Syncfusion WinForms AutoComplete Control

The AutoComplete control provides auto-suggestion functionality for text input fields in Windows Forms applications. It displays a dropdown list of suggestions as users type, enabling faster data entry and improved user experience with intelligent text completion.

When to Use This Skill

Use the AutoComplete control when you need to:

Add auto-suggestion to text input fields
Implement type-ahead search functionality
Create search boxes with intelligent suggestions
Enable URL or email address autocomplete
Build forms with frequently repeated input
Provide filtered suggestions from large datasets
Implement custom dropdown behaviors with multi-column displays

Installation

NuGet Installation

bash

Install-Package Syncfusion.Tools.Windows

Assembly Reference

Add reference to:

```
Syncfusion.Tools.Windows.dll
```
```
Syncfusion.Shared.Base.dll
```

Quick Start

Basic Setup

csharp

using System;
using System.Windows.Forms;
using Syncfusion.Windows.Forms.Tools;

namespace AutoCompleteDemo
{
    public partial class Form1 : Form
    {
        private AutoComplete autoComplete1;
        
        public Form1()
        {
            InitializeComponent();
            
            // Create AutoComplete control
            autoComplete1 = new AutoComplete();
            autoComplete1.Location = new System.Drawing.Point(20, 20);
            autoComplete1.Size = new System.Drawing.Size(200, 20);
            autoComplete1.ParentForm = this;
            
            // Add data source
            autoComplete1.DataSource = new string[] 
            { 
                "Australia", 
                "Austria", 
                "Brazil", 
                "Canada", 
                "China" 
            };
            
            // Add to form
            this.Controls.Add(autoComplete1);
        }
    }
}

Designer Setup

Drag
```
AutoComplete
```
control from Toolbox to Form
Set the
```
ParentForm
```
property to current form
Configure
```
DataSource
```
through Properties window or code
Customize appearance and behavior through Properties

Core Concepts

Data Source

The AutoComplete control can bind to various data sources:

String arrays
Generic collections (List<T>, ArrayList)
DataTable and DataSet
Custom objects with IList interface

Parent Form

The

ParentForm

property must be set to enable the control to display the dropdown suggestion list. This associates the AutoComplete with the parent form's container.

Filtering

Built-in filtering automatically matches user input against the data source, displaying relevant suggestions as the user types.

Navigation Guide

🚀 Getting Started

📄 Read: references/getting-started.md

Installation and assembly references
Creating WinForms application
Adding AutoComplete control via Designer
Adding AutoComplete control programmatically
Basic configuration and setup
Running the application

📊 Working with Data Sources

📄 Read: references/datasource.md

Binding to string collections
Binding to DataTable and DataSet
Binding to custom objects
Multiple data sources
Setting data source at design time
Dynamic data source updates

🎨 Customization

📄 Read: references/customization.md

Visual styles and themes
Font and color customization
Border styles
Dropdown appearance
Auto-size configuration
Column appearance in dropdown
Highlight matching text
Custom rendering

🔧 Working with AutoComplete

📄 Read: references/working-with-autocomplete.md

Auto-complete modes (Suggest, Append, SuggestAppend)
Character casing
Loading behavior
Auto-population
Default suggestions
Clearing and resetting values
Programmatic selection

📑 Multi-Column Dropdown

📄 Read: references/multicolumn-dropdown.md

Enabling multi-column mode
Column configuration
Column headers
Column width and sizing
Displaying multiple fields
Custom column formatting
Images in dropdown items
Grid-like appearance

⚡ Events

📄 Read: references/autocomplete-events.md

AutoCompleteCustomize event
AutoCompleteValueChanged event
BeforeCustomization event
Handling user selections
Validating input
Custom event handlers

🎯 Overview

📄 Read: references/overview.md

Feature overview
Use cases and scenarios
Component architecture
Performance considerations
Best practices

Common Patterns

Pattern 1: Simple String AutoComplete

csharp

AutoComplete autoComplete1 = new AutoComplete();
autoComplete1.Location = new System.Drawing.Point(20, 20);
autoComplete1.Size = new System.Drawing.Size(200, 20);
autoComplete1.ParentForm = this;

// Add string data
autoComplete1.DataSource = new string[] 
{
    "John", "Jane", "Bob", "Alice", "Charlie"
};

this.Controls.Add(autoComplete1);

Pattern 2: DataTable Binding

csharp

AutoComplete autoComplete1 = new AutoComplete();
autoComplete1.ParentForm = this;

// Create DataTable
DataTable dt = new DataTable();
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Email", typeof(string));
dt.Rows.Add("John Doe", "john@example.com");
dt.Rows.Add("Jane Smith", "jane@example.com");

autoComplete1.DataSource = dt;
autoComplete1.DisplayMember = "Name";

this.Controls.Add(autoComplete1);

Pattern 3: Multi-Column Display

csharp

AutoComplete autoComplete1 = new AutoComplete();
autoComplete1.ParentForm = this;
autoComplete1.Style = AutoCompleteStyle.Default;

// Create DataTable with multiple columns
DataTable dt = new DataTable();
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Country", typeof(string));
dt.Columns.Add("City", typeof(string));

dt.Rows.Add("John Doe", "USA", "New York");
dt.Rows.Add("Jane Smith", "UK", "London");
dt.Rows.Add("Bob Johnson", "Canada", "Toronto");

autoComplete1.DataSource = dt;

// Configure columns
autoComplete1.Columns.Add(new AutoCompleteDataColumnInfo("Name", 100));
autoComplete1.Columns.Add(new AutoCompleteDataColumnInfo("Country", 80));
autoComplete1.Columns.Add(new AutoCompleteDataColumnInfo("City", 80));

this.Controls.Add(autoComplete1);

