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softlion / WheelPicker-Samples

WheelPicker control samples for .NET8 / Maui
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wheel wheel-picker xamarin xamarin-android xamarin-forms xamarin-ios

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Maui (net8), Xamarin Forms, Native (xamarin & .net8) - iOS + Android
NuGet Nuget

Wheel Picker

Definition from Apple 🍏 :
A Wheel Picker is a view that uses a spinning-wheel or slot-machine metaphor to display one or more sets of values.

This interactive UI control mimics a slot machine user interface on Android, while on iOS, it makes it easy to use multi-wheel pickers.

Enterprise support available: contact sales
Source code available: contact sales

UI controls

Video presentations

Preview Preview

Quick start

Install the nuget package

dotnet add package Vapolia.WheelPicker

MAUI Specific

If using Maui, register the control in the CreateMauiApp() function:

...
using Vapolia.WheelPickers;

...
builder
    .UseMauiApp<App>()
    .UseWheelPicker();

Add a WheelPicker to your xaml UI

<wp:WheelPicker ItemsSourceSimple="{Binding MyListProperty}">
    <wp:WheelDefinition Width="Auto" HorizontalOptions="Left" Alignment="Center" />
</wp:WheelPicker>

Anatomy of the control

The WheelPicker is made of 2 parts:

The WheelPicker is bound to a single data source through ItemsSource="{Binding SomeProperty}".
The type of SomeProperty can be:

Full example

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
                xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
                xmlns:wp="clr-namespace:Vapolia.WheelPickers;assembly=Vapolia.WheelPicker"
                x:Class="WheelPickerDemo.Forms.MainPage">
    <VerticalStackLayout>

        <wp:WheelPicker HorizontalOptions="Fill" SelectedItemsIndex="0"
                        ItemsSource="{Binding Days}" 
                        Command="{Binding ItemSelectedCommand}">
            <wp:WheelDefinition Width="Auto" HorizontalOptions="Left" Alignment="Center" />
        </wp:WheelPicker>

    </VerticalStackLayout>
</ContentPage>

In the code behind, set the binding context to your view model containing the items to display.
For the example below ItemsSource is bound to a list of strings.

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
        BindingContext = new MainPageModel();
    }
}

public class MainPageModel
{
    public List<string> Days { get; } = new () { "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday" };

    public Command ItemSelectedCommand { get; }

    public MainPageModel() 
    {
        //Component is the index of the wheel triggering the command. 
        //Row is the index of the currently displayed item at the center of the wheel for this Component.
        //ItemIndexes are the current indexes of all wheels of the WheelPicker control
        ItemSelectedCommand = new Command<(int Component, int Row, IList<int> ItemIndexes)>(tuple =>
        {
            var selectedValue = Days[tuple.Row];
            //...
        });
    }
}

Using custom templates

You can customize how each item is rendered by using custom templates.
By default, the control converts all items to strings and renders those strings with the specified style.

You can fully customize the style and content of the items. However, there is a constraint: there is only one template per wheel, which renders all items of that wheel. If you have multiple wheels in the same WheelPicker, you can set one template per wheel.

For example, below is a templated picker with 3 wheels. All properties are bindable and can be dynamically changed.

Note how SelectedItemsIndex is used to initialize the position of the 3 wheels to the specified item indexes.

<wp:WheelPicker x:Name="SlotPicker" ItemsSource="{Binding Slot.ItemsSource}" 
                SelectedItemsIndex="1 10 7"
                Command="{Binding Slot.ItemSelectedCommand}" 
                ItemTextSelectedColor="Lime"
                ItemTextFont="Italic"
                HorizontalOptions="Fill"
                SelectionLinesColor="Aquamarine">
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True">
        <DataTemplate>
            <Label Text="{Binding .}" TextColor="Black" FontSize="30" />
        </DataTemplate>
    </wp:WheelDefinition>
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="100">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="100" Aspect="AspectFit" />
        </DataTemplate>
    </wp:WheelDefinition>
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="100">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="100" Aspect="AspectFit" />
        </DataTemplate>
    </wp:WheelDefinition>
</wp:WheelPicker>

Some examples

Those examples are extracted from the demo projects in this repository.

A simple picker with one wheel:

<wp:WheelPicker ItemsSource="{Binding DayPicker.ItemsSource}">
    <wp:WheelDefinition Width="Auto" HorizontalOptions="Left" Alignment="Center" />
</wp:WheelPicker>

A templated picker with one wheel:

<wp:WheelPicker ItemsSource="{Binding DayPicker.ItemsSource}">
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="48">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="48" Aspect="AspectFill" />
        </DataTemplate>
    </wp:WheelDefinition>
</wp:WheelPicker>

A picker with 3 wheels:
The width of the center wheel is computed automatically, and items are aligned differently inside each wheel.

