Add automatic axis labeling.

Since we don't support anything but REL/ABS x/y and sometimes pressure this is
bordering on pointlessness, but once the year of the Linux desktop comes
around this will be really handy. Or so.

Also, we don't allow changing axis labels, but should eventually rearrange
them if swapaxis is on.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/evdev.c

@@ -50,6 +50,7 @@
 #ifdef HAVE_PROPERTIES
 #include <X11/Xatom.h>
 #include <evdev-properties.h>
+#include <xserver-properties.h>
 #endif
 
 #ifndef MAXDEVICES
@@ -115,6 +116,7 @@ static Atom prop_invert = 0;
 static Atom prop_reopen = 0;
 static Atom prop_calibration = 0;
 static Atom prop_swap = 0;
+static Atom prop_label = 0;
 #endif
 
 /* All devices the evdev driver has allocated and knows about.
@@ -1702,7 +1704,6 @@ EvdevInitProperty(DeviceIntPtr dev)
     BOOL         invert[2];
     char         reopen;
 
-
     if (pEvdev->flags & (EVDEV_RELATIVE_EVENTS | EVDEV_ABSOLUTE_EVENTS))
     {
         invert[0] = pEvdev->invert_x;
@@ -1749,6 +1750,56 @@ EvdevInitProperty(DeviceIntPtr dev)
         return;
 
     XISetDevicePropertyDeletable(dev, prop_swap, FALSE);
+
+
+    /* Axis labelling
+       This is of course rather stupid. Because evdev doesn't really deal with
+       arbitrary axes yet, axis 0/1 must always be X/Y. If we have pressure,
+       then it's always axis 2. So the labelling is rather lame.
+     */
+    if ((prop_label = XIGetKnownProperty(AXIS_LABEL_PROP)))
+    {
+        Atom atom, atoms[3];
+
+        if (TestBit(REL_X, pEvdev->rel_bitmask))
+        {
+            atom = XIGetKnownProperty(AXIS_LABEL_PROP_REL_X);
+            if (atom)
+                atoms[0] = atom;
+        } else if (TestBit(ABS_X, pEvdev->abs_bitmask))
+        {
+            atom = XIGetKnownProperty(AXIS_LABEL_PROP_ABS_X);
+            if (atom)
+                atoms[0] = atom;
+        }
+
+        if (TestBit(REL_Y, pEvdev->rel_bitmask))
+        {
+            atom = XIGetKnownProperty(AXIS_LABEL_PROP_REL_Y);
+            if (atom)
+                atoms[1] = atom;
+        } else if (TestBit(ABS_Y, pEvdev->abs_bitmask))
+        {
+            atom = XIGetKnownProperty(AXIS_LABEL_PROP_ABS_Y);
+            if (atom)
+                atoms[1] = atom;
+        }
+
+        if (TestBit(ABS_PRESSURE, pEvdev->abs_bitmask))
+        {
+            atom = XIGetKnownProperty(AXIS_LABEL_PROP_ABS_PRESSURE);
+            if (atom)
+                atoms[2] = atom;
+        }
+
+        if (atoms[0] != -1 && atoms[1] != -1)
+        {
+            int natoms = (pEvdev->has_pressure && atoms[2] != -1) ? 3 : 2;
+            XIChangeDeviceProperty(dev, prop_label, XA_ATOM, 32,
+                                   PropModeReplace, natoms, &atoms, FALSE);
+            XISetDevicePropertyDeletable(dev, prop_label, FALSE);
+        }
+    }
 }
 
 static int
@@ -1811,7 +1862,8 @@ EvdevSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
 
         if (!checkonly)
             pEvdev->swap_axes = *((BOOL*)val->data);
-    }
+    } else if (atom == prop_label)
+        return BadAccess; /* Axis labels can't be changed */
 
     return Success;
 }