How can I draw on the desktop?

[Don]

Is there any way I can get an object that allows me to draw to the Windows
desktop using managed code? I've managed to figure out how to do it with
unmanaged code using API functions, but I was just wondering if there was a
more "proper" way to do it in VB.NET

- Don

 

[Herfried K. Wagner [MVP]]

Is there any way I can get an object that allows me to draw to the Windows
desktop using managed code? I've managed to figure out how to do it with
unmanaged code using API functions, but I was just wondering if there was a
more "proper" way to do it in VB.NET

AFAIS that's not supported by the .NET Framework.

 

[Don]

Is there any way I can get an object that allows me to draw to the
Windows

AFAIS that's not supported by the .NET Framework.

That would explain why System.Drawing.Graphics.FromHwnd() works when passed
a handle to a form but not when passed a handle to the desktop. :-(

- Don

 

[Armin Zingler]

Is there any way I can get an object that allows me to draw to the
Windows desktop using managed code? I've managed to figure out how
to do it with unmanaged code using API functions, but I was just
wondering if there was a more "proper" way to do it in VB.NET

Private Declare Function GetDC Lib "user32.dll" _
(ByVal hwnd As IntPtr) As IntPtr
Private Declare Function ReleaseDC Lib "user32.dll" _
(ByVal hwnd As IntPtr, ByVal hdc As IntPtr) As IntPtr

'...
Dim hdc As IntPtr

hdc = GetDC(IntPtr.Zero)

Try
Dim g As Graphics
g = Graphics.FromHdc(hdc)
Try
g.FillRectangle(Brushes.Red, 10, 10, 100, 100)
Finally
g.Dispose()
End Try
Finally
ReleaseDC(IntPtr.Zero, hdc)
End Try


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html

 

[Guest]

Sounds like you found the only way. The only thing I'd suggest is writing a managed code wrapper class for the unmanaged code functions you're using. At least that way you could call managed code methods from your application. (The wrapper calls the unmanaged code functions within the methods you define, and handles the exceptions.) That's what I do when I have to work with the shell, BITS, and other Windows APIs

Good luck
Ben

 

[Herfried K. Wagner [MVP]]

Is there any way I can get an object that allows me to draw to the
Windows desktop using managed code? I've managed to figure out how [...]

Private Declare Function GetDC Lib "user32.dll" _
(ByVal hwnd As IntPtr) As IntPtr
Private Declare Function ReleaseDC Lib "user32.dll" _
(ByVal hwnd As IntPtr, ByVal hdc As IntPtr) As IntPtr

That's not managed code...

 

[CJ Taylor]

All I have to say is Longhorn.

Hopefully.

Is there any way I can get an object that allows me to draw to the
Windows desktop using managed code? I've managed to figure out how

[...]
Private Declare Function GetDC Lib "user32.dll" _
(ByVal hwnd As IntPtr) As IntPtr
Private Declare Function ReleaseDC Lib "user32.dll" _
(ByVal hwnd As IntPtr, ByVal hdc As IntPtr) As IntPtr

That's not managed code...

 

[Armin Zingler]

That's not managed code...

Ahhh, sorry!! I didn't read conscientiously. :-/