CommonHostInterface: Compress screenshots in background/use worker thread

src/frontend-common/common_host_interface.cpp

@@ -2318,7 +2318,7 @@ void CommonHostInterface::StopDumpingAudio()
 }
 
 bool CommonHostInterface::SaveScreenshot(const char* filename /* = nullptr */, bool full_resolution /* = true */,
-                                         bool apply_aspect_ratio /* = true */)
+                                         bool apply_aspect_ratio /* = true */, bool compress_on_thread /* = true */)
 {
   if (System::IsShutdown())
     return false;
@@ -2342,7 +2342,14 @@ bool CommonHostInterface::SaveScreenshot(const char* filename /* = nullptr */, b
     filename = auto_filename.c_str();
   }
 
-  const bool screenshot_saved = m_display->WriteDisplayTextureToFile(filename, full_resolution, apply_aspect_ratio);
+  if (FileSystem::FileExists(filename))
+  {
+    AddFormattedOSDMessage(10.0f, TranslateString("OSDMessage", "Screenshot file '%s' already exists."), filename);
+    return false;
+  }
+
+  const bool screenshot_saved =
+    m_display->WriteDisplayTextureToFile(filename, full_resolution, apply_aspect_ratio, compress_on_thread);
   if (!screenshot_saved)
   {
     AddFormattedOSDMessage(10.0f, TranslateString("OSDMessage", "Failed to save screenshot to '%s'"), filename);

src/frontend-common/common_host_interface.h

@@ -151,7 +151,8 @@ public:
   void StopDumpingAudio();
 
   /// Saves a screenshot to the specified file. IF no file name is provided, one will be generated automatically.
-  bool SaveScreenshot(const char* filename = nullptr, bool full_resolution = true, bool apply_aspect_ratio = true);
+  bool SaveScreenshot(const char* filename = nullptr, bool full_resolution = true, bool apply_aspect_ratio = true,
+                      bool compress_on_thread = true);
 
   /// Loads the cheat list from the specified file.
   bool LoadCheatList(const char* filename);