Angular Gauge

View model

using System.Collections.Generic;
using LiveChartsCore;
using CommunityToolkit.Mvvm.ComponentModel;
using LiveChartsCore.SkiaSharpView;
using LiveChartsCore.SkiaSharpView.Extensions;
using LiveChartsCore.VisualElements;
using LiveChartsCore.SkiaSharpView.Drawing;
using LiveChartsCore.SkiaSharpView.VisualElements;
using LiveChartsCore.Defaults;
using CommunityToolkit.Mvvm.Input;
using System;

namespace ViewModelsSamples.Pies.AngularGauge;

public partial class ViewModel : ObservableObject
{
    private readonly Random _random = new();

    public ViewModel()
    {
        var sectionsOuter = 130;
        var sectionsWidth = 20;

        Needle = new NeedleVisual
        {
            Value = 45
        };

        Series = GaugeGenerator.BuildAngularGaugeSections(
            new GaugeItem(60, s => SetStyle(sectionsOuter, sectionsWidth, s)),
            new GaugeItem(30, s => SetStyle(sectionsOuter, sectionsWidth, s)),
            new GaugeItem(10, s => SetStyle(sectionsOuter, sectionsWidth, s)));

        VisualElements = new VisualElement<SkiaSharpDrawingContext>[]
        {
            new AngularTicksVisual
            {
                LabelsSize = 16,
                LabelsOuterOffset = 15,
                OuterOffset = 65,
                TicksLength = 20
            },
            Needle
        };
    }

    public IEnumerable<ISeries> Series { get; set; }

    public IEnumerable<VisualElement<SkiaSharpDrawingContext>> VisualElements { get; set; }

    public NeedleVisual Needle { get; set; }

    [RelayCommand]
    public void DoRandomChange()
    {
        // modifying the Value property updates and animates the chart automatically
        Needle.Value = _random.Next(0, 100);
    }

    private static void SetStyle(
        double sectionsOuter, double sectionsWidth, PieSeries<ObservableValue> series)
    {
        series.OuterRadiusOffset = sectionsOuter;
        series.MaxRadialColumnWidth = sectionsWidth;
    }
}

XAML

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="XamarinSample.Pies.AngularGauge.View"
             xmlns:lvc="clr-namespace:LiveChartsCore.SkiaSharpView.Xamarin.Forms;assembly=LiveChartsCore.SkiaSharpView.XamarinForms"
             xmlns:vms="clr-namespace:ViewModelsSamples.Pies.AngularGauge;assembly=ViewModelsSamples">
    <ContentPage.BindingContext>
        <vms:ViewModel/>
    </ContentPage.BindingContext>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="50"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <Button Grid.Row="0" Command="{Binding DoRandomChangeCommand}">Change Value</Button>

        <lvc:PieChart
            Grid.Row="1"
            Series="{Binding Series}"
            VisualElements="{Binding VisualElements}"
            InitialRotation="-225"
            MaxAngle="270"
            MinValue="0"
            Total="100">
        </lvc:PieChart>
    </Grid>
</ContentPage>

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