7 - States

Introduction

States allow you to set multiple variables at one time. Examples of states might include:

• A button with Regular, Highlighted, Pressed, and Disabled states

• A game logo in Large and Small modes

• A game HUD which can appear on and off screen

Prerequisites

This tutorial builds upon the previous tutorial where a Button component was created. If you haven't yet, you should read through the earlier tutorials to create a Button component.

Defining States

First we'll define two new states. All components and screens have a Default state automatically. This Default state is uncategorized, but all other states must be in a category. Therefore, we'll first add a new category:

1. Right-click in the States tab

2. Select Add Category

   
3. Enter the name ButtonStateCategory

To add a new state:

1. Right-click on ButtonStateCategory

2. Select Add State

   
3. Enter the name "Highlighted"

4. Click OK

The Button component now has a new state called Highlighted:

Setting Variables in States

Once a state is defined and selected, setting a variable associates that variable with the selected state. In other words, any variable that is set when the Highlighted state is selected results in that variable being added to that state.

For this example, we can make the button become a lighter blue when highlighted. To do this:

1. Verify the Highlighted state is selected

2. Select the ColoredRectangleInstance

3. Set the Green and Red values to 100

Notice that the Green and Red values are rendered with a white background rather than green - indicating that they are explicitly set in the Highlight state.

Switching Between States

The values that have just been set apply only to the state that was selected when the changes were made - the Highlight state. This means that clicking on the Default state switches the button back to the default colors. By clicking on the states in Gum you can preview and edit states easily.

Category Variables

Whenever a state in a category sets a variable, that variable is set across all states in that category. So far this tutorial only created a single state called Highlighted, but if additional states are set, all will explicitly set the Red and Green variables. This topic is covered in more detail in the next tutorial.