[gnome-control-center/gnome-3-30] display: Add function to run the snapping algorithm on a monitor

[Benjamin Berg <bberg src gnome org>]

commit 3f8afe150b32803a8fff628cbde7243cd696c98a
Author: Benjamin Berg <bberg redhat com>
Date:   Tue Oct 23 23:15:24 2018 +0200

    display: Add function to run the snapping algorithm on a monitor
    
    This is a function working only on a configuration which runs the
    snapping with infinite snapping. This allows forcing a monitor that has
    been modified to be adjacent to at least one monitor.
    
    (cherry picked from commit adf7cb26ea678a6c7c6e5ac7b27fe29604c92682)

 panels/display/cc-display-arrangement.c | 28 ++++++++++++++++++++++++++++
 panels/display/cc-display-arrangement.h |  5 +++++
 2 files changed, 33 insertions(+)
---
diff --git a/panels/display/cc-display-arrangement.c b/panels/display/cc-display-arrangement.c
index 936d05e4b..db72adca7 100644
--- a/panels/display/cc-display-arrangement.c
+++ b/panels/display/cc-display-arrangement.c
@@ -930,3 +930,31 @@ cc_display_arrangement_set_selected_output (CcDisplayArrangement *self,
 
   g_object_notify_by_pspec (G_OBJECT (self), props[PROP_SELECTED_OUTPUT]);
 }
+
+void
+cc_display_config_snap_output (CcDisplayConfig  *config,
+                               CcDisplayMonitor *output)
+{
+  struct SnapData snap_data;
+  gint x, y, w, h;
+
+  if (!cc_display_monitor_is_useful (output))
+    return;
+
+  if (cc_display_config_count_useful_monitors (config) <= 1)
+    return;
+
+  get_scaled_geometry (config, output, &x, &y, &w, &h);
+
+  snap_data.snapped = SNAP_DIR_NONE;
+  snap_data.mon_x = x;
+  snap_data.mon_y = y;
+  snap_data.dist_x = 0;
+  snap_data.dist_y = 0;
+  cairo_matrix_init_identity (&snap_data.to_widget);
+  snap_data.major_snap_distance = G_MAXUINT;
+
+  find_best_snapping (config, output, &snap_data);
+
+  cc_display_monitor_set_position (output, snap_data.mon_x, snap_data.mon_y);
+}
diff --git a/panels/display/cc-display-arrangement.h b/panels/display/cc-display-arrangement.h
index e7592c8b8..8d0e39bc0 100644
--- a/panels/display/cc-display-arrangement.h
+++ b/panels/display/cc-display-arrangement.h
@@ -34,5 +34,10 @@ CcDisplayMonitor*     cc_display_arrangement_get_selected_output (CcDisplayArran
 void                  cc_display_arrangement_set_selected_output (CcDisplayArrangement *arr,
                                                                   CcDisplayMonitor     *output);
 
+/* This is a bit of an odd-ball, but it currently makes sense to have it with
+ * the arrangement widget where the snapping code lives. */
+void                  cc_display_config_snap_output              (CcDisplayConfig  *config,
+                                                                  CcDisplayMonitor *output);
+
 G_END_DECLS