[client] spice: general improvements to cursor warp logic

Previously only up to two pending warp requests were possible, this
changes this so that additional warps can be queued if the cursor's
delta has moved more then 50px between each warp request.

The old code also had an error where it would null out any additional
movement since the warp was requested, but before it was processed, this
has been corrected.

client/src/main.c

@@ -78,10 +78,14 @@ struct CursorState g_cursor;
 // this structure is initialized in config.c
 struct AppParams params = { 0 };
 
-union WarpInfo
+struct WarpInfo
 {
-  unsigned long serial;
-  SDL_Point p;
+  int x, y;
+  union
+  {
+    unsigned long serial;
+    SDL_Point     p;
+  };
 };
 
 static void handleMouseMoveEvent(int ex, int ey);
@@ -785,13 +789,20 @@ static void warpMouse(int x, int y, bool disable)
   if (g_cursor.warpState == WARP_STATE_OFF)
     return;
 
-  if (ll_count(g_cursor.warpList) > 0 && !disable)
-    return;
-
   if (disable)
     g_cursor.warpState = WARP_STATE_OFF;
 
-  union WarpInfo * warp = malloc(sizeof(union WarpInfo));
+  struct WarpInfo * last;
+  struct WarpInfo * warp = malloc(sizeof(struct WarpInfo));
+  warp->x = g_cursor.last.x;
+  warp->y = g_cursor.last.y;
+
+  /* if there is a queued warp still, adjust for it */
+  if (ll_peek_tail(g_cursor.warpList, (void **)&last))
+  {
+    warp->x += x - last->x;
+    warp->y += y - last->y;
+  }
 
   if (g_state.wminfo.subsystem == SDL_SYSWM_X11)
   {
@@ -845,8 +856,10 @@ static void handleMouseMoveEvent(int ex, int ey)
   if (delta.x == 0 && delta.y == 0)
     return;
 
-  g_cursor.last.x = ex;
-  g_cursor.last.y = ey;
+  g_cursor.delta.x += delta.x;
+  g_cursor.delta.y += delta.y;
+  g_cursor.last.x   = ex;
+  g_cursor.last.y   = ey;
 
   /* if we don't have the current cursor pos just send cursor movements */
   if (!g_cursor.guest.valid)
@@ -855,9 +868,12 @@ static void handleMouseMoveEvent(int ex, int ey)
     {
       g_cursor.inView = true;
       spice_mouse_motion(delta.x, delta.y);
-      if (ex < g_state.windowCX - 25 || ex > g_state.windowCX + 25 ||
-          ey < g_state.windowCY - 25 || ey > g_state.windowCY + 25)
+      if (abs(g_cursor.delta.x) >= 50 || abs(g_cursor.delta.y) >= 50)
+      {
         warpMouse(g_state.windowCX, g_state.windowCY, false);
+        g_cursor.delta.x = 0;
+        g_cursor.delta.y = 0;
+      }
     }
 
     return;
@@ -886,9 +902,6 @@ static void handleMouseMoveEvent(int ex, int ey)
       g_cursor.redraw = true;
       g_cursor.draw   = true;
 
-      if (g_cursor.warpState == WARP_STATE_OFF)
-        g_cursor.warpState = WARP_STATE_ON;
-
       /* convert guest to local and calculate the delta */
       const int lx = (int)round(((g_cursor.guest.x + g_cursor.guest.hx) /
             g_cursor.scaleX)) + g_state.dstRect.x;
@@ -910,9 +923,12 @@ static void handleMouseMoveEvent(int ex, int ey)
   if (inView)
   {
     /* stop the mouse from runing into the edges of the window */
-    if (ex < g_state.windowCX - 25 || ex > g_state.windowCX + 25 ||
-        ey < g_state.windowCY - 25 || ey > g_state.windowCY + 25)
+    if (abs(g_cursor.delta.x) >= 50 || abs(g_cursor.delta.y) >= 50)
+    {
       warpMouse(g_state.windowCX, g_state.windowCY, false);
+      g_cursor.delta.x = 0;
+      g_cursor.delta.y = 0;
+    }
   }
   else
   {
@@ -1018,11 +1034,13 @@ static void handleWindowLeave()
 static void handleWindowEnter()
 {
   g_cursor.inWindow = true;
-
-  g_cursor.warpState = WARP_STATE_ON;
   if (!params.useSpiceInput)
     return;
 
+  /* set large values to force a warp to center */
+  g_cursor.delta.x = 0xFFFF;
+  g_cursor.delta.y = 0xFFFF;
+
   if (!g_cursor.guest.valid)
     return;
 
