# Syncfusion Winforms Radial Slider

> Implement and configure Syncfusion RadialSlider control in Windows Forms - a circular slider for visual numeric value selection with rotating needle. Use when creating circular value selection controls, rotary inputs, dial-based controls, or radial numeric input. Covers circular value selection, rotating needle control, dial-based input, visual value picker with divisions, and radial numeric input controls.

- Skill: `syncfusion/syncfusion-winforms-radial-slider` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add syncfusion/syncfusion-winforms-radial-slider`
- Raw SKILL.md: https://api.skillmd.com/api/skills/syncfusion/syncfusion-winforms-radial-slider/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: syncfusion (https://skillmd.com/u/syncfusion)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/syncfusion/syncfusion-winforms-radial-slider

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# Implementing Radial Sliders (RadialSlider)

A circular slider control for Windows Forms that provides visual numeric value selection through a rotating needle around a radial dial with customizable divisions and themes.

## When to Use This Skill

Use this skill when you need to:
- **Circular Value Selection**: Implement dial-based numeric input (like volume knobs, temperature dials)
- **Rotating Controls**: Create rotary controls with visual feedback
- **Value Pickers**: Build circular value selectors with minimum/maximum ranges
- **Division Markers**: Display value divisions around a circular dial
- **Visual Indicators**: Show numeric values in a radial/circular format
- **Interactive Dials**: Implement knob-style controls (gauges, sliders, rotary switches)
- **Themed Controls**: Apply Office 2016 visual themes to circular sliders
- **Custom Value Ranges**: Set specific min/max ranges with visual divisions

## Component Overview

The **RadialSlider** is an advanced circular slider control that provides:
- Circular/radial value selection with rotating needle
- Customizable minimum and maximum value ranges
- Division markers around the dial
- Two slider styles (Default with hollow circles, Frame with background)
- Five Office 2016 visual themes plus default style
- Customizable colors (background, circles, needle, foreground)
- Two needle types (Straight Line, Dotted Line)
- ValueChanged event for real-time value tracking
- Custom text formatting for division labels

**Key Capabilities:**
- `MinimumValue` and `MaximumValue` properties for range configuration
- `Value` property for getting/setting current selection
- `SliderDivision` property for configuring division markers
- `SliderStyle` enum (Default, Frame)
- `Style` property with 6 visual themes
- `NeedleType` enum (StraightLine, DottedLine)
- Color customization (BackgroundColor, InnerCircleColor, OuterCircleColor, SliderNeedleColor)
- `ValueChanged` event for tracking value changes
- `DrawText` event for custom text formatting

## Documentation and Navigation Guide

### Getting Started
📄 **Read:** [references/getting-started.md](references/getting-started.md)

**When to read:** Setting up RadialSlider for the first time, adding to forms, basic configuration

**Topics covered:**
- Assembly requirements and NuGet installation
- Designer-based setup (drag-and-drop from toolbox)
- Programmatic creation and configuration
- Basic size and property configuration
- Slider styles (Default vs Frame)
- ShowOuterCircle property
- Troubleshooting installation issues

### Value Configuration
📄 **Read:** [references/value-configuration.md](references/value-configuration.md)

**When to read:** Configuring value ranges, divisions, handling value changes, custom text formatting

**Topics covered:**
- MinimumValue and MaximumValue properties
- Value property (get/set current value)
- SliderDivision property for division markers
- ValueChanged event handling
- DrawText event for custom text formatting
- TextType enum (Interval, Pointer, Value)
- DrawTextEventArgs properties (Text, ForeColor, Font)
- Practical examples for value tracking

### Appearance Customization
📄 **Read:** [references/appearance-customization.md](references/appearance-customization.md)

**When to read:** Applying visual themes, customizing colors, changing needle appearance

**Topics covered:**
- BackgroundColor property
- InnerCircleColor and OuterCircleColor properties
- SliderNeedleColor property
- ForeColor property
- NeedleType enum (StraightLine, DottedLine)
- Visual styles (6 themes: Default, Office2016Colorful/White/DarkGray/Black)
- Complete theming examples
- Color combination best practices

## Quick Start Example

Create a basic RadialSlider for volume control:

