do we have any update on this? When i try this same method, it’s always inconsistent, and rarely goes and stays at the top. Sometimes it starts at the top, and self-propels itself to the middle, which is where it goes by default.
EDIT: Sorry - just noticed these posts are from today. I will wait a little longer
If someone would post a case number here of the reported bug then we’d know the issue had been reported. If nobody have reported it to our bug tracker, then no amount of waiting is going to help.
In case anyone is wondering, in 4.6b20, scrollRect.verticalNormalizedPosition = 0 (for bottom) and scrollRect.verticalNormalizedPosition = 1f for top does works correctly.
Funny thing is, when I put the code scrollRect.normalizedPosition = new Vector2(0.0F, 1.0F); into the OnValueChanged method then it immediately scrolls to the top. But it doesn’t scroll, until I do at least a minimal drag on the ScrollRect content. It totally ignores it if I manually try to set the value before dragging. Can someone confirm?
While things have improved with b21, there is still some weird behaviour. I get the feeling that the ScrollRect component, or other UI components, are modifying the scroll position in Start and/or OnEnable. So, if we try to alter the scroll position in either of these methods, the changes we make may be overwritten.
In the end, I used a coroutine to change the scroll position on the next frame to avoid conflicting with other OnEnable/Start methods.
Example:
using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class RepositionScrollRectOnEnable : MonoBehaviour {
private ScrollRect scrollRect;
private bool ready = false;
void Awake() {
scrollRect = GetComponent<ScrollRect>();
if (scrollRect == null) {
Debug.LogError("GameObject does not have a ScrollRect component. GameObject name: " + gameObject.name + " tag: " + gameObject.tag);
Destroy(this);
}
}
void OnEnable() {
// if we try to access scrollRect before Start, errors are thrown (scrollRect hasn't initialised yet?)
if (ready) {
StartCoroutine(ResetToTop());
}
}
void Start() {
ready = true;
}
IEnumerator ResetToTop() {
yield return null;
scrollRect.normalizedPosition = Vector2.one;
}
}
You want to save the current ScrollPosition via the OnValueChanged() method into PlayerPrefs?
Well you can save it, but the ScrollRect somehow “overwrites” the values on startup like this:
from 0.0F to 0.49999F => reloads with 0.0F
from 0.5F to 1.0F => reloads with 1.0F
Edit: above error is also avoided if you save the ScrollPosition 1 frame after generating the buttons.
It’s because there are issues with OnValueChanged being called more than necessary. The bug has been filed. Also with the above problem with scrolling, indeed “on the next frame” is the only way I’ve found of getting around it – same goes for Scrollbars as well.
Thanks for the example, I was looking for something that would run once without any additional ongoing overhead - looks like that’s what you’ve achieved here.
I was also having an issue with getting my Scroll Rect to scroll to the bottom immediately after appending text to the Text content inside; setting the verticalNormalizedPosition to 0f seemed to scroll the Text mostly to the bottom, but never quite all the way. The coroutine trick worked like a charm. Many thanks!
