[mutter] backends/native: Use libinput calibration matrix for calibration

[Carlos Garnacho <carlosg src gnome org>]

commit cfbc4fe4d0f37ca2b8cf3e07c7cf2387252dbd23
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Nov 8 18:27:16 2016 +0100

    backends/native: Use libinput calibration matrix for calibration
    
    We couldn't properly merge output-mapping matrix and calibration into
    one. Now that libinput calibration matrix is free to use, we can
    actually implement tablet calibration with it.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=774115

 src/backends/native/meta-input-settings-native.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)
---
diff --git a/src/backends/native/meta-input-settings-native.c 
b/src/backends/native/meta-input-settings-native.c
index 7a896ec..c2d362b 100644
--- a/src/backends/native/meta-input-settings-native.c
+++ b/src/backends/native/meta-input-settings-native.c
@@ -390,7 +390,16 @@ meta_input_settings_native_set_tablet_area (MetaInputSettings  *settings,
                                             gdouble             padding_top,
                                             gdouble             padding_bottom)
 {
-  /* FIXME: Implement */
+  struct libinput_device *libinput_device;
+  gfloat matrix[6] = { 1. - (padding_left + padding_right), 0., padding_left,
+                       0., 1. - (padding_top + padding_bottom), padding_top };
+
+  libinput_device = clutter_evdev_input_device_get_libinput_device (device);
+  if (!libinput_device ||
+      !libinput_device_config_calibration_has_matrix (libinput_device))
+    return;
+
+  libinput_device_config_calibration_set_matrix (libinput_device, matrix);
 }
 
 static void