**C#:**
```csharp
using System;
using System.Windows.Forms;
using Syncfusion.Windows.Forms.Tools;

public partial class VolumeControl : Form
{
    private RadialSlider volumeSlider;
    private Label lblVolume;
    
    public VolumeControl()
    {
        InitializeComponent();
        SetupVolumeControl();
    }
    
    private void SetupVolumeControl()
    {
        // Create radial slider
        volumeSlider = new RadialSlider
        {
            Location = new System.Drawing.Point(50, 50),
            Size = new System.Drawing.Size(250, 250),
            MinimumValue = 0,
            MaximumValue = 100,
            Value = 50,
            SliderDivision = 10,
            SliderStyle = SliderStyles.Frame
        };
        
        // Create label for volume display
        lblVolume = new Label
        {
            Location = new System.Drawing.Point(50, 310),
            Size = new System.Drawing.Size(250, 30),
            Text = "Volume: 50",
            TextAlign = System.Drawing.ContentAlignment.MiddleCenter
        };
        
        // Handle value changes
        volumeSlider.ValueChanged += VolumeSlider_ValueChanged;
        
        // Add to form
        this.Controls.Add(volumeSlider);
        this.Controls.Add(lblVolume);
    }
    
    private void VolumeSlider_ValueChanged(object sender, RadialSlider.ValueChangedEventArgs e)
    {
        lblVolume.Text = $"Volume: {volumeSlider.Value}";
    }
}
```

## Common Patterns

### Pattern 1: Temperature Control with Custom Text

**C#:**
```csharp
private RadialSlider tempSlider;

private void SetupTemperatureControl()
{
    tempSlider = new RadialSlider
    {
        MinimumValue = 0,
        MaximumValue = 100,
        Value = 25,
        SliderDivision = 10,
        Style = RadialSliderStyle.Office2016Colorful
    };
    
    // Custom text formatting with degree symbol
    tempSlider.DrawText += TempSlider_DrawText;
    
    this.Controls.Add(tempSlider);
}

private void TempSlider_DrawText(object sender, RadialSlider.DrawTextEventArgs e)
{
    // Add degree Celsius symbol
    e.Text += "°C";
    
    // Color code by temperature range
    int temp = int.Parse(e.Text.Replace("°C", ""));
    
    if (temp <= 33)
    {
        e.ForeColor = System.Drawing.Color.Blue; // Cold
    }
    else if (temp > 33 && temp <= 66)
    {
       e.ForeColor = System.Drawing.Color.Orange; // Warm
    }
    else
    {
        e.ForeColor = System.Drawing.Color.Red; // Hot
    }
}
```

## Key Properties

| Property | Type | Default | Purpose |
|----------|------|---------|---------|
| `MinimumValue` | `int` | `0` | Starting value of slider range |
| `MaximumValue` | `int` | `10` | Ending value of slider range |
| `Value` | `int` | `0` | Current selected value |
| `SliderDivision` | `int` | `10` | Number of division markers |
| `SliderStyle` | `SliderStyles` | `Default` | Visual style (Default, Frame) |
| `Style` | `RadialSliderStyle` | `Default` | Theme (Default, Office2016*) |
| `BackgroundColor` | `Color` | System default | Background color |
| `InnerCircleColor` | `Color` | System default | Inner circle color |
| `OuterCircleColor` | `Color` | System default | Outer circle color |
| `SliderNeedleColor` | `Color` | System default | Needle color |
| `ForeColor` | `Color` | System default | Text color |
| `NeedleType` | `SliderNeedleType` | `StraightLine` | Needle appearance |
| `ShowOuterCircle` | `bool` | `true` | Show/hide outer circle |

## Common Use Cases

### Volume/Audio Controls
Use RadialSlider for volume knobs, audio level controls, or media player controls where circular dials provide intuitive control.

### Temperature Settings
Implement temperature selectors for thermostats, climate controls, or weather applications with color-coded ranges.

### Speed Controls
Create speed selectors for motors, fans, or animations with visual feedback through division markers.

### Brightness/Opacity Adjustments
Build brightness controls for displays, image editors, or lighting controls with percentage-based ranges.

### Timer/Duration Selection
Implement countdown timers or duration selectors with minute/second divisions around a circular dial.

### Gauge Displays
Create interactive gauges that users can adjust (fuel gauges, pressure gauges, progress indicators).

### Settings Panels
Use for numeric settings that benefit from visual representation (zoom levels, quality settings, intensity controls).

### Data Visualization
Implement interactive data selectors where circular presentation is preferred over linear sliders.

## Additional Resources

- [Syncfusion RadialSlider API Reference](https://help.syncfusion.com/cr/windowsforms/Syncfusion.Windows.Forms.Tools.RadialSlider.html)
- [Control Dependencies](https://help.syncfusion.com/windowsforms/control-dependencies#radialslider)
- Assembly: `Syncfusion.Tools.Windows`
- Namespace: `Syncfusion.Windows.Forms.Tools`