sdl2_window_backend.cc

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// sdl2_window_backend.cc - SDL2 Window Backend Implementation
 
#include "app/platform/sdl2_window_backend.h"
 
#include "app/platform/sdl_compat.h"
 
#include <filesystem>
 
#include "absl/status/status.h"
#include "absl/strings/str_format.h"
#include "app/gfx/resource/arena.h"
#include "app/gui/core/imgui_diagnostics.h"
#include "app/gui/core/style.h"
#include "app/platform/font_loader.h"
#include "imgui/backends/imgui_impl_sdl2.h"
#include "imgui/backends/imgui_impl_sdlrenderer2.h"
#include "imgui/imgui.h"
#include "util/log.h"
#include "util/platform_paths.h"
 
namespace yaze {
 
// Forward reference to the global resize flag defined in window.cc
namespace core {
extern bool g_window_is_resizing;
}
 
namespace platform {
 
// Alias to core's resize flag for compatibility
#define g_window_is_resizing yaze::core::g_window_is_resizing
 
namespace {
// Marks wake events ("YAZE" in ASCII) so other SDL_USEREVENT users, such as
// SDL timers or future code, are not mistaken for wakes.
constexpr Sint32 kWakeEventCode = 0x59415A45;
}  // namespace
 
bool PushWakeEvent() {
  SDL_Event event;
  SDL_zero(event);
  event.type = SDL_USEREVENT;
  event.user.code = kWakeEventCode;
  // SDL_PushEvent is thread-safe and returns 1 when the event was queued.
  return SDL_PushEvent(&event) == 1;
}
 
bool IsWakeEvent(const SDL_Event& event) {
  return event.type == SDL_USEREVENT && event.user.code == kWakeEventCode;
}
 
SDL2WindowBackend::~SDL2WindowBackend() {
  if (initialized_) {
    Shutdown();
  }
}
 
absl::Status SDL2WindowBackend::Initialize(const WindowConfig& config) {
  if (initialized_) {
    LOG_WARN("SDL2WindowBackend", "Already initialized, shutting down first");
    RETURN_IF_ERROR(Shutdown());
  }
 
#ifdef _WIN32
  // Without this, Windows bitmap-stretches the DPI-unaware window at 125-150%
  // scaling. SDL reads the hint during video init.
  SDL_SetHint(SDL_HINT_WINDOWS_DPI_SCALING, "1");
#endif
 
  // Initialize SDL2 subsystems
  if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER |
               SDL_INIT_GAMECONTROLLER) != 0) {
    return absl::InternalError(
        absl::StrFormat("SDL_Init failed: %s", SDL_GetError()));
  }
 
  // Determine window size
  int screen_width = config.width;
  int screen_height = config.height;
 
  if (screen_width == 0 || screen_height == 0) {
    // Display bounds use window coordinates; with Windows DPI scaling the
    // display mode is in pixels and would oversize the window.
    SDL_Rect display_bounds;
    if (SDL_GetDisplayBounds(0, &display_bounds) == 0) {
      screen_width = static_cast<int>(display_bounds.w * config.display_scale);
      screen_height = static_cast<int>(display_bounds.h * config.display_scale);
    } else {
      // Fallback to reasonable defaults
      screen_width = 1280;
      screen_height = 720;
      LOG_WARN("SDL2WindowBackend",
               "Failed to get display bounds, using defaults: %dx%d",
               screen_width, screen_height);
    }
  }
 
  // Build window flags
  Uint32 flags = 0;
  if (config.resizable) {
    flags |= SDL_WINDOW_RESIZABLE;
  }
  if (config.maximized) {
    flags |= SDL_WINDOW_MAXIMIZED;
  }
  if (config.fullscreen) {
    flags |= SDL_WINDOW_FULLSCREEN_DESKTOP;
  }
  if (config.high_dpi) {
    flags |= SDL_WINDOW_ALLOW_HIGHDPI;
  }
  if (config.hidden) {
    flags |= SDL_WINDOW_HIDDEN;
  }
 
  // Create window
  window_ = std::unique_ptr<SDL_Window, util::SDL_Deleter>(
      SDL_CreateWindow(config.title.c_str(), SDL_WINDOWPOS_UNDEFINED,
                       SDL_WINDOWPOS_UNDEFINED, screen_width, screen_height,
                       flags),
      util::SDL_Deleter());
 
  if (!window_) {
    SDL_Quit();
    return absl::InternalError(
        absl::StrFormat("SDL_CreateWindow failed: %s", SDL_GetError()));
  }
 
  // Allocate legacy audio buffer for backwards compatibility
  const int audio_frequency = 48000;
  const size_t buffer_size = (audio_frequency / 50) * 2;  // Stereo PAL
  audio_buffer_ = std::shared_ptr<int16_t>(new int16_t[buffer_size],
                                           std::default_delete<int16_t[]>());
 
