Click passthrough on forms/controls

27 Jan 2006 2:24 AM

Timothy

Hi everyone,
I hope someone can tell me an answer to this.

I want to make a form that is transparent, however, when you click it, the
event does NOT fire. Instead I want the applicatoins/desktop to be clicked
instead.

So its basically like a dead form.

I have seen this funcitonality on a Winamp plugin called Toaster. Anybody
know how to do it?

Thanks heaps in advance,

Tim.

27 Jan 2006 6:30 PM

Gabriele G. Ponti

I don't believe it's supported by the .NET Framework, but if you don't mind
doing PInvoke you can use the Windows regions APIs.

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

namespace RegionsDemo
{
    public partial class RegionsDemoForm : Form
    {
        [DllImport( "gdi32.dll" )]
        static extern IntPtr CreateRectRgn( int nLeftRect, int nTopRect, int
nRightRect, int nBottomRect );

        public enum CombineRgnStyles : int
        {
            RGN_AND = 1,
            RGN_OR = 2,
            RGN_XOR = 3,
            RGN_DIFF = 4,
            RGN_COPY = 5,
            RGN_MIN = RGN_AND,
            RGN_MAX = RGN_COPY
        }

        [DllImport( "gdi32.dll" )]
        static extern int CombineRgn( IntPtr hrgnDest, IntPtr hrgnSrc1,
IntPtr hrgnSrc2, CombineRgnStyles fnCombineMode );

        [DllImport( "user32.dll" )]
        static extern int SetWindowRgn( IntPtr hWnd, IntPtr hRgn, bool
bRedraw );

        [DllImport( "gdi32.dll" )]
        static extern bool DeleteObject( IntPtr hObject );

        public RegionsDemoForm()
        {
            InitializeComponent();
            AddTransparentRegion();
        }

        private void AddTransparentRegion()
        {
            IntPtr windowRgn = CreateRectRgn( 0, 0, this.Width,
this.Height );
            IntPtr areaRgn = CreateRectRgn( 50, 50, 200, 200 );
            IntPtr combinedRgn = CreateRectRgn( 0, 0, 0, 0 );

            CombineRgn( combinedRgn, windowRgn, areaRgn,
CombineRgnStyles.RGN_XOR );

            SetWindowRgn( this.Handle, combinedRgn, true );

            DeleteObject( combinedRgn );
            DeleteObject( areaRgn );
            DeleteObject( combinedRgn );
        }

        private void Form1_Resize( object sender, EventArgs e )
        {
            AddTransparentRegion();
        }

    }
}

28 Jan 2006 1:44 AM

Timothy

Hi, thanks for your reply.

However, its just not what I'm looking for. I want to be able to click on a
label, and not have it be clicked.

Your code is close to what I'm looking for, however, the parts you can click
through are completely transparent. I only want it a little transparent.

Any ideas of how to do it?

Show quote

"Gabriele G. Ponti" <ggponti.at.hotmail.com> wrote in message
news:ebpI3%232IGHA.1760@TK2MSFTNGP10.phx.gbl...
>I don't believe it's supported by the .NET Framework, but if you don't mind
>doing PInvoke you can use the Windows regions APIs.
>
>
> using System;
> using System.Windows.Forms;
> using System.Runtime.InteropServices;
>
> namespace RegionsDemo
> {
>    public partial class RegionsDemoForm : Form
>    {
>        [DllImport( "gdi32.dll" )]
>        static extern IntPtr CreateRectRgn( int nLeftRect, int nTopRect,
> int nRightRect, int nBottomRect );
>
>        public enum CombineRgnStyles : int
>        {
>            RGN_AND = 1,
>            RGN_OR = 2,
>            RGN_XOR = 3,
>            RGN_DIFF = 4,
>            RGN_COPY = 5,
>            RGN_MIN = RGN_AND,
>            RGN_MAX = RGN_COPY
>        }
>
>        [DllImport( "gdi32.dll" )]
>        static extern int CombineRgn( IntPtr hrgnDest, IntPtr hrgnSrc1,
> IntPtr hrgnSrc2, CombineRgnStyles fnCombineMode );
>
>        [DllImport( "user32.dll" )]
>        static extern int SetWindowRgn( IntPtr hWnd, IntPtr hRgn, bool
> bRedraw );
>
>        [DllImport( "gdi32.dll" )]
>        static extern bool DeleteObject( IntPtr hObject );
>
>        public RegionsDemoForm()
>        {
>            InitializeComponent();
>            AddTransparentRegion();
>        }
>
>        private void AddTransparentRegion()
>        {
>            IntPtr windowRgn = CreateRectRgn( 0, 0, this.Width,
> this.Height );
>            IntPtr areaRgn = CreateRectRgn( 50, 50, 200, 200 );
>            IntPtr combinedRgn = CreateRectRgn( 0, 0, 0, 0 );
>
>            CombineRgn( combinedRgn, windowRgn, areaRgn,
> CombineRgnStyles.RGN_XOR );
>
>            SetWindowRgn( this.Handle, combinedRgn, true );
>
>            DeleteObject( combinedRgn );
>            DeleteObject( areaRgn );
>            DeleteObject( combinedRgn );
>        }
>
>        private void Form1_Resize( object sender, EventArgs e )
>        {
>            AddTransparentRegion();
>        }
>
>    }
> }
>

Click passthrough on forms/controls - help