Question

我必须将多个测量设备连接到我的应用程序（即卡尺，体重秤......），而不是绑定到特定的品牌或型号，所以在客户端我使用通用方法的接口（{{1 }}）。设备连接在COM端口上，并以异步方式访问：

要求一个值（=发送一个特定的字符序列 COM端口）
等待回复

在“业务”方面，我的组件在内部使用TComPort，数据接收事件为QueryValue。我想知道如何通过界面触发此事件？这是我到目前为止所做的：

TComPort.OnRxChar

但我需要一个事件来知道何时在客户端调用IDevice = interface procedure QueryValue; function GetValue: Double; end; TDevice = class(TInterfacedObject, IDevice) private FComPort: TComPort; FValue: Double; protected procedure ComPortRxChar; public constructor Create; procedure QueryValue; function GetValue: Double; end; constructor TDevice.Create; begin FComPort := TComPort.Create; FComPort.OnRxChar := ComPortRxChar; end; // COM port receiving data procedure TDevice.ComPortRxChar; begin FValue := ... end; procedure TDevice.GetValue; begin Result := FValue; end;。执行这种数据流的常用方法是什么？

Answer 1

您可以将事件属性添加到界面

IDevice = interface
  function GetValue: Double;
  procedure SetMyEvent(const Value: TNotifyEvent);
  function GetMyEvent: TNotifyEvent;
  property MyEvent: TNotifyEvent read GetMyEvent write SetMyEvent;
end;

并在TDevice类中实现它

TDevice = class(TInterfacedObject, IDevice)
private
  FMyEvent: TNotifyEvent;
  procedure SetMyEvent(const Value: TNotifyEvent);
  function GetMyEvent: TNotifyEvent;
public
  function GetValue: Double;
  procedure EmulChar;
end;

然后通常在FMyEvent的末尾调用ComPortRxChar处理程序（如果已分配）。

 Tform1...
  procedure EventHandler(Sender: TObject);

procedure TForm1.EventHandler(Sender: TObject);
var
  d: Integer;
  i: IDevice;
begin
  i := TDevice(Sender) as IDevice;
  d := Round(i.GetValue);
  ShowMessage(Format('The answer is %d...', [d]));
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  id: IDevice;
begin
  id:= TDevice.Create;
  id.MyEvent := EventHandler;
  (id as TDevice).EmulChar; //emulate rxchar arrival
end;

procedure TDevice.EmulChar;
begin
  if Assigned(FMyEvent) then
    FMyEvent(Self);
end;

function TDevice.GetMyEvent: TNotifyEvent;
begin
  Result := FMyEvent;
end;

function TDevice.GetValue: Double;
begin
  Result := 42;
end;

procedure TDevice.SetMyEvent(const Value: TNotifyEvent);
begin
  FMyEvent := Value;
end;

通过通用接口的异步事件

1 个答案: