I Code, Therefore I Am

Today we’re going to look at using Aero in your WinForms applications. I’ve been asked this so many times that I figured this would be a good thing to blog about.

NOTE: Requires Vista or Windows 7 with Aero enabled, so we’ll need to check for that.

So let’s get started, first we need to pick the Win32 API methods we’ll be using, for this we’ll be using:

• DwmExtendFrameIntoClientArea
• DwmIsCompositionEnabled

We’ll also need the MARGINS structure as well. What I did was make a seperate class for this, I named mine Win32. To use the Win32 we’ll need a reference to the System.Runtime.InteropService Namespace.

The struct looks like this:

[StructLayout(LayoutKind.Sequential)]
public struct MARGINS
{
    public int Left;
    public int Right;
    public int Top;
    public int Bottom;
}

Now we need to declare our Win32 methods:

[DllImport("dwmapi.dll", PreserveSig = false)]
public static extern void DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS margins);

[DllImport("dwmapi.dll", PreserveSig = false)]
public static extern bool DwmIsCompositionEnabled();

So our Win32.cs looks like this:

using System;
using System.Runtime.InteropServices;

namespace Aero.Code
{
    public class Win32
    {
        [StructLayout(LayoutKind.Sequential)]
        public struct MARGINS
        {
            public int Left;
            public int Right;
            public int Top;
            public int Bottom;
        }

        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern void DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS margins);

        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern bool DwmIsCompositionEnabled();
    }
}

Simple enough wouldn’t you say. Now that we have our class done we can implement it in our form(s). As I stated earlier we need to make sure the user is running the proper version of windows, we’ll check this in the OnLoad method:

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);

    if (!Win32.DwmIsCompositionEnabled())
    {
        MessageBox.Show("To use the Aero effect you need either Vista or Windows 7 with Aero enabled", "Aero Effect Error", MessageBoxButtons.OK);
        Application.Exit();
    }
    else
        GlassRegion();
            
}

Now we check and display an error before closing the application, otherwise we can GlassRegion to create our Aero. GlassRegion is where we set the glass look, it’s very simple and straight forward:

/// <summary>
/// Use the form padding values to define a Glass margin
/// </summary>
private void GlassRegion()
{
    // Set up the glass effect using padding as the defining glass region
    if (Win32.DwmIsCompositionEnabled())
    {
        _glassMargins = new Win32.MARGINS();
        _glassMargins.Top = Padding.Top + 5;
        _glassMargins.Left = Padding.Left + 5;
        _glassMargins.Bottom = Padding.Bottom + 5;
        _glassMargins.Right = Padding.Right + 5;
        Win32.DwmExtendFrameIntoClientArea(this.Handle, ref _glassMargins);
    }
}

You can change the margin to whatever size you wish. FInally we need to override the OnPaintBackground of the form, which looks like this when we get finished with it:

/// <summary>
/// Override the OnPaintBackground method, to draw the desired
/// Glass regions black and display as Glass
/// </summary>
protected override void OnPaintBackground(PaintEventArgs e)
{
    base.OnPaint(e);

    if (Win32.DwmIsCompositionEnabled())
    {
        e.Graphics.Clear(Color.Black);

        // put back the original form background for non-glass area
        var rectangle = new Rectangle(_glassMargins.Left, _glassMargins.Top,
        this.ClientRectangle.Width - _glassMargins.Left - _glassMargins.Right,
        this.ClientRectangle.Height - _glassMargins.Top - _glassMargins.Bottom);
        var brush = new SolidBrush(this.BackColor);
        e.Graphics.FillRectangle(brush, rectangle);
    }
}

that’s it, now the form(s) we apply this to will have the Aero glass effect. Not nearly as complicated as you may have thought. I hope you find this informative.

Happy Coding!

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This entry was posted by Richard McCutchen on Friday, January 27th, 2012 at 10:55 and is filed under C#, P/Invoke. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.