[gnome-flashback] backends: add gf_verify_monitor_mode_spec

[Alberts Muktupāvels <muktupavels src gnome org>]

commit bdc5f62a1c0aba02f86eec9dd9e2ecd13cd17632
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Wed Sep 20 17:56:08 2017 +0300

    backends: add gf_verify_monitor_mode_spec

 backends/gf-monitor-private.h |    3 +++
 backends/gf-monitor.c         |   19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)
---
diff --git a/backends/gf-monitor-private.h b/backends/gf-monitor-private.h
index 08d5da3..401ffbc 100644
--- a/backends/gf-monitor-private.h
+++ b/backends/gf-monitor-private.h
@@ -213,6 +213,9 @@ gboolean           gf_monitor_mode_foreach_output        (GfMonitor
                                                           gpointer                    user_data,
                                                           GError                    **error);
 
+gboolean           gf_verify_monitor_mode_spec           (GfMonitorModeSpec          *mode_spec,
+                                                          GError                    **error);
+
 G_END_DECLS
 
 #endif
diff --git a/backends/gf-monitor.c b/backends/gf-monitor.c
index 4d0e9ab..3426fb4 100644
--- a/backends/gf-monitor.c
+++ b/backends/gf-monitor.c
@@ -953,3 +953,22 @@ gf_monitor_mode_foreach_output (GfMonitor          *monitor,
 
   return TRUE;
 }
+
+gboolean
+gf_verify_monitor_mode_spec (GfMonitorModeSpec  *mode_spec,
+                             GError            **error)
+{
+  if (mode_spec->width > 0 &&
+      mode_spec->height > 0 &&
+      mode_spec->refresh_rate > 0.0f)
+    {
+      return TRUE;
+    }
+  else
+    {
+      g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                   "Monitor mode invalid");
+
+      return FALSE;
+    }
+}