KryptonSplitter

Overview

KryptonSplitter is a Krypton-themed wrapper around the standard System.Windows.Forms.Splitter control. It enables users to resize docked controls within a container while integrating seamlessly with the Krypton palette system for consistent theming across your application.

Key Features

Full Splitter Compatibility: Drop-in replacement with identical API
Krypton Palette Integration: Supports all Krypton palette modes (Global, Professional, Office, etc.)
Design-Time Support: Available in Visual Studio toolbox
Event Forwarding: All standard Splitter events are properly inherited
Visual Consistency: Matches the look and feel of other Krypton controls

Namespace

using Krypton.Toolkit;

Class Declaration

[ToolboxItem(true)]
[ToolboxBitmap(typeof(Splitter))]
[DefaultEvent(nameof(SplitterMoved))]
[DefaultProperty(nameof(Dock))]
[DesignerCategory(@"code")]
[Description(@"Enables the user to resize docked controls.")]
public class KryptonSplitter : Splitter

Inheritance Hierarchy

System.Object
  └─ System.MarshalByRefObject
      └─ System.ComponentModel.Component
          └─ System.Windows.Forms.Control
              └─ System.Windows.Forms.Splitter
                  └─ Krypton.Toolkit.KryptonSplitter

Constructors

KryptonSplitter()

Creates a new instance of KryptonSplitter with default settings.

var splitter = new KryptonSplitter();

Initial Values:

Dock: DockStyle.None
MinSize: (25, 25)
MinExtra: 25
BorderStyle: BorderStyle.None
PaletteMode: PaletteMode.Global
TabStop: false (inherited from Splitter)
Size: (3, 3) (default splitter size)

Properties

Dock

Gets or sets which edge of the parent container the splitter is docked to.

[Category(@"Layout")]
[Description(@"Determines which edge of the parent container a control is docked to.")]
[DefaultValue(DockStyle.None)]
[Localizable(true)]
public DockStyle Dock { get; set; }

DockStyle Enum Values:

None - Not docked (default)
Top - Docked to top edge
Bottom - Docked to bottom edge
Left - Docked to left edge
Right - Docked to right edge
Fill - Fills entire container (not typically used for splitters)

Example:

splitter.Dock = DockStyle.Left;   // Vertical splitter on left
splitter.Dock = DockStyle.Top;    // Horizontal splitter on top
splitter.Dock = DockStyle.Right;  // Vertical splitter on right
splitter.Dock = DockStyle.Bottom; // Horizontal splitter on bottom

Usage Pattern: Typically used between two docked controls:

First control docks to one edge (e.g., DockStyle.Left)
Splitter docks to the same edge (e.g., DockStyle.Left)
Second control docks to fill remaining space (e.g., DockStyle.Fill)

MinSize

Gets or sets the minimum size of the splitter control itself.

[Category(@"Layout")]
[Description(@"The minimum size of the splitter.")]
[Localizable(true)]
[DefaultValue(typeof(Size), "25,25")]
public Size MinSize { get; set; }

Example:

splitter.MinSize = new Size(50, 50);  // Minimum 50x50 pixels
splitter.MinSize = new Size(25, 25);  // Default minimum

Note: This controls the minimum size of the splitter control itself, not the minimum size of the adjacent controls.

MinExtra

Gets or sets the minimum size of the target control that the splitter is docked to.

[Category(@"Layout")]
[Description(@"The minimum size of the target control that the splitter is docked to.")]
[Localizable(true)]
[DefaultValue(25)]
public int MinExtra { get; set; }

Example:

splitter.MinExtra = 100;  // Adjacent control must be at least 100 pixels
splitter.MinExtra = 25;   // Default minimum

Usage:

For vertical splitters (DockStyle.Left or Right): Minimum width of adjacent control
For horizontal splitters (DockStyle.Top or Bottom): Minimum height of adjacent control

SplitPosition

Gets or sets the location of the splitter, in pixels, from the left or top edge of the docked control.

