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ToolStripRenderer Class

Note: This class is new in the .NET Framework version 2.0.

Handles the painting functionality for ToolStrip objects.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public abstract class ToolStripRenderer
public abstract class ToolStripRenderer
public abstract class ToolStripRenderer

With the ToolStripRenderer class, you can easily apply a particular style or theme to a ToolStrip object. Rather than custom painting a ToolStrip and the ToolStripItem objects it contains, you set the ToolStrip.Renderer property to an object that inherits from ToolStripRenderer. The painting specified by the ToolStripRenderer is applied to the ToolStrip, as well as the items it contains.

The following code example demonstrates how to implement a custom ToolStripRenderer class. The GridStripRenderer class customizes three aspects of the GridStrip control's appearance: GridStrip border, ToolStripButton border, and ToolStripButton image. For a full code listing, see How to: Implement a Custom ToolStripRenderer.

// This class implements a custom ToolStripRenderer for the 
// GridStrip control. It customizes three aspects of the 
// GridStrip control's appearance: GridStrip border, 
// ToolStripButton border, and ToolStripButton image.
internal class GridStripRenderer : ToolStripRenderer
{   
    // The style of the empty cell's text.
    private static StringFormat style = new StringFormat();

    // The thickness (width or height) of a 
    // ToolStripButton control's border.
    static int borderThickness = 2;

    // The main bitmap that is the source for the 
    // subimagesthat are assigned to individual 
    // ToolStripButton controls.
    private Bitmap bmp = null;

    // The brush that paints the background of 
    // the GridStrip control.
    private Brush backgroundBrush = null;

    // This is the static constructor. It initializes the
    // StringFormat for drawing the text in the empty cell.
    static GridStripRenderer()
    {
        style.Alignment = StringAlignment.Center;
        style.LineAlignment = StringAlignment.Center;
    }

    // This method initializes the GridStripRenderer by
    // creating the image that is used as the source for
    // the individual button images.
    protected override void Initialize(ToolStrip ts)
    {
        base.Initialize(ts);

        this.InitializeBitmap(ts);
    }

    // This method initializes an individual ToolStripButton
    // control. It copies a subimage from the GridStripRenderer's
    // main image, according to the position and size of 
    // the ToolStripButton.
    protected override void InitializeItem(ToolStripItem item)
    {
        base.InitializeItem(item);

        GridStrip gs = item.Owner as GridStrip;

        // The empty cell does not receive a subimage.
        if ((item is ToolStripButton) &&
            (item != gs.EmptyCell))
        {
            // Copy the subimage from the appropriate 
            // part of the main image.
            Bitmap subImage = bmp.Clone(
                item.Bounds,
                PixelFormat.Undefined);

            // Assign the subimage to the ToolStripButton
            // control's Image property.
            item.Image = subImage;
        }
    }

    // This utility method creates the main image that
    // is the source for the subimages of the individual 
    // ToolStripButton controls.
    private void InitializeBitmap(ToolStrip toolStrip)
    {
        // Create the main bitmap, into which the image is drawn.
        this.bmp = new Bitmap(
            toolStrip.Size.Width,
            toolStrip.Size.Height);

        // Draw a fancy pattern. This could be any image or drawing.
        using (Graphics g = Graphics.FromImage(bmp))
        {
            // Draw smoothed lines.
            g.SmoothingMode = SmoothingMode.AntiAlias;
            
            // Draw the image. In this case, it is 
            // a number of concentric ellipses. 
            for (int i = 0; i < toolStrip.Size.Width; i += 8)
            {
                g.DrawEllipse(Pens.Blue, 0, 0, i, i);
            }
        }
    }

    // This method draws a border around the GridStrip control.
    protected override void OnRenderToolStripBorder(
        ToolStripRenderEventArgs e)
    {
        base.OnRenderToolStripBorder(e);

        ControlPaint.DrawFocusRectangle(
            e.Graphics,
            e.AffectedBounds,
            SystemColors.ControlDarkDark,
            SystemColors.ControlDarkDark);
    }

    // This method renders the GridStrip control's background.
    protected override void OnRenderToolStripBackground(
        ToolStripRenderEventArgs e)
    {
        base.OnRenderToolStripBackground(e);

        // This late initialization is a workaround. The gradient
        // depends on the bounds of the GridStrip control. The bounds 
        // are dependent on the layout engine, which hasn't fully
        // performed layout by the time the Initialize method runs.
        if (this.backgroundBrush == null)
        {
            this.backgroundBrush = new LinearGradientBrush(
               e.ToolStrip.ClientRectangle,
               SystemColors.ControlLightLight,
               SystemColors.ControlDark,
               90,
               true);
        }

        // Paint the GridStrip control's background.
        e.Graphics.FillRectangle(
            this.backgroundBrush, 
            e.AffectedBounds);
    }

    // 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);
        }
    }
}

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

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0

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