Merge remote-tracking branch 'origin/master' into feature/android

2 files changed, 81 insertions, 18 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 67a34d8415d..d24f25c2e06 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2644,7 +2644,7 @@ internal_delete_file (Lisp_Object filename)
 #endif
 
 /* Return -1 if FILE is a case-insensitive file name, 0 if not,
-   and a positive errno value if the result cannot be determined.  */
+   and 1 if the result cannot be determined.  */
 
 static int
 file_name_case_insensitive_err (Lisp_Object file)
@@ -2678,7 +2678,7 @@ file_name_case_insensitive_err (Lisp_Object file)
     return - (res == 0);
 # endif
   if (errno != EINVAL)
-    return errno;
+    return 1;
 #endif
 
 #if defined CYGWIN || defined DOS_NT
diff --git a/src/xterm.c b/src/xterm.c
index 1865324d87a..f454733c659 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -5497,12 +5497,24 @@ xi_populate_device_from_info (struct x_display_info *dpyinfo,
      no input.
 
      The device attachment is a device ID whose meaning varies
-     depending on the device use.  If the device is a master device,
-     then the attachment is the device ID of the other device in its
-     seat (the master keyboard for master pointer devices, and vice
-     versa).  Otherwise, it is the ID of the master device the slave
+     depending on the device's use.  If a device is a master device,
+     then its attachment is the device ID of the other device in its
+     seat (the master keyboard for master pointer devices and vice
+     versa.)  Otherwise, it is the ID of the master device the slave
      device is attached to.  For slave devices not attached to any
-     seat, its value is undefined.  */
+     seat, its value is undefined.
+
+     Emacs receives ordinary pointer and keyboard events from the
+     master devices associated with each seat, discarding events from
+     slave devices.  However, multiplexing events from touch devices
+     onto a master device poses problems: if both dependent and direct
+     touch devices are attached to the same master pointer device, the
+     coordinate space of touch events sent from that seat becomes
+     ambiguous.  In addition, the X server does not send TouchEnd
+     events to cancel ongoing touch sequences if the slave device that
+     is their source is detached.  As a result of these ambiguities,
+     touch events are processed from and recorded onto their slave
+     devices instead.  */
 
   xi_device->device_id = device->deviceid;
   xi_device->grab = 0;
@@ -5516,7 +5528,7 @@ xi_populate_device_from_info (struct x_display_info *dpyinfo,
 #ifdef HAVE_XINPUT2_2
   xi_device->touchpoints = NULL;
   xi_device->direct_p = false;
-#endif
+#endif /* HAVE_XINPUT2_1 */
 
 #ifdef HAVE_XINPUT2_1
   if (!dpyinfo->xi2_version)
@@ -5582,9 +5594,34 @@ xi_populate_device_from_info (struct x_display_info *dpyinfo,
         case XITouchClass:
           {
             touch_info = (XITouchClassInfo *) device->classes[c];
-            xi_device->direct_p = touch_info->mode == XIDirectTouch;
+
+            /* touch_info->mode indicates the coordinate space that
+               this device reports in its touch events.
+
+               DirectTouch means that the device uses a coordinate
+               space that corresponds to locations on the screen.  It
+               is set by touch screen devices which are overlaid
+               over the raster itself.
+
+               The other value (DependentTouch) means that the device
+               uses a separate abstract coordinate space corresponding
+               to its own surface.  Emacs ignores events from these
+               devices because it does not support recognizing touch
+               gestures from surfaces other than the screen.
+
+               Master devices may report multiple touch classes for
+               attached slave devices, leaving the nature of touch
+               events they send ambiguous.  The problem of
+               discriminating between these events is bypassed
+               entirely through only processing touch events from the
+               slave devices where they originate.  */
+
+            if (touch_info->mode == XIDirectTouch)
+              xi_device->direct_p = true;
+            else
+              xi_device->direct_p = false;
           }
-#endif
+#endif /* HAVE_XINPUT2_2 */
         default:
           break;
         }
@@ -5611,7 +5648,7 @@ xi_populate_device_from_info (struct x_display_info *dpyinfo,
     }
 
   SAFE_FREE ();
-#endif
+#endif /* HAVE_XINPUT2_1 */
 }
 
 /* Populate our client-side record of all devices, which includes
@@ -13443,7 +13480,7 @@ xi_handle_new_classes (struct x_display_info *dpyinfo, struct xi_device_t *devic
   device->scroll_valuator_count = 0;
 #ifdef HAVE_XINPUT2_2
   device->direct_p = false;
-#endif
+#endif /* HAVE_XINPUT2_2 */
 
   for (i = 0; i < num_classes; ++i)
     {
@@ -13461,10 +13498,34 @@ xi_handle_new_classes (struct x_display_info *dpyinfo, struct xi_device_t *devic
         case XITouchClass:
           touch = (XITouchClassInfo *) classes[i];
 
+          /* touch_info->mode indicates the coordinate space that this
+             device reports in its touch events.
+
+             DirectTouch means that the device uses a coordinate space
+             that corresponds to locations on the screen.  It is set
+             by touch screen devices which are overlaid over the
+             raster itself.
+
+             The other value (DependentTouch) means that the device
+             uses a separate abstract coordinate space corresponding
+             to its own surface.  Emacs ignores events from these
+             devices because it does not support recognizing touch
+             gestures from surfaces other than the screen.
+
+             Master devices may report multiple touch classes for
+             attached slave devices, leaving the nature of touch
+             events they send ambiguous.  The problem of
+             discriminating between these events is bypassed entirely
+             through only processing touch events from the slave
+             devices where they originate.  */
+
           if (touch->mode == XIDirectTouch)
             device->direct_p = true;
+          else
+            device->direct_p = false;
+
           break;
-#endif
+#endif /* HAVE_XINPUT2_2 */
         }
     }
 
@@ -13502,7 +13563,7 @@ xi_handle_new_classes (struct x_display_info *dpyinfo, struct xi_device_t *devic
     }
 }
 
-#endif
+#endif /* HAVE_XINPUT2_1 */
 
 /* Handle EVENT, a DeviceChanged event.  Look up the device that
    changed, and update its information with the data in EVENT.  */
@@ -32250,10 +32311,12 @@ reported as iconified.  */);
 
   DEFVAR_BOOL ("x-input-grab-touch-events", x_input_grab_touch_events,
                doc: /* Non-nil means to actively grab touch events.
-This means touch sequences that started on an Emacs frame will
-reliably continue to receive updates even if the finger moves off the
-frame, but may cause crashes with some window managers and/or external
-programs.  */);
+This means touch sequences that are obtained through a passive grab on
+an Emacs frame (or a parent window of such a frame) will reliably
+continue to receive updates, but may cause crashes with some window
+managers and/or external programs.  Changing this option is only
+useful when other programs are making their own X requests pertaining
+to the window hierarchy of an Emacs frame.  */);
   x_input_grab_touch_events = true;
 
   DEFVAR_BOOL ("x-dnd-fix-motif-leave", x_dnd_fix_motif_leave,