[Category(@"Layout")]
[Description(@"The location of the splitter, in pixels, from the left or top edge of the docked control.")]
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public int SplitPosition { get; set; }

Example:

splitter.SplitPosition = 200;  // Position splitter 200 pixels from edge

Notes:

Not browsable in property grid
Automatically updated when user drags the splitter
Can be set programmatically to position the splitter
For vertical splitters: distance from left edge
For horizontal splitters: distance from top edge

BorderStyle

Gets or sets the border style for the splitter control.

[Category(@"Appearance")]
[Description(@"The border style for the control.")]
[DefaultValue(BorderStyle.None)]
public BorderStyle BorderStyle { get; set; }

BorderStyle Enum Values:

None - No border (default)
FixedSingle - Single-line border
Fixed3D - 3D border

Example:

splitter.BorderStyle = BorderStyle.FixedSingle;  // Single-line border
splitter.BorderStyle = BorderStyle.Fixed3D;      // 3D border
splitter.BorderStyle = BorderStyle.None;         // No border (default)

PaletteMode

Gets or sets the palette mode for Krypton integration.

[Category(@"Visuals")]
[Description(@"Sets the palette mode.")]
[DefaultValue(PaletteMode.Global)]
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public PaletteMode PaletteMode { get; set; }

PaletteMode Values:

Global - Uses the global Krypton palette (default)
ProfessionalSystem - Professional system theme
ProfessionalOffice2003 - Office 2003 theme
ProfessionalOffice2007 - Office 2007 theme
ProfessionalOffice2010 - Office 2010 theme
ProfessionalOffice2013 - Office 2013 theme
SparkleBlue - Sparkle Blue theme
SparkleOrange - Sparkle Orange theme
SparklePurple - Sparkle Purple theme
Custom - Use custom palette (requires Palette property)

Example:

splitter.PaletteMode = PaletteMode.ProfessionalOffice2010;

Note: This property is not browsable in the property grid but can be set programmatically.

Palette

Gets or sets the custom palette (only used when PaletteMode is Custom).

[Category(@"Visuals")]
[Description(@"Sets the custom palette to be used.")]
[DefaultValue(null)]
[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public PaletteBase? Palette { get; set; }

Example:

var customPalette = new KryptonPalette();
// Configure custom palette...
splitter.PaletteMode = PaletteMode.Custom;
splitter.Palette = customPalette;

Note: This property is not browsable in the property grid but can be set programmatically.

Inherited Properties

Since KryptonSplitter inherits from Splitter, it also has access to all standard Control and Splitter properties:

Common Control Properties

BackColor - Background color
ForeColor - Foreground color
Enabled - Whether the control is enabled
Visible - Whether the control is visible
Size - Size of the control
Location - Location of the control
Width - Width of the control
Height - Height of the control
TabStop - Whether the control can receive focus via Tab key (default: false)

Splitter-Specific Properties

Cursor - Cursor displayed when hovering over the splitter
DefaultCursor - Default cursor for the splitter

Events

SplitterMoved

Occurs when the splitter control is moved.

[Category(@"Behavior")]
[Description(@"Occurs when the splitter control is moved.")]
public event SplitterEventHandler? SplitterMoved;

Event Handler Signature:

void OnSplitterMoved(object sender, SplitterEventArgs e)

SplitterEventArgs Properties:

X (int): X-coordinate of the splitter
Y (int): Y-coordinate of the splitter
SplitX (int): X-coordinate where the splitter was moved
SplitY (int): Y-coordinate where the splitter was moved

Example:

splitter.SplitterMoved += (sender, e) =>
{
    Console.WriteLine($"Splitter moved to: ({e.SplitX}, {e.SplitY})");
    Console.WriteLine($"SplitPosition: {splitter.SplitPosition}");
    
    // Update UI, save position, etc.
    SaveSplitterPosition(splitter.SplitPosition);
};

SplitterMoving

Occurs when the splitter control is in the process of being moved.

[Category(@"Behavior")]
[Description(@"Occurs when the splitter control is in the process of being moved.")]
public event SplitterEventHandler? SplitterMoving;

Example:

splitter.SplitterMoving += (sender, e) =>
{
    // Update preview, show position indicator, etc.
    UpdatePositionIndicator(e.SplitX, e.SplitY);
};

Note: This event fires continuously while the user is dragging the splitter.

