Unity3D C# Button sprite swap - attach images at runtime

Question

I am creating buttons when my "Hero Selection Menu" is being created. These buttons will get their related images/Sprites depending on the "Hero" they will represent.

I have the following method, but I don't understand which variable I have to apply the sprites to .

Button _thisButton;
Sprite  _normalSprite;
Sprite _highlightSprite;

protected override void DoStateTransition (SelectionState state, bool instant){
    switch (state) {
    case Selectable.SelectionState.Normal:
        _thisButton.image = _normalSprite;    //.image is not correct
        Debug.Log("statenormalasd");
        break;
    case Selectable.SelectionState.Highlighted:
        _thisButton.image = _normalSprite;    //.image is not correct
//...
    }

The states are definitely working, I have confirmed it through Debug.Log(...);

Again the problem is: which value has to be changed if not.image?

Thanks in advance, Csharpest

Answer 1

You're trying to attach a sprite to a button component. The sprite is in the Image component. Check this out!

GameObject buttonGameObject;
Sprite newSprite;

void Start() {
    buttonGameObject.GetComponent<Image>().sprite = newSprite;   
}

But to fix your code, you'd probably do something like:

Button _thisButton;
Sprite  _normalSprite;
Sprite _highlightSprite;

protected override void DoStateTransition (SelectionState state, bool instant){
    switch (state) {
    case Selectable.SelectionState.Normal:
        _thisButton.GetComponent<Image>().sprite = _normalSprite;   
        Debug.Log("statenormalasd");
        break;
    case Selectable.SelectionState.Highlighted:
        _thisButton.GetComponent<Image>().sprite = _normalSprite;    
    }

Answer 2

If you want to change a button spriteswap sprites in a script you must use spriteState , you can do something like this;

Button _thisButton;
Sprite  _normalSprite;
Sprite _highlightSprite;

void ChangeSprites(){
  // _thisButton.transition = Selectable.Transition.SpriteSwap;
  var ss = _thisButton.spriteState;
  _thisButton.image.sprite = _normalSprite;
  //ss.disabledSprite = _disabledSprite;
  ss.highlightedSprite = _highlightSprite;
  //ss.pressedSprite = _pressedSprie;
  _thisButton.spriteState = ss;
}

Unity makes the swap in the button automatically if you are using a normal button and selecting SpriteSwap, if you need to change the transition option then uncomment the first line of the function.

Answer 3

You can do it by changing the sprite attribute of the image component at runtime.

button1.GetComponent<Image>().sprite = sprite;

Full demo code:

using UnityEngine;
using UnityEngine.UI;

public class SpriteChangeDemo : MonoBehaviour
{
    public Button button1;
    public Sprite sprite1, sprite2;

    void Start()
    {
        ChangeSprite(sprite1);
        ChangeSprite(sprite2);
    }

    public void ChangeSprite(Sprite sprite) {
        button1.GetComponent<Image>().sprite = sprite;  
    }
}