[client] all: make it possible to signal full window invalidation

Now that we are drawing with damage rects, when the window is hidden and
then exposed the window may not get fully redrawn. This provides
`app_invalidateWindow` for the display server backend to call when the
screen needs a full redraw.

client/src/app.c

@@ -418,6 +418,12 @@ void app_handleResizeEvent(int w, int h, double scale, const struct Border borde
   }
 }
 
+void app_invalidateWindow(void)
+{
+  atomic_store(&g_state.invalidateWindow, true);
+  lgSignalEvent(g_state.frameEvent);
+}
+
 void app_handleCloseEvent(void)
 {
   if (!g_params.ignoreQuit || !g_cursor.inView)

client/src/main.c

@@ -64,7 +64,6 @@ static int cursorThread(void * unused);
 static int renderThread(void * unused);
 
 static LGEvent  *e_startup = NULL;
-static LGEvent  *e_frame   = NULL;
 static LGThread *t_spice   = NULL;
 static LGThread *t_render  = NULL;
 static LGThread *t_cursor  = NULL;
@@ -170,7 +169,7 @@ static int renderThread(void * unused)
     {
       float ups = atomic_load_explicit(&g_state.ups, memory_order_relaxed);
 
-      if (!lgWaitEventAbs(e_frame, &time) || ups > g_params.fpsMin)
+      if (!lgWaitEventAbs(g_state.frameEvent, &time) || ups > g_params.fpsMin)
       {
         /* only update the time if we woke up early */
         clock_gettime(CLOCK_MONOTONIC, &time);
@@ -208,8 +207,11 @@ static int renderThread(void * unused)
     const bool newFrame = frameCount != lastFrameCount;
     lastFrameCount = frameCount;
 
+    const bool invalidate = atomic_exchange(&g_state.invalidateWindow, false);
+
     LG_LOCK(g_state.lgrLock);
-    if (!g_state.lgr->render(g_state.lgrData, g_params.winRotate, newFrame))
+    if (!g_state.lgr->render(g_state.lgrData, g_params.winRotate, newFrame,
+          invalidate))
     {
       LG_UNLOCK(g_state.lgrLock);
       break;
@@ -306,7 +308,7 @@ static int cursorThread(void * unused)
           );
 
           if (!g_state.stopVideo)
-            lgSignalEvent(e_frame);
+            lgSignalEvent(g_state.frameEvent);
         }
 
         const struct timespec req =
@@ -405,7 +407,7 @@ static int cursorThread(void * unused)
     );
 
     if (g_params.mouseRedraw && g_cursor.guest.visible && !g_state.stopVideo)
-      lgSignalEvent(e_frame);
+      lgSignalEvent(g_state.frameEvent);
   }
 
   lgmpClientUnsubscribe(&queue);
@@ -678,7 +680,7 @@ int main_frameThread(void * unused)
     g_state.lastFrameTimeValid = true;
 
     atomic_fetch_add_explicit(&g_state.frameCount, 1, memory_order_relaxed);
-    lgSignalEvent(e_frame);
+    lgSignalEvent(g_state.frameEvent);
     lgmpClientMessageDone(queue);
   }
 
@@ -950,7 +952,7 @@ static int lg_run(void)
   }
 
   // setup the new frame event
-  if (!(e_frame = lgCreateEvent(true, 0)))
+  if (!(g_state.frameEvent = lgCreateEvent(true, 0)))
   {
     DEBUG_ERROR("failed to create the frame event");
     return -1;
@@ -1092,7 +1094,7 @@ restart:
   if (g_state.state == APP_STATE_RESTART)
   {
     lgSignalEvent(e_startup);
-    lgSignalEvent(e_frame);
+    lgSignalEvent(g_state.frameEvent);
 
     core_stopFrameThread();
 
@@ -1116,7 +1118,7 @@ static void lg_shutdown(void)
   if (t_render)
   {
     lgSignalEvent(e_startup);
-    lgSignalEvent(e_frame);
+    lgSignalEvent(g_state.frameEvent);
     lgJoinThread(t_render, NULL);
   }
 
@@ -1129,10 +1131,10 @@ static void lg_shutdown(void)
     g_state.overlays = NULL;
   }
 
-  if (e_frame)
+  if (g_state.frameEvent)
   {
-    lgFreeEvent(e_frame);
-    e_frame = NULL;
+    lgFreeEvent(g_state.frameEvent);
+    g_state.frameEvent = NULL;
   }
 
   if (e_startup)

client/src/main.h

@@ -30,6 +30,7 @@
 #include "common/ivshmem.h"
 #include "common/locking.h"
 #include "common/ringbuffer.h"
+#include "common/event.h"
 
 #include "spice/spice.h"
 #include <lgmp/client.h>
@@ -103,6 +104,8 @@ struct AppState
   PLGMPClientQueue     pointerQueue;
 
   LGThread            * frameThread;
+  LGEvent             * frameEvent;
+  atomic_bool           invalidateWindow;
   bool                  formatValid;
   atomic_uint_least64_t frameTime;
   uint64_t              lastFrameTime;