【转载】SDK中调用COM的例子

 SDK中调用COM的例子

This method accesses AutoCAD ActiveX Automation through pure COM techniques. This method requires more coding, but does not rely on MFC. The sample program uses the COM ActiveX Automation interfaces to add a new shortcut menu to the AutoCAD menu bar. The following sections provide procedures that demonstrate the necessary steps:

• To set up a new ObjectARX project
• To import AutoCAD ActiveX interfaces
• To implement AutoCAD ActiveX Automation calls

To set up a new ObjectARX project

1. Start Visual C++ and create a new Win32 DLL project called AsdkPlainComSamp.
2. Add the appropriate values to the project settings to make the project build as an ObjectARX program. This program needs to link with the following libraries:

      acad.lib acdb16.lib rxapi.lib acedapi.lib

3. Add a new definitions (DEF) file named AsdkPlainComSamp.def to the project.
4. Open the new DEF file, and add the following lines to the EXPORTS section:

      acrxEntryPoint        PRIVATE

      acrxGetApiVersion     PRIVATE

5. Add a new source (CPP) file named AsdkPlainComSamp.cpp to the project.
6. Open the new CPP file, and add the following code to make the program ObjectARX compatible:

#include <rxregsvc.h>

#include <aced.h>

// Used to add/remove the menu with the same command.

//

static bool bIsMenuLoaded = false;

static void initApp()

}

7. Stub in your new AutoCAD command handler function by adding the following code to the AsdkPlainComSamp.cpp source file:

void addMenuThroughCom()

}

The next step is to decide which interfaces are necessary to access the AutoCAD menu bar. In this case, IAcadApplication, IAcadMenuBar, IAcadMenuGroups, IAcadMenuGroup, IAcadPopupMenus, IAcadPopupMenu, and IAcadPopupMenuItem are required. To get the definitions of these interfaces, use the AutoCAD type library, acax16<lang>.tlb, as shown in the next procedure.

To import AutoCAD ActiveX interfaces

1. Add the following line to the top of the AsdkPlainComSamp.cpp file, making sure to use the path where AutoCAD is installed on your system:

import "c:\\acad\\acad.tlb" no_implementation "

    raw_interfaces_only named_guids

2. Add the following declarations to the addMenuThroughCom() function:
   

AutoCAD::IAcadApplication *pAcad;
AutoCAD::IAcadMenuBar *pMenuBar;
AutoCAD::IAcadMenuGroups *pMenuGroups;
AutoCAD::IAcadMenuGroup *pMenuGroup;
AutoCAD::IAcadPopupMenus *pPopUpMenus;
AutoCAD::IAcadPopupMenu *pPopUpMenu;
AutoCAD::IAcadPopupMenuItem *pPopUpMenuItem;

Now that your application imports the proper interfaces, you can use them to implement AutoCAD functionality. The more direct COM approach to Automation uses QueryInterface to access the IUnknown of AutoCAD and its Automation components. The next procedure shows how to accomplish this. All code examples in this procedure should be added to your addMenuThroughCOM() function in the sequence presented.

To implement AutoCAD ActiveX Automation calls

1. In the AsdkPlainComSamp.cpp file, add the following code to the empty addMenuThroughCOM() function to get AutoCAD's IUnknown:
   

HRESULT hr = NOERROR;
CLSID clsid;
LPUNKNOWN pUnk = NULL;
LPDISPATCH pAcadDisp = NULL; 
hr = ::CLSIDFromProgID(L"AutoCAD.Application",
        &clsid);
if (FAILED(hr))
    return;
if(::GetActiveObject(clsid, NULL, &pUnk) != S_OK)
    return;
hr = pUnk->QueryInterface(IID_IDispatch, (LPVOID*) &pAcadDisp);
pUnk->Release();
if (FAILED(hr))
    return;

2. Use IUnknown to get the AutoCAD application object. Also, make sure AutoCAD is visible. This is shown in the following code:

hr = pAcadDisp->QueryInterface(AutoCAD::IID_IAcadApplication, (void**)&pAcad);
pAcadDisp->Release();
if (FAILED(hr))
    return;
pAcad->put_Visible(true);

3. From the AutoCAD application interface, get the menu bar and menu groups collections:
   

pAcad->get_MenuBar(&pMenuBar);
pAcad->get_MenuGroups(&pMenuGroups);
pAcad->Release();

4. Determine how many menus are current on the menu bar:
   

long numberOfMenus;
pMenuBar->get_Count(&numberOfMenus);
pMenuBar->Release();

5. Get the first menu from the menu groups collection. This normally is ACAD, but could be something else:
   

VARIANT index;
VariantInit(&index);
V_VT(&index) = VT_I4;
V_I4(&index) = 0;
pMenuGroups->Item(index, &pMenuGroup);
pMenuGroups->Release();

6. Get the shortcut menus collection from the first menu group:
   

pMenuGroup->get_Menus(&pPopUpMenus);
pMenuGroup->Release();

7. Depending on whether the menu is already created, either construct a new shortcut menu or remove the previously created one. The following code completes the example:

WCHAR wstrMenuName[256];
MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED,  "AsdkComAccess", -1, wstrMenuName, 256); 
Release();

Here is the finished function:

void addMenuThroughCom()
}

Both of these examples can be found in the ObjectARX SDK. They are located in the samples"com directory. Each sample contains code for adding a circle and a menu using either Win32 API or MFC programming techniques. Because these methods access AutoCAD through COM interfaces, these programming techniques can be used from other C++ contexts—not just from ObjectARX. Similar techniques can also be used in other languages, such as Visual Basic.