How do I invalidate a control including it’s NonClient area?
You can do so as follows in your Control: private void InvalidateWindow() { NativeMethods.RedrawWindow(this.Handle, IntPtr.Zero, IntPtr.Zero, 0x0400/*RDW_FRAME*/ | 0x0100/*RDW_UPDATENOW*/ | 0x0001/*RDW_INVALIDATE*/); }
How do I provide a 1 pixel border in the NonClient area of my Control?
You will have to first provide some space in the NC area by setting the WS_BORDER flag in CreateParams and then draw the border yourself by listening to the WM_NCPAINT message in your Control, as follows: protected override CreateParams CreateParams { get { System.Windows.Forms.CreateParams cp = base.CreateParams; if(this.needFlatBorder) { cparams.ExStyle &= ~512 /*WS_EX_CLIENTEDGE*/; cparams.Style &= ~8388608 /*WS_BORDER*/; cp.Style |= 0x800000; // WS_BORDER } } } protected override void WndProc(ref Message m) { if(m.Msg == 133/*WM_NCPAINT*/) { this.DrawFlatNCBorder(ref m); } base.WndProc(ref m); } private void DrawFlatNCBorder(ref Message msg) { IntPtr hRgn1 = (IntPtr) msg.WParam; // The update region is clipped to the window frame. When wParam is 1, the entire window frame needs to be updated. IntPtr hdc = NativeMethods.GetDCEx(msg.HWnd, hRgn1, 1/*DCX_WINDOW*/|0x0020/*DCX_PARENTCLIP*/); if (hdc != IntPtr.Zero) { using (Graphics g = Graphics.FromHdc(hdc)) { Rectangle bounds = new Rectangle(0,0,this.Width,this.Height); ControlPaint.DrawBorder(g,bounds,this.borderColor,ButtonBorderStyle.Solid); // create a clipping region for remaining parts to be drawn excluding // the border we did just drew bounds.Inflate(-1, -1); IntPtr hRgn2 = NativeMethods.CreateRectRgn(bounds.Left, bounds.Top, bounds.Right, bounds.Bottom); if(hRgn2 == (IntPtr)1) { // Provide a new clipping region. msg.WParam = (IntPtr) hRgn2; } else { // combine with existing clipping region. NativeMethods.CombineRgn(hRgn1, hRgn1, hRgn2, NativeMethods.RGN_AND); NativeMethods.DeleteObject(hRgn2); } } msg.Result = (IntPtr) 1; NativeMethods.ReleaseDC(msg.HWnd, hdc); } Invalidate(); }
How do I provide a 2 pixel 3d border in the Non-Client area of my Control derived class?
You can do so as follows by overriding the CreateParams property in your Control. The advantage with this approach is that drawing is handled by the system as soon as you set the flag below. protected override CreateParams CreateParams { get { CreateParams cparams; cparams = base.CreateParams; if(this.need3DBorder) { cparams.ExStyle &= ~512; cparams.Style &= ~8388608 /*WS_BORDER*/; cparams.ExStyle = cparams.ExStyle | 512 /*WS_EX_DLGFRAME*/; } return cparams; } }
How do I convert a color to integer and vice-versa?
You can do it using the FromArgb and ToArgb methods as follows: // from Color to int int blueInt = Color.Blue.ToArgb( ); // from int to Color Color newColor = Color.FromArgb( blueInt );
Why does a Control not draw transparent even after setting it’s BackColor to Transparent?
This is possible if the Control is drawn by the system, rather than by the framework. This is the case for example with the Label control when it’s set to FlatStyle.System. You should then set to to something else other than System for your transparent drawing to work.