add Specialised.LoadStageChanged event

1 files changed, 109 insertions, 0 deletions

diff --git a/src/SMAPI/Patches/LoadForNewGamePatch.cs b/src/SMAPI/Patches/LoadForNewGamePatch.cs
new file mode 100644
index 00000000..9e788e84
--- /dev/null
+++ b/src/SMAPI/Patches/LoadForNewGamePatch.cs
@@ -0,0 +1,109 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.Reflection;
+using Harmony;
+using StardewModdingAPI.Enums;
+using StardewModdingAPI.Framework.Patching;
+using StardewModdingAPI.Framework.Reflection;
+using StardewValley;
+using StardewValley.Menus;
+
+namespace StardewModdingAPI.Patches
+{
+    /// <summary>A Harmony patch for <see cref="Game1.loadForNewGame"/> which notifies SMAPI for save creation load stages.</summary>
+    /// <remarks>This patch hooks into <see cref="Game1.loadForNewGame"/>, checks if <c>TitleMenu.transitioningCharacterCreationMenu</c> is true (which means the player is creating a new save file), then raises <see cref="LoadStage.CreatedBasicInfo"/> after the location list is cleared twice (the second clear happens right before locations are created), and <see cref="LoadStage.CreatedLocations"/> when the method ends.</remarks>
+    internal class LoadForNewGamePatch : IHarmonyPatch
+    {
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>Simplifies access to private code.</summary>
+        private static Reflector Reflection;
+
+        /// <summary>A callback to invoke when the load stage changes.</summary>
+        private static Action<LoadStage> OnStageChanged;
+
+        /// <summary>Whether <see cref="Game1.loadForNewGame"/> was called as part of save creation.</summary>
+        private static bool IsCreating;
+
+        /// <summary>The number of times that <see cref="Game1.locations"/> has been cleared since <see cref="Game1.loadForNewGame"/> started.</summary>
+        private static int TimesLocationsCleared = 0;
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>A unique name for this patch.</summary>
+        public string Name => $"{nameof(LoadForNewGamePatch)}";
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="reflection">Simplifies access to private code.</param>
+        /// <param name="onStageChanged">A callback to invoke when the load stage changes.</param>
+        public LoadForNewGamePatch(Reflector reflection, Action<LoadStage> onStageChanged)
+        {
+            LoadForNewGamePatch.Reflection = reflection;
+            LoadForNewGamePatch.OnStageChanged = onStageChanged;
+        }
+
+        /// <summary>Apply the Harmony patch.</summary>
+        /// <param name="harmony">The Harmony instance.</param>
+        public void Apply(HarmonyInstance harmony)
+        {
+            MethodInfo method = AccessTools.Method(typeof(Game1), nameof(Game1.loadForNewGame));
+            MethodInfo prefix = AccessTools.Method(this.GetType(), nameof(LoadForNewGamePatch.Prefix));
+            MethodInfo postfix = AccessTools.Method(this.GetType(), nameof(LoadForNewGamePatch.Postfix));
+
+            harmony.Patch(method, new HarmonyMethod(prefix), new HarmonyMethod(postfix));
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <summary>The method to call instead of <see cref="Game1.loadForNewGame"/>.</summary>
+        /// <returns>Returns whether to execute the original method.</returns>
+        /// <remarks>This method must be static for Harmony to work correctly. See the Harmony documentation before renaming arguments.</remarks>
+        private static bool Prefix()
+        {
+            LoadForNewGamePatch.IsCreating = Game1.activeClickableMenu is TitleMenu menu && LoadForNewGamePatch.Reflection.GetField<bool>(menu, "transitioningCharacterCreationMenu").GetValue();
+            LoadForNewGamePatch.TimesLocationsCleared = 0;
+            if (LoadForNewGamePatch.IsCreating)
+            {
+                // raise CreatedBasicInfo after locations are cleared twice
+                ObservableCollection<GameLocation> locations = (ObservableCollection<GameLocation>)Game1.locations;
+                locations.CollectionChanged += LoadForNewGamePatch.OnLocationListChanged;
+            }
+
+            return true;
+        }
+
+        /// <summary>The method to call instead after <see cref="Game1.loadForNewGame"/>.</summary>
+        /// <remarks>This method must be static for Harmony to work correctly. See the Harmony documentation before renaming arguments.</remarks>
+        private static void Postfix()
+        {
+            if (LoadForNewGamePatch.IsCreating)
+            {
+                // clean up
+                ObservableCollection<GameLocation> locations = (ObservableCollection<GameLocation>) Game1.locations;
+                locations.CollectionChanged -= LoadForNewGamePatch.OnLocationListChanged;
+
+                // raise stage changed
+                LoadForNewGamePatch.OnStageChanged(LoadStage.CreatedLocations);
+            }
+        }
+
+        /// <summary>Raised when <see cref="Game1.locations"/> changes.</summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event arguments.</param>
+        private static void OnLocationListChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            if (++LoadForNewGamePatch.TimesLocationsCleared == 2)
+                LoadForNewGamePatch.OnStageChanged(LoadStage.CreatedBasicInfo);
+        }
+    }
+}