Delphi FMX TStringgrid, draw a checkbox on a single cell

Question

I want to put a checkbox on a single cell (not a checkcolunn) of a FMX stringgrid.

I think that I need to use 'StringGrid1.AddObject' but I do not know how to go from there.

Answer 1

I don't understand you can't (but you change my code). First I want to say I am not a Stringgrid fan on Android but that's another point. Second point I focused on drawing, I also wrote some code to manage some others style containing a Tpath instead of a TStyleObject

procedure TForm1.StringGrid1DrawColumnCell(Sender: TObject;
  const Canvas: TCanvas; const Column: TColumn; const Bounds: TRectF;
  const Row: Integer; const Value: TValue; const State: TGridDrawStates);
var sb : TFMXObject;
    aRectF : TRectF;
    img : tfmxobject;
begin
if Assigned(Stylebook) then sb:=Stylebook.Style  else sb:=TStyleManager.ActiveStyle(Self);
if Test.find(Column.Index,Row)>=0 then
 begin
    if Test[Test.Find(Column.Index,Row)].ischecked
      then img := sb.FindStyleResource('checkcellstyle.checkboxchecked')
      else img := sb.FindStyleResource('checkcellstyle.checkboxunchecked');
    if assigned(img) then
      begin
        aRectf:=Bounds;
        arectf.Left:=arectf.Right-20; // to adapt
        TStyleObject(img).DrawToCanvas(Canvas,arectf,1);
      end
    else begin
      img:= sb.FindStyleResource('checkcellstyle');
      if assigned(img) then img:=img.FindStyleResource('checkmark');
      if assigned(img) and (img is Tpath) then
       begin
        if Test[Test.Find(Column.Index,Row)].ischecked
          then Tpath(img).Fill.Color:=TColorAnimation(Img.Children[0]).StopValue
          else Tpath(img).Fill.Color:=TColorAnimation(Img.Children[0]).StartValue;
        var bmp:=Tpath(Img).MakeScreenshot;
        aRectf:=Bounds;
        arectf.Left:=arectf.Right-20; // to adapt
        Canvas.DrawBitmap(bmp,Trectf.Create(0,0,bmp.Width,bmp.Height),aRectf,1);
       end;

    end;
    end;
end;

but this is not a problem here.

Here is two screenshots, proving my code works. First one I use transparent.style wich as a default platform

then I add C:\Users\Public\Documents\Embarcadero\Studio\22.0\Styles\Android\AndroidWearDarkBlue.fsf and got this one

What is still not clear for me on Android is the way to check/oncheck value on Android. Sometimes CellDblclick event works, sometimes not !

Answer 2

As quick response you can't because Cells[col,raw] is a string, and there is no cell selection support. But if you manage a List of selected cells somewhere and use OnDrawCellEvent it's possible. Here is a "dirty" sample, but you can see I use Style

And how I manage this

procedure TForm1.FormCreate(Sender: TObject);
begin
 SelectedCells:=TList<String>.Create(['0,2']);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  SelectedCells.Free;
end;
procedure TForm1.StringGrid1CellDblClick(const Column: TColumn;
  const Row: Integer);
begin
 if SelectedCells.IndexOf(Format('%d,%d',[Column.Index,Row]))>=0
   then SelectedCells.Remove(Format('%d,%d',[Column.Index,Row]))
   else SelectedCells.Add(Format('%d,%d',[Column.Index,Row]));
end;

procedure TForm1.StringGrid1DrawColumnCell(Sender: TObject;
  const Canvas: TCanvas; const Column: TColumn; const Bounds: TRectF;
  const Row: Integer; const Value: TValue; const State: TGridDrawStates);
var sb : TFMXObject;
    aRectF : TRectF;
begin
if Assigned(Stylebook) then sb:=Stylebook.Style  else sb:=TStyleManager.ActiveStyle(Self);
if SelectedCells.IndexOf(Format('%d,%d',[Column.Index,Row]))>=0 then
 begin
    var img := sb.FindStyleResource('checkcellstyle.checkboxchecked');
    if assigned(img) then
      begin
        aRectf:=Bounds;
        arectf.Left:=arectf.Right-20; // to adapt
        TStyleObject(img).DrawToCanvas(Canvas,arectf,1);
      end;
 end;
end;

Caveats Not all styles can be used, I think.

