Image and raw image components in Unity - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Unity C# code snippet?

Consider the following Unity C# code that sets a sprite to an Image component and a texture to a RawImage component. What will be the result when this code runs?

Unity

using UnityEngine;
using UnityEngine.UI;

public class TestImage : MonoBehaviour {
    public Image imageComponent;
    public RawImage rawImageComponent;
    public Sprite sprite;
    public Texture2D texture;

    void Start() {
        imageComponent.sprite = sprite;
        rawImageComponent.texture = texture;
        Debug.Log(imageComponent.sprite.name);
        Debug.Log(rawImageComponent.texture.name);
    }
}

A Throws an error because RawImage cannot use Texture2D.

B Throws a NullReferenceException because sprite is not assigned.

C Logs the texture's name twice, ignoring the sprite.

D Logs the sprite's name and the texture's name correctly.

💡 Hint

Remember that Image uses Sprite and RawImage uses Texture.

The Image component uses a Sprite, and the RawImage component uses a Texture. Assigning them correctly and logging their names will output both names.

🧠 Conceptual

intermediate

Which statement correctly describes the difference between Image and RawImage components in Unity?

Choose the correct description of how Image and RawImage components differ in Unity UI.

A Image displays Textures and supports slicing; RawImage displays Sprites and supports slicing.

B Image displays Sprites and supports slicing; RawImage displays Textures and does not support slicing.

C Both Image and RawImage display Sprites and support slicing equally.

D RawImage displays Sprites and supports slicing; Image displays Textures and does not support slicing.

💡 Hint

Think about which component supports 9-slicing and which uses textures directly.

Image component is designed for Sprites and supports features like 9-slicing for UI scaling. RawImage displays Textures directly but does not support slicing.

🔧 Debug

advanced

What happens when this code runs?

Examine the code below. What best describes what happens at runtime?

Unity

using UnityEngine;
using UnityEngine.UI;

public class ImageTest : MonoBehaviour {
    public Image img;
    public Texture2D tex;

    void Start() {
        img.sprite = tex as Sprite;
    }
}

A Casting Texture2D to Sprite returns null, causing img.sprite to be null but no error.

B Casting Texture2D to Sprite fails, causing a runtime InvalidCastException.

C img.sprite cannot be assigned at runtime, causing an error.

D Texture2D cannot be assigned to img.sprite because they are incompatible types; no cast possible.

💡 Hint

Consider what happens when you cast incompatible types with 'as' keyword.

The 'as' keyword returns null if the cast fails. Assigning null to img.sprite is allowed and does not throw an error. So no runtime exception occurs, but the sprite is null.

📝 Syntax

advanced

Which option correctly sets a RawImage's texture in Unity C#?

Choose the correct syntax to assign a Texture2D named 'myTexture' to a RawImage component named 'rawImage'.

A rawImage.texture = myTexture;

B rawImage.texture = myTexture as Sprite;

C rawImage.SetTexture(myTexture);

D rawImage.sprite = myTexture;

💡 Hint

Remember RawImage uses a Texture, not a Sprite.

RawImage has a 'texture' property of type Texture. Assigning a Texture2D directly is correct. 'sprite' property does not exist on RawImage.

🚀 Application

expert

How many items are in the resulting dictionary after this Unity C# code runs?

Given this code snippet that uses Image and RawImage components in a dictionary, how many key-value pairs does the dictionary contain after execution?

Unity

using UnityEngine;
using UnityEngine.UI;
using System.Collections.Generic;

public class ImageDictTest : MonoBehaviour {
    public Image img1;
    public RawImage raw1;
    public Image img2;

    void Start() {
        var dict = new Dictionary<string, Object>();
        dict["first"] = img1.sprite;
        dict["second"] = raw1.texture;
        dict["first"] = img2.sprite;
        Debug.Log(dict.Count);
    }
}

A 1

B 3

C 2

D 0

💡 Hint

Think about what happens when you assign a value to an existing key in a dictionary.

Assigning to the same key 'first' twice overwrites the previous value. So the dictionary has keys 'first' and 'second', total 2 items.