92 lines
4.3 KiB
Markdown
92 lines
4.3 KiB
Markdown
# Loop Scroll Rect
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[](https://openupm.com/packages/me.qiankanglai.loopscrollrect/)
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[](https://opensource.org/licenses/MIT)
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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.
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中文说明请看[这里](http://qiankanglai.me/2015/08/15/LoopScrollRect/)。
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## Installation
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Open Package Manager and Add package from git URL `https://github.com/qiankanglai/LoopScrollRect.git`.
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With [OpenUPM](https://openupm.com/), just one command `openupm add me.qiankanglai.loopscrollrect`.
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With older Unity version, just clone the repo and put into `Assets/`.
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## Demo
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Demo for Loop Scroll Rect. Each cell knows its own index, and it is able to modify its content/size/color easily.
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Also ScrollBar is supported now! It supports both vertical & horizontal directions, back and forth.
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Demo without mask. As you can see, the cells are only instantiated when needed and recycled.
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**New**: Scroll to Index
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## Introduction
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The original idea comes from @ivomarel's [InfinityScroll](https://github.com/ivomarel/InfinityScroll). After serveral refactorisations, I almost rewrite all the codes:
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- Avoid using `sizeDelta` directly since it doesn't always mean size
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- Support GridLayout
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- Avoid blocking when dragging back
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- Take advantage of pool rather than instantiate/destroy every time
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- Improve some other details for performance
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- Supports reverse direction
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- **Supports ScrollBar** (this doesn't work in Infinite mode, and may behavior strange for cells with different size)
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My scripts copies `ScrollRect` from [UGUI](https://bitbucket.org/Unity-Technologies/ui) rather than inherit `ScrollRect` like InfinityScroll. 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.
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## Example
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Please refer to `InitOnStart.cs` for quick example implmentation. It's high recommended for implmentating your own cache pool.
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### Infinite Version
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If you need scroll infinitely, you can simply set `totalCount` to a negative number.
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### Quick Jump
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I've implemented a simple version with `Coroutine`. You can use the following API:
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public void SrollToCell(int index, float speed)
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Here is a corner case unsolved yet: You can't jump to the last cells which cannot be pulled to the start.
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## Example: Loop Vertical Scroll Rect
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These steps may be confusing, so you can just open the demo scene and copy & paste :D
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You can also remove EasyObjPool and use your pool instead.
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- Prepare cell prefabs
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- The cell needs `Layout Element` attached and preferred width/height
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- You should add a script receiving message `void ScrollCellIndex (int idx) `
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- 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.
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- Init in Start: call Refill cells automatically when Start
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- Prefab Pool: the EasyObjPool gameObject
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- Prefab Pool Name: the corresponding pool in step 1
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- Total Count: How many cells are available (index: 0 ~ TotalCount-1)
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- Threshold: How many additional pixels of content should be prepared before start or after end?
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- ReverseDirection: If you want scroll from bottom or right, you should toggle this
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- Clear Cells: remove existing cells and keep uninitialized
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- Refill Cells: initialize and fill up cells
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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).
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I highly suggests you trying these parameters by hand. More details can be found in the demo scene.
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