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ToolStripRenderer.OnRenderButtonBackground Method

Raises the RenderButtonBackground event.

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

protected virtual void OnRenderButtonBackground(
	ToolStripItemRenderEventArgs e
)

Parameters

e
Type: System.Windows.Forms.ToolStripItemRenderEventArgs
A ToolStripRenderEventArgs that contains the event data.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

The OnRenderButtonBackground method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When overriding OnRenderButtonBackground in a derived class, be sure to call the base class's OnRenderButtonBackground method so that registered delegates receive the event.

The following code example demonstrates how to override the OnRenderButtonBackground method to draw a border around a ToolStripButton control's Image. This code example is part of a larger example provided for the ToolStripRenderer class.


// This method draws a border around the button's image. If the background
// to be rendered belongs to the empty cell, a string is drawn. Otherwise,
// a border is drawn at the edges of the button.
protected override void OnRenderButtonBackground(
    ToolStripItemRenderEventArgs e)
{
    base.OnRenderButtonBackground(e);

    // Define some local variables for convenience.
    Graphics g = e.Graphics;
    GridStrip gs = e.ToolStrip as GridStrip;
    ToolStripButton gsb = e.Item as ToolStripButton;

    // Calculate the rectangle around which the border is painted.
    Rectangle imageRectangle = new Rectangle(
        borderThickness, 
        borderThickness, 
        e.Item.Width - 2 * borderThickness, 
        e.Item.Height - 2 * borderThickness);

    // If rendering the empty cell background, draw an 
    // explanatory string, centered in the ToolStripButton.
    if (gsb == gs.EmptyCell)
    {
        e.Graphics.DrawString(
            "Drag to here",
            gsb.Font, 
            SystemBrushes.ControlDarkDark,
            imageRectangle, style);
    }
    else
    {
        // If the button can be a drag source, paint its border red.
        // otherwise, paint its border a dark color.
        Brush b = gs.IsValidDragSource(gsb) ? b = 
            Brushes.Red : SystemBrushes.ControlDarkDark;

        // Draw the top segment of the border.
        Rectangle borderSegment = new Rectangle(
            0, 
            0, 
            e.Item.Width, 
            imageRectangle.Top);
        g.FillRectangle(b, borderSegment);

        // Draw the right segment.
        borderSegment = new Rectangle(
            imageRectangle.Right,
            0,
            e.Item.Bounds.Right - imageRectangle.Right,
            imageRectangle.Bottom);
        g.FillRectangle(b, borderSegment);

        // Draw the left segment.
        borderSegment = new Rectangle(
            0,
            0,
            imageRectangle.Left,
            e.Item.Height);
        g.FillRectangle(b, borderSegment);

        // Draw the bottom segment.
        borderSegment = new Rectangle(
            0,
            imageRectangle.Bottom,
            e.Item.Width,
            e.Item.Bounds.Bottom - imageRectangle.Bottom);
        g.FillRectangle(b, borderSegment);
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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