来自非托管 win32 dll 的 C# 运行对话框

Question

I've made a win32 DLL that records and plays using a dialog box. I'm trying to use it in my C# code by passing a pointer in through one function so I can keep the data and actually getting the dialog to open with another function the calls CreateDialog and gives it my DLGPROC. I'd like to have the dll run as independently as possible, only keeping a reference to the data and telling it when to open and close.

Header.h:

#pragma once
#pragma comment(lib, "winmm.lib")

#include <Windows.h>

#ifdef __cplusplus
#define EXPORT extern "C" __declspec (dllexport)
#else
#define EXPORT __declspec (dllexport)
#endif

EXPORT BOOLEAN StartDiag();
EXPORT BOOLEAN SetData(DOUBLE*);

Record.c:

#include <windows.h>
#include "resource.h"
#include "Header.h"

#define INP_BUFFER_SIZE 16384

BOOL CALLBACK DlgProc(HWND, UINT, WPARAM, LPARAM);

TCHAR szAppName[] = TEXT("Record1");
double* pData;

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    PSTR szCmdLine, int iCmdShow)
{
    return 0;
}

BOOLEAN StartDiag()
{
    if (CreateDialog(NULL, MAKEINTRESOURCE(DLG_RECORD), NULL, DlgProc) == 
        NULL)
    {
        return FALSE;
    }
    return TRUE;
}

BOOLEAN SetData(double* p)
{
    p = pData;
    return TRUE;
}

BOOL CALLBACK DlgProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
   ...
}

C#:

    [DllImport("RecordLib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
    public static extern Boolean SetData(ref double[] d);
    [DllImport("RecordLib.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
    public static extern Boolean StartDiag();

I am pretty confident StartDiag is getting called correctly because It always returns false, meaning the body of the function is entered and the if statement is evaluated properly. The obvious problem is this means the DLL isn't creating a dialog like I want it to. The Dialog is obviously in an rc file and should be included with the dll, so how does this work? How would I get my DLL to actually run the dialog resource?

Answer 1

if (CreateDialog(NULL, ...)

You cannot pass NULL here and hope for success. That only works in simple single module programs, the kind that has just a single EXE file that contains everything. In your scenario, Windows is going to search the managed assembly for the resource. That's a fail whale. It has to be the handle of the module that contains the dialog resource. Surely the DLL.

You need DllMain() instead of WinMain(). Store the handle you get so you can use it later. Boilerplate:

HMODULE ThisDllHandle;

BOOL APIENTRY DllMain(HMODULE hModule, DWORD reason, LPVOID)
{
    if (reason == DLL_PROCESS_ATTACH) {
        ThisDllHandle = hModule;
        DisableThreadLibraryCalls(hModule);
    }
    return TRUE;
}