Add commandline conversion for Windows (no-op on other platforms)

- add Fl::args_to_utf8() to convert commandline arguments to UTF-8

This new function closes the gap that previously only Visual Studio
applications converted their commandlines to UTF-8.

Tested with MinGW, MSYS2/MinGW-w64, and Visual Studio (2019).

1 files changed, 34 insertions, 0 deletions

diff --git a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
index faf89e979..d7b01465a 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_System_Driver.cxx
@@ -299,6 +299,40 @@ int Fl_WinAPI_System_Driver::rename(const char *fnam, const char *newnam) {
   return _wrename(wbuf, wbuf1);
 }
 
+// See Fl::args_to_utf8()
+int Fl_WinAPI_System_Driver::args_to_utf8(int argc, char ** &argv) {
+  int i;
+  char strbuf[2048]; // FIXME: allocate argv and strings dynamically
+
+  // Convert the command line arguments to UTF-8
+  LPWSTR *wideArgv = CommandLineToArgvW(GetCommandLineW(), &argc);
+  argv = (char **)malloc((argc + 1) * sizeof(char *));
+  for (i = 0; i < argc; i++) {
+    int ret = WideCharToMultiByte(CP_UTF8,        // CodePage
+                                  0,              // dwFlags
+                                  wideArgv[i],    // lpWideCharStr
+                                  -1,             // cchWideChar
+                                  strbuf,         // lpMultiByteStr
+                                  sizeof(strbuf), // cbMultiByte
+                                  NULL,           // lpDefaultChar
+                                  NULL);          // lpUsedDefaultChar
+
+    if (!ret)
+      strbuf[0] = '\0'; // return empty string
+    argv[i] = fl_strdup(strbuf);
+  }
+  argv[argc] = NULL; // required NULL pointer at end of list
+
+  // Free the wide character string array
+  LocalFree(wideArgv);
+
+  // Note: the allocated memory or argv[] will not be free'd by the system
+  // on exit. This does not constitute a memory leak.
+
+  return argc;
+}
+
+
 // Two Windows-specific functions fl_utf8_to_locale() and fl_locale_to_utf8()
 // from file fl_utf8.cxx are put here for API compatibility