Customize default tooltips

You can quickly change the position, the font, the text size or the background color:

View

using System.Windows.Forms;
using LiveChartsCore.SkiaSharpView.Painting;
using LiveChartsCore.SkiaSharpView.WinForms;
using SkiaSharp;
using ViewModelsSamples.Axes.NamedLabels;

namespace WinFormsSample.Axes.NamedLabels;

public partial class View : UserControl
{
    private readonly CartesianChart cartesianChart;

    public View()
    {
        InitializeComponent();
        Size = new System.Drawing.Size(50, 50);

        var viewModel = new ViewModel();

        cartesianChart = new CartesianChart
        {
            Series = viewModel.Series,
            XAxes = viewModel.XAxes,
            YAxes = viewModel.YAxes,
            TooltipTextSize = 16, // mark
            TooltipTextPaint = viewModel.TooltipTextPaint, // mark
            TooltipBackgroundPaint = viewModel.TooltipBackgroundPaint, // mark
            TooltipPosition = LiveChartsCore.Measure.TooltipPosition.Left, // mark

            // out of livecharts properties...
            Location = new System.Drawing.Point(0, 0),
            Size = new System.Drawing.Size(50, 50),
            Anchor = AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top | AnchorStyles.Bottom
        };

        Controls.Add(cartesianChart);
    }
}

View model

[ObservableObject]
public partial class ViewModel
{
    public ISeries[] Series { get; set; } = { ... };
    public Axis[] XAxes { get; set; } = { ... };
    public Axis[] YAxes { get; set; } = { ... };

    public SolidColorPaint TooltipTextPaint { get; set; } = // mark
        new SolidColorPaint // mark
        { // mark
            Color = new SKColor(242, 244, 195), // mark
            SKTypeface = SKTypeface.FromFamilyName("Courier New") // mark
        }; // mark

    public SolidColorPaint TooltipBackgroundPaint { get; set; } = // mark
        new SolidColorPaint(new SKColor(72, 0, 50)); // mark
}

Tooltip control from scratch

You can also create your own tooltip, the recommended way is to use the LiveCharts API (example bellow) but you can use anything as tooltip as soon as it implements the IChartTooltip<T> interface. AT the following example we build a custom control to render tooltips in our charts using the LiveCharts API.

CustomTooltip.cs

using System;
using System.Collections.Generic;
using LiveChartsCore;
using LiveChartsCore.Drawing;
using LiveChartsCore.Kernel;
using LiveChartsCore.Kernel.Sketches;
using LiveChartsCore.SkiaSharpView.Drawing;
using LiveChartsCore.SkiaSharpView.Drawing.Geometries;
using LiveChartsCore.SkiaSharpView.Painting;
using LiveChartsCore.SkiaSharpView.VisualElements;
using LiveChartsCore.VisualElements;
using SkiaSharp;

namespace ViewModelsSamples.General.TemplatedTooltips;

public class CustomTooltip : IChartTooltip<SkiaSharpDrawingContext>
{
    private StackPanel<RoundedRectangleGeometry, SkiaSharpDrawingContext>? _stackPanel;
    private static readonly int s_zIndex = 10100;
    private readonly SolidColorPaint _backgroundPaint = new(new SKColor(28, 49, 58)) { ZIndex = s_zIndex };
    private readonly SolidColorPaint _fontPaint = new(new SKColor(230, 230, 230)) { ZIndex = s_zIndex + 1 };

    public void Show(IEnumerable<ChartPoint> foundPoints, Chart<SkiaSharpDrawingContext> chart)
    {
        if (_stackPanel is null)
        {
            _stackPanel = new StackPanel<RoundedRectangleGeometry, SkiaSharpDrawingContext>
            {
                Padding = new Padding(25),
                Orientation = ContainerOrientation.Vertical,
                HorizontalAlignment = Align.Start,
                VerticalAlignment = Align.Middle,
                BackgroundPaint = _backgroundPaint
            };

            _stackPanel
                .Animate(
                    new Animation(EasingFunctions.BounceOut, TimeSpan.FromSeconds(1)),
                    nameof(_stackPanel.X),
                    nameof(_stackPanel.Y));
        }

        // clear the previous elements.
        foreach (var child in _stackPanel.Children.ToArray())
        {
            _ = _stackPanel.Children.Remove(child);
            chart.RemoveVisual(child);
        }

        foreach (var point in foundPoints)
        {
            var sketch = ((IChartSeries<SkiaSharpDrawingContext>)point.Context.Series).GetMiniaturesSketch();
            var relativePanel = sketch.AsDrawnControl(s_zIndex);

            var label = new LabelVisual
            {
                Text = point.Coordinate.PrimaryValue.ToString("C2"),
                Paint = _fontPaint,
                TextSize = 15,
                Padding = new Padding(8, 0, 0, 0),
                VerticalAlignment = Align.Start,
                HorizontalAlignment = Align.Start
            };

            var sp = new StackPanel<RoundedRectangleGeometry, SkiaSharpDrawingContext>
            {
                Padding = new Padding(0, 4),
                VerticalAlignment = Align.Middle,
                HorizontalAlignment = Align.Middle,
                Children =
                {
                    relativePanel,
                    label
                }
            };

            _stackPanel?.Children.Add(sp);
        }

        var size = _stackPanel.Measure(chart);

        var location = foundPoints.GetTooltipLocation(size, chart);

        _stackPanel.X = location.X;
        _stackPanel.Y = location.Y;

        chart.AddVisual(_stackPanel);
    }

    public void Hide(Chart<SkiaSharpDrawingContext> chart)
    {
        if (chart is null || _stackPanel is null) return;
        chart.RemoveVisual(_stackPanel);
    }
}

View

using System.Windows.Forms;
using LiveChartsCore.SkiaSharpView.WinForms;
using ViewModelsSamples.General.TemplatedTooltips;

namespace WinFormsSample.General.TemplatedTooltips;

public partial class View : UserControl
{
    private readonly CartesianChart cartesianChart;

    public View()
    {
        InitializeComponent();
        Size = new System.Drawing.Size(50, 50);

        var viewModel = new ViewModel();

        cartesianChart = new CartesianChart
        {
            Series = viewModel.Series,
            Tooltip = new CustomTooltip(),

            // out of livecharts properties...
            Location = new System.Drawing.Point(0, 0),
            Size = new System.Drawing.Size(50, 50),
            Anchor = AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top | AnchorStyles.Bottom
        };

        Controls.Add(cartesianChart);
    }
}