Author: Jonas Bilinkevicius

How to create a sizeable form with a 3D look

Answer:

Try these handlers for the WMNCPaint and WMNCHitTest messages. The form should have 
the Sizeable border style as the code uses the sizeable border area for drawing the 
3D effect, whether or not you want the user to be able to resize. To prohibit 
resizing, include the WMNCHitTest handler, to allow it, leave it out.
1   
2   procedure TForm1.WMNCPaint(var Msg: TWMNCPaint);
3   var
4     DC: HDC;
5     Frame_H: Integer;
6     Frame_W: Integer;
7     Menu_H: Integer;
8     Caption_H: Integer;
9     Frame: TRect;
10    Extra: Integer;
11    Canvas: TCanvas;
12  begin
13    { Predetermine some window parameters }
14    Frame_W := GetSystemMetrics(SM_CXFRAME);
15    Frame_H := GetSystemMetrics(SM_CYFRAME);
16    if (Menu <> nil) then
17      Menu_H := GetSystemMetrics(SM_CYMENU)
18    else
19      Menu_H := -1;
20    Caption_H := GetSystemMetrics(SM_CYCAPTION);
21    GetWindowRect(Handle, Frame);
22    Frame.Right := Frame.Right - Frame.Left - 1;
23    Frame.Left := 0;
24    Frame.Bottom := Frame.Bottom - Frame.Top - 1;
25    Frame.Top := 0;
26    { Let standard frame draw }
27    inherited;
28    { Repaint frame area in 3-D style }
29    DC := GetWindowDC(Handle);
30    Canvas := TCanvas.Create;
31    try
32      with Canvas do
33      begin
34        Handle := DC;
35        { Left and Top edges }
36        Pen.Color := clBtnShadow;
37        PolyLine([Point(Frame.Left, Frame.Bottom), Point(Frame.Left, Frame.Top),
38          Point(Frame.Right, Frame.Top)]);
39        { Right and Bottom edges }
40        Pen.Color := clWindowFrame;
41        PolyLine([Point(Frame.Left, Frame.Bottom), Point(Frame.Right, Frame.Bottom),
42          Point(Frame.Right, Frame.Top - 1)]);
43        { Left and Top edge, 1 pixel in }
44        Pen.Color := clBtnHighlight;
45        PolyLine([Point(Frame.Left + 1, Frame.Bottom - 1), Point(Frame.Left + 1,
46          Frame.Top + 1),
47          Point(Frame.Right - 1, Frame.Top + 1)]);
48        { Right and Bottom edge, 1 pixel in }
49        Pen.Color := clBtnFace;
50        PolyLine([Point(Frame.Left + 1, Frame.Bottom - 1), Point(Frame.Right - 1,
51          Frame.Bottom - 1),
52          Point(Frame.Right - 1, Frame.Top)]);
53        { Remainder of Sizing border }
54        for Extra := 2 to (GetSystemMetrics(SM_CXFRAME) - 1) do
55        begin
56          Brush.Color := clBtnFace;
57          FrameRect(Rect(Extra, Extra, Frame.Right - Extra + 1, Frame.Bottom - Extra +
58            1));
59        end;
60        { Left and Top Edge of Caption Area }
61        Pen.Color := clBtnShadow;
62        PolyLine([Point(Frame_W - 1, Frame_H + Caption_H + Menu_H - 1), Point(Frame_W 
63  -
64          1,
65            Frame_H - 1), Point(Frame.Right - Frame_W + 1, Frame_H - 1)]);
66        { Right and Bottom Edge of Caption Area }
67        Pen.Color := clBtnHighlight;
68        PolyLine([Point(Frame_W - 1, Frame_H + Caption_H + Menu_H - 1),
69          Point(Frame.Right - Frame_W + 1, Frame_H + Caption_H + Menu_H - 1),
70            Point(Frame.Right - Frame_W + 1, Frame_H - 1)]);
71      end;
72    finally
73      Canvas.Free;
74      ReleaseDC(Handle, DC);
75    end;
76  end;
77  
78  procedure TForm1.WMNCHitTest(var Msg: TWMNCHitTest);
79  var
80    HitCode: LongInt;
81  begin
82    inherited;
83    HitCode := Msg.Result;
84    if ((HitCode = HTLEFT) or (HitCode = HTRIGHT) or (HitCode = HTTOP) or (HitCode =
85      HTBOTTOM)
86      or (HitCode = HTTOPLEFT) or (HitCode = HTBOTTOMLEFT) or (HitCode = HTTOPRIGHT) 
87  or
88      (HitCode = HTBOTTOMRIGHT)) then
89    begin
90      HitCode := HTNOWHERE;
91    end;
92    Msg.Result := HitCode;
93  end;