[gnome-control-center] display-config: Use G_APPROX_VALUE to compare scale doubles

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 89cb1d99cbd3bda4eddebc0612fee207e86c49cd
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Sat May 29 18:38:18 2021 +0200

    display-config: Use G_APPROX_VALUE to compare scale doubles
    
    It's not safe to compare double values directly, use G_APPROX_VALUE with
    DBL_EPSILON instead.

 panels/display/cc-display-config-dbus.c | 13 +++++++++----
 panels/display/cc-display-settings.c    |  7 +++++--
 2 files changed, 14 insertions(+), 6 deletions(-)
---
diff --git a/panels/display/cc-display-config-dbus.c b/panels/display/cc-display-config-dbus.c
index cdc8f8aef..d97841bd6 100644
--- a/panels/display/cc-display-config-dbus.c
+++ b/panels/display/cc-display-config-dbus.c
@@ -17,6 +17,7 @@
  *
  */
 
+#include <float.h>
 #include <math.h>
 #include <gio/gio.h>
 
@@ -110,8 +111,12 @@ cc_display_mode_dbus_is_supported_scale (CcDisplayMode *pself,
 
   guint i;
   for (i = 0; i < self->supported_scales->len; i++)
-    if (g_array_index (self->supported_scales, double, i) == scale)
-      return TRUE;
+    {
+      double v = g_array_index (self->supported_scales, double, i);
+
+      if (G_APPROX_VALUE (v, scale, DBL_EPSILON))
+        return TRUE;
+    }
   return FALSE;
 }
 
@@ -246,7 +251,7 @@ cc_display_logical_monitor_equal (const CcDisplayLogicalMonitor *m1,
 
   return m1->x == m2->x &&
     m1->y == m2->y &&
-    m1->scale == m2->scale &&
+    G_APPROX_VALUE (m1->scale, m2->scale, DBL_EPSILON) &&
     m1->rotation == m2->rotation &&
     m1->primary == m2->primary;
 }
@@ -700,7 +705,7 @@ cc_display_monitor_dbus_set_scale (CcDisplayMonitor *pself,
   if (!self->logical_monitor)
     return;
 
-  if (self->logical_monitor->scale != scale)
+  if (!G_APPROX_VALUE (self->logical_monitor->scale, scale, DBL_EPSILON))
     {
       self->logical_monitor->scale = scale;
 
diff --git a/panels/display/cc-display-settings.c b/panels/display/cc-display-settings.c
index 383936eca..598075c25 100644
--- a/panels/display/cc-display-settings.c
+++ b/panels/display/cc-display-settings.c
@@ -21,6 +21,7 @@
 
 #include <handy.h>
 #include <glib/gi18n.h>
+#include <float.h>
 #include <math.h>
 #include "list-box-helper.h"
 #include "cc-display-settings.h"
@@ -399,7 +400,8 @@ cc_display_settings_rebuild_ui (CcDisplaySettings *self)
       if (!cc_display_config_is_scaled_mode_valid (self->config,
                                                    current_mode,
                                                    *scale) &&
-          cc_display_monitor_get_scale (self->selected_output) != *scale)
+          !G_APPROX_VALUE (cc_display_monitor_get_scale (self->selected_output),
+                           *scale, DBL_EPSILON))
         continue;
 
       scale_str = make_scale_string (*scale);
@@ -419,7 +421,8 @@ cc_display_settings_rebuild_ui (CcDisplaySettings *self)
                                G_CALLBACK (on_scale_btn_active_changed_cb),
                                self, 0);
 
-      if (cc_display_monitor_get_scale (self->selected_output) == *scale)
+      if (G_APPROX_VALUE (cc_display_monitor_get_scale (self->selected_output),
+                          *scale, DBL_EPSILON))
         gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (scale_btn), TRUE);
 
       buttons += 1;