Ruby Sketchup Error when calling dll library in Sketchup Ruby - ruby

Question

I want Sketchup can import muliple files. But unfortunately, Sketchup API dosen't support it. So i created one dll library. It call Window API function: GetOpenFileName for displaying multi-select dialog, get selected file names and display them in formatted string (selected directory | filename1 |filename2...). Then i put it and Win32API.so into Plugin folder of Sketchup. But when i open Sketchup, it display error: Error Loading File GetProcAddress: ShowDialog or ShowDialogA (ShowDialog is one function of my dll )
Here is my code in dllmain.cpp (C++ code)
#define EXPORT _declspec(dllexport)
HWND hDlg = NULL;
wchar_t* buffer = new wchar_t[32768];
EXPORT void ShowDialog(void)
{
OPENFILENAME ofn;
wchar_t szFile[32768];
// Initialize OPENFILENAME
ofn.lStructSize = sizeof(ofn);
ofn.hwndOwner = hDlg;
ofn.lpstrFile = (wchar_t*)szFile;
ofn.lpstrFile[0] = '\0';
ofn.nMaxFile = sizeof(szFile);
ofn.lpstrFileTitle = NULL;
ofn.nMaxFileTitle = 0;
ofn.lpstrInitialDir = NULL;
ofn.Flags = OFN_ALLOWMULTISELECT | OFN_ENABLESIZING | OFN_EXPLORER;
if(GetOpenFileName(&ofn) == TRUE)
{
if(szFile[ofn.nFileOffset-1] != '\0')
{
wcscpy_s(buffer,sizeof(szFile),szFile);
}
else
{
//Multi-select
wchar_t* p= szFile;
int i =0;
while(*p)
{
wchar_t* temp = new wchar_t[1024];
//Copy p into temp
wcscpy_s(temp,1024,p);
if(i==0)
{
wcscpy_s(buffer,1024,temp);
}
else
{
wcscat_s(buffer,1024,temp);
}
wcscat_s(buffer, sizeof(buffer) * wcslen(buffer), L"|");
i++;
p += lstrlen(p) + 1;
}
}
int len = wcslen(buffer);
buffer[len]='\0';
}
EXPORT void GetResult(char* pString)
{
int len = wcslen(buffer);
for(int i =0 ; i < wcslen(buffer);i++)
{
pString[i] = (char)buffer[i];
}
pString[len]='\0';
}
Here is my script in ruby file.
require 'sketchup.rb'
require "Win32API"
path = Sketchup.find_support_file("\Plugins\\")
#my dll has name MultiUploadProject.dll
mydll = path + "\\MultiUploadProject.dll"
if (!FileTest.exist?( mydll ) )
UI.messagebox(sprintf("MultiUploadProject.dll not found in SketchUp plugins folder: %s\n",mydll))
end
ShowDialog = Win32API.new(mydll,"ShowDialog",["V"],"V")
GetResult = Win32API.new(mydll,"GetResult",["P"],"V")
def load_dialog
ShowDialog.call
string = " " * 32768
GetResult.call(string)
end
I use Visual Studio 2012 to build dll and My Sketchup is Sketchup 8
Any suggestions would be appreciated.

Answer 1

The export needs to be C exports (without C++ name mangling). Try defining the EXPORT macro like this:
#define EXPORT extern "C" _declspec(dllexport)
or define the exported functions inside extern "C"
extern "C" {
// Exported functions here.
}