Usage Examples

Basic Vertical Splitter

using Krypton.Toolkit;
using System.Windows.Forms;

public partial class MainForm : KryptonForm
{
    private KryptonPanel _leftPanel;
    private KryptonSplitter _splitter;
    private KryptonPanel _rightPanel;

    public MainForm()
    {
        InitializeComponent();
        SetupSplitter();
    }

    private void SetupSplitter()
    {
        // Left panel
        _leftPanel = new KryptonPanel
        {
            Dock = DockStyle.Left,
            Width = 200,
            BackColor = Color.LightGray
        };
        Controls.Add(_leftPanel);

        // Splitter
        _splitter = new KryptonSplitter
        {
            Dock = DockStyle.Left,
            MinExtra = 100,  // Right panel minimum width
            MinSize = 25      // Left panel minimum width
        };
        _splitter.SplitterMoved += OnSplitterMoved;
        Controls.Add(_splitter);

        // Right panel
        _rightPanel = new KryptonPanel
        {
            Dock = DockStyle.Fill,
            BackColor = Color.White
        };
        Controls.Add(_rightPanel);
    }

    private void OnSplitterMoved(object sender, SplitterEventArgs e)
    {
        // Save position or update UI
        Properties.Settings.Default.SplitterPosition = _splitter.SplitPosition;
    }
}

Horizontal Splitter

private void SetupHorizontalSplitter()
{
    // Top panel
    var topPanel = new KryptonPanel
    {
        Dock = DockStyle.Top,
        Height = 150,
        BackColor = Color.LightBlue
    };
    Controls.Add(topPanel);

    // Horizontal splitter
    var splitter = new KryptonSplitter
    {
        Dock = DockStyle.Top,
        MinExtra = 50,   // Bottom panel minimum height
        MinSize = 50     // Top panel minimum height
    };
    Controls.Add(splitter);

    // Bottom panel
    var bottomPanel = new KryptonPanel
    {
        Dock = DockStyle.Fill,
        BackColor = Color.LightGreen
    };
    Controls.Add(bottomPanel);
}

Three-Panel Layout

private void SetupThreePanelLayout()
{
    // Left panel
    var leftPanel = new KryptonPanel
    {
        Dock = DockStyle.Left,
        Width = 150
    };
    Controls.Add(leftPanel);

    // First splitter (vertical)
    var splitter1 = new KryptonSplitter
    {
        Dock = DockStyle.Left,
        MinExtra = 200,
        MinSize = 100
    };
    Controls.Add(splitter1);

    // Middle panel
    var middlePanel = new KryptonPanel
    {
        Dock = DockStyle.Left,
        Width = 300
    };
    Controls.Add(middlePanel);

    // Second splitter (vertical)
    var splitter2 = new KryptonSplitter
    {
        Dock = DockStyle.Left,
        MinExtra = 200,
        MinSize = 100
    };
    Controls.Add(splitter2);

    // Right panel
    var rightPanel = new KryptonPanel
    {
        Dock = DockStyle.Fill
    };
    Controls.Add(rightPanel);
}

Splitter with Saved Position

public partial class MainForm : KryptonForm
{
    private KryptonSplitter _splitter;

    public MainForm()
    {
        InitializeComponent();
        SetupSplitter();
        LoadSplitterPosition();
    }

    private void SetupSplitter()
    {
        var leftPanel = new KryptonPanel { Dock = DockStyle.Left, Width = 200 };
        Controls.Add(leftPanel);

        _splitter = new KryptonSplitter
        {
            Dock = DockStyle.Left,
            MinExtra = 100,
            MinSize = 100
        };
        _splitter.SplitterMoved += OnSplitterMoved;
        Controls.Add(_splitter);

        var rightPanel = new KryptonPanel { Dock = DockStyle.Fill };
        Controls.Add(rightPanel);
    }

    private void LoadSplitterPosition()
    {
        var savedPosition = Properties.Settings.Default.SplitterPosition;
        if (savedPosition > 0)
        {
            _splitter.SplitPosition = savedPosition;
        }
    }

    private void OnSplitterMoved(object sender, SplitterEventArgs e)
    {
        Properties.Settings.Default.SplitterPosition = _splitter.SplitPosition;
        Properties.Settings.Default.Save();
    }
}

