Introduce thread-safe take_screenshot

src/main.cpp

@@ -42,8 +42,6 @@ bool g_bFilterGameWindow = true;
 
 bool g_bBorderlessOutputWindow = false;
 
-bool g_bTakeScreenshot = false;
-
 bool g_bNiceCap = false;
 int g_nOldNice = 0;
 int g_nNewNice = 0;

src/main.hpp

@@ -23,8 +23,6 @@ extern bool g_bFilterGameWindow;
 
 extern bool g_bBorderlessOutputWindow;
 
-extern bool g_bTakeScreenshot;
-
 extern bool g_bNiceCap;
 extern int g_nOldNice;
 extern int g_nNewNice;

src/sdlwindow.cpp

@@ -160,7 +160,7 @@ void inputSDLThreadRun( void )
 							g_bFilterGameWindow = !g_bFilterGameWindow;
 							break;
 						case KEY_S:
-							g_bTakeScreenshot = true;
+							take_screenshot();
 							break;
 						default:
 							handled = false;

src/steamcompmgr.cpp

@@ -276,12 +276,13 @@ static Bool		drawDebugInfo = False;
 static Bool		debugEvents = False;
 static Bool		steamMode = False;
 static Bool		alwaysComposite = False;
-static Bool		takeScreenshot = False;
 static Bool		useXRes = True;
 
 std::mutex wayland_commit_lock;
 std::vector<ResListEntry_t> wayland_commit_queue;
 
+static std::atomic< bool > g_bTakeScreenshot{false};
+
 static int g_nudgePipe[2];
 
 // poor man's semaphore
@@ -1249,11 +1250,7 @@ paint_all(Display *dpy, MouseCursor *cursor)
 	bool bDoComposite = true;
 
 	// Handoff from whatever thread to this one since we check ours twice
-	if ( g_bTakeScreenshot == true )
+	bool takeScreenshot = g_bTakeScreenshot.exchange(false);
-	{
-		takeScreenshot = true;
-		g_bTakeScreenshot = false;
-	}
 
 	if ( BIsNested() == false && alwaysComposite == False && takeScreenshot == False )
 	{
@@ -2913,6 +2910,11 @@ void nudge_steamcompmgr( void )
 		perror( "nudge_steamcompmgr: write failed" );
 }
 
+void take_screenshot( void )
+{
+	g_bTakeScreenshot = true;
+}
+
 void check_new_wayland_res( void )
 {
 	// When importing buffer, we'll potentially need to perform operations with

src/steamcompmgr.hpp

@@ -89,3 +89,4 @@ extern float focusedWindowOffsetX;
 extern float focusedWindowOffsetY;
 
 void nudge_steamcompmgr( void );
+void take_screenshot( void );

src/wlserver.cpp

@@ -71,7 +71,7 @@ void sig_handler(int signal)
 {
 	if ( signal == SIGUSR2 )
 	{
-		g_bTakeScreenshot = true;
+		take_screenshot();
 		return;
 	}