65 lines
2.5 KiB
C#
65 lines
2.5 KiB
C#
using UnityEngine;
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using UnityEngine.UI;
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using UnityEngine.EventSystems;
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using System.Collections;
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public class DrumScroller : MonoBehaviour
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{
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RectTransform scrollRectTransform;
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RectTransform contentPanel;
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RectTransform selectedRectTransform;
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GameObject lastSelected;
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void Start()
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{
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scrollRectTransform = GetComponent<RectTransform>();
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contentPanel = GetComponent<ScrollRect>().content;
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}
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void Update()
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{
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// Get the currently selected UI element from the event system.
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GameObject selected = EventSystem.current.currentSelectedGameObject;
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// Return if there are none.
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if (selected == null)
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{
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return;
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}
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// Return if the selected game object is not inside the scroll rect.
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// Return if the selected game object is the same as it was last frame,
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// meaning we haven't moved.
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if (selected == lastSelected)
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{
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return;
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}
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// Get the rect tranform for the selected game object.
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selectedRectTransform = selected.GetComponent<RectTransform>();
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// The position of the selected UI element is the absolute anchor position,
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// ie. the local position within the scroll rect + its height if we're
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// scrolling down. If we're scrolling up it's just the absolute anchor position.
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float selectedPositionY = Mathf.Abs(selectedRectTransform.anchoredPosition.y) + selectedRectTransform.rect.height;
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// The upper bound of the scroll view is the anchor position of the content we're scrolling.
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float scrollViewMinY = contentPanel.anchoredPosition.y;
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// The lower bound is the anchor position + the height of the scroll rect.
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float scrollViewMaxY = contentPanel.anchoredPosition.y + scrollRectTransform.rect.height;
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// If the selected position is below the current lower bound of the scroll view we scroll down.
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if (selectedPositionY > scrollViewMaxY)
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{
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float newY = selectedPositionY - scrollRectTransform.rect.height;
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contentPanel.anchoredPosition = new Vector2(contentPanel.anchoredPosition.x, newY);
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}
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// If the selected position is above the current upper bound of the scroll view we scroll up.
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else if (Mathf.Abs(selectedRectTransform.anchoredPosition.y) < scrollViewMinY)
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{
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contentPanel.anchoredPosition = new Vector2(contentPanel.anchoredPosition.x, Mathf.Abs(selectedRectTransform.anchoredPosition.y));
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}
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lastSelected = selected;
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}
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}
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