Splitter with Custom Palette

private void SetupSplitterWithCustomPalette()
{
    var splitter = new KryptonSplitter
    {
        Dock = DockStyle.Left,
        PaletteMode = PaletteMode.ProfessionalOffice2010
    };
    Controls.Add(splitter);
}

Splitter in User Control

public partial class ResizablePanelControl : UserControl
{
    private KryptonSplitter _splitter;

    public ResizablePanelControl()
    {
        InitializeComponent();
        SetupSplitter();
    }

    private void SetupSplitter()
    {
        var panel1 = new KryptonPanel
        {
            Dock = DockStyle.Left,
            Width = 200
        };
        Controls.Add(panel1);

        _splitter = new KryptonSplitter
        {
            Dock = DockStyle.Left,
            MinExtra = 150,
            MinSize = 150
        };
        Controls.Add(_splitter);

        var panel2 = new KryptonPanel
        {
            Dock = DockStyle.Fill
        };
        Controls.Add(panel2);
    }

    public int SplitterPosition
    {
        get => _splitter.SplitPosition;
        set => _splitter.SplitPosition = value;
    }
}

Best Practices

1. Control Order Matters

Add controls to the container in the correct order:

// Correct order:
Controls.Add(leftPanel);      // 1. First panel
Controls.Add(splitter);       // 2. Splitter
Controls.Add(rightPanel);     // 3. Second panel (fills remaining)

2. Set Minimum Sizes

Always set MinExtra and MinSize to prevent panels from becoming too small:

splitter.MinExtra = 100;  // Minimum size for adjacent control
splitter.MinSize = 50;    // Minimum size for control before splitter

3. Save and Restore Position

Save the splitter position for user preferences:

// Save
Properties.Settings.Default.SplitterPosition = splitter.SplitPosition;
Properties.Settings.Default.Save();

// Restore
if (Properties.Settings.Default.SplitterPosition > 0)
{
    splitter.SplitPosition = Properties.Settings.Default.SplitterPosition;
}

4. Handle SplitterMoved Event

Use the SplitterMoved event to respond to user actions:

splitter.SplitterMoved += (sender, e) =>
{
    // Update layout, save preferences, refresh content, etc.
};

5. Use Appropriate Dock Values

For vertical splitters: Use DockStyle.Left or DockStyle.Right
For horizontal splitters: Use DockStyle.Top or DockStyle.Bottom
Never use DockStyle.Fill for splitters

6. Consider BorderStyle

Set BorderStyle for visual feedback:

splitter.BorderStyle = BorderStyle.FixedSingle;  // Visible border

7. Set TabStop to False

Splitters should not receive keyboard focus:

splitter.TabStop = false;  // Default, but good to be explicit

Integration with Krypton Palette System

Using Global Palette

var splitter = new KryptonSplitter();
// Uses global palette automatically

Using Specific Theme

splitter.PaletteMode = PaletteMode.ProfessionalOffice2010;

Using Custom Palette

var customPalette = new KryptonPalette();
// Configure palette...
splitter.PaletteMode = PaletteMode.Custom;
splitter.Palette = customPalette;

Responding to Palette Changes

The splitter automatically responds to global palette changes when PaletteMode is set to Global:

// When global palette changes, splitter automatically updates
KryptonManager.GlobalPalette = new PaletteOffice2010Blue();
// Splitter will reflect the new palette

Layout Considerations

Vertical Splitter Layout

┌─────────┬──────────────┐
│         │              │
│  Left   │   Splitter   │   Right
│  Panel  │              │   Panel
│         │              │
└─────────┴──────────────┘

Dock Values:

Left Panel: DockStyle.Left
Splitter: DockStyle.Left
Right Panel: DockStyle.Fill

Horizontal Splitter Layout

┌──────────────────────┐
│     Top Panel        │
├──────────────────────┤
│     Splitter         │
├──────────────────────┤
│    Bottom Panel      │
└──────────────────────┘

