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 | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff --git a/ui/sdl2.c b/ui/sdl2.c
index bd4f5a9da14..ea3fd74dd63 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -303,6 +303,34 @@ 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 once 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 (dx,dy) VM
+ * calculates dx and dy using guest_x and guest_y ----> input driver
+ * ^ |
+ * | |
+ * | V
+ * | update
+ * | guest_x,guest_y input dispatcher --->
WindowManager
+ * | | |
+ * | | |
+ * | libdrm V |
+ * display device <------ drmModeMoveCursor <------ compositor <------- |
+ * (guest_x,guest_y) calculates guest_x and
+ * guest_y dy using dx and 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)
{
@@ -331,8 +359,8 @@ static void sdl_send_mouse_event(struct sdl2_console *scon,
int dx, int dy,
y -= guest_y;
guest_x += x;
guest_y += y;
- dx = x;
- dy = y;
+ dx = x / CONVERGENCE_FACTOR;
+ dy = y / CONVERGENCE_FACTOR;
}
qemu_input_queue_rel(scon->dcl.con, INPUT_AXIS_X, dx);
qemu_input_queue_rel(scon->dcl.con, INPUT_AXIS_Y, dy);
--
2.45.2
