Use a convergence factor to make the VM's input
global coordinates more closely approach the global
coordinates of host.
Change-Id: I2c3f12f1fe7dfb9306d1fc40c4fd4d299937f4c6
Signed-off-by: Lei Huang <lei.hu...@amd.com>
---
ui/sdl2.c | 45 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 37 insertions(+), 8 deletions(-)
diff --git a/ui/sdl2.c b/ui/sdl2.c
index bd4f5a9da14..7c815d276a2 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -303,6 +303,35 @@ static void sdl_mouse_mode_change(Notifier *notify, void
*data)
}
}
+/*
+ * guest_x and guest_y represent the global coordinates on the VM side,
+ * while x and y represent the global coordinates on the host side.
+ * The goal of this entire process is to align the global coordinates
+ * of the VM with those of host using dx and dy. The current approach
+ * aims for precise calibration in one attempt; however, because guest_x
+ * and guest_y are non-zero values, they are not accurate values when
+ * they are counted out to become negative. Therefore, achieving perfect
+ * alignment in one attempt is impossible. Since the same calibration
+ * method is used each time, repeated attempts cannot achieve alignment
+ * either. By introducing a convergence factor, guest_x and guest_y can
+ * be made to approach host x and y indefinitely.
+ *
+ * QEMU VM
+ * calculates (dx, dy) (dx, dy)
+ * using (guest_x, guest_y) ------------>input driver
+ * ^ |
+ * | |
+ * | update V
+ * | (guest_x, guest_y) input
+ * | dispatcher ---> WindowManager
+ * | | |
+ * | | |
+ * | libdrm V |
+ * display device <-- drmModeMoveCursor <-- compositor <---- |
+ * (e.g. virtio-gpu) (guest_x, guest_y) calculates (guest_x, guest_y)
+ * using (dx, dy)
+ */
+#define CONVERGENCE_FACTOR 3
static void sdl_send_mouse_event(struct sdl2_console *scon, int dx, int dy,
int x, int y, int state)
{
@@ -327,15 +356,15 @@ static void sdl_send_mouse_event(struct sdl2_console
*scon, int dx, int dy,
y, 0, surface_height(scon->surface));
} else {
if (guest_cursor) {
- x -= guest_x;
- y -= guest_y;
- guest_x += x;
- guest_y += y;
- dx = x;
- dy = y;
+ dx = x - guest_x;
+ dy = y - guest_y;
+ guest_x = x;
+ guest_y = y;
}
- qemu_input_queue_rel(scon->dcl.con, INPUT_AXIS_X, dx);
- qemu_input_queue_rel(scon->dcl.con, INPUT_AXIS_Y, dy);
+ qemu_input_queue_rel(scon->dcl.con,
+ INPUT_AXIS_X, dx / CONVERGENCE_FACTOR);
+ qemu_input_queue_rel(scon->dcl.con,
+ INPUT_AXIS_Y, dy / CONVERGENCE_FACTOR);
}
qemu_input_event_sync();
}
--
2.45.2