<wp:WheelPicker SelectionLinesColor="Navy" 
                HorizontalSpaceBetweenWheels="40" 
                ItemsSource="{Binding DatePicker.ItemsSource}"  
                SelectedItemsIndex="0,0,0" 
                Command="{Binding DatePicker.ItemSelectedCommand}"
                HorizontalOptions="Fill">
    <wp:WheelDefinition Width="*" HorizontalOptions="Right" />
    <wp:WheelDefinition Width="Auto" HorizontalOptions="Left"  />
    <wp:WheelDefinition Width="*" HorizontalOptions="Left"  />
</wp:WheelPicker>

A templated picker with 3 wheels:
All properties are bindable and can be dynamically changed.

<wp:WheelPicker x:Name="SlotPicker" ItemsSource="{Binding Slot.ItemsSource}" 
                SelectedItemsIndex="0 0 0"
                Command="{Binding Slot.ItemSelectedCommand}" 
                ItemTextSelectedColor="Lime"
                ItemTextFont="Italic"
                HorizontalOptions="Fill"
                SelectionLinesColor="Aquamarine">
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="100">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="100" Aspect="AspectFit" />
        </DataTemplate>
    </wp:WheelDefinition>
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="100">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="100" Aspect="AspectFit" />
        </DataTemplate>
    </wp:WheelDefinition>
    <wp:WheelDefinition Width="*" HorizontalOptions="Left" Alignment="Center" IsCircular="True" RowHeight="100">
        <DataTemplate>
            <Image Source="{Binding .}" HeightRequest="100" Aspect="AspectFit" />
        </DataTemplate>
    </wp:WheelDefinition>
</wp:WheelPicker>

Reference (Maui & Xamarin Forms)

Click to expand **WheelPicker** Definition - `IList` **`WheelDefinitions`** Default Content - `object` **`ItemsSource`** Accepts both `IReadOnlyCollection` and `IReadOnlyCollection>` Appearance - `double` **`HorizontalSpaceBetweenWheels`** - `Color` **`SelectionLinesColor`** Item appearance (used by the default item template, when no custom item template is specified) - `Font` **`ItemTextFont`** - `Color` **`ItemTextColor`** - `Color` **`ItemTextSelectedColor`** Selection - `IList` **`SelectedItemsIndex`** One index per wheel. - `ICommand` **`Command`** Triggered when any of the wheel's index has changed - `EventHandler` **`SelectedItemIndexChanged`** Triggered when any of the wheel's index has changed - `void` **`Spin`**`(int items, int wheelIndex = 0)` items: the number of item to spin `SelectedItemsIndex` is a list of integers, where each integer represents the selected index within a wheel. In XAML, you can use a space- or comma-separated string of integers. **WheelDefinition** - `GridLength` **`Width`** - `WheelItemAlign` **`HorizontalOptions`** - `WheelItemAlign` **`Alignment`** - `bool` **`IsCircular`** - `DataTemplate` **`ImageItemTemplate`** - `double` **`RowHeight`** When a wheel's `Width` is set to `Auto`, the control computes the max width of all strings in the data source (if object are strings). When set to `*` (star), the width of the wheel will be proportional to the remaining space. See the `Grid` control for more information about `GridLength`. `HorizontalOptions` is used to align a wheel inside the available width of the WheelPicker, if it is larger than the width of the wheel. `Alignment` is used to align the items within a wheel.

Reference (net8-android & Xamarin.Android)

