Modding:Modder Guide/APIs

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SMAPI simplifies mod development by providing APIs and events you can use, which are documented below. See Modding:Creating a SMAPI mod for a guide to creating a new SMAPI mod.

Mod APIs

Events

SMAPI publishes several C# events that tell you when something happens. For example, if you want to do something after the player loads their save, you can add this to your Entry method:

SaveEvents.AfterLoad += this.SaveEvents_AfterLoad;

Then declare a method like this. (The EventArgs e argument contains any extra data about the event.)

/// <summary>The method called after the player loads their save.</summary>
/// <param name="sender">The event sender.</param>
/// <param name="e">The event arguments.</param>
public void SaveEvents_AfterLoad(object sender, EventArgs e)
{
   this.Monitor.Log("The player loaded their game! This is a good time to do things.");
   this.Monitor.Log("Everything in the world is ready to interact with at this point.");
}

Here are the available events:

• ContentEvents are raised when the game loads content from its XNB files or changes locale.

  event	summary
  AfterLocaleChanged	Raised after the content language changes.

• ControlEvents are raised when the player uses a controller, keyboard, or mouse. They're raised before the game handles the input, so it's possible to selectively prevent the game from responding to it. (That's beyond the scope of this guide, but it involves overwriting Game1.oldKBState, Game1.oldMouseState, and Game1.oldPadState.) Most of these events are split into two variants, XPressed and XReleased. The Pressed variant is raised when the player presses the button (holding the button down only triggers the event once), and the Released variant is raised when they release it.

  event	summary
  ControllerButtonPressed ControllerButtonReleased	Raised after the player pressed/released a button on a gamepad or controller. These events aren't raised for trigger buttons.
  ControllerTriggerPressed ControllerTriggerReleased	Raised after the player pressed/released a trigger button on a gamepad or controller.
  KeyPressed KeyReleased	Raised after the player pressed/released a keyboard key.
  KeyboardChanged	Raised after the game's KeyboardState changed. That happens when the player presses or releases a key.
  MouseChanged	Raised after the game's MouseState changed. That happens when the player moves the mouse, scrolls the mouse wheel, or presses/releases a button.

• GameEvents are raised when the game changes state.

  event	summary
  GameLoaded	Raised when the game is ready and initialised. At this point the game data (like Game1.objectInformation) is in memory and ready for use.
  UpdateTick	Raised when the game updates its state (≈60 times per second).
  SecondUpdateTick	Raised every other tick (≈30 times per second).
  FourthUpdateTick	Raised every fourth tick (≈15 times per second).
  EighthUpdateTick	Raised every eighth tick (≈8 times per second).
  QuarterSecondTick	Raised every 15th tick (≈4 times per second).
  HalfSecondTick	Raised every 30th tick (≈twice per second).
  OneSecondTick	Raised every 60th tick (≈once per second).

• GraphicsEvents are raised during the game's draw loop, when the game is rendering content to the window.

  event	summary
  OnPreRenderEvent OnPostRenderEvent	Raised before and after drawing the world to the screen.
  OnPreRenderGuiEvent OnPostRenderGuiEvent	When a menu is open (Game1.activeClickableMenu != null), raised before and after drawing that menu to the screen. This includes the game's internal menus like the title screen.
  OnPreRenderHudEvent OnPostRenderHudEvent	Raised before and after drawing the HUD (item toolbar, clock, etc) to the screen. The HUD is available at this point, but not necessarily visible. (For example, the event is called even if a menu is open.)
  Resize	Raised after the game window is resized.

• LocationEvents are raised when the player transitions between game locations, a location is added or removed, or the objects in the current location change.

  event	summary
  CurrentLocationChanged	Raised after the player warps to a new location. Handlers are given the previous and new locations as arguments.
  LocationObjectsChanged	Raised after the list of objects in the current location changes (e.g. an object is added or removed). Handlers are given the new list of objects as an argument.
  LocationsChanged	Raised after a game location is added or removed. Handlers are passed the new list of locations as an argument.

