Loop Scroll Rect

v1.01

These scripts help make your ScrollRect Reusable, because it will only build cells when needed. If you have a large number of cells in a scroll rect, you absolutely need it! It will save a lot of time loading and draw call, along with memory in use, while still working smoothly.

中文说明请看这里。

Demo

Demo for Loop Scroll Rect. Each cell knows its index, and it is able to modify its content/size/color easily.

Demo without mask. As you can see, the cells are only instantiated when needed and recycled.

Demo for reverse direction.

Introduction

The original idea comes from @ivomarel's InfinityScroll. After serveral refactorisations, I almost rewrite all the codes:

• Avoid using sizeDelta directly since it doesn't always mean size
• Support GridLayout
• Avoid blocking when dragging back
• Take advantage of pool rather than instantiate/destroy every time
• Improve some other details for performance
• Supports reverse direction

Also, I modified Easy Object Pool for recycling the cells.

Warning: My scripts copies the ScrollRect from UGUI 5.1 rather than inherit ScrollRect like InfinityScroll, because I need to modify some private variants to make dragging smooth. All my codes is wrapped with comments like ==========LoopScrollRect==========, making maintaining a litter easier.

Infinite Version

If you need scroll infinitely, you can simply delete codes about itemTypeStart, itemTypeEnd in my scripts. I've completed a simple infinite version, for which you can open by adding INFINITE into define symbols.

Example: Loop Vertical Scroll Rect

These steps may be confusing, so you can just open the demo scene and copy & paste :D

You can also remove EasyObjPool and use your pool instead.

1. Prepare cell prefabs
   • The cell needs Layout Element attached and preferred width/height
   • You should add a script receiving message void ScrollCellIndex (int idx)
2. Prepare EasyObjectPool with different cell prefabs
3. Attach LoopVerticalScrollRect and Mask to the ScrollRect gameObject. I highly suggests you trying modify these when playing.
   • Clear Cells: remove existing cells and keep uninitialized
   • Refill Cells: initialize and fill up cells
   • Init in Start: call Refill cells automatically when Start
   • Prefab Pool: the EasyObjPool gameObject
   • Prefab Pool Name: the corresponding pool in step 2
   • Total Count: How many cells are available (index: 0 ~ TotalCount-1)
   • Threshold: How many additional pixels of content should be prepared before start or after end?
   • ReverseDirection: If you want scroll from bottom or right, you should toggle this
4. Attach Content Size Filter and Vertical Layout Group to the Content gameObject. Pay attention to the pivot.

If you need scroll from top or left, setting content's pivot to 1 and disable ReverseDirection. Otherwise, you should set 0 to pivot and enable ReverseDirection (I have made VerticalScroll_Reverse in the demo scene as reference).