动态调用带窗体的DLL出问题了.

Question

A:关闭调用的DLL窗体时报错:'access violation at 0x00031285:write of address 0x10c00000'.
B:主调窗体也最小化了.
DLL窗体代码如下:
unit DLL_Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls;type
  Tdllform = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
  private
    { Private declarations }
  public
    { Public declarations }
  end;
function showcalendar(ahandle:thandle):longint;stdcall;
var
  dllform: Tdllform;implementation{$R *.dfm}
function showcalendar(ahandle:thandle):longint;stdcall;begin  application.Handle:=ahandle;
  dllform:=tdllform.Create(application);
   try    dllform.ShowModal;
    result:=longint(dllform);
  finally
       dllform.Free;
       end;
end;
end.DLL代码如下:
library DLL;
uses
  SysUtils,
  Classes,
  DLL_Unit1 in 'DLL_Unit1.pas' {Form1};
  exports
 showcalendar;
{$R *.res}begin
end.
主调程序如下:
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons,wintypes,winprocs;
type
  tshowcalendar=function(ahandle:thandle;acaption:string):tdatetime;stdcall;
   EDLLLOADERROR=CLASS(EXCEPTION);
  Tmainform = class(TForm)    btngetcalendar: TBitBtn;
    BitBtn2: TBitBtn;
    lbldate: TLabel;
    procedure btngetcalendarClick(Sender: TObject);  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  mainform: Tmainform;implementation{$R *.dfm}procedure Tmainform.btngetcalendarClick(Sender: TObject);
var
 libhandle:thandle;
showcalendar:tshowcalendar;
begin
 libhandle:=loadlibrary('DLL.dll');
 try
   if libhandle = 0 then
   RAISE EDLLLOADERROR.CREATE('SFSE');// else showmessage('DLL不存在');   @showcalendar:=getprocaddress(libhandle,'showcalendar');
   if not (@showcalendar=nil)then
    showcalendar(application.Handle ,caption)
    else
     raiselastwin32error;
 finally
  freelibrary(libhandle);
  end;
end;end.

Answer 1

DLL内窗体关闭的时候
Action:=caFree;

Answer 2

unit DLL_Unit1; interface uses 
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
  Dialogs, StdCtrls, ComCtrls; type 
  Tdllform = class(TForm) 
    Label1: TLabel; 
    Edit1: TEdit; 
  private 
    { Private declarations } 
  public 
    { Public declarations } 
  end; 
function showcalendar(ahandle:thandle):longint;stdcall; {---------------这里注掉----------------}
//var 
 // dllform: Tdllform; implementation {$R *.dfm} 
function showcalendar(ahandle:thandle):longint;stdcall; 
var 
  dllform: Tdllform; {-------上边注掉的加到这里-----------------}
begin   application.Handle:=ahandle; 
  dllform:=tdllform.Create(application); 
  try     dllform.ShowModal; 
    result:=longint(dllform); 
  finally 
    dllform.Release; {-----------------改了这里}
  end; 
end; 
end. 

Answer 3

public 
    { Public declarations } 
  end; 
function showcalendar(ahandle:thandle):longint;stdcall; {---------------这里注掉----------------}
//var 
 // dllform: Tdllform; implementation {$R *.dfm} 
注掉后,又报错'error dll_project1.dpr(11):undeclared identifier:'dllform''

Answer 4

错得一踏糊涂!exe与dll交互的接口都 不一样，能不出错吗？没有办法，只好把你的代码重新调整了一下///exe
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;type
  //tshowcalendar = function(ahandle: thandle; acaption: string): tdatetime; stdcall;
  tshowcalendar = function(ahandle: thandle; acaption: PChar): tdatetime; stdcall;  EDLLLOADERROR = class(EXCEPTION);
  TMainForm = class(TForm)
    btngetcalendar: TButton;
    procedure btngetcalendarClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  MainForm: TMainForm;implementation{$R *.dfm}procedure TMainForm.btngetcalendarClick(Sender: TObject);
var
  libhandle: thandle;
  showcalendar: tshowcalendar;
begin
  libhandle := loadlibrary('DLL.dll');
  try
    if libhandle = 0 then
      raise EDLLLOADERROR.CREATE('SFSE'); // else showmessage('DLL不存在');    @showcalendar := getprocaddress(libhandle, 'showcalendar');
    if not (@showcalendar = nil) then
      showcalendar(application.Handle, PChar(caption))
    else
      raiselastwin32error;
  finally
    freelibrary(libhandle);
  end;
end;end.//dll
unit DLL_Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;type
  Tdllform = class(TForm)
    Label1: TLabel;
    Edit1: TEdit;
  private
    { Private declarations }
  public
    { Public declarations }
  end;function showcalendar(ahandle: thandle; acaption: PChar): tdatetime; stdcall;implementation{$R *.dfm}function showcalendar(ahandle: thandle; acaption: PChar): tdatetime; stdcall;
var
  dllform: Tdllform;
begin
  application.Handle := ahandle;
  dllform := tdllform.Create(application);
  try
    dllform.Caption := acaption; ///++++++++
    dllform.ShowModal;
    ///result := longint(dllform);
    Result := Now; ///+++++++++
  finally
    dllform.Free;
  end;
end;end.

Answer 5

DLL窗体关闭后,主调窗体被最小化了.怎么回事呀,我没有设它最小化呀.

Answer 6

TO:blazingfire     { Private declarations }
  public
    { Public declarations }
  end;
这个地方不加var
  dllform: Tdllform;就报错.'[error]dll_p.dpr(11):undeclared identifier;'dllform'',加了之后也行,请叫了.
function showcalendar(ahandle: thandle; acaption: PChar): tdatetime; stdcall;implementation{$R *.dfm}function showcalendar(ahandle: thandle; acaption: PChar): tdatetime; stdcall;
var
  dllform: Tdllform;
begin
  application.Handle := ahandle;

Answer 7

DLL窗体关闭后,主调窗体被最小化了.怎么回事呀,我没有设它最小化呀.

Answer 8

结出的信息不足，我也不懂。
别外你请教问题请用“请教”，不要用“请叫”，这样不点也不幽默，反而让人心里发毛!调用的时候别用Application.Handle,用Application.MainForm.Handle