[mutter/gnome-3-24] backends/x11: Account for non-zero device origin when setting tablet area

[Carlos Garnacho <carlosg src gnome org>]

commit c02638e614a5116d949c3b2ecb4fbbffd9e3462f
Author: Jason Gerecke <killertofu gmail com>
Date:   Tue Jun 20 15:36:34 2017 -0700

    backends/x11: Account for non-zero device origin when setting tablet area
    
    Wacom's display tablets typically do not have (0,0) coincident with the top
    left corner of the screen. This "outbound" area must be taken into account
    when setting the area or else an unexpected offset of the pointer will
    occur.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784009

 src/backends/x11/meta-input-settings-x11.c |   34 ++++++++++++++++++----------
 1 files changed, 22 insertions(+), 12 deletions(-)
---
diff --git a/src/backends/x11/meta-input-settings-x11.c b/src/backends/x11/meta-input-settings-x11.c
index d2e2d99..894e4bb 100644
--- a/src/backends/x11/meta-input-settings-x11.c
+++ b/src/backends/x11/meta-input-settings-x11.c
@@ -555,6 +555,8 @@ meta_input_settings_x11_set_tablet_mapping (MetaInputSettings     *settings,
 
 static gboolean
 device_query_area (ClutterInputDevice *device,
+                   gint               *x,
+                   gint               *y,
                    gint               *width,
                    gint               *height)
 {
@@ -580,9 +582,15 @@ device_query_area (ClutterInputDevice *device,
       if (valuator->type != XIValuatorClass)
         continue;
       if (valuator->label == abs_x)
-        *width = valuator->max - valuator->min;
+        {
+          *x = valuator->min;
+          *width = valuator->max - valuator->min;
+        }
       else if (valuator->label == abs_y)
-        *height = valuator->max - valuator->min;
+        {
+          *y = valuator->min;
+          *height = valuator->max - valuator->min;
+        }
     }
 
   XIFreeDeviceInfo (info);
@@ -606,15 +614,15 @@ meta_input_settings_x11_set_tablet_area (MetaInputSettings  *settings,
                                          gdouble             padding_top,
                                          gdouble             padding_bottom)
 {
-  gint32 width, height, area[4] = { 0 };
+  gint32 x, y, width, height, area[4] = { 0 };
 
-  if (!device_query_area (device, &width, &height))
+  if (!device_query_area (device, &x, &y, &width, &height))
     return;
 
-  area[0] = width * padding_left;
-  area[1] = height * padding_top;
-  area[2] = width - (width * padding_right);
-  area[3] = height - (height * padding_bottom);
+  area[0] = (width * padding_left) + x;
+  area[1] = (height * padding_top) + y;
+  area[2] = width - (width * padding_right) + x;
+  area[3] = height - (height * padding_bottom) + y;
   update_tablet_area (settings, device, area);
 }
 
@@ -624,9 +632,9 @@ meta_input_settings_x11_set_tablet_keep_aspect (MetaInputSettings  *settings,
                                                 MetaLogicalMonitor *logical_monitor,
                                                 gboolean            keep_aspect)
 {
-  gint32 width, height, dev_width, dev_height, area[4] = { 0 };
+  gint32 width, height, dev_x, dev_y, dev_width, dev_height, area[4] = { 0 };
 
-  if (!device_query_area (device, &dev_width, &dev_height))
+  if (!device_query_area (device, &dev_x, &dev_y, &dev_width, &dev_height))
     return;
 
   if (keep_aspect)
@@ -658,8 +666,10 @@ meta_input_settings_x11_set_tablet_keep_aspect (MetaInputSettings  *settings,
         dev_height = dev_width / aspect_ratio;
     }
 
-  area[2] = dev_width;
-  area[3] = dev_height;
+  area[0] = dev_x;
+  area[1] = dev_y;
+  area[2] = dev_width + dev_x;
+  area[3] = dev_height + dev_y;
   update_tablet_area (settings, device, area);
 }