# Extending IMGUI

> Build compound controls from standard ones and intercept events to process custom user input.

There are a number of ways to leverage and extend the IMGUI system to meet your needs. Controls can be mixed and created, and you have a lot of leverage in dictating how user input into the GUI is processed.

## Compound Controls

There might be situations in your GUI where two types of Controls always appear together. For example, maybe you are creating a Character Creation screen, with several Horizontal Sliders. All of those Sliders need a Label to identify them, so the player knows what they are adjusting. In this case, you could partner every call to **GUI.Label()** with a call to **GUI.HorizontalSlider()**, or you could create a **Compound Control** which includes both a Label and a Slider together.

```lang-cs
// Label and Slider Compound Control

using UnityEngine;
using System.Collections;

public class GUITest : MonoBehaviour {
		
	private float mySlider = 1.0f;
	
	void OnGUI () {
		mySlider = LabelSlider (new Rect (10, 100, 100, 20), mySlider, 5.0f, "Label text here");
	}
	
	float LabelSlider (Rect screenRect, float sliderValue, float sliderMaxValue, string labelText) {
		GUI.Label (screenRect, labelText);
	
		// <- Push the Slider to the end of the Label
		screenRect.x += screenRect.width; 
	
		sliderValue = GUI.HorizontalSlider (screenRect, sliderValue, 0.0f, sliderMaxValue);
		return sliderValue;
	}

}
```

In this example, calling **LabelSlider()** and passing the correct arguments will provide a Label paired with a Horizontal Slider. When writing Compound Controls, you have to remember to return the correct value at the end of the function to make it interactive.


**The above Compound Control always creates this pair of Controls:**
![](/api/media?file=/engine/6000.3/media/images/gsg-LabelSlider.png)

### Static Compound Controls

By using **Static** functions, you can create an entire collection of your own Compound Controls that are self-contained. This way, you do not have to declare your function in the same script you want to use it.

```lang-cs
// This script is called CompoundControls
using UnityEngine;
using System.Collections;

public class CompoundControls : MonoBehaviour {		
	
	public static float LabelSlider (Rect screenRect, float sliderValue, float sliderMaxValue, string labelText) {
		GUI.Label (screenRect, labelText);
	
		// <- Push the Slider to the end of the Label
		screenRect.x += screenRect.width; 
	
		sliderValue = GUI.HorizontalSlider (screenRect, sliderValue, 0.0f, sliderMaxValue);
		return sliderValue;
	}

}
```

By saving the above example in a script called **CompoundControls**, you can call the **LabelSlider()** function from any other script by simply typing **CompoundControls.LabelSlider()** and providing your arguments.

### Elaborate Compound Controls

You can get very creative with Compound Controls. They can be arranged and grouped in any way you like. The following example creates a re-usable RGB Slider.

```lang-cs
// RGB Slider Compound Control

using UnityEngine;
using System.Collections;

public class GUITest : MonoBehaviour {
		
	public Color myColor;
	
	void OnGUI () {
		myColor = RGBSlider (new Rect (10,10,200,10), myColor);
	}
	
	Color RGBSlider (Rect screenRect, Color rgb) {
		rgb.r = GUI.HorizontalSlider (screenRect, rgb.r, 0.0f, 1.0f);
	
		// <- Move the next control down a bit to avoid overlapping
		screenRect.y += 20; 
		rgb.g = GUI.HorizontalSlider (screenRect, rgb.g, 0.0f, 1.0f);
	
		// <- Move the next control down a bit to avoid overlapping
		screenRect.y += 20; 
	
		rgb.b = GUI.HorizontalSlider (screenRect, rgb.b, 0.0f, 1.0f);
		return rgb;
	}
}
```


**The RGB Slider created by the example above:**
![](/api/media?file=/engine/6000.3/media/images/gsg-RGBSlider.png)

Now let's build Compound Controls on top of each other, in order to demonstrate how Compound Controls can be used within other Compound Controls. To do this, we will create a new RGB Slider like the one above, but we will use the LabelSlider to do so. This way we'll always have a Label telling us which slider corresponds to which color.

```lang-cs
// RGB Label Slider Compound Control

using UnityEngine;
using System.Collections;

public class GUITest : MonoBehaviour {
		
	public Color myColor;
	
	void OnGUI () {
		myColor = RGBSlider (new Rect (10,10,200,30), myColor);
	}
	
	Color RGBSlider (Rect screenRect, Color rgb) {
		rgb.r = CompoundControls.LabelSlider (screenRect, rgb.r, 1.0f, "Red");
	
		// <- Move the next control down a bit to avoid overlapping
		screenRect.y += 20; 
		rgb.g = CompoundControls.LabelSlider (screenRect, rgb.g, 1.0f, "Green");
	
		// <- Move the next control down a bit to avoid overlapping
		screenRect.y += 20; 
	
		rgb.b = CompoundControls.LabelSlider (screenRect, rgb.b, 1.0f, "Blue");
		
		return rgb;
	}	
	
}
```


**The Compound RGB Label Slider created by the above code:**
![](/api/media?file=/engine/6000.3/media/images/gsg-RGBLabelSlider.png)