关于显示DLL中Frame的方法.急,高手请进!
我在DLL中包含了一个Frame,Dll原程序如后.
现在的问题是如果何在项目表单中显示出此Frame.
请写出调用方法,谢谢!
#include <vcl.h>
#include <windows.h>
#include "frame.h" //此处为包含Frame的头文件,Frame中只有一个按钮.
#pragma hdrstop
#pragma argsused
int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
return 1;
}
//定义引出---------------------------------------------------------------------------
extern "C" __declspec(dllexport) __stdcall void ShowFrame(TForm* MainForm);
//显示Frame
__declspec(dllexport) __stdcall void ShowFrame(TForm* MainForm)
{
TFrame1 *Frame2;
Frame2=new TFrame1(MainForm);
Frame2->Parent=MainForm;
Frame2->Align=alClient;
Frame2->Visible=true;
}
问题点数：100、回复次数：10Top
1 楼dxkh（沧海一粟）回复于 2006-05-04 09:21:27 得分 10
帮你顶。
学习Top
2 楼hongchen363（电脑爆）回复于 2006-05-04 15:01:24 得分 0
高手跑哪去了啊!
自己顶一下Top
3 楼day_dreamerabc（流浪牛）回复于 2006-05-04 15:07:15 得分 10
没有用过Frame,深表关注Top
4 楼jjwwang（(空园歌独酌，春日赋闲居)）回复于 2006-05-05 15:16:53 得分 0
参考一下吧.虽然是建立一下FORM.但意思一样.
There are lots of resources and solutions out there on the internet that are specific to this problem, however, in using the BusinessSkinForm components, that are tightly integrated with the VCL and messaging, I came across a few problems with the standard approaches.
The final solution came with the assistance of Steve Woods (aka Reconics).
The main problem with storing Forms in dlls and being able to create instances of them from within a host exe is that when Delphi compiles up a dll, it has its own TApplication and TScreen instances (as well as other info as to be discovered).
This means that the DLL and the EXE message loops are different, the RTTI information is different, and causes lots of problems like the well know "cannot assign a TFont to a TFont" message.
So how do we Coax the form in the DLL to think it is part of the EXE, we replace the Application and Screen Object in the DLL with the reference to the EXE's Application and Screen.
This is a standard approach that you will find on the net. However there is one additional element that needs to be passed from EXE to DLL and this is the tricky one.
From Steve Woods -
“The problem is caused by the ControlAtom local variable in the Controls.pas units. When the controls unit initializes it creates a global atom based on the string 'ControlOfs' + the HInstance and thread ID of the application and stores the atom in the ControlAtom local variable.
All well and good. Then when new wincontrols are added to the application a pointer to the control is stored under the window handle using the SetProp API function. This allows Delphi to get the TWinControl of a Handle.
The CM_MouseEnter etc. events are generated from the TApplication.DoMouseIdle method. In order to get the current wincontrol under the mouse, and thus pass the required messages, its searches for a property with a Atom equal to the local ControlAtom variable stored in the Controls units.
This all works fine for standalone apps but when you start putting forms in DLL's the following happens:
The controls unit is initialized again for the DLL. This creates a new global atom and stores it in the Controls unit local variable, so you now have TWO control global atoms, one for the main app and one for the DLL.
And thus, when the Application.DoMouseIdle method tries to find a property stored with the same name (atom) as the application on a DLL form, it fails. To solve this I had to hack the controls.pas units a little. I added a routine : Function GetControlAtom : Pointer that returns @ControlAtom from the controls units.
Then in your DLL's you initialize by passing the ControlAtom from the application Controls units and set this value in the Controls unit of the DLL:
eg
Library ADLL; Uses ... forms, Controls, //Add this here so it initializes unit before we try and change GetControlAtom; ...
procedure CreateForm(App : TApplication;Scr : TScreen;RealControlAtom : Integer); Var P : ^Word; Begin If (OldApp = Nil) Then Begin OldApp := Application; OldScr := Screen; P := GetControlAtom; OldAtom := P^; Application := App; Screen := Scr; P^ := RealControlAtom; end; TForm1.Create(Application.MainForm); end;
and make sure you clean-up before you unload the dll."
Stage 1) The ControlAtom variable is private to the controls.pas unit so we need to change Controls.pas for the EXE and DLL projects
Take a copy of controls.pas from the delphisourcevcl directory and save it into a directory that the EXE project and DLL project can access.
In the Interface Section add the function declaration for the function that will return the address of the current ControlAtom variable.
function GetControlAtom : pointer;
In the implementation section add the GetControlAtom function.
function GetControlAtom : pointer; begin result := @ControlAtom; end;
We now have an exposed function that will return the address of the Control Atom Variable.
Stage 2) Setting up the DLL exported functions
Add the modified Controls.pas to the project so it appears in the Project manager. Delphi will then use this source in preference to the standard controls.dcu.
