在Dll中重用两个窗体

[dyonggan]

在Dll中重用两个窗体，用其中一个窗体上的buttonclick事件来显示另一个窗体为什么会出错！代码如下：
.........................................主程序，用来调用DLL
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
Ttextdll = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
textdll: Ttextdll;

implementation
procedure ShowAboutDlg;stdcall;far;external'Project1.dll';//声明调用
{$R *.dfm}

procedure Ttextdll.Button1Click(Sender: TObject);
begin
ShowAboutDlg;//调用的过程
end;
.....................................................Dll的单元1，有三个button，为什么第三个会错
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, ExtCtrls, StdCtrls;

type
TForm1 = class(TForm)
Button1: TButton;
Label1: TLabel;
Image1: TImage;
Button2: TButton;
Button3: TButton;
procedure Button1Click(Sender: TObject);
procedure Button2Click(Sender: TObject);
procedure Button3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;
procedure ShowAboutDlg;export;//输出
implementation

uses Unit2;

{$R *.dfm}
procedure ShowAboutDlg;//函数
begin
Form1:=TForm1.Create(Application);
Try
Form1.ShowModal;

finally
Form1.Free;
end;
end;


procedure TForm1.Button1Click(Sender: TObject);
begin
close;//没有报错
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
showmessage('howoldareyou');//没有报错，正常使用
end;

procedure TForm1.Button3Click(Sender: TObject);export;
begin
form2.show;//这里出错，为什么form2出不来呢，且还报Access violation at address 003A1ADD in moudoue 'project1.dll'
end;

end.
.................................................DLL 的单元2。这里窗体什么也没做，只是让能够显示
unit Unit2;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;

type
TForm2 = class(TForm)
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form2: TForm2;

implementation

{$R *.dfm}

end.
.......................................................................dll的工程单元
library Project1;

uses
SysUtils,
Classes,
Unit1 in 'Unit1.pas' {Form1},
Unit2 in '..\..\..\..\Program Files\Borland\Delphi7\Projects\Unit2.pas' {Form2};

{$R *.res}
exports
ShowAboutDlg;//向调用程序输出过程
begin

end.

[fangsp]

帮楼主顶一个

[手指风]

form2有创建了,出错的那句?
另外dll的application对象和exe的application不是一样的。
需要传入exe的application,保存dll的application.返回时重新置回

[suton]

如果我没有猜错,你调showAboutDlg时,show出form1的时候,在任务栏里面,是另外再开一个的.

如果想只使用同一个,这样改:

procedure  ShowAboutDlg(H: HWND);
begin
  Application.Handle := H;
  Form1:=TForm1.Create(Application); 
  Try 
    Form1.ShowModal; 
  finally 
    Form1.Free; 
    Application.Handle := 0;
  end;
end;

主程序调用的时候:
ShowAboutDlg(Application.Handle);



procedure TForm1.Button3Click(Sender: TObject);export;
begin
form2.show;//这里出错，为什么form2出不来呢，且还报Access violation at address 003A1ADD in
这里报错,是因为Form2没有创建,根本没这个对象,当然会出现地址错误
moudoue 'project1.dll'
end;

[李_军]

你的form根本没有创建啊，dll中每个对象都要手工创建，手工释放

[dyonggan]

谢谢大家了，谢谢，我没有创建，用的不熟。