Load last saved GUI configuration on first load.

Also save theme to the configuration.

PiperOrigin-RevId: 843710929
Change-Id: I7ce9ce0f026d2cb5f79addf6c16c9b540bf11954

src/experimental/platform/imgui_widgets.h

@@ -47,9 +47,12 @@ static constexpr const char ICON_FA_SUN[] = "\xEF\x86\x85";
 static constexpr const char ICON_FA_TACHOMETER[] = "\xEF\x83\xA4";
 static constexpr const char ICON_FA_UNDO[] = "\xEF\x83\xA2";
 
-
 using KeyValues = std::unordered_map<std::string, std::string>;
 
+// This is a workaround to fix compilation on gcc <= 12 and clang <= 16
+template <typename T>
+struct dependent_false : std::false_type {};
+
 // Appends key/value pairs to an Ini file.
 void AppendIniSection(std::string& ini, const std::string& section,
                       const KeyValues& key_values);
@@ -58,6 +61,27 @@ void AppendIniSection(std::string& ini, const std::string& section,
 KeyValues ReadIniSection(const std::string& contents,
                          const std::string& section);
 
+template <typename T>
+T ReadIniValue(const KeyValues& key_values, const std::string& key, T def) {
+  auto iter = key_values.find(key);
+  if (iter == key_values.end()) {
+    return def;
+  }
+  if constexpr (std::is_same_v<T, int>) {
+    return std::stoi(iter->second);
+  } else if constexpr (std::is_same_v<T, float>) {
+    return std::stof(iter->second);
+  } else if constexpr (std::is_same_v<T, double>) {
+    return std::stod(iter->second);
+  } else if constexpr (std::is_same_v<T, std::string>) {
+    return iter->second;
+  } else if constexpr (std::is_enum_v<T>) {
+    return static_cast<T>(std::stoi(iter->second));
+  } else {
+    static_assert(dependent_false<T>::value, "Unsupported type");
+  }
+}
+
 // Helper class for setting ImGui style options; automatically resets the
 // styles when going out of scope.
 struct ScopedStyle {
@@ -179,10 +203,6 @@ struct ImGuiOpts {
   const char* format = std::is_floating_point_v<T> ? "%.3g" : "%d";
 };
 
-// This is a workaround to fix compilation on gcc <= 12 and clang <= 16
-template <typename T>
-struct dependent_false : std::false_type {};
-
 // A compile-time wrapper around ImGui::InputScalarN. This is useful because
 // MuJoCo uses an `mjtNum` type which is an alias for float or double.
 //

src/experimental/studio/app.cc

@@ -742,7 +742,7 @@ void App::LoadSettings() {
   if (!ini_path_.empty()) {
     std::string settings = platform::LoadText(ini_path_);
     if (!settings.empty()) {
-      ui_.FromDict(platform::ReadIniSection(settings, "[Simulate][Data]"));
+      ui_.FromDict(platform::ReadIniSection(settings, "[Studio][UX]"));
       ImGui::LoadIniSettingsFromMemory(settings.data(), settings.size());
     }
   }
@@ -751,7 +751,7 @@ void App::LoadSettings() {
 void App::SaveSettings() {
   if (!ini_path_.empty()) {
     std::string settings = ImGui::SaveIniSettingsToMemory();
-    platform::AppendIniSection(settings, "[Simulate][Data]", ui_.ToDict());
+    platform::AppendIniSection(settings, "[Studio][UX]", ui_.ToDict());
     platform::SaveText(settings, ini_path_);
   }
 }
@@ -912,6 +912,10 @@ void App::BuildGui() {
   }
 
   ImGuiIO& io = ImGui::GetIO();
+  if (tmp_.first_frame) {
+    LoadSettings();
+    tmp_.first_frame = false;
+  }
   if (io.WantSaveIniSettings) {
     SaveSettings();
     io.WantSaveIniSettings = false;
@@ -922,6 +926,7 @@ void App::SetupTheme(platform::GuiTheme theme) {
   if (!tmp_.style_editor) {
     platform::SetupTheme(theme);
     ui_.theme = theme;
+    ImGui::GetIO().WantSaveIniSettings = true;
   }
 }
 
@@ -1747,11 +1752,13 @@ std::vector<const char*> App::GetCameraNames() {
 
 App::UiState::Dict App::UiState::ToDict() const {
   return {
+    {"theme", std::to_string(static_cast<int>(theme))},
   };
 }
 
 void App::UiState::FromDict(const Dict& dict) {
   *this = UiState();
+  theme = ReadIniValue(dict, "theme", theme);
 }
 
 int App::LoadAssetCallback(const char* path, void* user_data,

src/experimental/studio/app.h

@@ -90,6 +90,7 @@ class App {
   // UI state that is transient and only needed while the application runs
   struct UiTempState {
     bool should_exit = false;
+    bool first_frame = true;
 
     // Windows.
     bool help = false;