background: Get Preview aspect ratio from primary monitor

Get the aspect ratio from Primary monitor, and allow the preview
to have smaller size, so that it works well on smaller screens

3 files changed, 82 insertions, 20 deletions

diff --git a/panels/background/cc-background-panel.ui b/panels/background/cc-background-panel.ui
index 25cc62ea5..3cde1aa78 100644
--- a/panels/background/cc-background-panel.ui
+++ b/panels/background/cc-background-panel.ui
@@ -11,26 +11,35 @@
         <property name="orientation">vertical</property>
 
         <child>
-          <object class="GtkBox">
-            <property name="visible">True</property>
-            <property name="can_focus">False</property>
-            <property name="spacing">24</property>
-            <property name="margin">32</property>
-            <property name="halign">center</property>
-            <child>
-              <object class="CcBackgroundPreview" id="desktop_preview">
-                <property name="visible">True</property>
-                <property name="can_focus">False</property>
-                <property name="halign">end</property>
-                <property name="valign">center</property>
-              </object>
-            </child>
+          <object class="HdyColumn">
+            <property name="visible">1</property>
+            <property name="maximum_width">600</property>
+            <property name="linear_growth_width">400</property>
             <child>
-              <object class="CcBackgroundPreview" id="lock_screen_preview">
+              <object class="GtkBox">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
-                <property name="is-lock-screen">True</property>
-                <property name="valign">center</property>
+                <property name="spacing">24</property>
+                <property name="margin-start">12</property>
+                <property name="margin-end">12</property>
+                <property name="margin-top">18</property>
+                <property name="margin-bottom">18</property>
+                <property name="hexpand">True</property>
+                <child>
+                  <object class="CcBackgroundPreview" id="desktop_preview">
+                    <property name="visible">True</property>
+                    <property name="can_focus">False</property>
+                    <property name="valign">center</property>
+                  </object>
+                </child>
+                <child>
+                  <object class="CcBackgroundPreview" id="lock_screen_preview">
+                    <property name="visible">True</property>
+                    <property name="can_focus">False</property>
+                    <property name="is-lock-screen">True</property>
+                    <property name="valign">center</property>
+                  </object>
+                </child>
               </object>
             </child>
           </object>
diff --git a/panels/background/cc-background-preview.c b/panels/background/cc-background-preview.c
index 14717377d..a4fa31233 100644
--- a/panels/background/cc-background-preview.c
+++ b/panels/background/cc-background-preview.c
@@ -247,6 +247,55 @@ cc_background_preview_set_property (GObject      *object,
     }
 }
 
+static GtkSizeRequestMode
+cc_background_preview_get_request_mode (GtkWidget *widget)
+{
+  return GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH;
+}
+
+static gfloat
+get_primary_monitor_aspect_ratio (void)
+{
+  GdkDisplay *display;
+  GdkMonitor *primary_monitor;
+  gfloat aspect_ratio;
+
+  display = gdk_display_get_default ();
+  primary_monitor = gdk_display_get_primary_monitor (display);
+  aspect_ratio = 16.0 / 9.0;
+
+  if (primary_monitor)
+    {
+      GdkRectangle monitor_layout;
+      gdk_monitor_get_geometry (primary_monitor, &monitor_layout);
+      aspect_ratio = monitor_layout.width / (gfloat) monitor_layout.height;
+    }
+
+  return aspect_ratio;
+}
+
+static void
+cc_background_preview_get_preferred_height_for_width (GtkWidget *widget,
+                                                      gint       width,
+                                                      gint      *minimum,
+                                                      gint      *natural)
+{
+  gfloat aspect_ratio = get_primary_monitor_aspect_ratio ();
+
+  *minimum = *natural = MAX (2, width / aspect_ratio);
+}
+
+static void
+cc_background_preview_get_preferred_width_for_height (GtkWidget *widget,
+                                                      gint       height,
+                                                      gint      *minimum,
+                                                      gint      *natural)
+{
+  gfloat aspect_ratio = get_primary_monitor_aspect_ratio ();
+
+  *minimum = *natural = MAX (2, height * aspect_ratio);
+}
+
 static void
 cc_background_preview_class_init (CcBackgroundPreviewClass *klass)
 {
@@ -257,6 +306,10 @@ cc_background_preview_class_init (CcBackgroundPreviewClass *klass)
   object_class->get_property = cc_background_preview_get_property;
   object_class->set_property = cc_background_preview_set_property;
 
+  widget_class->get_request_mode = cc_background_preview_get_request_mode;
+  widget_class->get_preferred_height_for_width = cc_background_preview_get_preferred_height_for_width;
+  widget_class->get_preferred_width_for_height = cc_background_preview_get_preferred_width_for_height;
+
   properties[PROP_IS_LOCK_SCREEN] = g_param_spec_boolean ("is-lock-screen",
                                                           "Lock screen",
                                                           "Whether the preview is of the lock screen",
diff --git a/panels/background/cc-background-preview.ui b/panels/background/cc-background-preview.ui
index c9a8d61f9..da1f23943 100644
--- a/panels/background/cc-background-preview.ui
+++ b/panels/background/cc-background-preview.ui
@@ -4,9 +4,8 @@
   <template class="CcBackgroundPreview" parent="GtkBox">
     <property name="visible">True</property>
     <property name="can-focus">False</property>
-    <property name="expand">False</property>
-    <property name="width-request">384</property>
-    <property name="height-request">208</property>
+    <property name="hexpand">True</property>
+    <property name="vexpand">False</property>
     <style>
       <class name="frame" />
     </style>
@@ -15,6 +14,7 @@
       <object class="GtkOverlay">
         <property name="visible">True</property>
         <property name="can-focus">False</property>
+        <property name="hexpand">True</property>
 
         <!-- Wallpaper -->
         <child>