Tooltips
Tooltips are popups that help the user to read a chart as the pointer moves.
Behaviour
On Windows or MacOS you can move the pointer over the chart to display the tooltip, tooltips will be closed when the pointer leaves the chart area.
On Android or iOS slide your finger over the chart to display the tooltip, the tooltip will be closed when the finger goes up.
TooltipPosition property
You can place a tooltip at Top
, Bottom
, Left
, Right
, Center
or Hidden
positions, for now
tooltips for the PieChart
class only support the Center
position, default value is Top
.
Notice the Hidden
position will disable tooltips in a chart.
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Top"><!-- mark -->
</lvc:CartesianChart>
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Bottom"><!-- mark -->
</lvc:CartesianChart>
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Left"><!-- mark -->
</lvc:CartesianChart>
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Right"><!-- mark -->
</lvc:CartesianChart>
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Center"><!-- mark -->
</lvc:CartesianChart>
<lvc:CartesianChart
Series="{Binding Series}"
TooltipPosition="Hidden"><!-- mark -->
</lvc:CartesianChart>
TooltipFindingStrategy property
Every point drawn by the library defines a HoverArea, it defines an area in the chart that "triggers" the point, it is specially important to fire tooltips, a point will be included in a tooltip when the hover area was triggered by the pointer position.
The TooltipFindingStrategy
property determines the hover area planes (X or Y) that a chart will use to trigger the HoverArea
instances.
In a chart, the following options are available:
CompareAll: Selects all the points whose hover area contain the pointer position.
CompareOnlyX: Selects all the points whose hover area contain the pointer position, but it ignores the Y plane.
CompareOnlyY: Selects all the points whose hover area contain the pointer position, but it ignores the X plane.
CompareAllTakeClosest: Selects all the points whose hover area contain the pointer position, it only takes the closest point to the pointer, one per series.
CompareOnlyXTakeClosest: Selects all the points whose hover area contain the pointer position, but it ignores the Y plane, it only takes the closest point to the pointer, one per series.
CompareOnlyYTakeClosest: Selects all the points whose hover area contain the pointer position, but it ignores the X plane, it only takes the closest point to the pointer, one per series.
Automatic (default): Based on the series in the chart, LiveCharts will determine a finding strategy (one of the previous mentioned),
all the series have a preferred finding strategy, normally vertical series prefer the CompareOnlyXTakeClosest
strategy,
horizontal series prefer CompareOnlyYTakeClosest
, and scatter series prefers CompareAllTakeClosest
, if all the series prefer the same strategy, then that
strategy will be selected for the chart, if any series differs then the CompareAllTakeClosest
strategy will be used.
Notice that the Axis.UnitWidth
property might affect the tooltips in DateTime
scaled charts, ensure your chart axis is using
the properly unit width.
<lvc:CartesianChart
Series="{Binding Series}"
TooltipFindingStrategy="CompareOnlyX"><!-- mark -->
</lvc:CartesianChart>
Tooltip point text
You can define the text the tooltip will display for a given point, using the Series.TooltipLabelFormatter
property, this
property is of type Func<ChartPoint, string>
this means that is is a function, that takes a point as parameter
and returns a string, the point will be injected by LiveCharts in this function to get a string out of it when it
requires to build the text for a point in a tooltip, the injected point will be different as the user moves the pointer over the
user interface.
By default the library already defines a default TooltipLabelFormatter
for every series, all the series have a different
formatter, but generally the default value uses the Series.Name
and the ChartPoint.PrimaryValue
properties, the following
code snippet illustrates how to build a custom tooltip formatter.
new LineSeries<double>
{
Name = "Sales",
Values = new ObservableCollection<double> { 200, 558, 458 },
// for the following formatter
// when the pointer is over the first point (200), the tooltip will display:
// Sales: 200
TooltipLabelFormatter =
(chartPoint) => $"{chartPoint.Context.Series.Name}: {chartPoint.PrimaryValue}"
},
new ColumnSeries<double>
{
Name = "Sales 2",
Values = new ObservableCollection<double> { 250, 350, 240 },
// now it will use a currency formatter to display the primary value
// result: Sales 2: $200.00
TooltipLabelFormatter =
(chartPoint) => $"{chartPoint.Context.Series.Name}: {chartPoint.PrimaryValue:C2}"
},
new StepLineSeries<ObservablePoint>
{
Name = "Average",
Values = new ObservableCollection<ObservablePoint>
{
new ObservablePoint(10, 5),
new ObservablePoint(5, 8)
},
// We can also display both coordinates (X and Y in a cartesian coordinate system)
// result: Average: 10, 5
TooltipLabelFormatter =
(chartPoint) => $"{chartPoint.Context.Series.Name}: {chartPoint.SecondaryValue}, {chartPoint.PrimaryValue}"
},
new ColumnSeries<ObservablePoint>
{
Values = new ObservableCollection<double> { 250, 350, 240 },
// or anything...
// result: Sales at this moment: $200.00
TooltipLabelFormatter =
(chartPoint) => $"Sales at this moment: {chartPoint.PrimaryValue:C2}"
}
Customize default tooltips
You can quickly change the position, the font, the text size or the background color:
View
<UserControl
x:Class="UnoWinUISample.Axes.NamedLabels.View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:lvc="using:LiveChartsCore.SkiaSharpView.WinUI"
xmlns:vms="using:ViewModelsSamples.Axes.NamedLabels"
mc:Ignorable="d">
<UserControl.DataContext>
<vms:ViewModel/>
</UserControl.DataContext>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<lvc:CartesianChart
Series="{Binding Series}"
XAxes="{Binding XAxes}"
YAxes="{Binding YAxes}"
TooltipPosition="Left"
TooltipTextPaint="{Binding TooltipTextPaint}"
TooltipBackgroundPaint="{Binding TooltipBackgroundPaint}"
TooltipTextSize="16">
</lvc:CartesianChart>
</Grid>
</UserControl>
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
}
Custom tooltip control
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. In the following example we build
a custom control to render tooltips in out 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.Measure;
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),
ClippingMode = ClipMode.None, // required on tooltips // mark
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
<UserControl
x:Class="UnoWinUISample.General.TemplatedTooltips.View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:lvc="using:LiveChartsCore.SkiaSharpView.WinUI"
xmlns:vms="using:ViewModelsSamples.General.TemplatedTooltips"
mc:Ignorable="d">
<UserControl.DataContext>
<vms:ViewModel/>
</UserControl.DataContext>
<Grid>
<lvc:CartesianChart Series="{Binding Series}" TooltipPosition="Top" >
<!-- mark -untilCloses CartesianChart.Tooltip -->
<lvc:CartesianChart.Tooltip>
<vms:CustomTooltip></vms:CustomTooltip>
</lvc:CartesianChart.Tooltip>
</lvc:CartesianChart>
</Grid>
</UserControl>