Using Delphi 10.2 Tokyo.
I use a DrawCell method to have all columns in a row the same color as the selected cell. This allows me to let user click in different cells but still show a "selected" row.
This uses the OnSelectCell method to invalidate the original row and newly selected row. Been using this method for years.
If I have a grid that has a horizontal scrollbar the grid does not draw properly when scrolled to the right and the user clicks in a cell.
Here is a simple example using a TDrawGrid with an OnDrawCell event and an OnSelectCell event:
The Form (DFM) code:
object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 299
ClientWidth = 635
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object DrawGrid1: TDrawGrid
Left = 0
Top = 0
Width = 635
Height = 299
Align = alClient
Color = clWhite
ColCount = 15
DefaultColWidth = 65
DefaultRowHeight = 48
DefaultDrawing = False
DrawingStyle = gdsGradient
RowCount = 12
GradientEndColor = clBtnFace
GradientStartColor = clBtnFace
Options = [goThumbTracking]
ParentShowHint = False
ShowHint = True
TabOrder = 0
OnDrawCell = DrawGrid1DrawCell
OnSelectCell = DrawGrid1SelectCell
ColWidths = (
65
65
65
65
65
65
65
65
65
65
65
65
65
65
65)
RowHeights = (
48
48
48
48
48
48
48
48
48
48
48
48)
end
end
The Unit (PAS) code:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.Grids, Math;
type
TGridCracker = class(TDrawGrid)// required to access protected method Invalidaterow - info gleaned from Team B member Peter Below on the Internet
private
public
end;
TForm1 = class(TForm)
DrawGrid1: TDrawGrid;
procedure DrawGrid1DrawCell(Sender: TObject; ACol, ARow: Integer; Rect: TRect; State: TGridDrawState);
procedure DrawGrid1SelectCell(Sender: TObject; ACol, ARow: Integer; var CanSelect: Boolean);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.DrawGrid1DrawCell(Sender: TObject; ACol, ARow: Integer; Rect: TRect; State: TGridDrawState);
var MyCanvas : TCanvas;
str : string;
MyRect : TRect;
begin
MyCanvas := TDrawGrid(Sender).Canvas;
MyCanvas.Font.Name := 'Arial'; // drawgrid uses Tahoma 8pt as its default font, not Arial
MyCanvas.Font.Size := 9;
MyCanvas.Brush.Color := TDrawGrid(Sender).FixedColor;
MyCanvas.Font.Color := TDrawGrid(Sender).Font.Color;
MyCanvas.FillRect(Rect);
if (ARow = 0) then begin
str := EmptyStr;
if (ACol > 0) then begin
str := ACol.ToString;
end
else begin
str := 'TEST';
end;
MyCanvas.Font.Color := clblack; // clGray;
MyRect.Left := Rect.Left + 1;
MyRect.Top := Rect.Top + 3;
MyRect.Right := Rect.Right - 1;
MyRect.Bottom := Rect.Bottom - 3;
MyCanvas.FillRect(MyRect);
MyCanvas.Brush.Color := clGray;
MyCanvas.FrameRect(MyRect);
MyCanvas.Brush.Color := clWhite;
MyCanvas.Font.Style := MyCanvas.Font.Style + [fsBold];
MyRect.Top := MyRect.Top + 2;
DrawText(MyCanvas.Handle, pChar(str), -1, MyRect, DT_VCENTER or DT_CENTER);
MyCanvas.Font.Style := MyCanvas.Font.Style - [fsBold];
end
else begin
if (ACol = 0) then begin
MyCanvas.Brush.Color := clMaroon;
MyCanvas.FillRect(Rect);
end
else begin//ACol > 0
if ARow = DrawGrid1.Row then begin
MyCanvas.Brush.Color := clBlue;
end
else begin
MyCanvas.Brush.Color := clwhite;
end;
MyCanvas.FillRect(Rect);
// other cell drawing of text happens after here
end;
end;
end;
procedure TForm1.DrawGrid1SelectCell(Sender: TObject; ACol, ARow: Integer; var CanSelect: Boolean);
begin
TGridCracker(Sender).InvalidateRow(TGridCracker(Sender).Row);
TGridCracker(Sender).InvalidateRow(ARow);
end;
end.
Run the program.
Click the horizontal scroll bar so column 14 is visible.
Click on column 13 in row 2.
Click on column 12 in row 3.
Notice the really messed up selection pattern?
Here is a screen capture of the result:
Ideally there should be one row of blue cells, not the jumbled mess. Row 3 should be solid blue.
Calling a DrawGrid1.Refresh within the OnSelectCell method does not even fix it.
Any ideas on how to make this really work? I cannot use RowSelect for this grid.
Cheers!
TJ
