Event Handler Description 事件处理描述 (自定义控件)
How should a new event handler be defined if it does not already belong to the base class? Let's look at this using the “TfrxEditControl” common control as an example:
一个新的事件处理程序应该如何定义，如果它不属于基类？让我们看看使用“TfrxEditControl“控件为例：
TfrxEditControl = class(TfrxDialogControl)
private
FEdit: TEdit;
{ new event }
FOnChange: TfrxNotifyEvent; //定义事件，注册类型。
procedure DoOnChange(Sender: TObject); //事件处理过程
...
public
constructor Create(AOwner: TComponent); override;
...
published
{ new event }
property OnChange: TfrxNotifyEvent read FOnChange write FOnChange; //定义事件
...
end;
constructor TfrxEditControl.Create(AOwner: TComponent);
begin
...
{ connect our handler }
FEdit.OnChange := DoOnChange; //在Create中关联事件(把TEdit控件的事件关联到自己的过程中)
InitControl(FEdit);
...
end;
procedure TfrxEditControl.DoOnChange(Sender: TObject);
begin
{ call event handler }
if Report <> nil then
Report.DoNotifyEvent(Sender, FOnChange); //处理事件(在过程中调用报表里的脚本)
end;
It is important to note that the event handler in FastReport is a procedure defined in the report script. The TfrxNotifyEvent type is declared as String[63] and in FastReport the link to the handler is a string containing its name. This is unlike the Delphi TNotifyEvent type, in which it is a method address.
很重要的提示，事件处理程序是在报表脚本中定义的过程。TfrxNotifyEvent 类型被声明为String[63]，并且在FastReport链接的事件处理过程是一个字符串（包含它的名字）。这个不像Delphi中的TNotifyEvent 类型，它是一个方法的地址。