How to add a custom view to the data label of a .NET MAUI chart

DataLabelTemplate/App.xaml

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+<?xml version = "1.0" encoding = "UTF-8" ?>
+<Application xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:DataLabelTemplate"
+             x:Class="DataLabelTemplate.App">
+    <Application.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="Resources/Styles/Colors.xaml" />
+                <ResourceDictionary Source="Resources/Styles/Styles.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>

DataLabelTemplate/App.xaml.cs

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+namespace DataLabelTemplate
+{
+    public partial class App : Application
+    {
+        public App()
+        {
+            InitializeComponent();
+
+            MainPage = new AppShell();
+        }
+    }
+}

DataLabelTemplate/AppShell.xaml

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+<?xml version="1.0" encoding="UTF-8" ?>
+<Shell
+    x:Class="DataLabelTemplate.AppShell"
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:local="clr-namespace:DataLabelTemplate"
+    Shell.FlyoutBehavior="Disabled"
+    Title="DataLabelTemplate">
+
+    <ShellContent
+        ContentTemplate="{DataTemplate local:MainPage}"
+        Route="MainPage" />
+
+</Shell>

DataLabelTemplate/AppShell.xaml.cs

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+namespace DataLabelTemplate
+{
+    public partial class AppShell : Shell
+    {
+        public AppShell()
+        {
+            InitializeComponent();
+        }
+    }
+}

DataLabelTemplate/Convertor.cs

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+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace DataLabelTemplate
+{
+    public class ValueToSummaryValueConverter : IValueConverter
+    {
+        private double sumOfValues = 0;
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        {
+            if (value == null || !(value is double))
+                return null;
+
+            double numericValue = (double)value;
+            sumOfValues += numericValue;
+            if (numericValue == 0)
+                return sumOfValues;
+            else
+                return numericValue;
+        }
+
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public class ValueToColorConverter : IValueConverter
+    {
+
+        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+        {
+            if (value == null || !(value is double))
+                return Colors.Transparent;
+
+            double numericValue = (double)value;
+            if (numericValue == 0)
+                return Color.FromHex("#3333cc");
+            else
+                return numericValue > 0 ? Color.FromHex("#3bab46") : Color.FromHex("#df3320");
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public class ValueToImageConvertor : IValueConverter
+    {
+        public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+        {
+            if (value == null || !(value is double))
+                return null;
+
+            double numericValue = (double)value;
+            if (numericValue == 0)
+                return null;
+            else
+                return numericValue > 0 ? "up.png" : "down.png";
+        }
+
+        public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

DataLabelTemplate/DataLabelTemplate.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFrameworks>net8.0-android;net8.0-ios;net8.0-maccatalyst</TargetFrameworks>
+		<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net8.0-windows10.0.19041.0</TargetFrameworks>
+		<!-- Uncomment to also build the tizen app. You will need to install tizen by following this: https://github.com/Samsung/Tizen.NET -->
+		<!-- <TargetFrameworks>$(TargetFrameworks);net8.0-tizen</TargetFrameworks> -->
+
+		<!-- Note for MacCatalyst:
+		The default runtime is maccatalyst-x64, except in Release config, in which case the default is maccatalyst-x64;maccatalyst-arm64.
+		When specifying both architectures, use the plural <RuntimeIdentifiers> instead of the singular <RuntimeIdentifier>.
+		The Mac App Store will NOT accept apps with ONLY maccatalyst-arm64 indicated;
+		either BOTH runtimes must be indicated or ONLY macatalyst-x64. -->
+		<!-- For example: <RuntimeIdentifiers>maccatalyst-x64;maccatalyst-arm64</RuntimeIdentifiers> -->
+
+		<OutputType>Exe</OutputType>
+		<RootNamespace>DataLabelTemplate</RootNamespace>
+		<UseMaui>true</UseMaui>
+		<SingleProject>true</SingleProject>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+
+		<!-- Display name -->
+		<ApplicationTitle>DataLabelTemplate</ApplicationTitle>
+
+		<!-- App Identifier -->
+		<ApplicationId>com.companyname.datalabeltemplate</ApplicationId>
+
+		<!-- Versions -->
+		<ApplicationDisplayVersion>1.0</ApplicationDisplayVersion>
+		<ApplicationVersion>1</ApplicationVersion>
+
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'ios'">11.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'maccatalyst'">13.1</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'android'">21.0</SupportedOSPlatformVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</SupportedOSPlatformVersion>
+		<TargetPlatformMinVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'windows'">10.0.17763.0</TargetPlatformMinVersion>
+		<SupportedOSPlatformVersion Condition="$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)')) == 'tizen'">6.5</SupportedOSPlatformVersion>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<!-- App Icon -->
+		<MauiIcon Include="Resources\AppIcon\appicon.svg" ForegroundFile="Resources\AppIcon\appiconfg.svg" Color="#512BD4" />
+
+		<!-- Splash Screen -->
+		<MauiSplashScreen Include="Resources\Splash\splash.svg" Color="#512BD4" BaseSize="128,128" />
+
+		<!-- Images -->
+		<MauiImage Include="Resources\Images\*" />
+		<MauiImage Update="Resources\Images\dotnet_bot.png" Resize="True" BaseSize="300,185" />
+
+		<!-- Custom Fonts -->
+		<MauiFont Include="Resources\Fonts\*" />
+
+		<!-- Raw Assets (also remove the "Resources\Raw" prefix) -->
+		<MauiAsset Include="Resources\Raw\**" LogicalName="%(RecursiveDir)%(Filename)%(Extension)" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiVersion)" />
+		<PackageReference Include="Microsoft.Maui.Controls.Compatibility" Version="$(MauiVersion)" />
+		<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="8.0.0" />
+		<PackageReference Include="Syncfusion.Maui.Toolkit" Version="*" />
+	</ItemGroup>
+
+</Project>

DataLabelTemplate/DataLabelTemplate.csproj.user

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+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <IsFirstTimeProjectOpen>False</IsFirstTimeProjectOpen>
+    <ActiveDebugFramework>net8.0-windows10.0.19041.0</ActiveDebugFramework>
+    <ActiveDebugProfile>Windows Machine</ActiveDebugProfile>
+  </PropertyGroup>
+  <ItemGroup>
+    <None Update="App.xaml">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="AppShell.xaml">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="MainPage.xaml">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="Platforms\Windows\App.xaml">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="Platforms\Windows\Package.appxmanifest">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="Resources\Styles\Colors.xaml">
+      <SubType>Designer</SubType>
+    </None>
+    <None Update="Resources\Styles\Styles.xaml">
+      <SubType>Designer</SubType>
+    </None>
+  </ItemGroup>
+</Project>

DataLabelTemplate/DataLabelTemplate.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.9.34622.214
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DataLabelTemplate", "DataLabelTemplate.csproj", "{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Debug|Any CPU.Deploy.0 = Debug|Any CPU
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Release|Any CPU.Build.0 = Release|Any CPU
+		{13A2C44B-3AC6-45CE-9F0B-1D17070557D0}.Release|Any CPU.Deploy.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {9D8766D1-6381-4336-BAA0-023A3227E2B8}
+	EndGlobalSection
+EndGlobal

