SystemHeatAssets.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Reflection;
using UnityEngine;


namespace SystemHeat.UI
{
  /// <summary>
  /// Loads and holds references to Asset Bundled things
  /// </summary>
  [KSPAddon(KSPAddon.Startup.Instantly, true)]
  public class SystemHeatAssets : MonoBehaviour
  {
    public static GameObject OverlayPanelPrefab { get; private set; }
    public static GameObject ToolbarPanelPrefab { get; private set; }
    public static GameObject ToolbarPanelLoopPrefab { get; private set; }
    public static GameObject ReactorWidgetPrefab { get; private set; }
    public static GameObject ReactorToolbarPanelPrefab { get; private set; }
    public static Dictionary<string, Sprite> Sprites { get; private set; }

    internal static string ASSET_PATH = "GameData/SystemHeat/UI/systemheatui.dat";
    internal static string SPRITE_ATLAS_NAME = "system-heat-sprites-1";

    private void Awake()
    {
      Utils.Log("[SystemHeatAssets]: Loading Assets", LogType.UI);
      AssetBundle prefabs = AssetBundle.LoadFromFile(Path.Combine(KSPUtil.ApplicationRootPath, ASSET_PATH));

      // Get the Prefabs
      OverlayPanelPrefab = prefabs.LoadAsset("SystemInfo") as GameObject;
      ToolbarPanelPrefab = prefabs.LoadAsset("SystemHeatToolbar") as GameObject;
      ToolbarPanelLoopPrefab = prefabs.LoadAsset("SystemHeatLoopData") as GameObject;
      ReactorToolbarPanelPrefab = prefabs.LoadAsset("ReactorWindow") as GameObject;
      ReactorWidgetPrefab = prefabs.LoadAsset("ReactorWidget") as GameObject;

      Utils.Log("[SystemHeatAssets]: Loaded UI Prefabs", LogType.UI);
      // Get the Sprite Atlas
      Sprite[] spriteSheet = prefabs.LoadAssetWithSubAssets<Sprite>(SPRITE_ATLAS_NAME);
      Sprites = new Dictionary<string, Sprite>();
      foreach (Sprite subSprite in spriteSheet)
      {
        Sprites.Add(subSprite.name, subSprite);
      }
      Utils.Log($"[SystemHeatAssets]: Loaded {Sprites.Count} sprites", LogType.UI);
    }

    // We can't load the asset bundle again - it is already loaded, and it would
    // instantiate the old types. Instead, we use reflection to read them out of
    // the old assembly. Hot-reloading will take care of replacing any widgets
    // within.
    private static void OnHotLoad(Assembly prev)
    {
      const BindingFlags Flags = BindingFlags.Public | BindingFlags.Static;

      var old = prev.GetType(typeof(SystemHeatAssets).FullName);
      OverlayPanelPrefab = GetPrefabProperty(old, nameof(OverlayPanelPrefab));
      ToolbarPanelPrefab = GetPrefabProperty(old, nameof(ToolbarPanelPrefab));
      ToolbarPanelLoopPrefab = GetPrefabProperty(old, nameof(ToolbarPanelLoopPrefab));
      ReactorWidgetPrefab = GetPrefabProperty(old, nameof(ReactorWidgetPrefab));
      ReactorToolbarPanelPrefab = GetPrefabProperty(old, nameof(ReactorToolbarPanelPrefab));
      Sprites = (Dictionary<string, Sprite>)old.GetProperty(nameof(Sprites), Flags).GetValue(null);
    }

    private static GameObject GetPrefabProperty(Type old, string name)
    {
      const BindingFlags Flags = BindingFlags.Public | BindingFlags.Static;
      return (GameObject)old.GetProperty(name, Flags).GetValue(null);
    }
  }
}