Pattern 4: Custom Filtering with Events

csharp

AutoComplete autoComplete1 = new AutoComplete();
autoComplete1.ParentForm = this;
autoComplete1.DataSource = GetDataSource();

// Handle custom filtering
autoComplete1.AutoCompleteControl.ItemsListBox.DrawItem += 
    new DrawItemEventHandler(ItemsListBox_DrawItem);

void ItemsListBox_DrawItem(object sender, DrawItemEventArgs e)
{
    if (e.Index >= 0)
    {
        // Custom drawing logic
        e.DrawBackground();
        e.Graphics.DrawString(
            autoComplete1.AutoCompleteControl.ItemsListBox.Items[e.Index].ToString(),
            e.Font,
            Brushes.Black,
            e.Bounds);
        e.DrawFocusRectangle();
    }
}

this.Controls.Add(autoComplete1);

Pattern 5: URL/Email AutoComplete

csharp

AutoComplete autoComplete1 = new AutoComplete();
autoComplete1.ParentForm = this;
autoComplete1.Size = new System.Drawing.Size(300, 20);

// Common URLs
autoComplete1.DataSource = new string[]
{
    "http://www.syncfusion.com",
    "http://www.google.com",
    "http://www.microsoft.com",
    "http://www.github.com"
};

// Enable append mode for URL completion
autoComplete1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;

this.Controls.Add(autoComplete1);

Key Properties Reference

Property	Type	Default	Description
`DataSource`	object	null	Data source for suggestions (array, DataTable, etc.)
`ParentForm`	Form	null	Parent form containing the control (required)
`AutoCompleteMode`	AutoCompleteMode	Suggest	Behavior mode: None, Suggest, Append, SuggestAppend
`DisplayMember`	string	""	Property name to display from data source
`ValueMember`	string	""	Property name for internal value
`Columns`	AutoCompleteDataColumnInfoCollection	-	Column configuration for multi-column display
`Style`	AutoCompleteStyle	Default	Visual style of the control
`Text`	string	""	Current text value
`SelectedValue`	object	null	Currently selected value
`CharacterCasing`	CharacterCasing	Normal	Text casing: Normal, Upper, Lower
`LoadOnDemand`	bool	false	Load suggestions on demand
`AutoCompleteControl`	AutoCompletePopup	-	Access to underlying popup control

Events

Common events for the AutoComplete control:

AutoCompleteValueChanged: Triggered when selected value changes
AutoCompleteCustomize: Before displaying the dropdown list
BeforeCustomization: Before applying customization
TextChanged: When text content changes
SelectedIndexChanged: When selection changes
GotFocus: When control receives focus
LostFocus: When control loses focus

Best Practices

Always Set ParentForm: The
```
ParentForm
```
property is mandatory for the dropdown to work properly
Use Appropriate Mode: Choose the right
```
AutoCompleteMode
```
:
- ```
Suggest
```
  : Show dropdown only
- ```
Append
```
  : Auto-complete text only
- ```
SuggestAppend
```
  : Both dropdown and text completion
Optimize Large Datasets: Use
```
LoadOnDemand
```
for large data sources to improve performance
Multi-Column for Complex Data: Use multi-column display when showing related information
Handle Events Properly: Use
```
AutoCompleteValueChanged
```
to respond to user selections
Clear Data Appropriately: Call
```
ResetItems()
```
or set
```
DataSource = null
```
to clear suggestions
Consider Character Casing: Set
```
CharacterCasing
```
based on data type (e.g., Upper for state codes)
Theme Consistency: Use matching visual styles across all Syncfusion controls

Visual Styles

The control supports multiple visual themes:

Default
Office2016Colorful
Office2016White
Office2016Black
Office2016DarkGray
Metro
Office2007
Office2010
VS2010

csharp

autoComplete1.Style = AutoCompleteStyle.Office2016Colorful;

Framework Support

.NET Framework 4.5 and above
.NET 6.0, .NET 7.0, .NET 8.0 (Windows)
.NET Core 3.1 (Windows)

Additional Resources

Related Controls

ComboBoxAdv: Advanced combo box with more customization options
TextBoxExt: Extended text box with additional features
AutoCompleteControl: Standalone popup control for custom scenarios
MultiColumnComboBox: Dedicated multi-column dropdown control

Troubleshooting

Issue: Dropdown doesn't appear

Ensure
```
ParentForm
```
property is set
Check that
```
DataSource
```
contains valid data
Verify control is added to form's Controls collection

Issue: Multi-column not displaying

Set appropriate
```
AutoCompleteStyle
```
Add columns to
```
Columns
```
collection
Ensure DataSource has matching column names

Issue: Performance issues with large datasets

Enable
```
LoadOnDemand
```
property
Reduce the number of columns displayed
Consider filtering data source before binding

Issue: Styling not applied

Ensure Syncfusion theme DLLs are referenced
Apply style after setting DataSource
Check for conflicting custom drawing code

syncfusion-winforms-autocomplete

NPX Install

Tags

SKILL.md Content

Syncfusion WinForms AutoComplete Control

When to Use This Skill

Installation

NuGet Installation

Assembly Reference

Quick Start

Basic Setup

Designer Setup

Core Concepts

Data Source

Parent Form

Filtering

Navigation Guide

🚀 Getting Started

📊 Working with Data Sources

🎨 Customization

🔧 Working with AutoComplete

📑 Multi-Column Dropdown

⚡ Events

🎯 Overview

Common Patterns

Pattern 1: Simple String AutoComplete

Pattern 2: DataTable Binding

Pattern 3: Multi-Column Display

Pattern 4: Custom Filtering with Events

Pattern 5: URL/Email AutoComplete

Key Properties Reference

Events

Best Practices

Visual Styles

Framework Support

Additional Resources

Related Controls

Troubleshooting