• MenuEvents are raised when a game menu is opened or closed (including internal menus like the title screen).

  event	summary
  MenuChanged	Raised after a game menu is opened or replaced with another menu. This event is not invoked when a menu is closed. Handlers are given the previous menu (if any) and new menu (if any).
  MenuClosed	Raised after a game menu is closed. Handlers are given the previous menu.

• MineEvents are raised when something happens in The Mines.

  event	summary
  MineLevelChanged	Raised after the player warps to a new level of the mine. Handlers are passed the previous and new mine level as arguments.

• PlayerEvents are raised when the player data changes.

  event	summary
  InventoryChanged	Raised after the player's inventory changes in any way (added or removed item, sorted, etc).
  LeveledUp	Raised after the player levels up a skill. This happens as soon as they level up, not when the game notifies the player after their character goes to bed.

• SaveEvents are raised when the player saves or loads the game.

  event	summary
  AfterLoad	Raised after the player loads a saved game. The world is ready for mods to modify at this point.
  BeforeSave	Raised before the game updates the save file. (The save won't be written until all mods have finished handling this event.)
  AfterSave	Raised after the game finishes updating the save file.
  AfterReturnToTitle	Raised after the player exits to the title screen.

• TimeEvents are raised when the in-game date or time changes.

  event	summary
  AfterDayStarted	Raised after the game begins a new day, including when loading a save.
  TimeOfDayChanged	Raised after the in-game clock changes.
  DayOfMonthChanged	Not recommended; most mods should use AfterDayStarted instead. Raised when Game1::dayOfMonth changes value. This happens before the new day starts. If you exit to title and then reload the same save, it will not trigger since the value hasn't changed.
  SeasonOfYearChanged	Raised after the season changes.
  YearOfGameChanged	Raised after the year changes.

Configuration

You can let users configure your mod through a config.json file. SMAPI will automatically create the file and take care of reading, normalising, and updating it.

Basic configuration

Here's the simplest way to use config.json:

1. Create your model. This is just a class with properties for the config options you want, and it can contain almost anything from a few boolean fields to a complex object graph. (You should try to keep it simple for your users, though.) You can set defaults directly:

   class ModConfig
   {
      public bool ExampleBoolean { get; set; } = true;
      public float ExampleFloat { get; set; } = 0.5;
   }
   

   ...or with a constructor:

   class ModConfig
   {
      public bool ExampleBoolean { get; set; }
      public float ExampleFloat { get; set; }
   
      public ModConfig()
      {
         this.ExampleBoolean = true;
         this.ExampleFloat = 0.5;
      }
   }
   

2. In your ModEntry::Entry method, add this line to read the config options:

   ModConfig config = helper.ReadConfig<ModConfig>();
   

That's it! When the player launches the game, SMAPI will create the config.json file automatically if it doesn't exist yet, using the default config options you provided in your model. If you need to edit and save the config, you can use helper.SaveConfig(config). You can access the helper in other methods using this.Helper.

Custom JSON files

Sometimes one config.json isn't enough, or you need to store data that's not meant to be edited by the user. This is pretty easy using the ModHelper:

1. Create your model (just like the previous section).
2. In your mod code, use this.Helper to read and write to a named file:

   // read file
   var model = this.Helper.ReadJsonFile<ModData>("data.json") ?? new ModData();
   
   // save file (if needed)
   this.Helper.WriteJsonFile("data.json", model);
   

   Note that ReadJsonFile will return null if the file doesn't exist. The above example will create a default instance if that happens; if you don't want to do that, just remove the ?? new ModData() part.

Per-save JSON files

You can also specify a directory path (relative to your mod directory) instead of just the file name. The directories will be created automatically if needed. For example, here's how you'd use per-save config files:

// read file
var model = this.Helper.ReadJsonFile<ModData>($"{Constants.SaveFolderName}/config.json") ?? new ModData();

// write file (if needed)
this.Helper.WriteJsonFile($"{Constants.SaveFolderName}/config.json", model);

Content

If your mod needs custom textures or maps, you can load them with SMAPI's content API. You can load any .xnb file the game supports, or load a .png file into a texture.

