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https://github.com/MPowerKit/VirtualizeListView

.NET MAUI ListView renderers. Improves performance for MAUI ListView, adds additional behaviors
https://github.com/MPowerKit/VirtualizeListView

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.NET MAUI ListView renderers. Improves performance for MAUI ListView, adds additional behaviors

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# MPowerKit.VirtualizeListView



#### MAUI Virtualize ListView with smooth scrolling and without platform-specific code



[![Nuget](https://img.shields.io/nuget/v/MPowerKit.VirtualizeListView)](https://www.nuget.org/packages/MPowerKit.VirtualizeListView)



It's not a secret to anybody, that ```ListView``` and ```CollectionView``` in MAUI have bad scrolling performance. This project started as an experimantal project POC to find a way to make a virtualize listview using ```ScrollView``` and ```AbsoluteLayout``` only. Suprisingly, the scrolling performance is way better, than was expected. So you can check it right now.



**It works on all platforms MAUI supports and it has the same behavior on all platforms, because it does not have platform-specific code.**



So, under the hood it is a ```ScrollView``` with custom ```typeof(Layout)``` as items layout. The main idea of virtualization for this listview is to change Translation (virtual position, but on Android it is still physical chage because of [#5](https://github.com/MPowerKit/VirtualizeListView/issues/5)) of items while keeping them attached to the layout. ```VirtualizeItemsLayoutManger``` is responsible for virtualization process and for creating / removing views and it will not create more views as necessary.



**Your PRs are welcome!**



| Android | Windows |

|-|-|

|  |  |



### Implemented features:



- [x] Linear items layout

- [ ] Grid items layout

- [x] Items spacing

- [x] Virtualization

- [x] Grouping

- [x] Collection padding

- [x] Scroll orientation (collection orientation)

- [x] Disable scrolling

- [x] Header / Footer

- [x] Load more

- [x] Scroll speed

- [x] Cache pool

- [x] Item tap handling

- [x] Item resize handling

- [x] Add, Remove, Replace, Move, Reset operations on collection

- [ ] Drag and drop (reordering)

- [ ] Sticky headers

- [ ] Animated add/remove/move operations



# Tips for better scrolling user experience



- Bindings - your enemy. Try to avoid bindings in your item templates or do ```OneTime``` where you can. But if you need them, use only compiled bindings or better [levitali/CompiledBindings](https://github.com/levitali/CompiledBindings) library.

- Try to avoid using triggers, they are slow.

- Use as less templates as possible. The more templates you have, the more time it takes to create a view.

- Use ```InitialCachePoolSize``` to set up the number of initial views to keep in cache. Default size is 4. The bigger value - the more cached views it creates during initialization. And if you have a lot of templates it can take some time to initialize pool for each template. So in this case just manipulate with the ```InitialCachePoolSize```. If you have only 1 template, you can set it to 2, it will be enough.

- Create separate view for ```DataTemplate``` and replace bindings where you can by manual setting the values from the code behind of that view.

- Use as less layouts as possible. Use only ```ContentView```, ```Grid```, ```VerticalStackLayout``` or ```HorizontalStackLayout```. Try to avoid using ```Border``` or ```Frame```, better create ```RoundBorderEffect```.

- Try to avoid using ```Shadow``` property in your templates. It can slow down the rendering process.

- Set the direct dimensions for your controls where you can in the template, especially for ```Image```.

- If you have very complex layout and the ```VirtualizeListView``` still not smooth and laggy, you can try to decrease ```ScrollSpeed```, it may help in some cases. (MAUI does a lot of redundant work remeasuring and relayouting views few times).



### Usage



Add ```UseMPowerKitListView()``` to your ```MauiProgram.cs``` file as next



```csharp

builder

    .UseMauiApp()

    .UseMPowerKitListView();

```



and in your xaml just use as a regular ```CollectionView```.



**Note: The root of the ItemTemplate has to be ```typeof(VirtualizeListViewCell)```, but group/header/footer templates are not allowed to have root of this type.**



To change items spacing you need to reset the ```ItemsLayout``` property as next:



```xaml



	

		 

	



```



By default it has zero spacing.



To change collection orientation just change the ```Orientation``` property of the ```VirtualizeListView``` as  you would do this in ```ScrollView```.



To disable scroll set ```CanScroll``` property to ```false```, and do not change ```Orientation``` property to ```Neither```.



## Other useful features



#### ```FixedRefreshView```



This package brings to you fixed MAUI's RefreshView as ```FixedRefreshView```. Here, you can disable refreshing without disabling entire collection. For this you may use ```IsPullToRefreshEnabled```.



#### ```ObservableRangeCollection```



Also, this package contains ```ObservableRangeCollection``` which is an ```ObservableCollection```, but it has a bunch of useful methods to manipulate the collection with batch updates. Recommended to use with ```VirtualizeListView```. It provides few methods: ```AddRange```, ```InsertRange```, ```RemoveRange```, ```ReplaceRange```.



## Known issues



- In debug mode it can have bad scrolling performance, especially on Windows, but in release mode it works surprisingly very well.