LayoutEngine Class

Provides the base class for implementing layout engines.

System.Object
  System.Windows.Forms.Layout.LayoutEngine

Namespace:  System.Windows.Forms.Layout
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public abstract class LayoutEngine

The LayoutEngine type exposes the following members.

  NameDescription
Protected methodLayoutEngineInitializes a new instance of the LayoutEngine class.
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  NameDescription
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodInitLayoutInitializes the layout engine.
Public methodLayoutRequests that the layout engine perform a layout operation.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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Use the LayoutEngine class when you want to create custom layout behavior at run time. Derive your own class from the LayoutEngine class and override the Layout method to define your custom layout behavior.

The following code example demonstrates the use of the LayoutEngine class to implement custom layout behavior.

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Windows.Forms.Layout;

// This class demonstrates a simple custom layout panel. 
// It overrides the LayoutEngine property of the Panel 
// control to provide a custom layout engine.  
public class DemoFlowPanel : Panel
{
    private DemoFlowLayout layoutEngine;

    public DemoFlowPanel()
    {
    }

    public override LayoutEngine LayoutEngine
    {
        get
        {
            if (layoutEngine == null)
            {
                layoutEngine = new DemoFlowLayout();
            }

            return layoutEngine;
        }
    }
}

// This class demonstrates a simple custom layout engine. 
public class DemoFlowLayout : LayoutEngine
{
    public override bool Layout(
        object container,
        LayoutEventArgs layoutEventArgs)
    {
        Control parent = container as Control;

        // Use DisplayRectangle so that parent.Padding is honored.
        Rectangle parentDisplayRectangle = parent.DisplayRectangle;
        Point nextControlLocation = parentDisplayRectangle.Location;

        foreach (Control c in parent.Controls)
        {
            // Only apply layout to visible controls. 
            if (!c.Visible)
            {
                continue;
            }

            // Respect the margin of the control: 
            // shift over the left and the top.
            nextControlLocation.Offset(c.Margin.Left, c.Margin.Top);

            // Set the location of the control.
            c.Location = nextControlLocation;

            // Set the autosized controls to their  
            // autosized heights. 
            if (c.AutoSize)
            {
                c.Size = c.GetPreferredSize(parentDisplayRectangle.Size);
            }

            // Move X back to the display rectangle origin.
            nextControlLocation.X = parentDisplayRectangle.X;

            // Increment Y by the height of the control  
            // and the bottom margin.
            nextControlLocation.Y += c.Height + c.Margin.Bottom;
        }

        // Optional: Return whether or not the container's  
        // parent should perform layout as a result of this  
        // layout. Some layout engines return the value of  
        // the container's AutoSize property. 

        return false;
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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