sdl2: Support mouse wheel

In SDL2, wheel movement is its own event, not a button event. Wire
it up similar to gtk.c
Signed-off-by: NCole Robinson <crobinso@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

ui/sdl2.c

@@ -359,16 +359,12 @@ static void sdl_mouse_mode_change(Notifier *notify, void *data)
 }
 
 static void sdl_send_mouse_event(struct sdl2_state *scon, int dx, int dy,
-                                 int dz, int x, int y, int state)
+                                 int x, int y, int state)
 {
     static uint32_t bmap[INPUT_BUTTON_MAX] = {
         [INPUT_BUTTON_LEFT]       = SDL_BUTTON(SDL_BUTTON_LEFT),
         [INPUT_BUTTON_MIDDLE]     = SDL_BUTTON(SDL_BUTTON_MIDDLE),
         [INPUT_BUTTON_RIGHT]      = SDL_BUTTON(SDL_BUTTON_RIGHT),
-#if 0
-        [INPUT_BUTTON_WHEEL_UP]   = SDL_BUTTON(SDL_BUTTON_WHEELUP),
-        [INPUT_BUTTON_WHEEL_DOWN] = SDL_BUTTON(SDL_BUTTON_WHEELDOWN),
-#endif
     };
     static uint32_t prev_state;
 
@@ -566,7 +562,7 @@ static void handle_mousemotion(SDL_Event *ev)
         }
     }
     if (gui_grab || qemu_input_is_absolute() || absolute_enabled) {
-        sdl_send_mouse_event(scon, ev->motion.xrel, ev->motion.yrel, 0,
+        sdl_send_mouse_event(scon, ev->motion.xrel, ev->motion.yrel,
                              ev->motion.x, ev->motion.y, ev->motion.state);
     }
 }
@@ -576,7 +572,6 @@ static void handle_mousebutton(SDL_Event *ev)
     int buttonstate = SDL_GetMouseState(NULL, NULL);
     SDL_MouseButtonEvent *bev;
     struct sdl2_state *scon = get_scon_from_window(ev->key.windowID);
-    int dz;
 
     bev = &ev->button;
     if (!gui_grab && !qemu_input_is_absolute()) {
@@ -585,23 +580,33 @@ static void handle_mousebutton(SDL_Event *ev)
             sdl_grab_start(scon);
         }
     } else {
-        dz = 0;
         if (ev->type == SDL_MOUSEBUTTONDOWN) {
             buttonstate |= SDL_BUTTON(bev->button);
         } else {
             buttonstate &= ~SDL_BUTTON(bev->button);
         }
-#ifdef SDL_BUTTON_WHEELUP
-        if (bev->button == SDL_BUTTON_WHEELUP &&
-            ev->type == SDL_MOUSEBUTTONDOWN) {
-            dz = -1;
-        } else if (bev->button == SDL_BUTTON_WHEELDOWN &&
-                   ev->type == SDL_MOUSEBUTTONDOWN) {
-            dz = 1;
-        }
-#endif
-        sdl_send_mouse_event(scon, 0, 0, dz, bev->x, bev->y, buttonstate);
+        sdl_send_mouse_event(scon, 0, 0, bev->x, bev->y, buttonstate);
+    }
+}
+
+static void handle_mousewheel(SDL_Event *ev)
+{
+    struct sdl2_state *scon = get_scon_from_window(ev->key.windowID);
+    SDL_MouseWheelEvent *wev = &ev->wheel;
+    InputButton btn;
+
+    if (wev->y > 0) {
+        btn = INPUT_BUTTON_WHEEL_UP;
+    } else if (wev->y < 0) {
+        btn = INPUT_BUTTON_WHEEL_DOWN;
+    } else {
+        return;
     }
+
+    qemu_input_queue_btn(scon->dcl.con, btn, true);
+    qemu_input_event_sync();
+    qemu_input_queue_btn(scon->dcl.con, btn, false);
+    qemu_input_event_sync();
 }
 
 static void handle_windowevent(DisplayChangeListener *dcl, SDL_Event *ev)
@@ -685,6 +690,9 @@ static void sdl_refresh(DisplayChangeListener *dcl)
         case SDL_MOUSEBUTTONUP:
             handle_mousebutton(ev);
             break;
+        case SDL_MOUSEWHEEL:
+            handle_mousewheel(ev);
+            break;
         case SDL_WINDOWEVENT:
             handle_windowevent(dcl, ev);
             break;