Annotations in Xamarin Linear Gauge (SfLinearGauge)

SfLinearGauge supports Annotations, which is used to mark the specific area of interest in the gauge area with texts, shapes, or images. You can add any number of annotations to the gauge.

Annotation

By using the View property of annotation object, you can specify the new element that needs to be displayed in the gauge area.

<gauge:SfLinearGauge>

         <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation OffsetX = "0.5" OffsetY ="0.45">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="CPU Utilization" TextColor="Black" FontSize ="20"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

            <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1">
                    <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>

        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();
            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.OffsetX = 0.5;
            linearGaugeAnnotation.OffsetY = 0.45;
            linearGaugeAnnotation.View = new Label() { Text = "CPU Utilization", TextColor = Color.Black, FontSize = 20 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);
            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
             linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

Linear Gauge Annotation

Positioning the annotation

You can place the annotation anywhere in gauge area by using the Offset or ScaleValue property.

Change annotation position by using offset

You can position the annotation anywhere in the linear gauge by using the OffsetX and OffsetY properties. It ranges from 0 to 1.

<gauge:SfLinearGauge>

          <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation OffsetX = "0.5" OffsetY ="0.6">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="CPU Utilization" TextColor="Black" FontSize ="20"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

              <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1">
                   <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>
        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();
            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.OffsetX = 0.5;
            linearGaugeAnnotation.OffsetY = 0.6;
            linearGaugeAnnotation.View = new Label() { Text = "CPU Utilization", TextColor = Color.Black, FontSize = 20 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);
            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
             linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

Linear Gauge Annotation Position

Change annotation position by using scale value

You can also place the annotation by specifying the ScaleValue property.

<gauge:SfLinearGauge>

        <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation ScaleValue ="60">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="60%" FontAttributes = "Bold" TextColor="Black" FontSize ="15"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

              <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1" ScaleBarSize ="40">
                     <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                    <gauge:LinearScale.Pointers>
					<gauge:BarPointer  Value="60" Color = "#f95c85" Thickness = "20" CornerRadius ="10" CornerRadiusType ="End"/>
				</gauge:LinearScale.Pointers>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>
        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();
            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.ScaleValue = 60;
            linearGaugeAnnotation.View = new Label() { Text = "60%", FontAttributes = FontAttributes.Bold, TextColor = Color.Black, FontSize = 15 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
             linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.ScaleBarSize = 40;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

            BarPointer barPointer = new BarPointer();
            barPointer.Value = 60;
            barPointer.Thickness = 20;
            barPointer.CornerRadius = 10;
            barPointer.CornerRadiusType = CornerRadiusType.End;
            barPointer.Color = Color.FromRgb(249, 92, 133);
            linearScale.Pointers.Add(barPointer);

Linear Gauge Annotation Scale Value

Set margin to the annotation

You can adjust the annotation by specifying the ViewMargin property in pixel, which adjusts the annotation element from its current position.

<gauge:SfLinearGauge>
  
     <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation ScaleValue ="60" ViewMargin ="10,60">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="60%" FontAttributes = "Bold" TextColor= "#F95C85" FontSize ="15"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

              <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1" ScaleBarSize ="40">
                    <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                    <gauge:LinearScale.Pointers>
					<gauge:BarPointer  Value="60" Color = "#F95C85" Thickness = "20" CornerRadius ="10" CornerRadiusType ="End"/>
				</gauge:LinearScale.Pointers>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>
        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();
            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.ScaleValue = 60;
            linearGaugeAnnotation.ViewMargin = new Point(10, 60);
            linearGaugeAnnotation.View = new Label() { Text = "60%", FontAttributes = FontAttributes.Bold, TextColor = Color.FromHex("#F95C85"), FontSize = 15 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
             linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.ScaleBarSize = 40;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

            BarPointer barPointer = new BarPointer();
            barPointer.Value = 60;
            barPointer.Thickness = 20;
            barPointer.CornerRadius = 10;
            barPointer.CornerRadiusType = CornerRadiusType.End;
            barPointer.Color = Color.FromRgb(249, 92, 133);
            linearScale.Pointers.Add(barPointer);

Linear Gauge Annotation Margin

Alignment of annotation

You can align the annotation using the HorizontalViewAlignment and VerticalViewAlignment properties.

