gnome: replace labels with icons on call control buttons

Also make the buttons round. This is in order to reduce the
size of the buttons to be able to add more.

Refs #76660

Change-Id: Ie7e62ffb22176c0da8c7b21d60fa8d4606638687
diff --git a/src/currentcallview.cpp b/src/currentcallview.cpp
index e37d3ad..8bce598 100644
--- a/src/currentcallview.cpp
+++ b/src/currentcallview.cpp
@@ -73,6 +73,8 @@
     GtkWidget *entry_chat_input;
     GtkWidget *scrolledwindow_chat;
     GtkWidget *fullscreen_window;
+    GtkWidget *buttonbox_call_controls;
+    GtkWidget *button_hangup;
 
     Call *call;
 
@@ -169,6 +171,18 @@
      * the chat treeview */
     GtkAdjustment *adjustment = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(priv->scrolledwindow_chat));
     g_signal_connect(adjustment, "changed", G_CALLBACK(scroll_to_bottom), NULL);
+
+    GtkCssProvider *provider = gtk_css_provider_new();
+    GdkDisplay *display = gdk_display_get_default();
+    GdkScreen *screen = gdk_display_get_default_screen(display);
+    gtk_css_provider_load_from_data(provider,
+        "GtkBox#call-controls GtkButton {\n"
+        "   border-radius: 21px;\n"
+        "}\n"
+        , -1, NULL);
+    gtk_style_context_add_provider_for_screen(screen,
+        GTK_STYLE_PROVIDER(provider),
+        GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
 }
 
 static void
@@ -190,6 +204,8 @@
     gtk_widget_class_bind_template_child_private(GTK_WIDGET_CLASS (klass), CurrentCallView, button_chat_input);
     gtk_widget_class_bind_template_child_private(GTK_WIDGET_CLASS (klass), CurrentCallView, entry_chat_input);
     gtk_widget_class_bind_template_child_private(GTK_WIDGET_CLASS (klass), CurrentCallView, scrolledwindow_chat);
+    gtk_widget_class_bind_template_child_private(GTK_WIDGET_CLASS (klass), CurrentCallView, buttonbox_call_controls);
+    gtk_widget_class_bind_template_child_private(GTK_WIDGET_CLASS (klass), CurrentCallView, button_hangup);
 }
 
 GtkWidget *