We now need to provide a DLLInitialization procedure and a DLLFinalization Procedure. The DLLInitialization must be called before trying to use any forms from the DLL, usually this is
called just after loading the dll into memory. The DLLFinalization procedure should be called before the DLL is unloaded from memory.
Below is an example of the code needed to be exposed in the DLL. Notice the dll exports 3 functions/procedures DLLInitiailize, DLLFinalize and GetInstance
GetInstance is the call that actually returns an instance of a the dlls Form.
library plugin; uses ShareMem, SysUtils, Classes, Windows, Forms, Controls in 'Controls.pas', pluginform in 'pluginform.pas' {MyPlugin};
{$R *.res}
var OldApp : TApplication; OldScreen : TScreen; OldControlAtom : TAtom;
procedure DLLInitialize(App : TApplication; Scr : TScreen; RealControlAtom :Integer); var x : pointer; p : ^Word; begin If (OldApp = Nil) Then Begin // store away the current application, screen and control atom OldApp := Application; OldScreen := Screen; p := GetControlAtom; OldControlAtom := p^; // Assign the EXE's application, screen and control atom Application := App; Screen := Scr; p^ := RealControlAtom; end; ASkin := Skin; end; function GetInstance(AOwner : TComponent) : TForm; begin // create an instance of the form result := TMyPlugin.create(Application.MainForm); end; procedure DLLFinalize; var p : ^Word; begin // restore the DLL's application, screen and control atom p := GetControlAtom; p^ := OldControlAtom; Screen := OldScreen; Application := OldApp; end; exports GetInstance, DLLInitialize, DLLFinalize; begin OldApp := nil; OldScreen := nil; OldControlAtom := 0; end.
Stage 3) Setting up the EXE.
Add the modified Controls.pas to the project so it appears in the Project manager. Delphi will then use this source in preference to the standard controls.dcu.
Declare some procedure / function types to be used to reference the exported procs in the dll.
type TDLLInitialize = procedure (App : TApplication; Scr : TScreen; RealControlAtom :
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5 楼hongchen363（电脑爆）回复于 2006-05-05 16:50:08 得分 0
显示DLL中的Form表单我是会的.
不过显示Frame就不行了.
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6 楼jjwwang（(空园歌独酌，春日赋闲居)）回复于 2006-05-05 17:44:45 得分 0
绝不是显示FORM的事情呀Top
7 楼jjwwang（(空园歌独酌，春日赋闲居)）回复于 2006-05-05 22:01:57 得分 80
/*
以下代码在WIN2003企业版+BCB6下通过.
by 风归叶
转载请保证文档的完整性
*/
//DLL
//---------------------------------------------------------------------------
#include <System.hpp>
#include <vcl.h>
#include <windows.h>
#include "AADD.h"
#pragma hdrstop
//---------------------------------------------------------------------------
#pragma argsused
TFrame *f;
int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved)
{
if( reason==DLL_PROCESS_DETACH )
delete f;
return 1;
}
//---------------------------------------------------------------------------
extern "C"
{
__declspec(dllexport) void __stdcall ShowFrame(TWinControl *P);
}
void __stdcall ShowFrame(TWinControl *P)
{
f = new TFrame(P);
f->ParentFont = false;
f->Parent = P;
f->Font->Color = clRed;
f->Left = 10;
f->Top = 10;
f->Width = 150;
f->Height = 150;
f->Color = clRed;
ShowWindow(f->Handle, SW_SHOW);
}Top
8 楼jjwwang（(空园歌独酌，春日赋闲居)）回复于 2006-05-05 22:02:28 得分 0
//---------------------------------------------------------------------------
#include <System.hpp>
#include <vcl.h>
#pragma hdrstop
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
HINSTANCE h;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
h = LoadLibrary( "Project1.dll" );
if( !h )
{
ShowMessage("LOAD ERROR");
return;
}
typedef void __stdcall PShowFrame(TWinControl *F);
PShowFrame *p = (PShowFrame *)GetProcAddress( h, "ShowFrame" );
if( p )
(*p)( Form1 );
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
Caption = this->ControlCount;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormClose(TObject *Sender, TCloseAction &Action)
{
FreeLibrary( h );
}
//---------------------------------------------------------------------------
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9 楼jjwwang（(空园歌独酌，春日赋闲居)）回复于 2006-05-05 22:02:45 得分 0
//---------------------------------------------------------------------------
#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published: // IDE-managed Components
TButton *Button1;
TButton *Button2;
void __fastcall Button1Click(TObject *Sender);
void __fastcall Button2Click(TObject *Sender);
void __fastcall FormClose(TObject *Sender, TCloseAction &Action);
private: // User declarations
public: // User declarations
__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endifTop
10 楼hongchen363（电脑爆）回复于 2006-05-05 23:54:40 得分 0
苦等两天的问题终于成了！
在此特别感谢 jjwwang(风归叶) 朋友．
也感谢各位对此问题表示了关注的朋友！
结帖给分！
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