Add configuration option for disabling mouse warping

This patch adds a new configuration option "mouse_warping [output|none]".

When mouse warping is disabled, mouse cursor does not jump to middle of current
screen when changing workspaces between multiple outputs. This introduces a
"special" cursor state, where focus is in one window and cursor on another.
Useful for eg. scrolling a web page with mouse wheel while typing into another
window on keyboard.

docs/userguide

@@ -810,6 +810,26 @@ focus_follows_mouse <yes|no>
 focus_follows_mouse no
 ----------------------
 
+=== Mouse warping
+
+By default, when switching focus to a window on a different output (e.g.
+focusing a window on workspace 3 on output VGA-1, coming from workspace 2 on
+LVDS-1), the mouse cursor is warped to the center of that window.
+
+With the +mouse_warping+ option, you can control when the mouse cursor should
+be warped. +none+ disables warping entirely, whereas +output+ is the default
+behavior described above.
+
+*Syntax*:
+---------------------------
+mouse_warping <output|none>
+---------------------------
+
+*Example*:
+------------------
+mouse_warping none
+------------------
+
 === Popups during fullscreen mode
 
 When you are in fullscreen mode, some applications still open popup windows

include/config.h

@@ -109,6 +109,16 @@ struct Config {
      * It is not planned to add any different focus models. */
     bool disable_focus_follows_mouse;
 
+    /** By default, when switching focus to a window on a different output
+     * (e.g. focusing a window on workspace 3 on output VGA-1, coming from
+     * workspace 2 on LVDS-1), the mouse cursor is warped to the center of
+     * that window.
+     *
+     * With the mouse_warping option, you can control when the mouse cursor
+     * should be warped. "none" disables warping entirely, whereas "output"
+     * is the default behavior described above. */
+    warping_t mouse_warping;
+
     /** Remove borders if they are adjacent to the screen edge.
      * This is useful if you are reaching scrollbar on the edge of the
      * screen or do not want to waste a single pixel of displayspace.

include/config_directives.h

@@ -46,6 +46,7 @@ CFGFUN(default_orientation, const char *orientation);
 CFGFUN(workspace_layout, const char *layout);
 CFGFUN(workspace_back_and_forth, const char *value);
 CFGFUN(focus_follows_mouse, const char *value);
+CFGFUN(mouse_warping, const char *value);
 CFGFUN(force_focus_wrapping, const char *value);
 CFGFUN(force_xinerama, const char *value);
 CFGFUN(fake_outputs, const char *outputs);

include/data.h

@@ -99,6 +99,14 @@ typedef enum {
     B_MOUSE = 1
 } input_type_t;
 
+/**
+ * Mouse pointer warping modes.
+ */
+typedef enum {
+    POINTER_WARPING_OUTPUT = 0,
+    POINTER_WARPING_NONE = 1
+} warping_t;
+
 /**
  * Stores a rectangle, for example the size of a window, the child window etc.
  * It needs to be packed so that the compiler will not add any padding bytes.

parser-specs/config.spec

@@ -32,6 +32,7 @@ state INITIAL:
   'for_window'                             -> FOR_WINDOW
   'assign'                                 -> ASSIGN
   'focus_follows_mouse'                    -> FOCUS_FOLLOWS_MOUSE
+  'mouse_warping'                          -> MOUSE_WARPING
   'force_focus_wrapping'                   -> FORCE_FOCUS_WRAPPING
   'force_xinerama', 'force-xinerama'       -> FORCE_XINERAMA
   'workspace_auto_back_and_forth'          -> WORKSPACE_BACK_AND_FORTH
@@ -172,6 +173,11 @@ state FOCUS_FOLLOWS_MOUSE:
   value = word
       -> call cfg_focus_follows_mouse($value)
 
+# mouse_warping warping_t
+state MOUSE_WARPING:
+  value = 'none', 'output'
+      -> call cfg_mouse_warping($value)
+
 # force_focus_wrapping
 state FORCE_FOCUS_WRAPPING:
   value = word

src/config_directives.c

@@ -298,6 +298,13 @@ CFGFUN(focus_follows_mouse, const char *value) {
     config.disable_focus_follows_mouse = !eval_boolstr(value);
 }
 
