koobas.hobune.stream
Scrollbar value of 0 resets to 1
Hello, sorry if I missed a question related to this. If there is one out there please point me to it.
I have a scrollbar behaving oddly. I wrote a script to change the scrollbar value of a dropdown list to match the currently selected object when the user expands a dropdown so that the selected item is visible. I do this by finding index of the active element(of the active children) and dividing this by the total number of active children associated with the dropdown to come up with a 0-1 number to position the scroll bar.
The following script behaves as expected when the selected value is anything besides the highest index (ex: activeChild = 12 and activeChildren = 24). However, when the current selection is the last option (ex activeChild = 24 and activeChildren = 24) the scrollbar sets it's value to 1.
private IEnumerator SetScrollbarValue() {
int activeChildren = 0;
int activeChild = 0;
//Get all active child objects in dropdown list
for (int i = 0; i < transform.childCount - 1; i++) {
if (transform.GetChild(i).gameObject.activeInHierarchy) {
activeChildren++;
}
}
//get the index of the currently selected child
for (int i = 0; i < transform.childCount - 1; i++) {
if (transform.GetChild(i).gameObject.activeInHierarchy) {
if (!transform.GetChild(i).GetComponent<Toggle>().isOn) {
activeChild++;
} else {
break;
}
}
}
//get the scrollbar
Scrollbar scrollbar = transform.GetComponentInParent<ScrollRect>().verticalScrollbar;
//set the value of the scrollbar for BottomToTop direction
if (scrollbar.direction == Scrollbar.Direction.BottomToTop) {
float value = (1.0f - ((float)activeChild / (float)activeChildren)); //Case where activeChild = 0 and activeChildren = 0
scrollbar.value = value;
yield return new WaitForEndOfFrame();
Debug.Log("value = " + value); //logs 0
Debug.Log("Scrollbar value = " + scrollbar.value); //logs 1
}
}
Now, when I manually check for 0 and force the value to be near 0 it keeps the number and acts as expected (I guess). Note the change directly after 'value' is created
private IEnumerator SetScrollbarValue() {
int activeChildren = 0;
int activeChild = 0;
//Get all active child objects in dropdown list
for (int i = 0; i < transform.childCount - 1; i++) {
if (transform.GetChild(i).gameObject.activeInHierarchy) {
activeChildren++;
}
}
//get the index of the currently selected child
for (int i = 0; i < transform.childCount - 1; i++) {
if (transform.GetChild(i).gameObject.activeInHierarchy) {
if (!transform.GetChild(i).GetComponent<Toggle>().isOn) {
activeChild++;
} else {
break;
}
}
}
//get the scrollbar
Scrollbar scrollbar = transform.GetComponentInParent<ScrollRect>().verticalScrollbar;
//set the value of the scrollbar for BottomToTop direction
if (scrollbar.direction == Scrollbar.Direction.BottomToTop) {
float value = (1.0f - ((float)activeChild / (float)activeChildren)); //Case where activeChild = 0 and activeChildren = 0
//Force 0 to be near 0
if (value == 0.0f) {
value = 0.0001f;
}
scrollbar.value = value;
yield return new WaitForEndOfFrame();
Debug.Log("value = " + value); //logs 0.0001
Debug.Log("Scrollbar value = " + scrollbar.value); //logs 9.994933E-05
}
}
Any info as to why this may be happening or what I am overlooking would be great. I know this script is severely limited at the moment. But I would like to expand on it to make a fun little utility to help with my use of dropdown menus in Unity.
Thank you,
Scrollbars really aren't meant to be positioned arbitrarily through their value property. You'll want to instead position the content of the ScrollView. You'll have to calculate the relative position of the object you want to bring into view and then adjust the localPosition of the content RectTransform accordingly.
Hmm, I will look into this. I was using the scrollbar value because it seemed fairly simple and I had seen a few other solutions that revolved around this. Thank you, Ill look more into that.