@@ -1060,21 +1078,38 @@ static void keyboardUngrab()
   );
 }
 
-static bool processXWarp(const XEvent xe, int x, int y)
+static void processWarp(int x, int y)
 {
-  union WarpInfo * warp;
-  if (ll_peek_head(g_cursor.warpList, (void **)&warp) &&
-      xe.xany.serial == warp->serial)
-  {
-    ll_shift(g_cursor.warpList, NULL);
-    free(warp);
+  struct WarpInfo * warp;
+  if (!ll_peek_head(g_cursor.warpList, (void **)&warp) ||
+      warp->p.x != x || warp->p.y != y)
+    return;
 
-    g_cursor.last.x = x;
-    g_cursor.last.y = y;
-    return true;
-  }
+  ll_shift(g_cursor.warpList, NULL);
 
-  return false;
+  g_cursor.last.x = x + (g_cursor.last.x - warp->x);
+  g_cursor.last.y = y + (g_cursor.last.y - warp->y);
+  free(warp);
+
+  if (ll_count(g_cursor.warpList) == 0 && g_cursor.inWindow)
+    g_cursor.warpState = WARP_STATE_ON;
+}
+
+static void processXWarp(const XEvent xe, int x, int y)
+{
+  struct WarpInfo * warp;
+  if (!ll_peek_head(g_cursor.warpList, (void **)&warp) ||
+      xe.xany.serial != warp->serial)
+    return;
+
+  ll_shift(g_cursor.warpList, NULL);
+
+  g_cursor.last.x = x + (g_cursor.last.x - warp->x);
+  g_cursor.last.y = y + (g_cursor.last.y - warp->y);
+  free(warp);
+
+  if (ll_count(g_cursor.warpList) == 0 && g_cursor.inWindow)
+    g_cursor.warpState = WARP_STATE_ON;
 }
 
 int eventFilter(void * userdata, SDL_Event * event)
@@ -1168,10 +1203,7 @@ int eventFilter(void * userdata, SDL_Event * event)
             const int x = round(device->event_x);
             const int y = round(device->event_y);
 
-            /* detect and filter out warp events */
-            if (processXWarp(xe, x, y))
-              break;
-
+            processXWarp(xe, x, y);
             handleMouseMoveEvent(x, y);
             break;
           }
@@ -1181,10 +1213,7 @@ int eventFilter(void * userdata, SDL_Event * event)
            * motion events when a button is held */
           case MotionNotify:
           {
-            /* detect and filter out warp events */
-            if (processXWarp(xe, xe.xmotion.x, xe.xmotion.y))
-              break;
-
+            processXWarp(xe, xe.xmotion.x, xe.xmotion.y);
             handleMouseMoveEvent(xe.xmotion.x, xe.xmotion.y);
             break;
           }
@@ -1203,8 +1232,8 @@ int eventFilter(void * userdata, SDL_Event * event)
 
           case EnterNotify:
           {
-            processXWarp(xe, xe.xcrossing.x, xe.xcrossing.y);
             handleWindowEnter();
+            processXWarp(xe, xe.xcrossing.x, xe.xcrossing.y);
             break;
           }
 
@@ -1239,7 +1268,7 @@ int eventFilter(void * userdata, SDL_Event * event)
 
           default:
           {
-            union WarpInfo * warp;
+            struct WarpInfo * warp;
             if (ll_peek_head(g_cursor.warpList, (void **)&warp) &&
                 xe.xany.serial == warp->serial)
             {
@@ -1262,19 +1291,7 @@ int eventFilter(void * userdata, SDL_Event * event)
         break;
 
       /* detect and filter out warp events */
-      union WarpInfo * warp;
-      if (ll_peek_head(g_cursor.warpList, (void **)&warp) &&
-        warp->p.x == event->motion.x &&
-        warp->p.y == event->motion.y)
-      {
-        ll_shift(g_cursor.warpList, NULL);
-        free(warp);
-
-        g_cursor.last.x = event->motion.x;
-        g_cursor.last.y = event->motion.y;
-        break;
-      }
-
+      processWarp(event->motion.x, event->motion.y);
       handleMouseMoveEvent(event->motion.x, event->motion.y);
       break;
     }
@@ -2096,7 +2113,7 @@ static void lg_shutdown()
 
   if (g_cursor.warpList)
   {
-    union WarpInfo * warp;
+    struct WarpInfo * warp;
     while(ll_shift(g_cursor.warpList, (void **)&warp))
       free(warp);
     ll_free(g_cursor.warpList);

client/src/main.h

@@ -210,6 +210,9 @@ struct CursorState
   /* the last local X & Y positions */
   SDL_Point last;
 
+  /* the delta since the last warp to CX/CY */
+  SDL_Point delta;
+
   /* the scale factors for the mouse sensitiviy */
   int   sens;
   float sensX, sensY;