videoio: plugins support on Win32

modules/core/src/utils/datafile.cpp

@@ -144,11 +144,38 @@ static cv::String getModuleLocation(const void* addr)
     return cv::String();
 }
 
-std::string getBinLocation()
+bool getBinLocation(std::string& dst)
 {
-    return getModuleLocation((void*)getModuleLocation); // use code addr, doesn't work with static linkage!
+    dst = getModuleLocation((void*)getModuleLocation); // using code address, doesn't work with static linkage!
+    return !dst.empty();
 }
 
+#ifdef _WIN32
+bool getBinLocation(std::wstring& dst)
+{
+    void* addr = (void*)getModuleLocation; // using code address, doesn't work with static linkage!
+    HMODULE m = 0;
+#if _WIN32_WINNT >= 0x0501
+    ::GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
+        reinterpret_cast<LPCTSTR>(addr),
+        &m);
+#endif
+    if (m)
+    {
+        wchar_t path[4096];
+        const size_t path_size = sizeof(path)/sizeof(*path);
+        size_t sz = GetModuleFileNameW(m, path, path_size);
+        if (sz > 0 && sz < path_size)
+        {
+            path[sz] = '\0';
+            dst.assign(path, sz);
+            return true;
+        }
+    }
+    return false;
+}
+#endif
+
 cv::String findDataFile(const cv::String& relative_path,
                         const char* configuration_parameter,
                         const std::vector<String>* search_paths,
@@ -292,8 +319,15 @@ cv::String findDataFile(const cv::String& relative_path,
         }
     }
 
-    cv::String module_path = getBinLocation();
-    CV_LOG_DEBUG(NULL, "Detected module path: '" << module_path << '\'');
+    cv::String module_path;
+    if (getBinLocation(module_path))
+    {
+        CV_LOG_DEBUG(NULL, "Detected module path: '" << module_path << '\'');
+    }
+    else
+    {
+        CV_LOG_INFO(NULL, "Can't detect module binaries location");
+    }
 
     if (!has_tested_build_directory &&
         (isSubDirectory(build_dir, module_path) || isSubDirectory(utils::fs::canonical(build_dir), utils::fs::canonical(module_path)))

modules/core/src/utils/filesystem.cpp

@@ -91,6 +91,14 @@ CV_EXPORTS cv::String getParent(const cv::String &path)
     return std::string(path, 0, loc);
 }
 
+CV_EXPORTS std::wstring getParent(const std::wstring& path)
+{
+    std::wstring::size_type loc = path.find_last_of(L"/\\");
+    if (loc == std::wstring::npos)
+        return std::wstring();
+    return std::wstring(path, 0, loc);
+}
+
 #if OPENCV_HAVE_FILESYSTEM_SUPPORT
 
 cv::String canonical(const cv::String& path)