Setting horizontal view alignment

<gauge:SfLinearGauge>
  
     <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation ScaleValue ="60" HorizontalViewAlignment ="Start">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="60%" FontAttributes = "Bold" TextColor= "Black" FontSize ="15"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

              <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1" ScaleBarSize ="40">
                     <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                    <gauge:LinearScale.Pointers>
					<gauge:BarPointer  Value="60" Color = "#f95c85" Thickness = "20" CornerRadius ="10" CornerRadiusType ="End"/>
				</gauge:LinearScale.Pointers>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>

        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();

            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.ScaleValue = 60;
            linearGaugeAnnotation.HorizontalViewAlignment = ViewAlignment.Start;
            linearGaugeAnnotation.View = new Label() { Text = "60%", FontAttributes = FontAttributes.Bold, TextColor = Color.Black, FontSize = 15 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
             linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.ScaleBarSize = 40;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

            BarPointer barPointer = new BarPointer();
            barPointer.Value = 60;
            barPointer.Thickness = 20;
            barPointer.CornerRadius = 10;
            barPointer.CornerRadiusType = CornerRadiusType.End;
            barPointer.Color = Color.FromRgb(249, 92, 133);
            linearScale.Pointers.Add(barPointer);

Linear Gauge Annotation Alignment

Setting vertical view alignment

<gauge:SfLinearGauge>
  
        <gauge:SfLinearGauge.Annotations>
                    <gauge:LinearGaugeAnnotation ScaleValue ="60" VerticalViewAlignment ="Start">
                        <gauge:LinearGaugeAnnotation.View>
                            <Label Text="60%" FontAttributes = "Bold" TextColor= "Black" FontSize ="15"/>
                        </gauge:LinearGaugeAnnotation.View>
                    </gauge:LinearGaugeAnnotation>
                </gauge:SfLinearGauge.Annotations>

                <gauge:SfLinearGauge.Scales>
                    <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1" ScaleBarSize ="40">
                        <gauge:LinearScale.MajorTickSettings>
                            <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                        </gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearScale.MinorTickSettings>
                            <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                        </gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearScale.Pointers>
                        <gauge:BarPointer  Value="60" Color = "#f95c85" Thickness = "20" CornerRadius ="10" CornerRadiusType ="End"/>
                    </gauge:LinearScale.Pointers>
                    </gauge:LinearScale>
                </gauge:SfLinearGauge.Scales>

        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();

            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.ScaleValue = 60;
            linearGaugeAnnotation.VerticalViewAlignment = ViewAlignment.Start;
            linearGaugeAnnotation.View = new Label() { Text = "60%", FontAttributes = FontAttributes.Bold, TextColor = Color.Black, FontSize = 15 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearScale linearScale = new LinearScale();
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
            linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.ScaleBarSize = 40;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

            BarPointer barPointer = new BarPointer();
            barPointer.Value = 60;
            barPointer.Thickness = 20;
            barPointer.CornerRadius = 10;
            barPointer.CornerRadiusType = CornerRadiusType.End;
            barPointer.Color = Color.FromRgb(249, 92, 133);
            linearScale.Pointers.Add(barPointer);

Linear Gauge Annotation Vertical Alignment

Setting scale index for annotation

You can set the index for the scale by using ScaleIndex

<gauge:SfLinearGauge>

          <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation OffsetX = "0.5" OffsetY ="0.45" ScaleIndex = "0">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="CPU Utilization" TextColor="Black" FontSize ="20"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
                <gauge:LinearGaugeAnnotation OffsetX = "0.5" OffsetY ="0.6" ScaleIndex ="1">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="Thermometer" TextColor="Black" FontSize ="20"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

            <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1">
                    <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                </gauge:LinearScale>

                <gauge:LinearScale ScaleBarColor="#e0e0e0" LabelColor="#424242" MinorTicksPerInterval ="1" Offset ="100">
                    <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="15"/>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1"  Color="Gray" Length="7"/>
                    </gauge:LinearScale.MinorTickSettings>
                </gauge:LinearScale>

            </gauge:SfLinearGauge.Scales>

        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();

            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.OffsetX = 0.5;
            linearGaugeAnnotation.OffsetY = 0.45;
            linearGaugeAnnotation.ScaleIndex = 0;
            linearGaugeAnnotation.View = new Label() { Text = "CPU Utilization", TextColor = Color.Black, FontSize = 18 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearGaugeAnnotation linearGaugeAnnotation1 = new LinearGaugeAnnotation();
            linearGaugeAnnotation1.OffsetX = 0.5;
            linearGaugeAnnotation1.OffsetY = 0.6;
            linearGaugeAnnotation1.ScaleIndex = 1;
            linearGaugeAnnotation1.View = new Label() { Text = "Thermometer", TextColor = Color.Black, FontSize = 18 };
            linearGauge.Annotations.Add(linearGaugeAnnotation1);

