C# Signature:

[DllImport("gdi32.dll")]
static extern IntPtr CreateRectRgn(int nLeftRect, int nTopRect, int nRightRect, int nBottomRect);

VB.NET Signature:

<DllImport("gdi32.dll")> _
Private Shared Function CreateRectRgn(ByVal nLeftRect As Integer, ByVal nTopRect As Integer, ByVal nRightRect As Integer, ByVal nBottomRect As Integer) As IntPtr
End Function

static extern IntPtr CreateRectRgn(int nLeftRect, int nTopRect, int nRightRect,
   int nBottomRect);

User-Defined Types:

None.

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

// Up Top

        [DllImport("user32.dll",EntryPoint="GetDC")]
        static extern IntPtr GetDC(IntPtr hWnd);

        [DllImport("gdi32.dll")]
        static extern bool FillRgn(IntPtr hdc, IntPtr hrgn, IntPtr hbr);

        [DllImport("gdi32.dll")]
        static extern IntPtr CreateRectRgn(int nLeftRect, int nTopRect, int nRightRect,
            int nBottomRect);

        [DllImport("gdi32.dll")]
        static extern IntPtr CreateSolidBrush(uint crColor);

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

// Then whereever:

                // This paints the current form black
                IntPtr wDc = GetDC(this.Handle);
                int mx = Screen.PrimaryScreen.WorkingArea.Width;
                int my = Screen.PrimaryScreen.WorkingArea.Height;
                IntPtr brush = CreateSolidBrush(0x0); // black, of format : //0x00bbggrr
                FillRgn(wDc, CreateRectRgn(0,0,mx,my), brush);
                DeleteObject(brush);

Alternative Managed API:

No managed API. GraphicsPath can be used to create a similar functionality.

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