Add support for axes swapping.

New option: SwapAxes (boolean)
New property: EVDEV_PROP_SWAP_AXES.

Actual swapping code written by Donnie Berkholz.

Signed-off-by: Peter Hutterer <peter.hutterer@redhat.com>
(cherry picked from commit 4826969f23)

include/evdev-properties.h

@@ -62,4 +62,8 @@
 /* CARD32, 4 values [minx, maxx, miny, maxy], or no values for unset */
 #define EVDEV_PROP_CALIBRATION "Evdev Axis Calibration"
 
+/* Swap x and y axis. */
+/* BOOL */
+#define EVDEV_PROP_SWAP_AXES "Evdev Axes Swap"
+
 #endif

man/evdev.man

@@ -147,6 +147,9 @@ waking up from suspend). In between each attempt is a 100ms wait. Default: 10.
 .BI "Option \*qInvertY\*q \*q" Bool \*q
 Invert the given axis. Default: off. Property: "Evdev Axis Inversion".
 .TP 7
+.BI "Option \*qSwapAxes\*q \*q" Bool \*q
+Swap x/y axes. Default: off. Property: "Evdev Axes Swap".
+.TP 7
 .BI "Option \*qGrabDevice\*q \*q" boolean \*q
 Force a grab on the event device. Doing so will ensure that no other driver
 can initialise the same device and it will also stop the device from sending
@@ -191,6 +194,9 @@ value.
 run-time axis calibration. This feature is required for devices that need to
 scale to a different coordinate system than originally reported to the X
 server, such as touchscreens that require run-time calibration.
+.TP 7
+.BI "Evdev Axis Swap"
+1 boolean values (8 bit, 0 or 1). 1 swaps x/y axes.
 
 .SH AUTHORS
 Kristian Høgsberg.

src/evdev.c

@@ -109,6 +109,7 @@ static int EvdevSetProperty(DeviceIntPtr dev, Atom atom,
 static Atom prop_invert = 0;
 static Atom prop_reopen = 0;
 static Atom prop_calibration = 0;
+static Atom prop_swap = 0;
 #endif
 
 
@@ -227,13 +228,14 @@ EvdevReadInput(InputInfoPtr pInfo)
 {
     struct input_event ev;
     int len, value;
-    int dx, dy;
+    int dx, dy, tmp;
     unsigned int abs;
     unsigned int button;
     EvdevPtr pEvdev = pInfo->private;
 
     dx = 0;
     dy = 0;
+    tmp = 0;
     abs = 0;
 
     while (xf86WaitForInput (pInfo->fd, 0) > 0) {
@@ -369,6 +371,11 @@ EvdevReadInput(InputInfoPtr pInfo)
     }
 
     if (dx != 0 || dy != 0) {
+        if (pEvdev->swap_axes) {
+            tmp = dx;
+            dx = dy;
+            dy = tmp;
+        }
         if (pEvdev->invert_x)
             dx *= -1;
         if (pEvdev->invert_y)
@@ -387,8 +394,8 @@ EvdevReadInput(InputInfoPtr pInfo)
      */
     if (abs && pEvdev->tool) {
         int abs_x, abs_y;
-        abs_x = pEvdev->abs_x;
-        abs_y = pEvdev->abs_y;
+        abs_x = (pEvdev->swap_axes) ? pEvdev->abs_y : pEvdev->abs_x;
+        abs_y = (pEvdev->swap_axes) ? pEvdev->abs_x : pEvdev->abs_y;
 
         if (pEvdev->flags & EVDEV_CALIBRATED)
         {
@@ -1382,6 +1389,7 @@ EvdevPreInit(InputDriverPtr drv, IDevPtr dev, int flags)
     pEvdev->reopen_attempts = xf86SetIntOption(pInfo->options, "ReopenAttempts", 10);
     pEvdev->invert_x = xf86SetBoolOption(pInfo->options, "InvertX", FALSE);
     pEvdev->invert_y = xf86SetBoolOption(pInfo->options, "InvertY", FALSE);
+    pEvdev->swap_axes = xf86SetBoolOption(pInfo->options, "SwapAxes", FALSE);
 
     /* Grabbing the event device stops in-kernel event forwarding. In other
        words, it disables rfkill and the "Macintosh mouse button emulation".
@@ -1565,6 +1573,16 @@ EvdevInitProperty(DeviceIntPtr dev)
         return;
 
     XISetDevicePropertyDeletable(dev, prop_calibration, FALSE);
+
+    prop_swap = MakeAtom(EVDEV_PROP_SWAP_AXES,
+                         strlen(EVDEV_PROP_SWAP_AXES), TRUE);
+
+    rc = XIChangeDeviceProperty(dev, prop_swap, XA_INTEGER, 8,
+                                PropModeReplace, 1, &pEvdev->swap_axes, FALSE);
+    if (rc != Success)
+        return;
+
+    XISetDevicePropertyDeletable(dev, prop_swap, FALSE);
 }
 
 static int
@@ -1620,6 +1638,13 @@ EvdevSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
                 pEvdev->calibration.max_y = vals[3];
             }
         }
+    } else if (atom == prop_swap)
+    {
+        if (val->format != 8 || val->type != XA_INTEGER || val->size != 1)
+            return BadMatch;
+
+        if (!checkonly)
+            pEvdev->swap_axes = *((BOOL*)val->data);
     }
 
     return Success;

src/evdev.h

@@ -64,6 +64,7 @@ typedef struct {
     int flags;
     int tool;
     int buttons;            /* number of buttons */
+    BOOL swap_axes;
     BOOL invert_x;
     BOOL invert_y;