  LOG_INFO("SDL2WindowBackend", "Initialized: %dx%d, audio buffer: %zu samples",
           screen_width, screen_height, buffer_size);
 
  initialized_ = true;
  active_ = true;
  return absl::OkStatus();
}
 
absl::Status SDL2WindowBackend::Shutdown() {
  if (!initialized_) {
    return absl::OkStatus();
  }
 
  // Pause and close audio device if open
  if (audio_device_ != 0) {
    SDL_PauseAudioDevice(audio_device_, 1);
    SDL_CloseAudioDevice(audio_device_);
    audio_device_ = 0;
  }
 
  // Shutdown ImGui if initialized
  if (imgui_initialized_) {
    ShutdownImGui();
  }
 
  // Shutdown graphics arena while renderer is still valid
  LOG_INFO("SDL2WindowBackend", "Shutting down graphics arena...");
  gfx::Arena::Get().Shutdown();
 
  // Destroy window
  if (window_) {
    LOG_INFO("SDL2WindowBackend", "Destroying window...");
    window_.reset();
  }
 
  // Quit SDL
  LOG_INFO("SDL2WindowBackend", "Shutting down SDL...");
  SDL_Quit();
 
  initialized_ = false;
  LOG_INFO("SDL2WindowBackend", "Shutdown complete");
  return absl::OkStatus();
}
 
bool SDL2WindowBackend::PollEvent(WindowEvent& out_event) {
  SDL_Event sdl_event;
  if (SDL_PollEvent(&sdl_event)) {
    // Let ImGui process the event first
    if (imgui_initialized_) {
      ImGui_ImplSDL2_ProcessEvent(&sdl_event);
    }
 
    // Convert to platform-agnostic event
    out_event = ConvertSDL2Event(sdl_event);
    out_event.has_native_event = true;
    out_event.native_event = sdl_event;
    return true;
  }
  return false;
}
 
bool SDL2WindowBackend::WaitForEvent(int timeout_ms) {
  // A null event pointer waits without removing the event from the queue.
  return SDL_WaitEventTimeout(nullptr, timeout_ms) == 1;
}
 
void SDL2WindowBackend::ProcessNativeEvent(void* native_event) {
  if (native_event && imgui_initialized_) {
    ImGui_ImplSDL2_ProcessEvent(static_cast<SDL_Event*>(native_event));
  }
}
 
WindowEvent SDL2WindowBackend::ConvertSDL2Event(const SDL_Event& sdl_event) {
  WindowEvent event;
  event.type = WindowEventType::None;
 
  switch (sdl_event.type) {
    case SDL_QUIT:
      event.type = WindowEventType::Quit;
      break;
 
    case SDL_KEYDOWN:
      event.type = WindowEventType::KeyDown;
      event.key_code = sdl_event.key.keysym.sym;
      event.scan_code = sdl_event.key.keysym.scancode;
      UpdateModifierState();
      event.key_shift = key_shift_;
      event.key_ctrl = key_ctrl_;
      event.key_alt = key_alt_;
      event.key_super = key_super_;
      break;
 
    case SDL_KEYUP:
      event.type = WindowEventType::KeyUp;
      event.key_code = sdl_event.key.keysym.sym;
      event.scan_code = sdl_event.key.keysym.scancode;
      UpdateModifierState();
      event.key_shift = key_shift_;
      event.key_ctrl = key_ctrl_;
      event.key_alt = key_alt_;
      event.key_super = key_super_;
      break;
 
    case SDL_MOUSEMOTION:
      event.type = WindowEventType::MouseMotion;
      event.mouse_x = static_cast<float>(sdl_event.motion.x);
      event.mouse_y = static_cast<float>(sdl_event.motion.y);
      break;
 
    case SDL_MOUSEBUTTONDOWN:
      event.type = WindowEventType::MouseButtonDown;
      event.mouse_x = static_cast<float>(sdl_event.button.x);
      event.mouse_y = static_cast<float>(sdl_event.button.y);
      event.mouse_button = sdl_event.button.button;
      break;
 
    case SDL_MOUSEBUTTONUP:
      event.type = WindowEventType::MouseButtonUp;
      event.mouse_x = static_cast<float>(sdl_event.button.x);
      event.mouse_y = static_cast<float>(sdl_event.button.y);
      event.mouse_button = sdl_event.button.button;
      break;
 
    case SDL_MOUSEWHEEL:
      event.type = WindowEventType::MouseWheel;
      event.wheel_x = static_cast<float>(sdl_event.wheel.x);
      event.wheel_y = static_cast<float>(sdl_event.wheel.y);
      break;
 
