这个组件为什么不能保存上一次的值?在线等等.

Question

unit MyEdit;interfaceuses
  Windows, Messages, SysUtils, Classes, Controls, StdCtrls,Graphics,INIFiles;type
  TMyEdit = class(TEdit)
  private
    { Private declarations }
  protected
    { Protected declarations }
  public
    constructor Create(AOwner:TComponent);override;
    destructor Destroy;override;
    { Public declarations }
  published
    { Published declarations }
  end;procedure Register;implementationconstructor TMyEdit.Create(AOwner:TComponent);
var
 tmpINI:TINIFile;
begin
 inherited Create(AOwner);
 tmpINI:=TINIFile.Create('c:\component.ini');
 Text:=tmpINI.ReadString('Label','Name','无标题');
 tmpINI.Free;
end;destructor TMYEdit.Destroy;
var
  tmpINI:TINIFile;
begin
  tmpINI:=TINIFile.Create('c:\component.ini');
  tmpINI.WriteString('Label','Name',self.Text);
  tmpINI.Free;
  inherited Destroy;
end;procedure Register;
begin
  RegisterComponents('Samples', [TMyEdit]);
end;end.

Answer 1

在你DESTORY的时候，TEXT的内容已经被改为‘’了，用一个全局变量，改成这样：
unit MyEdit;interfaceuses
  dialogs,Windows, Messages, SysUtils, Classes, Controls, StdCtrls,Graphics,INIFiles;type
  TMyEdit = class(TEdit)
  private
    { Private declarations }
  protected
    { Protected declarations }
  public
    constructor Create(AOwner:TComponent);override;
    destructor Destroy;override;
    procedure onchg(Sender: TObject);
    { Public declarations }
  published
    { Published declarations }
  end;procedure Register;var s : string;
implementationconstructor TMyEdit.Create(AOwner:TComponent);
var
 tmpINI:TINIFile;
begin
 inherited Create(AOwner);
 tmpINI:=TINIFile.Create('c:\component.txt');
 Text:=tmpINI.ReadString('Label','Name','无标题');
 tmpINI.Free;
 onchange:=onchg;
end;
  procedure TMyEdit.onchg(Sender: TObject);
  begin
   s:=text;
  end;destructor TMYEdit.Destroy;
var
  tmpINI:TINIFile;
begin
  tmpINI:=TINIFile.Create('c:\component.ini');
  tmpINI.WriteString('Label','Name',s);
  tmpINI.Free;
  inherited Destroy;
end;procedure Register;
begin
  RegisterComponents('Samples', [TMyEdit]);
end;end.

Answer 2

To lxl:
   可是onchg是自己定义的过程，并不是OnChange?

Answer 3

我还发现，如果在设计的时候给edit赋值，那么上面的控件就不能调入component.ini中的值.why?

Answer 4

unit MyEdit;interfaceuses
  Windows, Messages, SysUtils, Classes, Controls, StdCtrls,Graphics,INIFiles;type
  TMyEdit = class(TEdit)
  private
    { Private declarations }
    IniText:String;                  //增加一私有变量  
  protected
    { Protected declarations }
  public
    constructor Create(AOwner:TComponent);override;
    destructor Destroy;override;
    procedure Change;override;       //重载该过程；
  public
    { Public declarations }
  published
    { Published declarations }
  end;procedure Register;implementationprocedure TMyEdit.Change;      //重载过程，将改变后的值记录下。 
begin
  inherited;
  IniText:=self.Text;
end;constructor TMyEdit.Create(AOwner:TComponent);
var
 tmpINI:TINIFile;
begin
 inherited Create(AOwner);
 tmpINI:=TINIFile.Create('c:\component.ini');
 Text:=tmpINI.ReadString('Label','Name','无标题');
 tmpINI.Free;
end;destructor TMYEdit.Destroy;
var
  tmpINI:TINIFile;
begin
  tmpINI:=TINIFile.Create('c:\component.ini');
  tmpINI.WriteString('Label','Name',IniText);  //将记录下的值写回Ini文件
  tmpINI.Free;
  inherited Destroy;
end;procedure Register;
begin
  RegisterComponents('Samples', [TMyEdit]);
end;end.