Update README.md

Author: tineshsf4652

README.md

@@ -12,7 +12,7 @@ The Horizontal Line Annotation includes following property:
 
 Learn step-by-step instructions and gain insights to create and dynamically update the target line.
 
-**Step 1:** The layout is created using a Grid with two columns.
+**Step 1:** The layout is created using a grid with two columns.
 
 **XAML**
 
@@ -27,7 +27,7 @@ Learn step-by-step instructions and gain insights to create and dynamically upda
 </Grid> 
  ```
 
-**Step 2:** In first column of grid layout, initialize the [SfChart](https://help.syncfusion.com/wpf/charts/getting-started) and add the axes and series to the [SfChart](https://help.syncfusion.com/wpf/charts/getting-started) as shown below.
+**Step 2:** In first column of grid layout, initialize the [SfChart](https://help.syncfusion.com/wpf/charts/getting-started)and add the axes and series as shown below.
 
 **XAML**
 
@@ -50,7 +50,7 @@ Learn step-by-step instructions and gain insights to create and dynamically upda
         <chart:ColumnSeries.ColorModel>
             <chart:ChartColorModel>
                 <chart:ChartColorModel.CustomBrushes>
-                    .....
+                    ......
                 </chart:ChartColorModel.CustomBrushes>
             </chart:ChartColorModel>
         </chart:ColumnSeries.ColorModel>
@@ -59,7 +59,8 @@ Learn step-by-step instructions and gain insights to create and dynamically upda
 </chart:SfChart> 
  ```
 
-**Step 3:** The [HorizontalLineAnnotation](https://help.syncfusion.com/wpf/charts/annotations#vertical-and-horizontal-line-annotation) is initialized within the [Annotations](https://help.syncfusion.com/wpf/charts/annotations) collection of the [SfChart](https://help.syncfusion.com/wpf/charts/getting-started) to mark a dynamic target value on the Y-axis. The Y1 value is data-bound, enabling the target line to update dynamically based on the ViewModel.
+**Step 3:** The [HorizontalLineAnnotation](https://help.syncfusion.com/wpf/charts/annotations#vertical-and-horizontal-line-annotation) is initialized within the [Annotations](https://help.syncfusion.com/wpf/charts/annotations) collection of the [SfChart](https://help.syncfusion.com/wpf/charts/getting-started) to mark a dynamic target value on the Y-axis. The Y1 property is data-bound to the ViewModel, allowing the target line to adjust dynamically when the value changes.
+
 
 **XAML**
 
@@ -118,7 +119,7 @@ internal class ViewModel : INotifyPropertyChanged
 } 
  ```
 
-**Step 4:** The second column of the grid layout contains a StackPanel with a Slider, TextBox and TextBlock, allowing the user to change the annotation value dynamically.
+**Step 4:** The second column of the grid layout contains a StackPanel with a Slider, TextBox and TextBlock, allowing the user to change the annotation value dynamically. The TextBox_TextChanged event ensures valid input by clamping values between 0 and the maximum of the Y_Axis.
 
 **XAML**
 
@@ -134,6 +135,107 @@ internal class ViewModel : INotifyPropertyChanged
 </StackPanel> 
  ```
 
