WindowInfo: Add surface_scale field

src/common/window_info.h

@@ -29,6 +29,7 @@ struct WindowInfo
   void* window_handle = nullptr;
   u32 surface_width = 0;
   u32 surface_height = 0;
+  float surface_scale = 1.0f;
   SurfaceFormat surface_format = SurfaceFormat::RGB8;
 
   // Needed for macOS.

src/duckstation-libretro/libretro_host_interface.cpp

@@ -767,6 +767,7 @@ void LibretroHostInterface::SwitchToHardwareRenderer()
   wi.display_connection = &g_libretro_host_interface.m_hw_render_callback;
   wi.surface_width = avi.geometry.base_width;
   wi.surface_height = avi.geometry.base_height;
+  wi.surface_scale = 1.0f;
   if (!display || !display->CreateRenderDevice(wi, {}, g_libretro_host_interface.m_settings.gpu_use_debug_device))
   {
     Log_ErrorPrintf("Failed to create hardware host display");

src/duckstation-qt/qtdisplaywidget.cpp

@@ -86,6 +86,7 @@ std::optional<WindowInfo> QtDisplayWidget::getWindowInfo() const
 
   wi.surface_width = scaledWindowWidth();
   wi.surface_height = scaledWindowHeight();
+  wi.surface_scale = devicePixelRatioFromScreen();
   wi.surface_format = WindowInfo::SurfaceFormat::RGB8;
 
   return wi;

src/duckstation-sdl/sdl_host_interface.cpp

@@ -47,36 +47,6 @@ ALWAYS_INLINE static TinyString GetWindowTitle()
   return TinyString::FromFormat("DuckStation %s (%s)", g_scm_tag_str, g_scm_branch_str);
 }
 
-float SDLHostInterface::GetDPIScaleFactor(SDL_Window* window)
-{
-#ifdef __APPLE__
-  static constexpr float DEFAULT_DPI = 72.0f;
-#else
-  static constexpr float DEFAULT_DPI = 96.0f;
-#endif
-
-  if (!window)
-  {
-    SDL_Window* dummy_window = SDL_CreateWindow("", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 1, 1,
-                                                SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_HIDDEN);
-    if (!dummy_window)
-      return 1.0f;
-
-    const float scale = GetDPIScaleFactor(dummy_window);
-
-    SDL_DestroyWindow(dummy_window);
-
-    return scale;
-  }
-
-  int display_index = SDL_GetWindowDisplayIndex(window);
-  float display_dpi = DEFAULT_DPI;
-  if (SDL_GetDisplayDPI(display_index, &display_dpi, nullptr, nullptr) != 0)
-    return 1.0f;
-
-  return display_dpi / DEFAULT_DPI;
-}
-
 bool SDLHostInterface::CreateSDLWindow()
 {
   static constexpr u32 DEFAULT_WINDOW_WIDTH = 900;
@@ -92,7 +62,7 @@ bool SDLHostInterface::CreateSDLWindow()
 #ifndef __APPLE__
   {
     // scale by default monitor's DPI
-    float scale = GetDPIScaleFactor(nullptr);
+    float scale = SDLUtil::GetDPIScaleFactor(nullptr);
     window_width = static_cast<u32>(std::round(static_cast<float>(window_width) * scale));
     window_height = static_cast<u32>(std::round(static_cast<float>(window_height) * scale));
   }
@@ -214,7 +184,7 @@ void SDLHostInterface::DestroyDisplay()
 
 void SDLHostInterface::CreateImGuiContext()
 {
-  const float framebuffer_scale = GetDPIScaleFactor(m_window);
+  const float framebuffer_scale = SDLUtil::GetDPIScaleFactor(m_window);
 
   ImGui::CreateContext();
   ImGui::GetIO().IniFilename = nullptr;
@@ -229,7 +199,7 @@ void SDLHostInterface::CreateImGuiContext()
 
 void SDLHostInterface::UpdateFramebufferScale()
 {
-  const float framebuffer_scale = GetDPIScaleFactor(m_window);
+  const float framebuffer_scale = SDLUtil::GetDPIScaleFactor(m_window);
   ImGui::GetIO().DisplayFramebufferScale.x = framebuffer_scale;
   ImGui::GetIO().DisplayFramebufferScale.y = framebuffer_scale;
 }

src/duckstation-sdl/sdl_host_interface.h

@@ -60,8 +60,6 @@ protected:
 private:
   bool HasSystem() const { return static_cast<bool>(m_system); }
 
-  static float GetDPIScaleFactor(SDL_Window* window);
-
   bool CreateSDLWindow();
   void DestroySDLWindow();
   bool CreateDisplay();

src/duckstation-sdl/sdl_util.cpp

@@ -32,6 +32,7 @@ std::optional<WindowInfo> GetWindowInfoForSDLWindow(SDL_Window* window)
   WindowInfo wi;
   wi.surface_width = static_cast<u32>(window_width);
   wi.surface_height = static_cast<u32>(window_height);
+  wi.surface_scale = GetDPIScaleFactor(window);
   wi.surface_format = WindowInfo::SurfaceFormat::RGB8;
 
   switch (syswm.subsystem)
@@ -65,4 +66,34 @@ std::optional<WindowInfo> GetWindowInfoForSDLWindow(SDL_Window* window)
 
   return wi;
 }
+
+float GetDPIScaleFactor(SDL_Window* window)
+{
+#ifdef __APPLE__
+  static constexpr float DEFAULT_DPI = 72.0f;
+#else
+  static constexpr float DEFAULT_DPI = 96.0f;
+#endif
+
+  if (!window)
+  {
+    SDL_Window* dummy_window = SDL_CreateWindow("", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 1, 1,
+                                                SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_HIDDEN);
+    if (!dummy_window)
+      return 1.0f;
+
+    const float scale = GetDPIScaleFactor(dummy_window);
+
+    SDL_DestroyWindow(dummy_window);
+
+    return scale;
+  }
+
+  int display_index = SDL_GetWindowDisplayIndex(window);
+  float display_dpi = DEFAULT_DPI;
+  if (SDL_GetDisplayDPI(display_index, &display_dpi, nullptr, nullptr) != 0)
+    return 1.0f;
+
+  return display_dpi / DEFAULT_DPI;
+}
 } // namespace SDLUtil

src/duckstation-sdl/sdl_util.h

@@ -7,4 +7,5 @@ struct SDL_Window;
 
 namespace SDLUtil {
 std::optional<WindowInfo> GetWindowInfoForSDLWindow(SDL_Window* window);
+float GetDPIScaleFactor(SDL_Window* window);
 }