UIScrollView 滑動復位

需求

在每次打開界面滑動列表都是復位狀態（未滑動）。

分析

在制作滑動列表時常常會結合UIPanel和UIScrollView

要讓滑動列表回到未滑動時的位置，那么就需要改變Panel的Clipping和transform的position

演示

 

以前做法

以前是保存Panel的初始信息，每時打開面板時再還原

public class CUIShopVIP : CUIController
{
    private UIPanel GridPanel;
    private UIScrollView GridPanel_ScrollView;
    private float BakGridPanel_Y;
    private Vector4 BakGridPanel_ClipRegion;

    public override void OnInit()
    {
        base.OnInit();
        //...... 初始化代碼

        GridPanel = GetControl<UIPanel>("GridPanel");
        GridPanel_ScrollView = GridPanel.GetComponent<UIScrollView>();

        BakGridPanel_Y = GridPanel.transform.GetLocalPositionY();
        BakGridPanel_ClipRegion = GridPanel.baseClipRegion;
    } 
    
    public override void OnOpen(params object[] args)
    {
        base.OnOpen(args);

        //打開前 重設Scrollview的屬性到初始

        GridPanel.baseClipRegion = BakGridPanel_ClipRegion;//NOTE 不建議直接修改此值
        GridPanel_ScrollView.UpdatePosition();
        GridPanel_ScrollView.ResetPosition();
        GridPanel.transform.SetLocalPositionY(BakGridPanel_Y);   
    }
}

之前的做法是 修改 Panel的 localPosition 和 Panel的 baseClipRegion，但官方不建議直接修改baseClipRegion。然后更新ScrollView的信息

/// <summary>
/// Clipping position (XY) and size (ZW).
/// Note that you should not be modifying this property at run-time to reposition the clipping. Adjust clipOffset instead.
/// </summary>

public Vector4 baseClipRegion

 

編寫組件

現在做了一個PanelResetHelper，修改Panel的 clipOffset和 localPosition 而不直接修改baseClipRegion

/// <summary>
/// Clipping area offset used to make it possible to move clipped panels (scroll views) efficiently.
/// Scroll views move by adjusting the clip offset by one value, and the transform position by the inverse.
/// This makes it possible to not have to rebuild the geometry, greatly improving performance.
/// </summary>

public Vector2 clipOffset

原理

和之前做法一樣，初始化時保存Panel的屬性，界面打開時，再還原值。

組件源碼

Helper代碼如下

/// <summary>
/// 可以對UIPanel進行滾動復位
/// </summary>
public class CUIPanelResetHelper
{
    private UIPanel _panel;
    private Vector2 _initPanelClipOffset;
    private Vector3 _initPanelLocalPos;

    public CUIPanelResetHelper(UIPanel uiPanel)
    {
        _panel = uiPanel;
        _initPanelClipOffset = _panel.clipOffset;
        _initPanelLocalPos = _panel.cachedTransform.localPosition;
    }

    public void ResetScroll()
    {
        _panel.clipOffset = _initPanelClipOffset;
        _panel.cachedTransform.localPosition = _initPanelLocalPos;
    }
}

組件用法

public class CUIShopVIP : CUIController
{
    private UIPanel GridPanel;
    private CUIPanelResetHelper GridPanelResetHelper;

    public override void OnInit()
    {
        base.OnInit();
        //...... 初始化代碼
        GridPanel = GetControl<UIPanel>("GridPanel");
        GridPanelResetHelper = new CUIPanelResetHelper(GridPanel);
    }

    public override void OnOpen(params object[] args)
    {
        base.OnOpen(args);
        
        //打開前 重設Scrollview的屬性到初始
        GridPanelResetHelper.ResetScroll();
    }
}

UIScrollView

uiscrollview中的屬性

/// <summary>
/// Whether the dragging will be restricted to be within the scroll view's bounds.
/// </summary>
public bool restrictWithinPanel = true;

/// <summary>
/// Whether dragging will be disabled if the contents fit.
/// </summary>
public bool disableDragIfFits = false;