Answer 3

I reworked the answer of SergeGirard

unit Main;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes,
  System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, System.Rtti,
  FMX.Grid.Style, FMX.Grid, FMX.Controls.Presentation, FMX.ScrollBox, FMX.Edit,
  System.Generics.Collections, FMX.Styles, FMX.Styles.Objects, FMX.StdCtrls,
  FMX.Objects;

Const
  CHECKBOX_COLUMN = 0;
  CHECKBOX_ROW    = 2;

  SYSTEM_ON  = $101;
  SYSTEM_OFF = $100;

type
  TForm1 = class(TForm)
    StringGrid1: TStringGrid;
    CurrencyColumn1: TCurrencyColumn;
    StyleBook1: TStyleBook;
    procedure FormCreate(Sender: TObject);
    procedure StringGrid1DrawColumnCell(Sender: TObject; const Canvas: TCanvas;
      const Column: TColumn; const Bounds: TRectF; const Row: Integer;
      const Value: TValue; const State: TGridDrawStates);
    procedure Grid1GetValue(Sender: TObject; const ACol, ARow: Integer;
      var Value: TValue);
    procedure FormDestroy(Sender: TObject);
    procedure StringGrid1CellClick(const Column: TColumn; const Row: Integer);
    procedure StringGrid1SelectCell(Sender: TObject; const ACol, ARow: Integer;
      var CanSelect: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  SelectedCells: TList<string>;

implementation

{$R *.fmx}
{$R *.LgXhdpiTb.fmx ANDROID}
{$R *.LgXhdpiPh.fmx ANDROID}
{$R *.Windows.fmx MSWINDOWS}
{$R *.NmXhdpiPh.fmx ANDROID}
{$R *.SmXhdpiPh.fmx ANDROID}

procedure TForm1.FormCreate(Sender: TObject);
Var
  iRow: Integer;
  MyStyle: TFmxObject;
begin
  for iRow := 0 to 10 do
    StringGrid1.Cells[0, iRow] := iRow.ToString;

  StringGrid1.Cells[CHECKBOX_COLUMN, CHECKBOX_ROW] := SYSTEM_OFF.ToString;

  SelectedCells := TList<String>.Create
    ([CHECKBOX_COLUMN.ToString + ',' + CHECKBOX_ROW.ToString]);

end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  SelectedCells.Free;
end;

procedure TForm1.Grid1GetValue(Sender: TObject; const ACol, ARow: Integer;
  var Value: TValue);
Var
  i: Integer;
begin
//Fill column with some numbers
  for i := 1 to 10 do
    if (ACol = 0) AND (ARow = i - 1) then
      Value := i;
end;

procedure TForm1.StringGrid1CellClick(const Column: TColumn;
  const Row: Integer);
begin
  if (Column.Index = CHECKBOX_COLUMN) AND (Row = CHECKBOX_ROW) then
  Begin
    If StringGrid1.Cells[CHECKBOX_COLUMN, CHECKBOX_ROW] = 
      SYSTEM_OFF.ToString
    then
      StringGrid1.Cells[CHECKBOX_COLUMN, CHECKBOX_ROW] := 
       SYSTEM_ON.ToString
    else
      StringGrid1.Cells[CHECKBOX_COLUMN, CHECKBOX_ROW] := 
        SYSTEM_OFF.ToString;
  End;
  StringGrid1.Repaint;
end;

procedure TForm1.StringGrid1DrawColumnCell(Sender: TObject;
  const Canvas: TCanvas; const Column: TColumn; const Bounds: TRectF;
  const Row: Integer; const Value: TValue; const State: TGridDrawStates);
var
  sb: TFmxObject;
  aRectF: TRectF;
  img: TFmxObject;
begin
  if Assigned(Stylebook) then
    sb := Stylebook.Style
  else
    sb := TStyleManager.ActiveStyle(Self);

  if SelectedCells.IndexOf(Format('%d,%d', [Column.Index, Row])) >= 0 then
  begin
    if StringGrid1.Cells[CHECKBOX_COLUMN, CHECKBOX_ROW].ToInteger = SYSTEM_ON
    then
    Begin
      img := sb.FindStyleResource('checkcellstyle.checkboxchecked');
    End
    else
    Begin
      img := sb.FindStyleResource('checkcellstyle.checkboxunchecked');
    End;

    if Assigned(img) then
    begin
      aRectF := Bounds;
      aRectF.Left := aRectF.Right - 90; // to adapt
      TStyleObject(img).DrawToCanvas(Canvas, aRectF, 1);
      StringGrid1.Repaint;
    end;
  end;

end;

procedure TForm1.StringGrid1SelectCell(Sender: TObject;
  const ACol, ARow: Integer; var CanSelect: Boolean);
begin
  if (ACol = CHECKBOX_COLUMN) AND (ARow = CHECKBOX_ROW) then
    CanSelect := False
  else
    CanSelect := true;
end;

end.`

As the pictures show this works perfectly on windows 32. However not on Android. Indeed it has something to do with the style (checkcellstyle.checkboxchecked is never found). I can not find a working style for Android any suggestions?