From 2c5668af4696ea4e5f6ec6d7d72f9965ca082af6 Mon Sep 17 00:00:00 2001
From: Prateek Machiraju <prateek.machiraju@gmail.com>
Date: Sat, 5 Dec 2020 21:04:02 -0500
Subject: [PATCH] [wpigui] Add platform-specific preferences save

---
 glass/src/app/native/cpp/main.cpp             |  2 +-
 wpigui/src/main/native/cpp/wpigui.cpp         | 21 +++++++++++++++++++
 wpigui/src/main/native/include/wpigui.h       | 10 +++++++++
 .../src/main/native/include/wpigui_internal.h |  2 ++
 4 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/glass/src/app/native/cpp/main.cpp b/glass/src/app/native/cpp/main.cpp
index 4a0f1b790d..44ce0c294e 100644
--- a/glass/src/app/native/cpp/main.cpp
+++ b/glass/src/app/native/cpp/main.cpp
@@ -91,7 +91,7 @@ int main() {
   gPlotProvider = std::make_unique<glass::PlotProvider>("Plot");
   gNtProvider = std::make_unique<glass::NetworkTablesProvider>("NTProvider");
 
-  gui::AddInit([] { ImGui::GetIO().IniFilename = "glass.ini"; });
+  gui::ConfigurePlatformSaveFile("glass.ini");
   gPlotProvider->GlobalInit();
   gui::AddInit([] { gPlotProvider->ResetTime(); });
   gNtProvider->GlobalInit();
diff --git a/wpigui/src/main/native/cpp/wpigui.cpp b/wpigui/src/main/native/cpp/wpigui.cpp
index 955b3f52e7..cbaa3b84fa 100644
--- a/wpigui/src/main/native/cpp/wpigui.cpp
+++ b/wpigui/src/main/native/cpp/wpigui.cpp
@@ -140,6 +140,8 @@ bool gui::Initialize(const char* title, int width, int height) {
   iniHandler.WriteAllFn = IniWriteAll;
   ImGui::GetCurrentContext()->SettingsHandlers.push_back(iniHandler);
 
+  io.IniFilename = gContext->iniPath.c_str();
+
   for (auto&& initialize : gContext->initializers) {
     if (initialize) initialize();
   }
@@ -331,6 +333,25 @@ void gui::SetStyle(Style style) {
 
 void gui::SetClearColor(ImVec4 color) { gContext->clearColor = color; }
 
+void gui::ConfigurePlatformSaveFile(const std::string& name) {
+  gContext->iniPath = name;
+#if defined(_MSC_VER)
+  const char* env = std::getenv("APPDATA");
+  if (env) gContext->iniPath = env + std::string("/" + name);
+#elif defined(__APPLE__)
+  const char* env = std::getenv("HOME");
+  if (env)
+    gContext->iniPath = env + std::string("/Library/Preferences/" + name);
+#else
+  const char* xdg = std::getenv("XDG_CONFIG_HOME");
+  const char* env = std::getenv("HOME");
+  if (xdg)
+    gContext->iniPath = xdg + std::string("/" + name);
+  else if (env)
+    gContext->iniPath = env + std::string("/.config/" + name);
+#endif
+}
+
 void gui::EmitViewMenu() {
   if (ImGui::BeginMenu("View")) {
     if (ImGui::BeginMenu("Style")) {
diff --git a/wpigui/src/main/native/include/wpigui.h b/wpigui/src/main/native/include/wpigui.h
index c1dbc15dfa..8a9bb79c38 100644
--- a/wpigui/src/main/native/include/wpigui.h
+++ b/wpigui/src/main/native/include/wpigui.h
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <functional>
+#include <string>
 
 #include <imgui.h>
 
@@ -123,6 +124,15 @@ void SetStyle(Style style);
  */
 void SetClearColor(ImVec4 color);
 
+/**
+ * Configures a save file (.ini) in a platform specific location. On Windows,
+ * the .ini is saved in %APPDATA%; on macOS the .ini is saved in
+ * ~/Library/Preferences; on Linux the .ini is stored in $XDG_CONFIG_HOME or
+ * ~/.config if the former is not defined. This must be called before
+ * gui::Initialize().
+ */
+void ConfigurePlatformSaveFile(const std::string& name);
+
 /**
  * Emits a View menu (e.g. for a main menu bar) that allows setting of
  * style and zoom.  Internally starts with ImGui::BeginMenu("View").
diff --git a/wpigui/src/main/native/include/wpigui_internal.h b/wpigui/src/main/native/include/wpigui_internal.h
index 9a2c70f5c2..8cbede0bdd 100644
--- a/wpigui/src/main/native/include/wpigui_internal.h
+++ b/wpigui/src/main/native/include/wpigui_internal.h
@@ -56,6 +56,8 @@ struct Context : public SavedSettings {
 
   int fontScale = 2;  // updated by main loop
   std::vector<Font> fonts;
+
+  std::string iniPath = "imgui.ini";
 };
 
 extern Context* gContext;