procedure GraG(bit:TBitMap; col1:TColor; col2:TColor);
var a:integer; r1,g1,b1,r2,g2,b2:byte;
begin
     r1:=GetRValue(col1); g1:=GetGValue(col1); b1:=GetBValue(col1);
     r2:=GetRValue(col2); g2:=GetGValue(col2); b2:=GetBValue(col2);
     for a:=0 to bit.Width-1 do begin
         bit.Canvas.Pen.Color:=RGB(trunc(r1-(r1-r2)/(bit.Width-1)*a), trunc(g1-(g1-g2)/(bit.Width-1)*a), trunc(b1-(b1-b2)/(bit.Width-1)*a));
         bit.Canvas.MoveTo(a,0);
         bit.Canvas.LineTo(a,bit.Height);
     end;
end;

var k:array[0..255]of boolean;
//.................................................
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
         k[key]:=true;
end;

procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
         k[key]:=false;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
         if k[32] then begin ... end;
end;