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Question Continues Horizontal Scroll

Discussion in 'Immediate Mode GUI (IMGUI)' started by Artpen, Mar 1, 2022.

  1. Artpen

    Artpen

    Joined:
    Jan 24, 2015
    Posts:
    291
    Hey guys,

    I am working on a simple continuous horizontal scroll. I know there are a couple of assets available, but I want something simple.

    My approach:
    I have a list of buttons that I instantiate at Start to a content holder. (Typical)
    I use
    Code (CSharp):
    1. scrollRect.onValueChanged.AddListener(UpdatedButtonsPosition);
    to detect the scroll.
    If I am scrolling to the right I just move buttons back in the list and in inspector using
    Code (CSharp):
    1. newButton.transform.SetSiblingIndex(siblingIndex);
    So now where I have a problem. For the above to work I have to also shift the actual content holder.
    But while dragging it will not allow it. As soon as I let go of the mouse it works perfectly.

    Here is a code and a video with a problem.
    Help will be much appreciated.

    LoopScroll.gif

    Code (CSharp):
    1. using System.Collections;
    2. using System.Collections.Generic;
    3. using UnityEngine;
    4. using UnityEngine.EventSystems;
    5. using UnityEngine.UI;
    6.  
    7. public class ScrollSnap : MonoBehaviour
    8. {
    9.     [SerializeField] private List<StreetData> streetsData = new List<StreetData>();
    10.     private List<GameObject> buttons = new List<GameObject>();
    11.     [SerializeField] private GameObject buttonPrefab;
    12.     [SerializeField] private GameObject contentPanel;
    13.     private ScrollRect scrollRect;
    14.     private float startScrollPosition;
    15.  
    16.     // Start is called before the first frame update
    17.     void Start()
    18.     {
    19.         // Access ScrollRect
    20.         scrollRect = this.GetComponent<ScrollRect>();
    21.         scrollRect.onValueChanged.AddListener(UpdatedButtonsPosition);
    22.         startScrollPosition = scrollRect.horizontalNormalizedPosition;
    23.  
    24.         // Instantiate buttons in content parent game object
    25.         AddButtons();
    26.     }
    27.  
    28.     // Instantiate buttons
    29.     private void AddButtons()
    30.     {
    31.         int siblingIndex = 0;
    32.  
    33.         foreach (var streetData in streetsData)
    34.         {
    35.             GameObject newButton = Instantiate(buttonPrefab);
    36.             newButton.GetComponent<Image>().color = streetData.Color;
    37.             newButton.name = streetData.StreetName;
    38.             newButton.transform.SetParent(contentPanel.transform);
    39.             newButton.GetComponent<RectTransform>().localScale = new Vector3(1, 1, 1);
    40.             newButton.transform.SetSiblingIndex(siblingIndex);
    41.             siblingIndex++;
    42.             buttons.Add(newButton);
    43.         }
    44.     }
    45.  
    46.     // Check scroll direction
    47.     private bool IsScrollingRight(Vector2 value)
    48.     {
    49.         if (value.x < startScrollPosition)
    50.         {
    51.             //Debug.Log("You are scrolling right");
    52.             startScrollPosition = value.x;
    53.             return true;
    54.         }
    55.         else
    56.         {
    57.             //Debug.Log("You are scrolling left");
    58.             startScrollPosition = value.x;
    59.             return false;
    60.         }
    61.     }
    62.  
    63.     // Updated buttons position if outside the mask boundaries
    64.     private void UpdatedButtonsPosition(Vector2 scrollValue)
    65.     {
    66.         // 1. Check which direction is scrolling
    67.         // 2. Check if button moved beyond threshold
    68.         // 3. Move button to the begining of the content list
    69.        
    70.         if (IsScrollingRight(scrollValue))
    71.         {
    72.             //Debug.Log(buttons[buttons.Count - 1].transform.position.x);
    73.            
    74.             if (buttons[buttons.Count - 1].transform.position.x > 1750)
    75.             {
    76.                 buttons[buttons.Count - 1].transform.SetAsFirstSibling();
    77.                 GameObject button = buttons[buttons.Count - 1];
    78.                 buttons.RemoveAt(buttons.Count - 1);
    79.                 buttons.Insert(0, button);
    80.                 contentPanel.GetComponent<RectTransform>().anchoredPosition -= new Vector2 (110, 0);
    81.                 //scrollRect.horizontalNormalizedPosition = 0.5f;
    82.             }
    83.         }
    84.         else
    85.         {
    86.             //Debug.Log(buttons[0].transform.position.x);
    87.  
    88.             if (buttons[0].transform.position.x < 1100)
    89.             {
    90.                 buttons[0].transform.SetAsFirstSibling();
    91.                 GameObject button = buttons[0];
    92.                 buttons.RemoveAt(0);
    93.                 buttons.Insert(buttons.Count - 1, button);
    94.                 contentPanel.GetComponent<RectTransform>().anchoredPosition += new Vector2(110, 0);
    95.                 //scrollRect.horizontalNormalizedPosition = 0.5f;
    96.             }
    97.         }
    98.  
    99.     }
    100.  
    101.  
    102. }
    103.