Sim GUI: Support High DPI monitors

Add user setting for scaling on top of DPI scaling.
Add user setting for visual style (light/dark/normal).
Save window position, size, maximized state, scale, and style to ini file.

simulation/halsim_gui/src/main/native/cpp/DIOGui.cpp

@@ -56,7 +56,7 @@ static void DisplayDIO() {
     }
   }
 
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(ImGui::GetFontSize() * 8);
   for (int i = 0; i < numDIO; ++i) {
     if (HALSIM_GetDIOInitialized(i)) {
       hasAny = true;

simulation/halsim_gui/src/main/native/cpp/DriverStationGui.cpp

@@ -351,7 +351,7 @@ static void DisplayFMS() {
   static const char* stations[] = {"Red 1",  "Red 2",  "Red 3",
                                    "Blue 1", "Blue 2", "Blue 3"};
   int allianceStationId = HALSIM_GetDriverStationAllianceStationId();
-  ImGui::SetNextItemWidth(100);
+  ImGui::SetNextItemWidth(ImGui::GetFontSize() * 8);
   if (ImGui::Combo("Alliance Station", &allianceStationId, stations, 6))
     HALSIM_SetDriverStationAllianceStationId(
         static_cast<HAL_AllianceStationID>(allianceStationId));
@@ -362,7 +362,7 @@ static void DisplayFMS() {
 
   static double startMatchTime = 0.0;
   double matchTime = HALSIM_GetDriverStationMatchTime();
-  ImGui::SetNextItemWidth(100);
+  ImGui::SetNextItemWidth(ImGui::GetFontSize() * 8);
   if (ImGui::InputDouble("Match Time", &matchTime, 0, 0, "%.1f",
                          ImGuiInputTextFlags_EnterReturnsTrue)) {
     HALSIM_SetDriverStationMatchTime(matchTime);
@@ -380,7 +380,7 @@ static void DisplayFMS() {
 
   // Game Specific Message
   static HAL_MatchInfo matchInfo;
-  ImGui::SetNextItemWidth(100);
+  ImGui::SetNextItemWidth(ImGui::GetFontSize() * 8);
   if (ImGui::InputText("Game Specific",
                        reinterpret_cast<char*>(matchInfo.gameSpecificMessage),
                        sizeof(matchInfo.gameSpecificMessage),
@@ -420,7 +420,7 @@ static void DisplaySystemJoysticks() {
 
 static void DisplayJoysticks() {
   // imgui doesn't size columns properly with autoresize, so force it
-  ImGui::Dummy(ImVec2(14.0 * 9 * HAL_kMaxJoysticks, 0));
+  ImGui::Dummy(ImVec2(ImGui::GetFontSize() * 10 * HAL_kMaxJoysticks, 0));
 
   ImGui::Columns(HAL_kMaxJoysticks, "Joysticks", false);
   for (int i = 0; i < HAL_kMaxJoysticks; ++i) {

simulation/halsim_gui/src/main/native/cpp/EncoderGui.cpp

@@ -54,7 +54,7 @@ static void EncodersWriteAll(ImGuiContext* ctx, ImGuiSettingsHandler* handler,
 static void DisplayEncoders() {
   bool hasAny = false;
   static int numEncoder = HAL_GetNumEncoders();
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(ImGui::GetFontSize() * 8);
   for (int i = 0; i < numEncoder; ++i) {
     if (HALSIM_GetEncoderInitialized(i)) {
       hasAny = true;

simulation/halsim_gui/src/main/native/cpp/ExtraGuiWidgets.cpp

@@ -12,6 +12,8 @@ namespace halsimgui {
 void DrawLEDs(int* values, int numValues, int cols, const ImU32* colors,
               float size, float spacing) {
   if (numValues == 0) return;
+  if (size == 0) size = ImGui::GetFontSize() / 2.0;
+  if (spacing == 0) spacing = ImGui::GetFontSize() / 3.0;
 