Click to expand Sample usage in axml: ```xml ``` ```csharp var wheelView = FindViewById(Resource.Id.wheelView); wheelView.SelectedItemIndexChanged += (sender, args) => { var text = $"Wheel {args.WheelIndex} selection changed to item index {args.SelectedItemIndex}"; }; wheelView.ItemsSource = new List { "Monday", "Tuesday", "Wednesday" }; wheelView.SelectedItemsIndex = new [] { 0 }; ``` **vapolia.WheelPicker** Definition - object ItemsSource (either IReadOnlyCollection<T> or IReadOnlyCollection<IReadOnlyCollection<T>>) - IReadOnlyCollection<T> ItemsSourceSimple (shortcut for ItemsSourceMulti with one wheel) - IReadOnlyCollection<IReadOnlyCollection<T>> ItemsSourceMulti - int VisibleItemCount WheelPicker Appearance - float HorizontalSpaceBetweenWheels - float VerticalSpaceBetweenItems - float ItemTextSize - Typeface ItemTextTypeface - Color ItemTextColor - Color ItemTextSelectedColor - bool ShowSelectionLines - float SelectionLinesThickness - Color SelectionLinesColor - bool HasFadingItems - bool IsCurved Appearance of a wheel (a picker can have multiple wheels) - string ItemWidths (width of each wheel, see ItemWidths chapter below) - IList<GravityFlags> Gravities - GravityFlags Gravity (shortcut for Gravities[0], used only when ItemWidths is set) - IList ItemHeights Appearance of items inside a wheel - IList Alignments (same as gravities. Uses WheelItemAlign instead of GravityFlags) - WheelItemAlign ItemAlign (shortcut for ItemAligns[0]) - IList ItemAligns Selection - ICommand SelectedItemIndexChangedCommand - EventHandler<WheelChangedEventArgs> SelectedItemIndexChanged - int SelectedItemIndex (shortcut for SelectedItemsIndex[0]) - IList<int> SelectedItemsIndex Templating - ItemsSimpleTemplates (currently reserved, used by the renderer) `SelectedItemsIndex` is a list of integers. Each integer represents the selected index within a wheel. `ItemWidths`: see chapter below `Alignments` or `Gravities` is used to align a wheel inside the available WheelPicker's width, if it is larger than the width of the wheel. `ItemAligns` is used to align the items within a wheel.

Reference (net8-ios & Xamarin.iOS)

Click to expand On iOS, this library utilizes the native UIPickerView along with a custom UIPickerViewModel to significantly simplify the use of this control. Sample usage: ```csharp var picker = new UIPickerView {ShowSelectionIndicator = true, BackgroundColor = UIColor.White}; var pickerViewModel = new WheelPickerModel(picker); picker.Model = pickerViewModel; pickerViewModel.ItemsSource = new [] { "Monday", "Tuesday", "Wednesday" }; pickerViewModel.SelectedItemsIndex = new [] { 0 }; pickerViewModel.ItemAligns = new List { WheelItemAlign.Left }; ``` **Vapolia.WheelPickerIos.WheelPickerModel** Definition - object ItemsSource (either IReadOnlyCollection<T> or IReadOnlyCollection<IReadOnlyCollection<T>>) - IReadOnlyCollection<T> ItemsSourceSimple (shortcut for ItemsSourceMulti with one wheel) - IReadOnlyCollection<IReadOnlyCollection<T>> ItemsSourceMulti Appearance - nfloat HorizontalSpaceBetweenWheels Item appearance - string ItemWidths - UIFont ItemFont - UIColor ItemTextColor - IList Alignments - IList ItemAligns Selection - ICommand SelectedItemIndexChangedCommand - int SelectedItemIndex (shortcut for SelectedItemsIndex[0]) - IEnumerable SelectedItemsIndex Templating - ItemsSimpleTemplates (currently reserved, used by the renderer) `SelectedItemsIndex` is a list of integer. Each integer represents the selected index inside a wheel. `ItemWidths`: see chapter below `Alignments` is used to align a wheel inside the available WheelPicker's width, if it is larger than the wheel's width. `ItemAligns` is used to align the items inside a wheel.

ItemWidths (net8-android and net8-ios only, excluding Maui & Xamarn Forms)

Click to expand `ItemWidths` is used to choose the width of each wheel. It is a space separated string consisting of a combination of float numbers, stars (optionally prepended with a float number), or the "Auto" string. The total width of the WheelPicker is distributed between the wheels by respecting either : - float number: the exact width - Auto: the width of the largest string in ItemsSource for a given wheel (if ItemsSource contains strings) - star: the remaining space not assigned by the above rules, distributed among the other wheels using the optional float number as a weight Examples of ItemWidths: - `"*"`: one wheel having the full width of WheelPicker - `"* *"`: two wheels, each of the same width, exactly half of the width of the Wheel Picker - `"* * *"`: three wheels, each of the same width, exactly one third of the width of the Wheel Picker - `"100 2* *"`: three wheels, first has a `100` device pixel width, second is twice the size of the third, and `3*-100=width` of the WheelPicker, which resolves to `*=WheelPickerWidth-100` - `"* Auto *"`: three wheels, the middle wheel's width is computed from the largest string in its items source (if items source contains strings).

Supported Platforms

Mvvm friendly

The Wheel Picker provides an event and a Command when the selection changes, making it easy to use with or without mvvm frameworks.
It also implements INotifyPropertyChanged.

Live Preview

This control supports hot reload and live preview.

Commercial Support

Enterprise support is available: contact sales
Source code is available: contact sales