View Driven Cell Sizes with Remote Image Loading.

[sniper199999]

I want to combine 2 demo scenes for my project (View Driven Cell Sizes and Remote Loading). It it seems like in Set Data function, data.cellSize is getting called for every Cell, before the cellImage.sprite is set. The outcome for this is same CellView size for all cells. I suspect it is something to do with StartCoroutine().

(Also all the Image sizes are different)

My Code:

namespace EnhancedScrollerDemos1.RemoteResourcesDemo1
{
   public class CellView : EnhancedScrollerCellView
   {
       public Image cellImage;
       public Sprite defaultSprite;
public RectTransform textRectTransform;
       private Coroutine _loadImageCoroutine;

       public void SetData(Data data,bool calculateLayout )
       {
           _loadImageCoroutine = StartCoroutine(LoadRemoteImage(data));
   if (calculateLayout)
           {
               Canvas.ForceUpdateCanvases();
               Debug.Log("here");
               data.cellSize = textRectTransform.rect.height + textBuffer.top + textBuffer.bottom;
           }
}
       public IEnumerator LoadRemoteImage(Data data)
       
           string path = data.imageUrl;

           Texture2D texture = null;


#if UNITY_2020_1_OR_NEWER
           var webRequest = UnityWebRequestTexture.GetTexture(path);
           yield return webRequest.SendWebRequest();
           if (webRequest.result != UnityWebRequest.Result.Success)
           {
               Debug.LogError("Failed to download image [" + path + "]: " + webRequest.error);
           }
           else
           {
               texture = ((DownloadHandlerTexture)webRequest.downloadHandler).texture;
           }
#endif

           if (texture != null)
           {
               cellImage.sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), Vector2.zero);
           }
           else
           {
               ClearImage();
           }
       }

       public void ClearImage()
       {
           cellImage.sprite = defaultSprite;
       }

       public void WillRecycle()
       {
           if (_loadImageCoroutine != null)
           {
               StopCoroutine(_loadImageCoroutine);
           }
       }
   }
}


I tried to calculate Layout in setting cellImage.sprite in IEnumerator LoadRemoteImage, but that doesnt work as well. I am quite new to C# scripting, and I know it would be something really stupid that I am missing, can anyone help me with this. Thanks

[echo17]

So a little background:

In order for the plugin to virtualize cells (keep only the cells that are visible in memory) it has to first calculate all the cell positions in the scroller. In order to do that, it needs to know the size of each cell. In the view driven demo, the scroller is loading in all the cells, calculating their size based on the view, then setting that size in the data structure so that it can then use that in the second call to ReloadData. So two calls are happening, one to get the cell size, then one to virtualize the list based on those cell sizes.

In the remote resources demo, the cells are being streamed in as needed. So the cell sizes won't be known if they each have a different size. The remote resources demo needs to have a fixed size for each cell. Otherwise you are going to have to load every remote resource, get the sizes, then call ReloadData again to virtualize (like in the view driven demo). That's counter to the purpose of the remote cell demo since it is focused on streaming.

What I would recommend is storing the cell sizes of your resources somewhere else. Load that in first, setting the cell size in your data in the controller. Then you can use those sizes in the GetCellSize method of the controller. In other words, don't try to do a view-driven remote resource combination since the two are pretty much mutually exclusive.

[sniper199999]

Thank you, got it working. Although high resolution images makes the app (On Mobile environment) very slow, as they keep loading when I scroll down (I know its not related to your asset). But do you have any suggestions to get smooth 60fps scroll with High Resolution images in the scroller?

[echo17]

I don't have any experience with improving remote resource streaming, unfortunately. This is outside the scope of the plugin.

However, here is a link to a FAQ that may help with scrolling smoothness: link