Author: Tomas Rutkauskas
Is there any way to draw just borders around the selected cell(s) or row of a
string grid? Similar to what you can do in Excel?
Answer:
Using the OnDrawCell event you have full control over how a cell is drawn since you
do all the work, including drawing a cells background and content yourself.
Paint a thick border around the selection in a grid:
1 unit Unit1;
2
3 interface
4
5 uses
6 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
7 StdCtrls, ComCtrls, Grids;
8
9 type
10 TForm1 = class(TForm)
11 StatusBar1: TStatusBar;
12 StringGrid1: TStringGrid;
13 procedure StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
14 Rect: TRect; State: TGridDrawState);
15 procedure StringGrid1MouseDown(Sender: TObject; Button: TMouseButton;
16 Shift: TShiftState; X, Y: Integer);
17 procedure StringGrid1MouseMove(Sender: TObject; Shift: TShiftState; X, Y:
18 Integer);
19 private
20 { Private declarations }
21 FLastCell: TGridCoord;
22 public
23 { Public declarations }
24 end;
25
26 var
27 Form1: TForm1;
28
29 implementation
30
31 {$R *.DFM}
32
33 procedure TForm1.StringGrid1DrawCell(Sender: TObject; ACol, ARow: Integer;
34 Rect: TRect; State: TGridDrawState);
35
36 procedure DrawLine(onCanvas: TCanvas; x1, y1, x2, y2: Integer);
37 begin
38 onCanvas.MoveTo(x1, y1);
39 onCanvas.LineTo(x2, y2);
40 end;
41
42 begin
43 if gdFixed in State then
44 Exit;
45 with Sender as TStringgrid do
46 begin
47 Canvas.Brush.Color := $C0FFFF;
48 Canvas.Brush.Style := bsSolid;
49 Canvas.FillRect(Rect);
50 if gdSelected in State then
51 begin
52 Canvas.Pen.Width := 1;
53 Canvas.Pen.Color := clBlue;
54 Canvas.Pen.Style := psSolid;
55 if aCol = Selection.Left then
56 begin
57 DrawLine(Canvas, rect.left, rect.top, rect.left, rect.bottom);
58 DrawLine(Canvas, rect.left + 1, rect.top, rect.left + 1, rect.bottom);
59 end;
60 if aCol = Selection.Right then
61 begin
62 DrawLine(Canvas, rect.right, rect.top, rect.right, rect.bottom);
63 DrawLine(Canvas, rect.right - 1, rect.top, rect.right - 1, rect.bottom);
64 end;
65 if arow = Selection.Top then
66 begin
67 DrawLine(Canvas, rect.left, rect.top, rect.right, rect.top);
68 DrawLine(Canvas, rect.left, rect.top + 1, rect.right, rect.top + 1);
69 end;
70 if arow = Selection.Bottom then
71 begin
72 DrawLine(Canvas, rect.left, rect.bottom, rect.right, rect.bottom);
73 DrawLine(Canvas, rect.left, rect.bottom - 1, rect.right, rect.bottom - 1);
74 end;
75 Canvas.Font.Color := clBlack;
76 end;
77 InflateRect(rect, -2, -2);
78 Canvas.TextRect(rect, rect.left, rect.top, Cells[acol, arow]);
79 end;
80 end;
81
82 type
83 tgridcracker = class(tstringgrid);
84
85 procedure TForm1.StringGrid1MouseDown(Sender: TObject; Button: TMouseButton;
86 Shift: TShiftState; X, Y: Integer);
87 begin
88 (Sender as TStringgrid).MouseToCell(X, Y, FLastCell.X, FLastCell.Y);
89 end;
90
91 procedure TForm1.StringGrid1MouseMove(Sender: TObject; Shift: TShiftState; X, Y:
92 Integer);
93 var
94 currentcell: TGridCoord;
95 i, k: Integer;
96 begin
97 if ssLeft in Shift then
98 begin
99 (Sender as TStringgrid).MouseToCell(X, Y, currentcell.X, currentcell.Y);
100 if (FLastCell.X <> CurrentCell.X) or (FLastCell.Y <> CurrentCell.Y) then
101 begin
102 with TGridCracker(Sender) do
103 for i := Selection.Left to Selection.Right do
104 for k := selection.top to Selection.bottom do
105 InvalidateCell(i, k);
106 end;
107 end;
108 end;
109
110 end.
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