I am running Lazarus v0.9.30 (32 bit compiler).
I have a TForm with a standard TStringGrid on it. The grid has the following properties set. RowCount = 5, ColumnCount = 5, FixedCols = 0, FixedRows = 0.
I Googled some code that showed me how to change the cell colour and add some text to the cell when a user clicks on a TStringGrid cell. All works fine and I have extended it slightly to toggle the color/text on and off on the GridClick event.
The questions I have are more to better understand the purpose behind some of the elements of the code.
There is an array of Foregroud (FG) and Background (BG) TColor objects. Are they there to store the cell color attributes that are set on the GridClick event, so if the DrawCell event needs to get triggered again for any reason the cell can redraw itself? Can you avoid using the array of TColors and just set the colour / text in the DrawCell event as required?
If you need to use the arrays, I would assume that dimensions must match the Grid.ColCount and Grid.RowCount (ie. set via the SetLength call in Form.Create)
Is there a way to detect that you are clicking outside of the 5 x 5 cells of the stringgrid (ie in the whitespace) and thus prevent the GridClick from calling the DrawCell event. No matter where you click you always get a valid value for Row and Col.
unit testunit;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs,
ExtCtrls, Menus, ComCtrls, Buttons, Grids, StdCtrls, Windows, Variants,
LCLType;
type
{ TForm1 }
TForm1 = class(TForm)
Grid: TStringGrid;
procedure FormCreate(Sender: TObject);
procedure GridClick(Sender: TObject);
procedure GridDrawCell(Sender: TObject; aCol, aRow: Integer;
aRect: TRect; aState: TGridDrawState);
end;
var
Form1: TForm1;
implementation
var
FG: array of array of TColor;
BG: array of array of TColor;
{$R *.lfm}
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
var
Col, Row: integer;
begin
// Set the sizes of the arrays
SetLength(FG, 5, 5);
SetLength(BG, 5, 5);
// Initialize with default colors
for Col := 0 to Grid.ColCount - 1 do begin
for Row := 0 to Grid.RowCount - 1 do begin
FG[Col, Row] := clBlack;
BG[Col, Row] := clWhite;
end;
end;
end;
procedure TForm1.GridDrawCell(Sender: TObject; aCol, aRow: Integer;
aRect: TRect; aState: TGridDrawState);
var
S: string;
begin
S := Grid.Cells[ACol, ARow];
// Fill rectangle with colour
Grid.Canvas.Brush.Color := BG[ACol, ARow];
Grid.Canvas.FillRect(aRect);
// Next, draw the text in the rectangle
Grid.Canvas.Font.Color := FG[ACol, ARow];
Grid.Canvas.TextOut(aRect.Left + 22, aRect.Top + 2, S);
end;
procedure TForm1.GridClick(Sender: TObject);
var
Col, Row: integer;
begin
Col := Grid.Col;
Row := Grid.Row;
// Set the cell color and text to be displayed
if (Grid.Cells[Col,Row] <> 'Yes') then
begin
BG[Col, Row] := rgb(131, 245, 44);
FG[Col, Row] := RGB(0, 0, 0);
Grid.Cells[Col, Row] := 'Yes'
end {if}
else
begin
BG[Col, Row] := rgb(255, 255, 255);
FG[Col, Row] := RGB(255, 255, 255);
Grid.Cells[Col, Row] := '';
end; {else}
end;
end.