   ImDrawList* drawList = ImGui::GetWindowDrawList();
   const ImVec2 p = ImGui::GetCursorScreenPos();

simulation/halsim_gui/src/main/native/cpp/HALSimGui.cpp

@@ -13,6 +13,7 @@
 #include <GL/gl3w.h>
 #include <GLFW/glfw3.h>
 #include <imgui.h>
+#include <imgui_ProggyDotted.h>
 #include <imgui_impl_glfw.h>
 #include <imgui_impl_opengl3.h>
 #include <imgui_internal.h>
@@ -43,6 +44,12 @@ struct WindowInfo {
 
 static std::atomic_bool gExit{false};
 static GLFWwindow* gWindow;
+static bool gWindowLoadedWidthHeight = false;
+static int gWindowWidth = 1280;
+static int gWindowHeight = 720;
+static int gWindowMaximized = 0;
+static int gWindowXPos = -1;
+static int gWindowYPos = -1;
 static std::vector<std::function<void()>> gInitializers;
 static std::vector<std::function<void()>> gExecutors;
 static std::vector<WindowInfo> gWindows;
@@ -50,15 +57,39 @@ static wpi::StringMap<int> gWindowMap;   // index into gWindows
 static std::vector<int> gSortedWindows;  // index into gWindows
 static std::vector<std::function<void()>> gOptionMenus;
 static std::vector<std::function<void()>> gMenus;
+static int gUserScale = 2;
+static int gStyle = 0;
+static constexpr int kScaledFontLevels = 9;
+static ImFont* gScaledFont[kScaledFontLevels];
 
 static void glfw_error_callback(int error, const char* description) {
   wpi::errs() << "GLFW Error " << error << ": " << description << '\n';
 }
 
+static void glfw_window_size_callback(GLFWwindow*, int width, int height) {
+  if (!gWindowMaximized) {
+    gWindowWidth = width;
+    gWindowHeight = height;
+  }
+}
+
+static void glfw_window_maximize_callback(GLFWwindow* window, int maximized) {
+  gWindowMaximized = maximized;
+}
+
+static void glfw_window_pos_callback(GLFWwindow* window, int xpos, int ypos) {
+  if (!gWindowMaximized) {
+    gWindowXPos = xpos;
+    gWindowYPos = ypos;
+  }
+}
+
 // read/write open state to ini file
 static void* SimWindowsReadOpen(ImGuiContext* ctx,
                                 ImGuiSettingsHandler* handler,
                                 const char* name) {
+  if (wpi::StringRef{name} == "GLOBAL") return &gWindow;
+
   int index = gWindowMap.try_emplace(name, gWindows.size()).first->second;
   if (index == static_cast<int>(gWindows.size())) {
     gSortedWindows.push_back(index);
@@ -71,11 +102,35 @@ static void* SimWindowsReadOpen(ImGuiContext* ctx,
 
 static void SimWindowsReadLine(ImGuiContext* ctx, ImGuiSettingsHandler* handler,
                                void* entry, const char* lineStr) {
-  auto element = static_cast<WindowInfo*>(entry);
   wpi::StringRef line{lineStr};
   auto [name, value] = line.split('=');
   name = name.trim();
   value = value.trim();
+
+  if (entry == &gWindow) {
+    int num;
+    if (value.getAsInteger(10, num)) return;
+    if (name == "width") {
+      gWindowWidth = num;
+      gWindowLoadedWidthHeight = true;
+    } else if (name == "height") {
+      gWindowHeight = num;
+      gWindowLoadedWidthHeight = true;
+    } else if (name == "maximized") {
+      gWindowMaximized = num;
+    } else if (name == "xpos") {
+      gWindowXPos = num;
+    } else if (name == "ypos") {
+      gWindowYPos = num;
+    } else if (name == "userScale") {
+      gUserScale = num;
+    } else if (name == "style") {
+      gStyle = num;
+    }
+    return;
+  }
+
+  auto element = static_cast<WindowInfo*>(entry);
   if (name == "visible") {
     int num;
     if (value.getAsInteger(10, num)) return;
@@ -89,12 +144,31 @@ static void SimWindowsReadLine(ImGuiContext* ctx, ImGuiSettingsHandler* handler,
 
 static void SimWindowsWriteAll(ImGuiContext* ctx, ImGuiSettingsHandler* handler,
                                ImGuiTextBuffer* out_buf) {
+  out_buf->appendf(
+      "[SimWindow][GLOBAL]\nwidth=%d\nheight=%d\nmaximized=%d\n"
+      "xpos=%d\nypos=%d\nuserScale=%d\nstyle=%d\n\n",
+      gWindowWidth, gWindowHeight, gWindowMaximized, gWindowXPos, gWindowYPos,
+      gUserScale, gStyle);
   for (auto&& window : gWindows)
     out_buf->appendf("[SimWindow][%s]\nvisible=%d\nenabled=%d\n\n",
                      window.name.c_str(), window.visible ? 1 : 0,
                      window.enabled ? 1 : 0);
 }
 