            LinearScale linearScale = new LinearScale();
            linearScale.MinimumValue = 0;
            linearScale.MaximumValue = 100;
            linearScale.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale.LabelColor = Color.FromHex("#424242");
            linearScale.MajorTickSettings.Thickness = 1;
             linearScale.MajorTickSettings.Length = 15;
             linearScale.MajorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Color = Color.Gray;
             linearScale.MinorTickSettings.Length = 7;
            linearScale.MinorTickSettings.Thickness = 1;
            linearScale.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale);

            LinearScale linearScale1 = new LinearScale();
            linearScale1.MinimumValue = 0;
            linearScale1.MaximumValue = 100;
            linearScale1.ScaleBarColor = Color.FromHex("#e0e0e0");
            linearScale1.LabelColor = Color.FromHex("#424242");
            linearScale1.MajorTickSettings.Thickness = 1;
             linearScale1.MajorTickSettings.Length = 15;
             linearScale1.MajorTickSettings.Color = Color.Gray;
             linearScale1.MinorTickSettings.Color = Color.Gray;
             linearScale1.MinorTickSettings.Length = 7;
            linearScale1.MinorTickSettings.Thickness = 1;
            linearScale1.Offset = 100;
            linearScale1.MinorTicksPerInterval = 1;
            linearGauge.Scales.Add(linearScale1);

Linear Gauge Annotation Scale Index

Multiple annotations

You can add multiple annotations to the gauge as demonstrated below.

<gauge:SfLinearGauge>
            <gauge:SfLinearGauge.Annotations>
                <gauge:LinearGaugeAnnotation  ScaleValue="15" ViewMargin ="0,30" >
                    <gauge:LinearGaugeAnnotation.View>
                        <Image Source="Low.png" WidthRequest="30" HeightRequest="30"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>

                <gauge:LinearGaugeAnnotation ScaleValue="45" ViewMargin ="0,30">
                    <gauge:LinearGaugeAnnotation.View>
                        <Image Source="Moderate.png" WidthRequest="30" HeightRequest="30"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>

                <gauge:LinearGaugeAnnotation ScaleValue="75" ViewMargin ="0,30">
                    <gauge:LinearGaugeAnnotation.View>
                        <Image Source="High.png" WidthRequest="30" HeightRequest="30"/>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>

                <gauge:LinearGaugeAnnotation ScaleValue="15" ViewMargin ="0,80">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="Low" TextColor="#30b32d" FontSize ="18"></Label>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>

                <gauge:LinearGaugeAnnotation ScaleValue="45" ViewMargin ="0,80">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="Moderate" TextColor="#ffdd00" FontSize ="18"></Label>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>

                <gauge:LinearGaugeAnnotation ScaleValue="75" ViewMargin ="0,80">
                    <gauge:LinearGaugeAnnotation.View>
                        <Label Text="High" TextColor="#f03e3e" FontSize ="18"></Label>
                    </gauge:LinearGaugeAnnotation.View>
                </gauge:LinearGaugeAnnotation>
            </gauge:SfLinearGauge.Annotations>

            <gauge:SfLinearGauge.Scales>
                <gauge:LinearScale MinimumValue="0" MaximumValue="90"
                                ShowLabels="False" ScaleBarColor="Transparent"
              MinorTicksPerInterval="1" ScaleBarSize="13" ScalePosition="BackWard" ShowTicks ="False">
                    <gauge:LinearScale.Ranges>
                        <gauge:LinearRange StartValue="0" Color="#30b32d" EndValue="30" StartWidth="60" EndWidth="60" />
                        <gauge:LinearRange StartValue="30" Color="#ffdd00" EndValue="60" StartWidth="60" EndWidth="60" />
                        <gauge:LinearRange StartValue="60" Color="#f03e3e" EndValue="90" StartWidth="60" EndWidth="60" />
                    </gauge:LinearScale.Ranges>
                    <gauge:LinearScale.Pointers>
                        <gauge:SymbolPointer Color="Red" MarkerShape="InvertedTriangle" Value="35" Thickness="12" />
                    </gauge:LinearScale.Pointers>
                    <gauge:LinearScale.MajorTickSettings>
                        <gauge:LinearTickSettings Thickness="1" Color="Transparent" Length="0"></gauge:LinearTickSettings>
                    </gauge:LinearScale.MajorTickSettings>
                    <gauge:LinearScale.MinorTickSettings>
                        <gauge:LinearTickSettings Thickness="1" Color="Transparent" Length="0"></gauge:LinearTickSettings>
                    </gauge:LinearScale.MinorTickSettings>
                </gauge:LinearScale>
            </gauge:SfLinearGauge.Scales>
        </gauge:SfLinearGauge>
SfLinearGauge linearGauge = new SfLinearGauge();
            LinearGaugeAnnotation linearGaugeAnnotation = new LinearGaugeAnnotation();
            linearGaugeAnnotation.ScaleValue = 75;
            linearGaugeAnnotation.ViewMargin = new Point(0, 30);
            linearGaugeAnnotation.View = new Image() { Source = "High.png", HeightRequest = 30, WidthRequest = 30 };
            linearGauge.Annotations.Add(linearGaugeAnnotation);

