delphi – 如何读取键输入？

发布时间：2020-12-15 09:18:40 所属栏目：大数据来源：网络整理

导读：我想要一个关键控制相机. TForm没有Onkeypress所以如何从键盘读取这个输入？ procedure TForm2.FormKeyPress(Sender: TObject; var Key: Char);var ok: boolean;begin ok := true; case Key of 'a': camera1.Position.y:=camera1.Position.y+1; 'A': camera1

我想要一个关键控制相机. TForm没有Onkeypress所以如何从键盘读取这个输入？

procedure TForm2.FormKeyPress(Sender: TObject; var Key: Char);
var
  ok: boolean;
begin
  ok := true;
  case Key of
    'a': camera1.Position.y:=camera1.Position.y+1;
    'A': camera1.Position.y:=camera1.Position.y+1;
    'd': camera1.Position.y:=camera1.Position.y-1;
    'D': camera1.Position.y:=camera1.Position.y-1;
    'w': camera1.Position.X:=camera1.Position.X-1;
    'W': camera1.Position.X:=camera1.Position.X-1;
    'x': camera1.Position.X:=camera1.Position.X+1;
    'X': camera1.Position.X:=camera1.Position.X+1;
    'q': camera1.RotationAngle.z := camera1.RotationAngle.z-1;
    'Q': camera1.RotationAngle.z := camera1.RotationAngle.z-1;
    'e': camera1.RotationAngle.z := camera1.RotationAngle.z+1;
    'E': camera1.RotationAngle.z := camera1.RotationAngle.z+1;
    'z': camera1.Position.z:=camera1.Position.z+1;
    'Z': camera1.Position.z:=camera1.Position.z+1;
    'c': camera1.Position.z:=camera1.Position.z-1;
    'C': camera1.Position.z:=camera1.Position.z-1;
    else
      ok := false;
  end; {case}
  //if ok then
   // Invalidate;
  positionChange(camera1);
  RotationAngleChange(camera1);
end;

解决方法

更新到最新版本的XE2(AFAIK Update 4 Hotfix 1)和

请改用TForm.OnKeyDown或TForm.OnKeyUp事件.这是我用过的快速测试：

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
  Shift: TShiftState);
begin
  case KeyChar of
    'A'..'Z','a'..'z': Caption := 'Got an alpha ' + KeyChar;
    '0'..'9': Caption := 'Got a number ' + KeyChar;
  else
    Caption := 'Got something else ' + KeyChar;
  end;
  KeyChar := #0;
end;

根据这个Embarcadero forums post,在没有上述更新的XE2中你需要实际覆盖TForm.KeyDown事件(根据@ TLama的请求添加;他是找到它并在评论中发布到我的答案的人)：

type
  TForm1 = class(TForm)
    Memo1: TMemo;
  private
  public
    procedure KeyDown(var Key: Word; var KeyChar: Char; 
      Shift: TShiftState); override;
  end;

implementation

procedure TForm1.KeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
  Shift: TShiftState);
begin
  case KeyChar of
    'A'..'Z','a'..'z': Caption := 'Got an alpha ' + KeyChar;
    '0'..'9': Caption := 'Got a number ' + KeyChar;
  else
    Caption := 'Got something else ' + KeyChar;
  end;
  KeyChar := #0;
end;

(就像一个注释,你可以稍微缩短你的代码)：

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char;
  Shift: TShiftState);
begin
  ok := true;
  case KeyChar of
    'A','a': camera1.Position.y:=camera1.Position.y+1;
    'D','d': camera1.Position.y:=camera1.Position.y-1;
    'W','w': camera1.Position.X:=camera1.Position.X-1;
    'X','x': camera1.Position.X:=camera1.Position.X+1;
    'Q','q': camera1.RotationAngle.z := camera1.RotationAngle.z-1;
    'E','e': camera1.RotationAngle.z := camera1.RotationAngle.z+1;
    'Z','z': camera1.Position.z:=camera1.Position.z+1;
    'C','c': camera1.Position.z:=camera1.Position.z-1;
  else
    ok := false;
  end; {case}
  if ok then
  begin
   // Invalidate;
   KeyChar := #0;  // Remove keystroke,because you've handled it
  end;
  positionChange(camera1);
  RotationAngleChange(camera1);      
end;

（编辑：李大同）

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