Returning sprite from coroutine [duplicate]

问题

I currently have 2 functions.

My first one is an IEnumerator, let's call it LoadImage, it handles downloading the image from a URL.

IEnumerator LoadImage()
{
    WWW www = new WWW("https://s3-ap-northeast-1.amazonaws.com/myeyehouse/uimg/scimg/sc661120171130095837184/pano/thumb_Eyehouse.jpg");
    while (!www.isDone)
    {
        Debug.Log("Download image on progress" + www.progress);
        yield return null;
    }

    if (!string.IsNullOrEmpty(www.error))
    {
        Debug.Log("Download failed");
    }
    else
    {
        Debug.Log("Download succes");
        Texture2D texture = new Texture2D(1, 1);
        www.LoadImageIntoTexture(texture);

        Sprite sprite = Sprite.Create(texture,
            new Rect(0, 0, texture.width, texture.height), Vector2.zero);
        return sprite;

    }
}

My second function needs to assign that LoadImage()'s output (which is a sprite) to my GameObject. I cant just put my GameObject and load it in the LoadImage() function. If possible, I need advice on how I can assign my the sprite from the LoadImage() function.

回答1:

You can't return a value from coroutine. So you need to use delegate. I would return the Texture and leave the Sprite creation out.

IEnumerator LoadImage(Action<Texture2D> callback)
{
    WWW www = new WWW("https://s3-ap-northeast-1.amazonaws.com/myeyehouse/uimg/scimg/sc661120171130095837184/pano/thumb_Eyehouse.jpg");
    while (!www.isDone)
    {
        Debug.Log("Download image on progress" + www.progress);
        yield return null;
    }

    if (!string.IsNullOrEmpty(www.error))
    {
        Debug.Log("Download failed");
        callback(null);
    }
    else
    {
        Debug.Log("Download succes");
        Texture2D texture = new Texture2D(1, 1);
        www.LoadImageIntoTexture(texture);
        callback(texture;)
    }
}

Then you call:

void Start()
{
    StartCoroutine(LoadImage(CreateSpriteFromTexture));
}
private CreateSpriteFromTexture(Texture2D texture)
{
        if(texture == null) { return;}
        Sprite sprite = Sprite.Create(texture,
            new Rect(0, 0, texture.width, texture.height), Vector2.zero);
        // Assign sprite to image
}

The whole challenge is to understand how delegate and action work.

来源：https://stackoverflow.com/questions/47805381/returning-sprite-from-coroutine

标签

image

unity3d

ienumerator