            LinearGaugeAnnotation linearGaugeAnnotation1 = new LinearGaugeAnnotation();
            linearGaugeAnnotation1.ScaleValue = 45;
            linearGaugeAnnotation1.ViewMargin = new Point(0, 30);
            linearGaugeAnnotation1.View = new Image() { Source = "Moderate.png", HeightRequest = 30, WidthRequest = 30 };
            linearGauge.Annotations.Add(linearGaugeAnnotation1);

            LinearGaugeAnnotation linearGaugeAnnotation2 = new LinearGaugeAnnotation();
            linearGaugeAnnotation2.ScaleValue = 15;
            linearGaugeAnnotation2.ViewMargin = new Point(0, 30);
            linearGaugeAnnotation2.View = new Image() { Source = "Low.png", HeightRequest = 30, WidthRequest = 30 };
            linearGauge.Annotations.Add(linearGaugeAnnotation2);

            LinearGaugeAnnotation linearGaugeAnnotation3 = new LinearGaugeAnnotation();
            linearGaugeAnnotation3.ScaleValue = 75;
            linearGaugeAnnotation3.ViewMargin = new Point(0, 80);
            linearGaugeAnnotation3.View = new Label() { Text = "High", TextColor = Color.Red, FontSize = 18 };
            linearGauge.Annotations.Add(linearGaugeAnnotation3);

            LinearGaugeAnnotation linearGaugeAnnotation4 = new LinearGaugeAnnotation();
            linearGaugeAnnotation4.ScaleValue = 45;
            linearGaugeAnnotation4.ViewMargin = new Point(0, 80);
            linearGaugeAnnotation4.View = new Label() { Text = "Moderate", TextColor = Color.Yellow, FontSize = 18 };
            linearGauge.Annotations.Add(linearGaugeAnnotation4);

            LinearGaugeAnnotation linearGaugeAnnotation5 = new LinearGaugeAnnotation();
            linearGaugeAnnotation5.ScaleValue = 15;
            linearGaugeAnnotation5.ViewMargin = new Point(0, 80);
            linearGaugeAnnotation5.View = new Label() { Text = "Low", TextColor = Color.Green, FontSize = 18 };
            linearGauge.Annotations.Add(linearGaugeAnnotation5);

            LinearScale linearScale = new LinearScale();
            linearScale.MinimumValue = 0;
            linearScale.MaximumValue = 90;
            linearScale.ShowLabels = false;
            linearScale.ScaleBarColor = Color.Transparent;
            linearScale.MinorTicksPerInterval = 1;
            linearScale.ShowTicks = false;
            linearScale.ScalePosition = ScalePosition.BackWard;
            linearGauge.Scales.Add(linearScale);

            LinearRange linearRange = new LinearRange();
            linearRange.StartValue = 0;
            linearRange.Color = Color.FromHex("#30b32d");
            linearRange.EndValue = 30;
            linearRange.StartWidth = 60;
            linearRange.EndWidth = 60;
            linearScale.Ranges.Add(linearRange);

            LinearRange linearRange1 = new LinearRange();
            linearRange1.StartValue = 30;
            linearRange1.Color = Color.FromHex("#ffdd00");
            linearRange1.EndValue = 60;
            linearRange1.StartWidth = 60;
            linearRange1.EndWidth = 60;
            linearScale.Ranges.Add(linearRange1);

            LinearRange linearRange2 = new LinearRange();
            linearRange2.StartValue = 60;
            linearRange2.Color = Color.FromHex("#f03e3e");
            linearRange2.EndValue = 90;
            linearRange2.StartWidth = 60;
            linearRange2.EndWidth = 60;
            linearScale.Ranges.Add(linearRange2);

Linear Gauge Multiple Annotation