Dock Values:

Top Panel: DockStyle.Top
Splitter: DockStyle.Top
Bottom Panel: DockStyle.Fill

Common Patterns

Explorer-Style Layout

// Tree view on left, content on right
var treeView = new KryptonTreeView { Dock = DockStyle.Left, Width = 200 };
Controls.Add(treeView);

var splitter = new KryptonSplitter { Dock = DockStyle.Left, MinExtra = 300 };
Controls.Add(splitter);

var contentPanel = new KryptonPanel { Dock = DockStyle.Fill };
Controls.Add(contentPanel);

Property Grid Layout

// Properties on right, content on left
var contentPanel = new KryptonPanel { Dock = DockStyle.Fill };
Controls.Add(contentPanel);

var splitter = new KryptonSplitter { Dock = DockStyle.Right, MinExtra = 200 };
Controls.Add(splitter);

var propertyGrid = new KryptonPropertyGrid { Dock = DockStyle.Right, Width = 300 };
Controls.Add(propertyGrid);

Limitations and Considerations

Deprecated Control: The underlying Splitter control is deprecated in favor of SplitContainer. Consider using KryptonSplitContainer for new development.
Control Order: The order in which controls are added to the container is critical for proper layout.
Docking Required: Splitters must be docked to function properly. They don't work well with absolute positioning.
Minimum Sizes: Always set appropriate minimum sizes to prevent UI issues.
Visual Appearance: The splitter's visual appearance is limited compared to KryptonSplitContainer.

Troubleshooting

Splitter Not Appearing

Ensure controls are added in correct order
Verify Dock property is set correctly
Check that Visible is true
Verify Size is appropriate (default is 3x3 pixels)

Splitter Not Resizing

Check MinExtra and MinSize values
Verify adjacent controls are properly docked
Ensure splitter is between two docked controls

Splitter Position Not Saving

Save position in SplitterMoved event
Restore position after controls are added and layout is complete
Consider using Form.Load or Form.Shown event

Visual Inconsistencies

Set PaletteMode to match application theme
Use KryptonSplitContainer for better visual integration

Migration from Standard Splitter

To migrate from standard Splitter to KryptonSplitter:

// Before
var splitter = new Splitter();

// After
var splitter = new KryptonSplitter();

All properties and events remain the same - it's a drop-in replacement.

KryptonSplitContainer - Modern alternative with better visual integration
KryptonSeparator - For visual separators without resizing
KryptonPanel - Container panels for splitter layouts
KryptonManager - For global palette management

Notes

KryptonSplitter is provided for compatibility with existing code that uses the standard Splitter control
For new development, consider using KryptonSplitContainer which provides better visual integration and more features
The splitter automatically integrates with the Krypton palette system for consistent theming

KryptonSplitter

Overview

Key Features

Namespace

Class Declaration

Inheritance Hierarchy

Constructors

KryptonSplitter()

Properties

Dock

MinSize

MinExtra

SplitPosition

BorderStyle

PaletteMode

Palette

Inherited Properties

Common Control Properties

Splitter-Specific Properties

Events

SplitterMoved

SplitterMoving

Usage Examples

Basic Vertical Splitter

Horizontal Splitter

Three-Panel Layout

Splitter with Saved Position

Splitter with Custom Palette

Splitter in User Control

Best Practices

1. Control Order Matters

2. Set Minimum Sizes

3. Save and Restore Position

4. Handle SplitterMoved Event

5. Use Appropriate Dock Values

6. Consider BorderStyle

7. Set TabStop to False

Integration with Krypton Palette System

Using Global Palette

Using Specific Theme

Using Custom Palette

Responding to Palette Changes

Layout Considerations

Vertical Splitter Layout

Horizontal Splitter Layout

Common Patterns

Explorer-Style Layout

Property Grid Layout

Limitations and Considerations

Troubleshooting

Splitter Not Appearing

Splitter Not Resizing

Splitter Position Not Saving

Visual Inconsistencies

Migration from Standard Splitter

Related Components

See Also

Notes