+CFGFUN(mouse_warping, const char *value) {
+    if (strcmp(value, "none") == 0)
+        config.mouse_warping = POINTER_WARPING_NONE;
+    else if (strcmp(value, "output") == 0)
+        config.mouse_warping = POINTER_WARPING_OUTPUT;
+}
+
 CFGFUN(force_xinerama, const char *value) {
     config.force_xinerama = eval_boolstr(value);
 }

src/x.c

@@ -1142,7 +1142,8 @@ void x_set_i3_atoms(void) {
  */
 void x_set_warp_to(Rect *rect)
 {
-    if (!config.disable_focus_follows_mouse)
+    if (!config.disable_focus_follows_mouse &&
+        config.mouse_warping != POINTER_WARPING_NONE)
         warp_to = rect;
 }
 

testcases/t/201-config-parser.t

@@ -309,6 +309,24 @@ is(parser_calls($config),
    $expected,
    'focus_follows_mouse ok');
 
+################################################################################
+# mouse_warping
+################################################################################
+
+$config = <<'EOT';
+mouse_warping output
+mouse_warping none
+EOT
+
+$expected = <<'EOT';
+cfg_mouse_warping(output)
+cfg_mouse_warping(none)
+EOT
+
+is(parser_calls($config),
+   $expected,
+   'mouse_warping ok');
+
 ################################################################################
 # force_display_urgency_hint
 ################################################################################
@@ -413,7 +431,7 @@ client.focused          #4c7899 #285577 #ffffff #2e9ef4
 EOT
 
 my $expected_all_tokens = <<'EOT';
-ERROR: CONFIG: Expected one of these tokens: <end>, '#', 'set', 'bindsym', 'bindcode', 'bind', 'bar', 'font', 'mode', 'floating_minimum_size', 'floating_maximum_size', 'floating_modifier', 'default_orientation', 'workspace_layout', 'new_window', 'new_float', 'hide_edge_borders', 'for_window', 'assign', 'focus_follows_mouse', 'force_focus_wrapping', 'force_xinerama', 'force-xinerama', 'workspace_auto_back_and_forth', 'fake_outputs', 'fake-outputs', 'force_display_urgency_hint', 'workspace', 'ipc_socket', 'ipc-socket', 'restart_state', 'popup_during_fullscreen', 'exec_always', 'exec', 'client.background', 'client.focused_inactive', 'client.focused', 'client.unfocused', 'client.urgent'
+ERROR: CONFIG: Expected one of these tokens: <end>, '#', 'set', 'bindsym', 'bindcode', 'bind', 'bar', 'font', 'mode', 'floating_minimum_size', 'floating_maximum_size', 'floating_modifier', 'default_orientation', 'workspace_layout', 'new_window', 'new_float', 'hide_edge_borders', 'for_window', 'assign', 'focus_follows_mouse', 'mouse_warping', 'force_focus_wrapping', 'force_xinerama', 'force-xinerama', 'workspace_auto_back_and_forth', 'fake_outputs', 'fake-outputs', 'force_display_urgency_hint', 'workspace', 'ipc_socket', 'ipc-socket', 'restart_state', 'popup_during_fullscreen', 'exec_always', 'exec', 'client.background', 'client.focused_inactive', 'client.focused', 'client.unfocused', 'client.urgent'
 EOT
 
 my $expected_end = <<'EOT';

testcases/t/519-mouse-warping.t

@@ -0,0 +1,52 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+
+use i3test i3_autostart => 0;
+
+# Ensure the pointer is at (0, 0) so that we really start on the first
+# (the left) workspace.
+$x->root->warp_pointer(0, 0);
+
+my $config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+fake-outputs 1024x768+0+0,1024x768+1024+0
+mouse_warping none
+EOT
+my $pid = launch_with_config($config);
+
+my $i3 = i3(get_socket_path());
+
+######################################################
+# Open one workspace with one window on both outputs #
+######################################################
+
+# Open window on workspace 1, left output
+is(focused_ws, '1', 'starting with focus on workspace 1');
+open_window;
+
+# Open window on workspace 2, right output
+cmd 'focus output right';
+is(focused_ws, '2', 'moved focus to workspace 2');
+open_window;
+
+# If mouse_warping is disabled, the pointer has not moved from
+# position (0, 0) when focus was switched to workspace 2
+$x->root->warp_pointer(0, 0);
+
+# Ensure focus is still on workspace 2
+is(focused_ws, '2', 'warped mouse cursor to (0, 0), focus still in workspace 2');
+
+# Exit gracefully
+exit_gracefully($pid);
+done_testing;