    case SDL_DROPFILE:
      event.type = WindowEventType::DropFile;
      if (sdl_event.drop.file) {
        event.dropped_file = sdl_event.drop.file;
        SDL_free(sdl_event.drop.file);
      }
      break;
 
    case SDL_WINDOWEVENT:
      switch (sdl_event.window.event) {
        case SDL_WINDOWEVENT_CLOSE:
          event.type = WindowEventType::Close;
          break;
 
        case SDL_WINDOWEVENT_SIZE_CHANGED:
        case SDL_WINDOWEVENT_RESIZED:
          event.type = WindowEventType::Resize;
          event.window_width = sdl_event.window.data1;
          event.window_height = sdl_event.window.data2;
          is_resizing_ = true;
          g_window_is_resizing = true;
          break;
 
        case SDL_WINDOWEVENT_MINIMIZED:
          event.type = WindowEventType::Minimized;
          is_resizing_ = false;
          g_window_is_resizing = false;
          break;
 
        case SDL_WINDOWEVENT_MAXIMIZED:
          event.type = WindowEventType::Maximized;
          break;
 
        case SDL_WINDOWEVENT_RESTORED:
          event.type = WindowEventType::Restored;
          is_resizing_ = false;
          g_window_is_resizing = false;
          break;
 
        case SDL_WINDOWEVENT_SHOWN:
          event.type = WindowEventType::Shown;
          is_resizing_ = false;
          g_window_is_resizing = false;
          break;
 
        case SDL_WINDOWEVENT_HIDDEN:
          event.type = WindowEventType::Hidden;
          is_resizing_ = false;
          g_window_is_resizing = false;
          break;
 
        case SDL_WINDOWEVENT_EXPOSED:
          event.type = WindowEventType::Exposed;
          is_resizing_ = false;
          g_window_is_resizing = false;
          break;
 
        case SDL_WINDOWEVENT_FOCUS_GAINED:
          event.type = WindowEventType::FocusGained;
          break;
 
        case SDL_WINDOWEVENT_FOCUS_LOST:
          event.type = WindowEventType::FocusLost;
          break;
      }
      break;
  }
 
  return event;
}
 
void SDL2WindowBackend::UpdateModifierState() {
  SDL_Keymod mod = SDL_GetModState();
  key_shift_ = (mod & KMOD_SHIFT) != 0;
  key_ctrl_ = (mod & KMOD_CTRL) != 0;
  key_alt_ = (mod & KMOD_ALT) != 0;
  key_super_ = (mod & KMOD_GUI) != 0;
}
 
WindowStatus SDL2WindowBackend::GetStatus() const {
  WindowStatus status;
  status.is_active = active_;
  status.is_resizing = is_resizing_;
 
  if (window_) {
    Uint32 flags = SDL_GetWindowFlags(window_.get());
    status.is_minimized = (flags & SDL_WINDOW_MINIMIZED) != 0;
    status.is_maximized = (flags & SDL_WINDOW_MAXIMIZED) != 0;
    status.is_fullscreen =
        (flags & (SDL_WINDOW_FULLSCREEN | SDL_WINDOW_FULLSCREEN_DESKTOP)) != 0;
    status.is_focused = (flags & SDL_WINDOW_INPUT_FOCUS) != 0;
 
    SDL_GetWindowSize(window_.get(), &status.width, &status.height);
  }
 
  return status;
}
 
void SDL2WindowBackend::GetSize(int* width, int* height) const {
  if (window_) {
    SDL_GetWindowSize(window_.get(), width, height);
  } else {
    if (width)
      *width = 0;
    if (height)
      *height = 0;
  }
}
 
void SDL2WindowBackend::SetSize(int width, int height) {
  if (window_) {
    SDL_SetWindowSize(window_.get(), width, height);
  }
}
 
std::string SDL2WindowBackend::GetTitle() const {
  if (window_) {
    const char* title = SDL_GetWindowTitle(window_.get());
    return title ? title : "";
  }
  return "";
}
 
void SDL2WindowBackend::SetTitle(const std::string& title) {
  if (window_) {
    SDL_SetWindowTitle(window_.get(), title.c_str());
  }
}
 
void SDL2WindowBackend::ShowWindow() {
  if (window_) {
    SDL_ShowWindow(window_.get());
  }
}
 
void SDL2WindowBackend::HideWindow() {
  if (window_) {
    SDL_HideWindow(window_.get());
  }
}
 
bool SDL2WindowBackend::InitializeRenderer(gfx::IRenderer* renderer) {
  if (!window_ || !renderer) {
    return false;
  }
 
  if (renderer->GetBackendRenderer()) {
    // Already initialized
    return true;
  }
 
  return renderer->Initialize(window_.get());
}
 
absl::Status SDL2WindowBackend::InitializeImGui(gfx::IRenderer* renderer) {
  if (imgui_initialized_) {
    return absl::OkStatus();
  }
 
  if (!renderer) {
    return absl::InvalidArgumentError("Renderer is null");
  }
 
  IMGUI_CHECKVERSION();
  ImGui::CreateContext();
 
