Drawing a TextBox in an extended Glass Frame w/o WPF

Question

I am trying to draw a TextBox on the extended glass frame of my form. I won't describe this technique, it's well-known. Here's an example for those who haven't heard of it: http://www.danielmoth.com/Blog/Vista-Glass-In-C.aspx

The thing is, it is complex to draw over this glass frame. Since black is considered to be the 0-alpha color, anything black disappears.

There are apparently ways of countering this problem: drawing complex GDI+ shapes are not affected by this alpha-ness. For example, this code can be used to draw a Label on glass (note: GraphicsPath is used instead of DrawString in order to get around the horrible ClearType problem):

public class GlassLabel : Control
{
    public GlassLabel()
    {
        this.BackColor = Color.Black;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        GraphicsPath font = new GraphicsPath();

        font.AddString(
            this.Text,
            this.Font.FontFamily,
            (int)this.Font.Style,
            this.Font.Size,
            Point.Empty,
            StringFormat.GenericDefault);

        e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
        e.Graphics.FillPath(new SolidBrush(this.ForeColor), font);
    }
}

Similarly, such an approach can be used to create a container on the glass area. Note the use of the polygons instead of the rectangle - when using the rectangle, its black parts are considered as alpha.

public class GlassPanel : Panel
{
    public GlassPanel()
    {
        this.BackColor = Color.Black;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        Point[] area = new Point[]
            {
                new Point(0, 1),
                new Point(1, 0),
                new Point(this.Width - 2, 0),
                new Point(this.Width - 1, 1),
                new Point(this.Width -1, this.Height - 2),
                new Point(this.Width -2, this.Height-1),
                new Point(1, this.Height -1),
                new Point(0, this.Height - 2)
            };

        Point[] inArea = new Point[]
            {
                new Point(1, 1),
                new Point(this.Width - 1, 1),
                new Point(this.Width - 1, this.Height - 1),
                new Point(this.Width - 1, this.Height - 1),
                new Point(1, this.Height - 1)
            };

        e.Graphics.FillPolygon(new SolidBrush(Color.FromArgb(240, 240, 240)), inArea);
        e.Graphics.DrawPolygon(new Pen(Color.FromArgb(55, 0, 0, 0)), area);

        base.OnPaint(e);
    }
}

Now my problem is: How can I draw a TextBox? After lots of Googling, I came up with the following solutions:

• Subclassing the TextBox's OnPaint method. This is possible, although I could not get it to work properly. It should involve painting some magic things I don't know how to do yet.
• Making my own custom TextBox, perhaps on a TextBoxBase. If anyone has good, valid and working examples, and thinks this could be a good overall solution, please tell me.
• Using BufferedPaintSetAlpha. (http://msdn.microsoft.com/en-us/library/ms649805.aspx). The downsides of this method may be that the corners of the textbox might look odd, but I can live with that. If anyone knows how to implement that method properly from a Graphics object, please tell me. I personally don't, but this seems the best solution so far. To be honest, I found a great C++ article, but I am way too lazy to convert it. http://weblogs.asp.net/kennykerr/archive/2007/01/23/controls-and-the-desktop-window-manager.aspx

Note: If I ever succeed with the BufferedPaint methods, I swear to s/o that I will make a simple DLL with all the common Windows Forms controls drawable on glass.

Answer 1

I have spent some time on this topic a while ago. Basically what you need is a transparent textbox. My initial approach was to use codeproject AlphaBlendTextBox - A transparent/translucent textbox for .NET. But I was having a few difficult to solve issues with that control. After a while I have found required solution, it will work only on Windows XP and up. As well to get this control to behave like single line text box set RichTextBox.Multiline to false.

// Source:
// http://www.dotnetjunkies.com/WebLog/johnwood/archive/2006/07/04/transparent_richtextbox.aspx

// It seems there are 4 versions of the RichEdit control out there - when I'm talking about the 
// RichEdit control, I'm talking about the C DLL that either comes with Windows or some version 
// of Office. The files are named either RICHEDXX.DLL (XX is the version number), or MSFTEDIT.DLL 
// and they're in the System32 folder.

// .Net RichTextBox control is bound to version 2. The biggest problem with this version (at least 
// for me) is that it does not render properly if you try to make the window transparent. Later versions, 
// however, do.

// We can fix that. If you create a control deriving from the original RichTextBox control, but overriding 
// the CreateParams property, you can put in a new Windows class name (this is the window class name, 
// nothing to do with classes in the C# sense). This effectively gives us a free upgrade. When the .Net 
// RichTextBox control instantiates, it will now use the latest RichEdit control and not the old, archaic, 
// version 2.

// There are other benefits too - version 3 and beyond of the RichEdit control support quite an extensive 
// array of layout features, such as tables and full text justification. This is the version of the RichEdit 
// that WordPad uses in Windows XP. To really see what it's capable of displaying you can create documents in 
// Word and save them in RTF, load these into the new RichEdit and in a lot of cases it'll look identical, 
// it's that powerful. A full list of features can be found here:
// http://msdn.microsoft.com/library/default.asp?url=/library/en-us/shellcc/platform/commctls/richedit/richeditcontrols/aboutricheditcontrols.asp

// There are a couple of caveats:
// 
// 1. The control that this is bound to was shipped with Windows XP, and so this code won't work in 
//    Windows 2000 or earlier. 
//
// 2. The RichTextBox control in C# only knows about version 2, so the interface doesn't include 
//    all the new features. You can wrap a few of the features yourself through new methods on the 
//    RichEdit class.

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

internal class RichEdit : RichTextBox
{

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr LoadLibrary(string lpFileName);

    protected override CreateParams CreateParams
    {
        get
        {
            CreateParams parameters = base.CreateParams;
            if (LoadLibrary("msftedit.dll") != IntPtr.Zero)
            {
                parameters.ExStyle |= 0x020; // transparent
                parameters.ClassName = "RICHEDIT50W";
            }
            return parameters;
        }
    }
}