Example usage:

• Load an image from your mod folder (from an assets subfolder in this example):

  // load an XNB file
  var texture = helper.Content.Load<Texture2D>(@"assets\texture.xnb", ContentSource.ModFolder);
  
  // load a PNG file
  var texture = helper.Content.Load<Texture2D>(@"assets\texture.png", ContentSource.ModFolder);
  

• Load an asset from game's content folder:

  var data = helper.Content.Load<Dictionary<int, string>>(@"Data\ObjectInformation.xnb", ContentSource.GameContent);
  

• Load a custom tilesheet for a map:

  tilesheet.ImageSource = helper.Content.GetActualAssetKey(@"assets\tilesheet.png");
  

Notes:

• Don't call content.Load<T> in draw code for performance reasons, since drawing happens ≈60 times per second. Instead, load your content ahead of time and reuse it.
• Don't worry about which path separators you use; SMAPI will normalise them automatically.

Logging

Your mod can write messages to the console window and log file using the monitor. For example, this code:

this.Monitor.Log("a trace message", LogLevel.Trace);
this.Monitor.Log("a debug message", LogLevel.Debug);
this.Monitor.Log("an info message", LogLevel.Info);
this.Monitor.Log("a warning message", LogLevel.Warn);
this.Monitor.Log("an error message", LogLevel.Error);

will log something like this:

[18:00:00 TRACE Mod Name] a trace message
[18:00:00 DEBUG Mod Name] a debug message
[18:00:00 INFO Mod Name] an info message
[18:00:00 WARN Mod Name] a warning message
[18:00:00 ERROR Mod Name] an error message

Note that LogLevel.Trace messages won't appear in the console window by default, they'll only be written to the log file. Trace messages are for troubleshooting details that are useful when someone sends you their error log, but which the player normally doesn't need to see. (You can see trace messages in the console if you install the "SMAPI for developers" version.)

Reflection

SMAPI provides an API for robustly accessing the game's private fields or methods. You can use it from helper.Reflection in your entry method, or this.Helper.Reflection elsewhere in your entry class. It consists of three methods:

• GetPrivateValue<TValue>(...) returns the value of a private field.
• GetPrivateField<TValue>(...) returns an object you can use to get or set a field's value.
• GetPrivateMethod(...) returns an object you can use to invoke a method.

Here are a few examples of what this lets you do:

// did you pet your pet today?
bool wasPet = this.Helper.Reflection.GetPrivateValue<bool>(pet, "wasPetToday");

// what is the spirit forecast today?
string forecast = this.Helper.Reflection
   .GetPrivateMethod(new TV(), "getFortuneForecast")
   .Invoke<string>();

// randomise the mines
if(Game1.currentLocation is MineShaft)
   this.Helper.Reflection.GetPrivateField<Random>(Game1.currentLocation, "mineRandom").SetValue(new Random());

This works with static or instance fields/methods, caches the reflection to improve performance, and will throw useful errors automatically when reflection fails.

If you need to do more, you can also switch to C#'s underlying reflection API:

FieldInfo field = this.Helper.Reflection.GetPrivateField<string>(…).FieldInfo;
MethodInfo method = this.Helper.Reflection.GetPrivateMethod(…).MethodInfo;

Mod registry

Your mod can get information about loaded mods, or check if a particular mod is loaded. (All mods are loaded by the time your mod's Entry(…) method is called.)

// check if a mod is loaded
bool isLoaded = this.Helper.ModRegistry.IsLoaded("UniqueModID");

// get manifest info for a mod (name, description, version, etc.)
IManifest manifest = this.Helper.ModRegistry.Get("UniqueModID");

// get manifest info for all loaded mods
foreach(IManifest manifest in this.Helper.ModRegistry.GetAll()) { … }