commit 27df4e9c7f5efb87e06750a351ae46eded10b5cb
Author: Éric Brunet <Eric.Brunet@lps.ens.fr>
Date:   Thu Apr 16 15:41:12 2015 +0200

    Change the man page to explain the "Coordinate Transformation Matrix"
    property
    
    Signed-off-by: Éric Brunet <Eric.Brunet@lps.ens.fr>

diff --git a/man/libinput.man b/man/libinput.man
index e807578..d68aa1b 100644
--- a/man/libinput.man
+++ b/man/libinput.man
@@ -155,6 +155,46 @@ Indicates which click methods are enabled on this device.
 The above properties have a
 .BI "libinput <property name> Default"
 equivalent that indicates the default value for this setting on this device.
+.PP
+The following property is directly provided by the X server.
+.TP 7
+.BI "Coordinate Transformation Matrix"
+9 32-bit float values, representing a 3x3 calibration matrix, order is row
+1, row 2, row 3. The third row is unused and should be kept at its (0,0,1)
+default. The six remaining values define an affine transformation
+(x',y')=M(x,y)+(x0,y0), where the 2x2 matrix M is encoded in the first two
+values of the first two rows and (x0, y0) are the third values of the first
+two rows. The coordinates (x,y) and (x',y') are numbers between
+0 (completly to the left or at the top) and 1 (completly to the right or at
+the bottom). This property is useful when rotating the screen, and it
+should be updated each time
+.B xrandr -o <something>
+is run:
+
+When using
+.B xrandr -o left
+:
+
+  xinput set-prop <device> "Coordinate Transformation Matrix" 0 -1 1  1 0 0  0 0 1
+
+When using
+.B xrandr -o right
+:
+
+  xinput set-prop <device> "Coordinate Transformation Matrix" 0 1 0  -1 0 1  0 0 1
+
+When using
+.B xrandr -o inverted
+:
+
+  xinput set-prop <device> "Coordinate Transformation Matrix" -1 0 1  0 -1 1  0 0 1
+
+And of course, when using
+.B xrandr -o normal
+(the default orientation):
+
+  xinput set-prop <device> "Coordinate Transformation Matrix" 1 0 0  0 1 0  0 0 1
+
 
 .SH AUTHORS
 Peter Hutterer