From c02638e614a5116d949c3b2ecb4fbbffd9e3462f Mon Sep 17 00:00:00 2001
From: Jason Gerecke <killertofu@gmail.com>
Date: Tue, 20 Jun 2017 15:36:34 -0700
Subject: [PATCH] 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 file 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 d2e2d99f1..894e4bb9e 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);
 }