在您的表单上放置一个TLabel和一个TButton.

双击该按钮并写入

procedure TForm1.Button1Click(Sender: TObject);
begin
  Label1.Caption := TimeToStr(Time);
end;

练习2

要获得自动更新的时间,请将TTimer添加到表单中,然后双击它(如果您愿意,可以删除该按钮).然后写

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Label1.Caption := TimeToStr(Time);
end;

该代码将运行一秒钟(TTimer的默认间隔,这对我们来说是完美的,所以我们不需要更改它).

练习3

为了使时钟更烦人,您可以尝试以下方式：在窗体的界面中,添加一个名为FHighlight的私有字段,如下所示：

TForm1 = class(TForm)
  Button1: TButton;
  Label1: TLabel;
  Timer1: TTimer;
  procedure Button1Click(Sender: TObject);
  procedure Timer1Timer(Sender: TObject);
private
  { Private declarations }
  FHighlight: boolean;
public
  { Public declarations }
end;

现在你可以做

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Label1.Caption := TimeToStr(Time);
  if FHighlight then
  begin
    Label1.Color := clWhite;
    Label1.Font.Color := clBlack;
  end
  else
  begin
    Label1.Color := clBlack;
    Label1.Font.Color := clWhite;
  end;
  FHighlight := not FHighlight;
end;

为了实现这一效果,您需要更改TLabel控件的一个属性(设计时间).将透明度更改为false,使用对象检查器(如果尚未).

更新(练习4)

由于Warren P认为这是一个简单的TLabel太无聊了,这就是您如何实现“真正的”七段数字时钟：

procedure TForm1.FormPaint(Sender: TObject);
type
  TDigitData = array[0..6] of boolean;
  TPhysDigit = array[0..7] of TRect;
const
  DIGIT: array[0..9] of TDigitData =
    (
      (true,true,false),(false,false,(true,true),true)
    );
var
  PaddingW,PaddingH,UnitX,UnitY,DigitWidth,DigitHeight,BarLengthX,BarLengthY,DigitSeparation,FieldSeparation: integer;
  SEGMENTS: array[0..5] of TPhysDigit;
  i: Integer;

  function TranslatePhysDigit(const PhysDigit: TPhysDigit; const DX: integer; const DY: integer = 0): TPhysDigit;
  var
    i: Integer;
  begin
    for i := 0 to 7 do
    begin
      result[i].Left := PhysDigit[i].Left + DX;
      result[i].Right := PhysDigit[i].Right + DX;
      result[i].Top := PhysDigit[i].Top + DY;
      result[i].Bottom := PhysDigit[i].Bottom + DY;
    end;
  end;

  procedure DrawDigit(const Position,Value: integer);
  var
    i: integer;
  begin
    for i := 0 to 6 do
      if DIGIT[Value,i] then
        Canvas.FillRect(SEGMENTS[Position,i]);
  end;

  procedure DrawColon(const Position: integer);
  var
    ColonRect1: TRect;
    ColonRect2: TRect;
  begin
    ColonRect1 := Rect(PaddingW + Position*UnitX,PaddingH + UnitY,PaddingW + (Position+1)*UnitX,PaddingH + 2*UnitY);
    ColonRect2 := Rect(PaddingW + Position*UnitX,PaddingH + 3*UnitY,PaddingH + 4*UnitY);
    Canvas.FillRect(ColonRect1);
    Canvas.FillRect(ColonRect2);
  end;

var
  t: string;

begin
  PaddingW := Width div 20;
  PaddingH := Height div 20;
  UnitX := (ClientWidth - 2*PaddingW) div 27;
  UnitY := (ClientHeight - 2*PaddingH) div 5;
  DigitWidth := 3*UnitX;
  DigitHeight := 5*UnitY;
  BarLengthX := 3*UnitX;
  BarLengthY := 3*UnitY;
  DigitSeparation := 4*UnitX;
  FieldSeparation := 6*UnitX;
  SEGMENTS[0,0] := Rect(0,UnitY);
  SEGMENTS[0,1] := Rect(DigitWidth - UnitX,BarLengthY);
  SEGMENTS[0,2] := Rect(DigitWidth - UnitX,2*UnitY,DigitHeight);
  SEGMENTS[0,3] := Rect(0,DigitHeight - UnitY,4] := Rect(0,5] := Rect(0,6] := Rect(0,3*UnitY);
  SEGMENTS[0] := TranslatePhysDigit(SEGMENTS[0],PaddingW,PaddingH);
  SEGMENTS[1] := TranslatePhysDigit(SEGMENTS[0],DigitSeparation);
  SEGMENTS[2] := TranslatePhysDigit(SEGMENTS[1],FieldSeparation);
  SEGMENTS[3] := TranslatePhysDigit(SEGMENTS[2],DigitSeparation);
  SEGMENTS[4] := TranslatePhysDigit(SEGMENTS[3],FieldSeparation);
  SEGMENTS[5] := TranslatePhysDigit(SEGMENTS[4],DigitSeparation);
  Canvas.Brush.Color := clBlack;
  Canvas.FillRect(ClientRect);
  Canvas.Brush.Color := clBlack;
  Canvas.FillRect(Rect(PaddingW,ClientWidth - PaddingW,ClientHeight - PaddingH));
  Canvas.Brush.Color := clRed;
  t := FormatDateTime('hhnnss',Time);

  for i := 0 to 5 do
    DrawDigit(i,StrToInt(Copy(t,i+1,1)));

  if odd(StrToInt(Copy(t,6,1))) then
  begin
    DrawColon(8);
    DrawColon(18);
  end;
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  Invalidate;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Invalidate;
end;

Seven-segment digital clock http://privat.rejbrand.se/seven-segment-clock.png

玩GDI画笔：

Seven-segment digital clock http://privat.rejbrand.se/seven-segment-clock-brush.png