Gum in Code

Introduction

Gum can be used purely in code (no editor), or by referencing a Gum project. Both approaches are well-supported so you can use Gum to fit your development style.

Gum Code-Only

Gum can be used fully in code. A code-only setup requires minimal code. The following shows a simple MonoGame Game1 class with a few functional Gum controls. All lines of code related to Gum are highlighted:

using Gum.Forms.Controls;
using Gum.Wireframe;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using MonoGameGum;
using System;

namespace MonoGameAndGum;

public class Game1 : Game
{
    private GraphicsDeviceManager _graphics;
    GumService GumUI => GumService.Default;
    public Game1()
    {
        _graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
        IsMouseVisible = true;
    }

    protected override void Initialize()
    {
        GumUI.Initialize(this, Gum.Forms.DefaultVisualsVersion.V3);

        var stackPanel = new StackPanel();
        stackPanel.AddToRoot();
        stackPanel.Spacing = 6;
        stackPanel.Anchor(Anchor.Center);

        var button = new Button();
        stackPanel.AddChild(button);
        button.Text = "Click Me";
        button.Click += (s, e) => 
        {
            button.Text = DateTime.Now.ToString();
        };

        var textBox = new TextBox();
        textBox.Width = 150;
        stackPanel.AddChild(textBox);

        var listBox = new ListBox();
        stackPanel.AddChild(listBox);
        for(int i = 0; i < 10; i++)
        {
            listBox.Items.Add("Item " + i);
        }

        base.Initialize();
    }


    protected override void Update(GameTime gameTime)
    {
        GumUI.Update(gameTime);
        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);
        GumUI.Draw();
        base.Draw(gameTime);
    }
}

Code-only Gum Controls

Gum Tool Projects in Code

The Gum Tool can be used to create projects visually. These projects can be loaded into your project and accessed in a type-safe way using Gum's generated code.

The following image shows a screen similar to the one above created in the Gum tool:

The following code can be used to load and interact with the controls:

public class Game1 : Game
{
    private GraphicsDeviceManager _graphics;
    GumService GumUI => GumService.Default;
    public Game1()
    {
        _graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
        IsMouseVisible = true;
    }

    protected override void Initialize()
    {
        GumUI.Initialize(this, "GumProject/GumProject.gumx");

        var screen = new ExampleScreen();
        screen.AddToRoot();

        screen.ButtonStandardInstance.Click += (s,e) =>
        {
            screen.ButtonStandardInstance.Text = DateTime.Now.ToString();
        };

        for(int i = 0; i < 10; i++)
        {
            screen.ListBoxInstance.Items.Add("Item " + (i + 1));
        }

        base.Initialize();
    }

    protected override void Update(GameTime gameTime)
    {
        GumUI.Update(gameTime);
        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);
        GumUI.Draw();
        base.Draw(gameTime);
    }
}

Generated code is optional - code can access Gum objects without any generated code as shown in the following block:

public class Game1 : Game
{
    private GraphicsDeviceManager _graphics;
    GumService GumUI => GumService.Default;
    public Game1()
    {
        _graphics = new GraphicsDeviceManager(this);
        Content.RootDirectory = "Content";
        IsMouseVisible = true;
    }

    protected override void Initialize()
    {
        GumUI.Initialize(this, "GumProject/GumProject.gumx");

        var screen = ObjectFinder.Self.GumProjectSave.Screens
            .First().ToGraphicalUiElement();
        screen.AddToRoot();

        var button = screen.GetFrameworkElementByName<Button>("ButtonStandardInstance");
        button.Click += (s,e) =>
        {
            button.Text = DateTime.Now.ToString();
        };

        var listBox = screen.GetFrameworkElementByName<ListBox>("ListBoxInstance");
        for (int i = 0; i < 10; i++)
        {
            listBox.Items.Add("Item " + (i + 1));
        }

        base.Initialize();
    }


    protected override void Update(GameTime gameTime)
    {
        GumUI.Update(gameTime);
        base.Update(gameTime);
    }

    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);
        GumUI.Draw();
        base.Draw(gameTime);
    }
}