+static void UpdateStyle() {
+  switch (gStyle) {
+    case 0:
+      ImGui::StyleColorsClassic();
+      break;
+    case 1:
+      ImGui::StyleColorsDark();
+      break;
+    case 2:
+      ImGui::StyleColorsLight();
+      break;
+  }
+}
+
 void HALSimGui::Add(std::function<void()> initialize) {
   if (initialize) gInitializers.emplace_back(std::move(initialize));
 }
@@ -184,6 +258,7 @@ bool HALSimGui::Initialize() {
   glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
   glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);  // 3.2+ only
   glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);  // Required on Mac
+  glfwWindowHint(GLFW_COCOA_GRAPHICS_SWITCHING, GLFW_TRUE);
 #else
   // GL 3.0 + GLSL 130
   const char* glsl_version = "#version 130";
@@ -193,10 +268,52 @@ bool HALSimGui::Initialize() {
   // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // 3.0+
 #endif
 
+  // Setup Dear ImGui context
+  IMGUI_CHECKVERSION();
+  ImGui::CreateContext();
+  ImGuiIO& io = ImGui::GetIO();
+  (void)io;
+
+  // Hook ini handler to save settings
+  ImGuiSettingsHandler iniHandler;
+  iniHandler.TypeName = "SimWindow";
+  iniHandler.TypeHash = ImHashStr(iniHandler.TypeName);
+  iniHandler.ReadOpenFn = SimWindowsReadOpen;
+  iniHandler.ReadLineFn = SimWindowsReadLine;
+  iniHandler.WriteAllFn = SimWindowsWriteAll;
+  ImGui::GetCurrentContext()->SettingsHandlers.push_back(iniHandler);
+
+  for (auto&& initialize : gInitializers) {
+    if (initialize) initialize();
+  }
+
+  // Load INI file
+  ImGui::LoadIniSettingsFromDisk(io.IniFilename);
+
+  // Set initial window settings
+  glfwWindowHint(GLFW_MAXIMIZED, gWindowMaximized ? GLFW_TRUE : GLFW_FALSE);
+  if (!gWindowLoadedWidthHeight)
+    glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_TRUE);
+  if (gWindowXPos != -1 && gWindowYPos != -1)
+    glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
+
   // Create window with graphics context
-  gWindow =
-      glfwCreateWindow(1280, 720, "Robot Simulation GUI", nullptr, nullptr);
+  gWindow = glfwCreateWindow(gWindowWidth, gWindowHeight,
+                             "Robot Simulation GUI", nullptr, nullptr);
   if (!gWindow) return false;
+
+  // Update window settings
+  if (gWindowXPos != -1 && gWindowYPos != -1) {
+    glfwSetWindowPos(gWindow, gWindowXPos, gWindowYPos);
+    glfwShowWindow(gWindow);
+  }
+
+  // Set window callbacks
+  glfwGetWindowSize(gWindow, &gWindowWidth, &gWindowHeight);
+  glfwSetWindowSizeCallback(gWindow, glfw_window_size_callback);
+  glfwSetWindowMaximizeCallback(gWindow, glfw_window_maximize_callback);
+  glfwSetWindowPosCallback(gWindow, glfw_window_pos_callback);
+
   glfwMakeContextCurrent(gWindow);
   glfwSwapInterval(1);  // Enable vsync
 
@@ -206,15 +323,8 @@ bool HALSimGui::Initialize() {
     return false;
   }
 
-  // Setup Dear ImGui context
-  IMGUI_CHECKVERSION();
-  ImGui::CreateContext();
-  ImGuiIO& io = ImGui::GetIO();
-  (void)io;
-
   // Setup Dear ImGui style
-  // ImGui::StyleColorsDark();
-  ImGui::StyleColorsClassic();
+  UpdateStyle();
 
   // Setup Platform/Renderer bindings
   ImGui_ImplGlfw_InitForOpenGL(gWindow, true);
@@ -244,17 +354,14 @@ bool HALSimGui::Initialize() {
   // io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f,
   // NULL, io.Fonts->GetGlyphRangesJapanese()); IM_ASSERT(font != NULL);
 
