[Xen-devel] [PATCH 3/3] xenfb: Add "feature-no-abs-rescale" for Windows PV frontend

[Owen smith <owen.smith@xxxxxxxxxx>]

Windows PV frontend requires absolute mouse values in the range
[0, 0x7fff]. Add a feature to not rescale the axes to DisplaySurface
size. Also allows Windows PV frontend to connect without a vfb
device. Moves the rescaling of axes to a seperate function with
additional null-pointer checks.

Signed-off-by: Owen smith <owen.smith@xxxxxxxxxx>
---
 hw/display/xenfb.c | 52 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 15 deletions(-)

diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index c4375c8..65c373b 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -61,6 +61,7 @@ struct common {
 struct XenInput {
     struct common c;
     int abs_pointer_wanted; /* Whether guest supports absolute pointer */
+    int no_abs_rescale;     /* Whether guest wants rescaled abs axes */
     int button_state;       /* Last seen pointer button state */
     int extended;
     QEMUPutKbdEntry *qkbd;
@@ -325,6 +326,25 @@ static void xenfb_key_event(void *opaque, int scancode)
     xenfb_send_key(xenfb, down, scancode2linux[scancode]);
 }
 
+static void xenfb_rescale_mouse(struct XenInput *xenfb, int *dx, int *dy)
+{
+    DisplaySurface *surface;
+    int dw, dh;
+
+    if (xenfb->c.con == NULL) {
+        return;
+    }
+    surface = qemu_console_surface(xenfb->c.con);
+    if (surface == NULL) {
+        return;
+    }
+    dw = surface_width(surface);
+    dh = surface_height(surface);
+
+    *dx = *dx * (dw - 1) / 0x7fff;
+    *dy = *dy * (dh - 1) / 0x7fff;
+}
+
 /*
  * Send a mouse event from the client to the guest OS
  *
@@ -338,18 +358,16 @@ static void xenfb_mouse_event(void *opaque,
                              int dx, int dy, int dz, int button_state)
 {
     struct XenInput *xenfb = opaque;
-    DisplaySurface *surface = qemu_console_surface(xenfb->c.con);
-    int dw = surface_width(surface);
-    int dh = surface_height(surface);
     int i;
 
-    if (xenfb->abs_pointer_wanted)
-       xenfb_send_position(xenfb,
-                           dx * (dw - 1) / 0x7fff,
-                           dy * (dh - 1) / 0x7fff,
-                           dz);
-    else
+    if (xenfb->abs_pointer_wanted) {
+        if (!xenfb->no_abs_rescale) {
+            xenfb_rescale_mouse(xenfb, &dx, &dy);
+        }
+        xenfb_send_position(xenfb, dx, dy, dz);
+    } else {
        xenfb_send_motion(xenfb, dx, dy, dz);
+    }
 
     for (i = 0 ; i < 8 ; i++) {
        int lastDown = xenfb->button_state & (1 << i);
@@ -366,6 +382,7 @@ static void xenfb_mouse_event(void *opaque,
 static int input_init(struct XenDevice *xendev)
 {
     xenstore_write_be_int(xendev, "feature-abs-pointer", 1);
+    xenstore_write_be_int(xendev, "feature-no-abs-rescale", 1);
     return 0;
 }
 
@@ -374,7 +391,17 @@ static int input_initialise(struct XenDevice *xendev)
     struct XenInput *in = container_of(xendev, struct XenInput, c.xendev);
     int rc;
 
-    if (!in->c.con) {
+    if (xenstore_read_fe_int(xendev, "request-abs-pointer",
+                             &in->abs_pointer_wanted) == -1) {
+        in->abs_pointer_wanted = 0;
+    }
+
+    if (xenstore_read_fe_int(xendev, "request-no-abs-rescale",
+                             &in->no_abs_rescale) == -1) {
+        in->no_abs_rescale = 0;
+    }
+
+    if (!in->c.con && !in->no_abs_rescale) {
         xen_be_printf(xendev, 1, "ds not set (yet)\n");
         return -1;
     }
@@ -390,11 +417,6 @@ static void input_connected(struct XenDevice *xendev)
 {
     struct XenInput *in = container_of(xendev, struct XenInput, c.xendev);
 
-    if (xenstore_read_fe_int(xendev, "request-abs-pointer",
-                             &in->abs_pointer_wanted) == -1) {
-        in->abs_pointer_wanted = 0;
-    }
-
     if (in->qmouse) {
         qemu_remove_mouse_event_handler(in->qmouse);
     }
-- 
2.1.0


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