Author: Tomas Rutkauskas

How to create a TStatusBar with resizable panels

Answer:

In this demo the TStatusBar has three panels. Only panels 1 and 2 need to be 
adjustable and each has a set minimum width of 20. The StatusBar OnResize event is 
used to keep the panels in view, regardless of form resizing, except where the 
StatusBar width is less than 40.

1   { ... }
2   private
3   {Private declarations}
4   StatusMouseDown: Boolean;
5   Split: Integer;
6   { ... }
7   
8   procedure TMainForm.FormCreate(Sender: TObject);
9   begin
10    StatusMouseDown := false;
11  end;
12  
13  procedure TMainForm.StatusBar1MouseUp(Sender: TObject;
14    Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
15  begin
16    StatusMouseDown := false;
17  end;
18  
19  procedure TMainForm.StatusBar1MouseDown(Sender: TObject;
20    Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
21  var
22    S1, S2: Integer;
23  begin
24    if Button = mbLeft then
25    begin
26      StatusMouseDown := true;
27      Split := 0;
28      S1 := StatusBar1.Panels[0].Width;
29      S2 := StatusBar1.Panels[1].Width + S1;
30      if ((X > S1 - 3) and (X < (S1 + 3))) then
31        Split := 1
32      else if ((X > S2 - 3) and (X < (S2 + 3))) then
33        Split := 2;
34    end;
35  end;
36  
37  procedure TMainForm.StatusBar1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: 
38  Integer);
39  var
40    S1, S2, S3: Integer;
41    Split1, Split2: Boolean;
42  begin
43    Split1 := false;
44    Split2 := false;
45    S1 := StatusBar1.Panels[0].Width;
46    S2 := StatusBar1.Panels[1].Width + StatusBar1.Panels[0].Width;
47    S3 := StatusBar1.Width;
48    if ((X > S1 - 3) and (X < (S1 + 3))) then
49      Split1 := true
50    else if ((X > S2 - 3) and (X < (S2 + 3))) then
51      Split2 := true;
52    if (Split1 or Split2) then
53      StatusBar1.Cursor := crHSplit
54    else
55      StatusBar1.Cursor := crDefault;
56    if StatusMouseDown then
57    begin
58      if (Split = 1) then
59      begin
60        if (X < 20) then
61          StatusBar1.Panels[0].Width := 20
62        else if (X > (S3 - 40)) then
63        begin
64          StatusBar1.Panels[0].Width := S3 - 40;
65          StatusBar1.Panels[1].Width := S3 - S1 - 20;
66        end
67        else if (X >= 20) and (X <= S3 - 20) then
68        begin
69          StatusBar1.Panels[0].Width := X;
70          if ((X + StatusBar1.Panels[1].Width + 20) >= S3) then
71            StatusBar1.Panels[1].Width := S3 - X - 20;
72        end;
73      end;
74      if (Split = 2) then
75      begin
76        if (X < (S1 + 20)) then
77          StatusBar1.Panels[1].Width := 20
78        else if (X > (S3 - 20)) then
79          StatusBar1.Panels[1].Width := S3 - S1 - 20
80        else if (X >= S1 + 20) and (X <= S3 - 20) then
81          StatusBar1.Panels[1].Width := X - S1;
82      end;
83    end;
84  end;
85  
86  procedure TMainForm.StatusBar1Resize(Sender: TObject);
87  var
88    S1, S2, S3: Integer;
89  begin
90    S1 := StatusBar1.Panels[0].Width;
91    S2 := StatusBar1.Panels[1].Width + StatusBar1.Panels[0].Width;
92    S3 := StatusBar1.Width;
93    if (S1 >= (S3 - 40)) then
94    begin
95      StatusBar1.Panels[0].Width := S3 - 40;
96      StatusBar1.Panels[1].Width := 20;
97    end
98    else if (S2 >= (S3 - 20)) then
99      StatusBar1.Panels[1].Width := S3 - S1 - 20;
100 end;