-  // hook ini handler to save settings
-  ImGuiSettingsHandler iniHandler;
-  iniHandler.TypeName = "SimWindow";
-  iniHandler.TypeHash = ImHashStr(iniHandler.TypeName);
-  iniHandler.ReadOpenFn = SimWindowsReadOpen;
-  iniHandler.ReadLineFn = SimWindowsReadLine;
-  iniHandler.WriteAllFn = SimWindowsWriteAll;
-  ImGui::GetCurrentContext()->SettingsHandlers.push_back(iniHandler);
-
-  for (auto&& initialize : gInitializers) {
-    if (initialize) initialize();
+  // this range is based on 13px being the "nominal" 100% size and going from
+  // ~0.5x (7px) to ~2.0x (25px)
+  for (int i = 0; i < kScaledFontLevels; ++i) {
+    float size = 7.0f + i * 3.0f;
+    ImFontConfig cfg;
+    std::snprintf(cfg.Name, sizeof(cfg.Name), "ProggyDotted-%d",
+                  static_cast<int>(size));
+    gScaledFont[i] = ImGui::AddFontProggyDotted(io, size, &cfg);
   }
 
   return true;
@@ -273,6 +380,16 @@ void HALSimGui::Main(void*) {
     ImGui_ImplGlfw_NewFrame();
     ImGui::NewFrame();
 
+    // Scale based on OS window content scaling
+    float windowScale = 1.0;
+    glfwGetWindowContentScale(gWindow, &windowScale, nullptr);
+    // map to closest font size: 0 = 0.5x, 1 = 0.75x, 2 = 1.0x, 3 = 1.25x,
+    // 4 = 1.5x, 5 = 1.75x, 6 = 2x
+    int fontScale =
+        std::clamp(gUserScale + static_cast<int>((windowScale - 1.0) * 4), 0,
+                   kScaledFontLevels - 1);
+    ImGui::GetIO().FontDefault = gScaledFont[fontScale];
+
     for (auto&& execute : gExecutors) {
       if (execute) execute();
     }
@@ -287,6 +404,42 @@ void HALSimGui::Main(void*) {
         ImGui::EndMenu();
       }
 
+      if (ImGui::BeginMenu("View")) {
+        if (ImGui::BeginMenu("Style")) {
+          bool selected;
+          selected = gStyle == 0;
+          if (ImGui::MenuItem("Classic", nullptr, &selected, true)) {
+            gStyle = 0;
+            UpdateStyle();
+          }
+          selected = gStyle == 1;
+          if (ImGui::MenuItem("Dark", nullptr, &selected, true)) {
+            gStyle = 1;
+            UpdateStyle();
+          }
+          selected = gStyle == 2;
+          if (ImGui::MenuItem("Light", nullptr, &selected, true)) {
+            gStyle = 2;
+            UpdateStyle();
+          }
+          ImGui::EndMenu();
+        }
+
+        if (ImGui::BeginMenu("Zoom")) {
+          for (int i = 0; i < kScaledFontLevels && (25 * (i + 2)) <= 200; ++i) {
+            char label[20];
+            std::snprintf(label, sizeof(label), "%d%%", 25 * (i + 2));
+            bool selected = gUserScale == i;
+            bool enabled = (fontScale - gUserScale + i) >= 0 &&
+                           (fontScale - gUserScale + i) < kScaledFontLevels;
+            if (ImGui::MenuItem(label, nullptr, &selected, enabled))
+              gUserScale = i;
+          }
+          ImGui::EndMenu();
+        }
+        ImGui::EndMenu();
+      }
+
       if (ImGui::BeginMenu("Window")) {
         for (auto&& windowIndex : gSortedWindows) {
           auto& window = gWindows[windowIndex];

simulation/halsim_gui/src/main/native/cpp/PDPGui.cpp

@@ -21,7 +21,7 @@ static void DisplayPDP() {
   bool hasAny = false;
   static int numPDP = HAL_GetNumPDPModules();
   static int numChannels = HAL_GetNumPDPChannels();
-  ImGui::PushItemWidth(150);
+  ImGui::PushItemWidth(ImGui::GetFontSize() * 13);
   for (int i = 0; i < numPDP; ++i) {
     if (HALSIM_GetPDPInitialized(i)) {
       hasAny = true;

simulation/halsim_gui/src/main/native/cpp/RoboRioGui.cpp

@@ -18,7 +18,7 @@ static void DisplayRoboRio() {
   ImGui::Button("User Button");
   HALSIM_SetRoboRioFPGAButton(0, ImGui::IsItemActive());
 
-  ImGui::PushItemWidth(100);
+  ImGui::PushItemWidth(ImGui::GetFontSize() * 8);
 
   if (ImGui::CollapsingHeader("RoboRIO Input")) {
     {