DataLabelTemplate/MainPage.xaml

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+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="DataLabelTemplate.MainPage"
+             xmlns:chart="clr-namespace:Syncfusion.Maui.Toolkit.Charts;assembly=Syncfusion.Maui.Toolkit"
+             xmlns:local="clr-namespace:DataLabelTemplate">
+
+    <ContentPage.BindingContext>
+        <local:ChartViewModel x:Name="ViewModel"></local:ChartViewModel>
+    </ContentPage.BindingContext>
+
+    <ContentPage.Resources>
+        <ResourceDictionary>
+            <local:ValueToSummaryValueConverter x:Key="ValueToValueConverter"/>
+            <local:ValueToColorConverter x:Key="ValueToColorConverter"/>
+            <local:ValueToImageConvertor x:Key="ValueToImageConverter"></local:ValueToImageConvertor>
+            <DataTemplate x:Key="dataLabel">
+                <StackLayout Orientation="Horizontal" Spacing="3">
+                    <Label FontSize="14" FontAttributes="Bold">
+                        <Label.Text>
+                            <Binding Path="Item.Value" Converter="{StaticResource ValueToValueConverter}" StringFormat="{}$.{0}"/>
+                        </Label.Text>
+                        <Label.TextColor>
+                            <Binding Path="Item.Value" Converter="{StaticResource ValueToColorConverter}"/>
+                        </Label.TextColor>
+                    </Label>
+                    <Image Source="{Binding Item.Value,Converter={StaticResource ValueToImageConverter}}" HeightRequest="15" WidthRequest="15"></Image>
+                </StackLayout>
+            </DataTemplate>
+        </ResourceDictionary>
+    </ContentPage.Resources>
+
+
+    <chart:SfCartesianChart >
+        <chart:SfCartesianChart.XAxes>
+            <chart:CategoryAxis></chart:CategoryAxis>
+        </chart:SfCartesianChart.XAxes>
+
+        <chart:SfCartesianChart.YAxes>
+            <chart:NumericalAxis Minimum="0" Maximum="20000" Interval="4000"></chart:NumericalAxis>
+        </chart:SfCartesianChart.YAxes>
+
+
+        <chart:WaterfallSeries ItemsSource="{Binding Data}"
+                            XBindingPath="Department"
+                            YBindingPath="Value"
+                            Fill="#3bab46"
+                            NegativePointsBrush="#df3320"
+                            ShowDataLabels="True"
+                            LabelTemplate="{StaticResource dataLabel}"
+                            SummaryBindingPath="IsSummary"
+                            SummaryPointsBrush="#3333cc">
+
+
+            <chart:WaterfallSeries.DataLabelSettings>
+                <chart:CartesianDataLabelSettings LabelPlacement="Outer" UseSeriesPalette="False"></chart:CartesianDataLabelSettings>
+            </chart:WaterfallSeries.DataLabelSettings>
+        </chart:WaterfallSeries>
+    </chart:SfCartesianChart>
+
+</ContentPage>

DataLabelTemplate/MainPage.xaml.cs

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+namespace DataLabelTemplate
+{
+    public partial class MainPage : ContentPage
+    {
+
+
+        public MainPage()
+        {
+            InitializeComponent();
+        }
+
+
+    }
+
+}

DataLabelTemplate/MauiProgram.cs

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+using Microsoft.Extensions.Logging;
+using Syncfusion.Maui.Toolkit.Hosting;
+
+namespace DataLabelTemplate
+{
+    public static class MauiProgram
+    {
+        public static MauiApp CreateMauiApp()
+        {
+            var builder = MauiApp.CreateBuilder();
+            builder
+                .UseMauiApp<App>() 
+                .ConfigureSyncfusionToolkit()
+                .ConfigureFonts(fonts =>
+                {
+                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
+                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
+                });
+
+#if DEBUG
+    		builder.Logging.AddDebug();
+#endif
+
+            return builder.Build();
+        }
+    }
+}

DataLabelTemplate/Model/Model.cs

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+
+namespace DataLabelTemplate
+{
+    public class Model
+    {
+        public string? Department { get; set; }
+
+        public double Value { get; set; }
+
+        public bool IsSummary { get; set; }
+    }
+}

DataLabelTemplate/Platforms/Android/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+	<application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true"></application>
+	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+	<uses-permission android:name="android.permission.INTERNET" />
+</manifest>

DataLabelTemplate/Platforms/Android/MainActivity.cs

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+using Android.App;
+using Android.Content.PM;
+using Android.OS;
+
+namespace DataLabelTemplate
+{
+    [Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize | ConfigChanges.Density)]
+    public class MainActivity : MauiAppCompatActivity
+    {
+    }
+}