  ImGuiIO& io = ImGui::GetIO();
  gui::ConfigureImGuiDiagnostics(io);
  io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
  io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
  // Note: ViewportsEnable is intentionally NOT set for SDL2 + SDL_Renderer
  // It causes scaling issues on macOS Retina displays
 
  // Ensure macOS-style behavior (Cmd acts as Ctrl for shortcuts)
  // ImGui should set this automatically based on __APPLE__, but force it to be safe
#ifdef __APPLE__
  io.ConfigMacOSXBehaviors = true;
  LOG_INFO("SDL2WindowBackend", "Enabled ConfigMacOSXBehaviors for macOS");
#endif
 
  if (auto ini_path = util::PlatformPaths::GetImGuiIniPath(); ini_path.ok()) {
    static std::string ini_path_str;
    if (ini_path_str.empty()) {
      ini_path_str = ini_path->string();
    }
    io.IniFilename = ini_path_str.c_str();
  } else {
    io.IniFilename = nullptr;
    LOG_WARN("SDL2WindowBackend", "Failed to resolve ImGui ini path: %s",
             ini_path.status().ToString().c_str());
  }
 
  // Initialize ImGui backends
  SDL_Renderer* sdl_renderer =
      static_cast<SDL_Renderer*>(renderer->GetBackendRenderer());
 
  if (!sdl_renderer) {
    return absl::InternalError("Failed to get SDL renderer from IRenderer");
  }
 
  if (!ImGui_ImplSDL2_InitForSDLRenderer(window_.get(), sdl_renderer)) {
    return absl::InternalError("ImGui_ImplSDL2_InitForSDLRenderer failed");
  }
 
  if (!ImGui_ImplSDLRenderer2_Init(sdl_renderer)) {
    ImGui_ImplSDL2_Shutdown();
    return absl::InternalError("ImGui_ImplSDLRenderer2_Init failed");
  }
 
  // Load fonts
  RETURN_IF_ERROR(LoadPackageFonts());
 
  // Apply default style
  gui::ColorsYaze();
 
  imgui_initialized_ = true;
  LOG_INFO("SDL2WindowBackend", "ImGui initialized successfully");
  return absl::OkStatus();
}
 
void SDL2WindowBackend::ShutdownImGui() {
  if (!imgui_initialized_) {
    return;
  }
 
  LOG_INFO("SDL2WindowBackend", "Shutting down ImGui implementations...");
  ImGui_ImplSDLRenderer2_Shutdown();
  ImGui_ImplSDL2_Shutdown();
 
  LOG_INFO("SDL2WindowBackend", "Destroying ImGui context...");
  ImGui::DestroyContext();
 
  imgui_initialized_ = false;
}
 
void SDL2WindowBackend::NewImGuiFrame() {
  if (!imgui_initialized_) {
    return;
  }
 
  ImGui_ImplSDLRenderer2_NewFrame();
  ImGui_ImplSDL2_NewFrame();
  // ImGui_ImplSDL2_NewFrame() automatically handles DisplaySize and
  // DisplayFramebufferScale via ImGui_ImplSDL2_GetWindowSizeAndFramebufferScale()
  // which uses SDL_GetRendererOutputSize() when renderer is available.
}
 
void SDL2WindowBackend::RenderImGui(gfx::IRenderer* renderer) {
  if (!imgui_initialized_) {
    return;
  }
 
  // Finalize ImGui frame and render draw data
  ImGui::Render();
 
  if (renderer) {
    SDL_Renderer* sdl_renderer =
        static_cast<SDL_Renderer*>(renderer->GetBackendRenderer());
    if (sdl_renderer) {
      // The SDL_Renderer backend scales clip rects but not vertices unless the
      // renderer scale is set; SDL then scales both and the backend skips it.
      ImDrawData* draw_data = ImGui::GetDrawData();
      SDL_RenderSetScale(sdl_renderer, draw_data->FramebufferScale.x,
                         draw_data->FramebufferScale.y);
      ImGui_ImplSDLRenderer2_RenderDrawData(draw_data, sdl_renderer);
      SDL_RenderSetScale(sdl_renderer, 1.0f, 1.0f);
    }
  }
 
  // Multi-viewport support
  ImGuiIO& io = ImGui::GetIO();
  if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) {
    ImGui::UpdatePlatformWindows();
    ImGui::RenderPlatformWindowsDefault();
  }
}
 
}  // namespace platform
}  // namespace yaze