Loop Scroll Rect

v1.03

compatible with Unity 5.2/5.3

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。

License: WTFPL Are You Serious? Yes.

Demo

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

Also ScrollBar is supported now! It supports both vertical & horizontal directions, back and forth.

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

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
Supports ScrollBar (this doesn't work in Infinite mode, and may behavior strange for cells with different size)

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

Warning: My scripts copies the ScrollRect from UGUI source code, 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 little easier.

Infinite Version

If you need scroll infinitely, you can simply set totalCount to a negative number.

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.

Prepare cell prefabs
- The cell needs Layout Element attached and preferred width/height
- You should add a script receiving message void ScrollCellIndex (int idx)

Right click in Hierarchy and click UI/Loop Horizontal Scroll Rect or UI/Loop Vertical Scroll Rect. It is the same for these two in the Component Menu.
- Init in Start: call Refill cells automatically when Start
- Prefab Pool: the EasyObjPool gameObject
- Prefab Pool Name: the corresponding pool in step 1
- 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
- Clear Cells: remove existing cells and keep uninitialized
- Refill Cells: initialize and fill up cells

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).

I highly suggests you trying these parameters by hand. More details can be found in the demo scene.