Hello,
I was having a look at the mouse events that the guest receives, and was
surprised to get
pos x:452 y:220 z:0
pos x:452 y:220 z:0
pos x:452 y:220 z:0
pos x:452 y:220 z:0
pos x:452 y:220 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:430 y:304 z:0
pos x:350 y:344 z:0
pos x:350 y:344 z:0
pos x:350 y:344 z:0
i.e. the guest receives the same position several times. This revealed
to be because sdl.c uses SDL_GetRelativeMouseState() instead of just
using the value from the event, and thus when several X11 events are
processed in one execution of sdl_refresh(), the intermediate positions
are not taken into account. I asked on the SDL mailing list, and they
answered that qemu should indeed not use SDL_GetRelativeMouseState(),
since that only provides the latest mouse position, not the position at
the time of the event. The patch below fixes this, and now I am getting
pos x:401 y:457 z:0
pos x:393 y:461 z:0
pos x:387 y:465 z:0
pos x:384 y:465 z:0
pos x:378 y:469 z:0
pos x:378 y:470 z:0
pos x:379 y:472 z:0
pos x:387 y:478 z:0
pos x:385 y:494 z:0
pos x:381 y:512 z:0
which provides a much more smooth feedback of the mouse cursor. It also
permits accessibility features such as mouse trail to work much better.
It also fixes some of the double-clic issues noticed when the machine is
sluggish (since it now always uses the button state at the time of the
event, not the current button state).
Samuel
Index: sdl.c
===================================================================
RCS file: /sources/qemu/qemu/sdl.c,v
retrieving revision 1.45
diff -u -p -r1.45 sdl.c
--- sdl.c 17 Nov 2007 17:14:38 -0000 1.45
+++ sdl.c 26 Feb 2008 12:24:33 -0000
@@ -276,8 +276,6 @@ static void sdl_grab_start(void)
} else
sdl_hide_cursor();
SDL_WM_GrabInput(SDL_GRAB_ON);
- /* dummy read to avoid moving the mouse */
- SDL_GetRelativeMouseState(NULL, NULL);
gui_grab = 1;
sdl_update_caption();
}
@@ -290,10 +288,9 @@ static void sdl_grab_end(void)
sdl_update_caption();
}
-static void sdl_send_mouse_event(int dz)
+static void sdl_send_mouse_event(int dx, int dy, int dz, int x, int y, int
state)
{
- int dx, dy, state, buttons;
- state = SDL_GetRelativeMouseState(&dx, &dy);
+ int buttons;
buttons = 0;
if (state & SDL_BUTTON(SDL_BUTTON_LEFT))
buttons |= MOUSE_EVENT_LBUTTON;
@@ -311,18 +308,18 @@ static void sdl_send_mouse_event(int dz)
absolute_enabled = 1;
}
- SDL_GetMouseState(&dx, &dy);
- dx = dx * 0x7FFF / width;
- dy = dy * 0x7FFF / height;
+ dx = x * 0x7FFF / width;
+ dy = y * 0x7FFF / height;
} else if (absolute_enabled) {
sdl_show_cursor();
absolute_enabled = 0;
} else if (guest_cursor) {
- SDL_GetMouseState(&dx, &dy);
- dx -= guest_x;
- dy -= guest_y;
- guest_x += dx;
- guest_y += dy;
+ x -= guest_x;
+ y -= guest_y;
+ guest_x += x;
+ guest_y += y;
+ dx = x;
+ dy = y;
}
kbd_mouse_event(dx, dy, dz, buttons);
@@ -347,6 +344,7 @@ static void sdl_refresh(DisplayState *ds
{
SDL_Event ev1, *ev = &ev1;
int mod_state;
+ int buttonstate = SDL_GetMouseState(NULL, NULL);
if (last_vm_running != vm_running) {
last_vm_running = vm_running;
@@ -474,7 +472,8 @@ static void sdl_refresh(DisplayState *ds
case SDL_MOUSEMOTION:
if (gui_grab || kbd_mouse_is_absolute() ||
absolute_enabled) {
- sdl_send_mouse_event(0);
+ sdl_send_mouse_event(ev->motion.xrel, ev->motion.yrel, 0,
+ ev->motion.x, ev->motion.y, ev->motion.state);
}
break;
case SDL_MOUSEBUTTONDOWN:
@@ -483,13 +482,18 @@ static void sdl_refresh(DisplayState *ds
SDL_MouseButtonEvent *bev = &ev->button;
if (!gui_grab && !kbd_mouse_is_absolute()) {
if (ev->type == SDL_MOUSEBUTTONDOWN &&
- (bev->state & SDL_BUTTON_LMASK)) {
+ (bev->button == SDL_BUTTON_LEFT)) {
/* start grabbing all events */
sdl_grab_start();
}
} else {
int dz;
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;
@@ -497,7 +501,7 @@ static void sdl_refresh(DisplayState *ds
dz = 1;
}
#endif
- sdl_send_mouse_event(dz);
+ sdl_send_mouse_event(0, 0, dz, bev->x, bev->y,
buttonstate);
}
}
break;
