How Can WM_SETREDRAW Improve Performance During Complex Control Modifications?

Boosting Performance During Extensive Control Modifications

When making significant changes to controls, preventing unnecessary repainting is crucial for optimal performance. While SuspendLayout and ResumeLayout offer some control, WM_SETREDRAW provides a more robust solution.

The WM_SETREDRAW Advantage

The WM_SETREDRAW Win32 message offers superior control over painting suspension, impacting both parent and child controls. Setting the wParam argument to false effectively halts all painting.

Implementation Details

Here's how to implement painting suspension and resumption:

public static void SuspendDrawing(Control parent)
{
    SendMessage(parent.Handle, WM_SETREDRAW, false, 0);
}

public static void ResumeDrawing(Control parent)
{
    SendMessage(parent.Handle, WM_SETREDRAW, true, 0);
    parent.Refresh();
}

Key Benefits

• Complete Painting Suppression: Eliminates performance overhead caused by repeated repainting.
• Parent and Child Control Impact: Ensures consistent behavior across the control hierarchy.
• Simple and Efficient: Offers a straightforward and effective solution.

Further Exploration

For in-depth information and comprehensive code examples in C# and VB.NET, explore these resources:

• C# Jitter (link to resource if available)
• Suspending Layouts (link to resource if available)
• Extension Methods for Control Using WM_SETREDRAW (link to resource if available)

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