+**C#**
+ 
+ ```csharp
+private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
+{
+    if (Y_Axis == null) return;
+    var maxValue = Y_Axis.Maximum;
+
+    if (sender is TextBox textBox)
+    {
+        textBox.TextChanged -= TextBox_TextChanged;
+
+        if (string.IsNullOrWhiteSpace(textBox.Text))
+        {
+            viewModel.Y1 = double.MinValue;
+            textBox.Text = string.Empty;
+        }
+        else
+        {
+            if (int.TryParse(textBox.Text, out int newValue))
+            {
+                if (newValue > maxValue)
+                    newValue = (int)maxValue;
+                else if (newValue < 0)
+                    newValue = 0;
+
+                viewModel.Y1 = newValue;
+
+                textBox.Text = newValue.ToString();
+                textBox.CaretIndex = textBox.Text.Length;
+            }
+            else
+            {
+                textBox.Text = ((int)viewModel.Y1).ToString();
+                textBox.CaretIndex = textBox.Text.Length;
+            }
+        }
+
+        textBox.TextChanged += TextBox_TextChanged;
+    }
+} 
+ ```
+ 
+**Step 5:** This XAML code for creates a grid layout with a chart and controls for adjusting a target line. The [SfChart](https://help.syncfusion.com/wpf/charts/getting-started) displays revenue data with a horizontal annotation line, adjustable using a TextBox and Slider in the adjacent StackPanel.
+
+**XAML**
+  
+ ```
+<Grid>
+    <Grid.ColumnDefinitions>
+        <ColumnDefinition Width="*"></ColumnDefinition>
+        <ColumnDefinition Width="200"></ColumnDefinition>
+    </Grid.ColumnDefinitions>
+
+    <chart:SfChart Grid.Column="0">
+
+        <chart:SfChart.PrimaryAxis>
+            <chart:CategoryAxis EdgeLabelsDrawingMode="Fit" ShowGridLines="False" Header="Months"/>
+        </chart:SfChart.PrimaryAxis>
+
+        <chart:SfChart.SecondaryAxis>
+            <chart:NumericalAxis x:Name="Y_Axis" Minimum="0" Maximum="20000" Interval="5000" ShowGridLines="False" Header="Revenue" LabelFormat="'$'0" PlotOffsetEnd="30"/>
+        </chart:SfChart.SecondaryAxis>
+
+        <chart:SfChart.Annotations>
+            <chart:HorizontalLineAnnotation Y1="{Binding Y1}"
+                                        Stroke="Black"
+                                        StrokeThickness="2"
+                                        StrokeDashArray="5,2,2"
+                                        Text="Target"
+                                        FontSize="14"
+                                        FontWeight="Bold" 
+                                        HorizontalTextAlignment="Left"
+                                        VerticalTextAlignment="Top">
+            </chart:HorizontalLineAnnotation>
+        </chart:SfChart.Annotations>
+
+        <chart:ColumnSeries ItemsSource="{Binding Data}"
+                        XBindingPath="Months"
+                        YBindingPath="Revenue"
+                        Palette="Custom"
+                        Opacity="0.7">
+            <chart:ColumnSeries.ColorModel>
+                <chart:ChartColorModel>
+                    .....
+                </chart:ChartColorModel>
+            </chart:ColumnSeries.ColorModel>
+        </chart:ColumnSeries>
+
+    </chart:SfChart>
+
+    <StackPanel Orientation="Vertical" Margin="10" Grid.Column="1">
+        <TextBlock Text="Adjust Target Line" FontSize="16" FontWeight="Bold" TextAlignment="Center" HorizontalAlignment="Center" Margin="0,0,0,20"/>
+        <TextBox Text="{Binding Y1}" HorizontalAlignment="Stretch" VerticalAlignment="Center" TextChanged="TextBox_TextChanged" Margin="0,0,0,20" Padding="10"/>
+        <Slider Minimum="{Binding Minimum, Source={x:Reference Y_Axis}}" 
+                Maximum="{Binding Maximum, Source={x:Reference Y_Axis}}" 
+                Value="{Binding Y1}" HorizontalAlignment="Stretch"/>
+    </StackPanel>
+</Grid> 
+ ```
+
 
 **Output:**
 
@@ -145,4 +247,4 @@ Path too long exception
 
 If you are facing a path too long exception when building this example project, close Visual Studio and rename the repository to a shorter name before building the project.
 
-For more details, refer to the KB on [how to create and dynamically update target line for WPF Chart?](https://support.syncfusion.com/agent/kb/18542).
+For more details, refer to the KB on [how to create and dynamically update target line for WPF Chart](https://support.syncfusion.com/agent/kb/18542).