DC Handle

[Vitaly]

Does anyone know how if there is an easy way to substitute in .NET VB6 windows DC Handles, i.e properties like Form.hdc, PictureBox.hdc, etc? I need it for BitBlt and some other API functions that expect HDC for both source and destination Device Contexts.

Thank You.

 

[Derek Stone]

As provided by the .NET SDK.

<System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")>  _
Private Shared Function Rectangle(hdc As IntPtr, _
ulCornerX As Integer, ulCornerY As Integer, lrCornerX As Integer, _
lrCornerY As Integer) As Boolean
End Function

Public Sub GetHdcForGDI(e As PaintEventArgs)
      Create pen.
     Dim redPen As New Pen(Color.Red, 1)
      Draw rectangle with GDI+.
     e.Graphics.DrawRectangle(redPen, 10, 10, 100, 50)
      Get handle to device context.
     Dim hdc As IntPtr = e.Graphics.GetHdc()
      Draw rectangle with GDI using default pen.
     Rectangle(hdc, 10, 70, 110, 120)
      Release handle to device context.
     e.Graphics.ReleaseHdc(hdc)
End Sub

 

[Vitaly]

Thanks for the reply.
So, in .NET if I have a picture box I need to draw a rectangle with same coordinates and get DC Handle for that?

 

[Derek Stone]

No, not at all. Those two lines are just showing you how to accomplish the same thing in .NET.

 

[Vitaly]

Derek, I am relatively new in .NET, I cant see how can I use this example for something like picture box control or a form, not a bitmap object or client rectangle in memory.

Thank you.

 

[Derek Stone]

Dim g As Graphics
g = PictureBox1.CreateGraphics()
MessageBox.Show(g.GetHdc.ToString(), Application.ProductName)

 

[Vitaly]

Thats it. Thank you.

 

[Vitaly]

Interestingly, gethdc and releasehdc are misisng from IntelliSense method list, but you can still see them in object browser.

 

[Divil]

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