[mutter] monitor: Add scale 1 if no other supported scale was added

[Jonas Ådahl <jadahl src gnome org>]

commit 67ce04993ee05bd1cd19a51ca351eca6574a2064
Author: Jonas Ådahl <jadahl gmail com>
Date:   Mon Sep 11 14:12:29 2017 +0800

    monitor: Add scale 1 if no other supported scale was added
    
    We currently have a hard coded limit on logical monitor sizes, meant
    for filtering out monitor scales that would result in awkward desktop
    sizes. This has the side effect of also disqualifying scale 1 for
    resolutions that themself are lower than the mentioned limit. To avoid
    listing no supported scales, always add the fallback scale 1 if no
    other was added.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787477

 src/backends/meta-monitor.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-monitor.c b/src/backends/meta-monitor.c
index ed48a45..8ca6ea8 100644
--- a/src/backends/meta-monitor.c
+++ b/src/backends/meta-monitor.c
@@ -1550,6 +1550,14 @@ meta_monitor_calculate_supported_scales (MetaMonitor                *monitor,
         }
     }
 
+  if (supported_scales->len == 0)
+    {
+      float fallback_scale;
+
+      fallback_scale = 1.0;
+      g_array_append_val (supported_scales, fallback_scale);
+    }
+
   *n_supported_scales = supported_scales->len;
   return (float *) g_array_free (supported_scales, FALSE);
 }