Fix Latex not working on Windows

kpsewhich could not be found because GTK on windows needs to use the
`gspawn-win32-helper` program to spawn processes.

This commit also improves kpsewhich error reporting.

src/Xournalpp.cpp

@@ -16,7 +16,17 @@
 #include "CrashHandler.h"
 #include "Stacktrace.h"
 
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 auto main(int argc, char* argv[]) -> int {
+#ifdef _WIN32
+    // Show and hide the console here. Otherwise, gspawn-win32-helper will create annoying console popups.
+    AllocConsole();
+    ShowWindow(GetConsoleWindow(), SW_HIDE);
+#endif
+
     // init crash handler
     installCrashHandlers();
 

src/control/LatexController.cpp

@@ -80,8 +80,10 @@ auto LatexController::findTexDependencies() -> LatexController::FindDependencySt
     g_spawn_sync(nullptr, kpsewhichArgs, nullptr, kpsewhichFlags, nullptr, nullptr, nullptr, nullptr, &kpsewhichStatus,
                  &kpsewhichErr);
     if (kpsewhichErr != nullptr) {
+        string msg =
+                FS(_F("Error: {1}\nCould not find kpsewhich in PATH; please install kpsewhich and put it on path.") %
+                   kpsewhichErr->message);
         g_error_free(kpsewhichErr);
-        string msg = _("Could not find kpsewhich in PATH; please install kpsewhich and put it on path.");
         return LatexController::FindDependencyStatus(false, msg);
     }
     if (kpsewhichStatus != 0) {

windows-setup/build-setup.sh

@@ -64,6 +64,10 @@ cp -r /mingw64/share/icons setup/share/
 echo "copy glib shared"
 cp -r /mingw64/share/glib-2.0 setup/share/
 
+echo "copy gspawn-win64-helper"
+cp /mingw64/bin/gspawn-win64-helper.exe setup/bin
+cp /mingw64/bin/gspawn-win64-helper-console.exe setup/bin
+
 echo "pack setup"
 "/c/Program Files (x86)/NSIS/Bin/makensis.exe" xournalpp.nsi