGui.BeginGroup();

        ImGui.PopStyleVar(2);

        ImGui.PushItemWidth(MathF.Max(0, ImGui.CalcItemWidth() - frameHeight));
    }

    public static void EndGroupPanel()
    {
        ImGui.PopItemWidth();

        var itemSpacing = ImGui.GetStyle().ItemSpacing;

        ImGui.PushStyleVar(ImGuiStyleVar.FramePadding, Vector2.Zero);
        ImGui.PushStyleVar(ImGuiStyleVar.ItemSpacing, Vector2.Zero);

        var frameHeight = ImGui.GetFrameHeight();

        ImGui.EndGroup();

        ImGui.EndGroup();

        ImGui.SameLine(0, 0);
        ImGui.Dummy(new Vector2(frameHeight * 0.5f, 0));
        ImGui.Dummy(new Vector2(0f, frameHeight * 0.5f - itemSpacing.Y));

        ImGui.EndGroup();

        var itemMin = ImGui.GetItemRectMin();
        var itemMax = ImGui.GetItemRectMax();
        var labelRect = GroupPanelLabelStack.Pop();

        var halfFrame = new Vector2(frameHeight * 0.25f, frameHeight) * 0.5f;
        (Vector2 Min, Vector2 Max) frameRect = (itemMin + halfFrame, itemMax - new Vector2(halfFrame.X, 0));
        labelRect.Min.X -= itemSpacing.X;
        labelRect.Max.X += itemSpacing.X;
        for (var i = 0; i < 4; ++i)
        {
            var (minClip, maxClip) = i switch
            {
                0 => (new Vector2(float.NegativeInfinity), new Vector2(labelRect.Min.X, float.PositiveInfinity)),
                1 => (new Vector2(labelRect.Max.X, float.NegativeInfinity), new Vector2(float.PositiveInfinity)),
                2 => (new Vector2(labelRect.Min.X, float.NegativeInfinity), new Vector2(labelRect.Max.X, labelRect.Min.Y)),
                3 => (new Vector2(labelRect.Min.X, labelRect.Max.Y), new Vector2(labelRect.Max.X, float.PositiveInfinity)),
                _ => (Vector2.Zero, Vector2.Zero)
            };

            ImGui.PushClipRect(minClip, maxClip, true);
            ImGui.GetWindowDrawList().AddRect(
                frameRect.Min, frameRect.Max,
                ImGui.GetColorU32(ImGuiCol.Border),
                halfFrame.X);
            ImGui.PopClipRect();
        }

        ImGui.PopStyleVar(2);

        ImGui.Dummy(Vector2.Zero);

        ImGui.EndGroup();
    }
}