linkbutton: Use GtkFileLauncher for file URI

The GtkUriLauncher calls into the openuri portal, which distinguishes
between files, directories, and URI. The GtkFileLauncher contains logic
to deal with this, because it can already handle the file and folder
differences.

If we have a file:// URI it's easier to create a GFile out of it, and
use the GtkFileLauncher API, while leaving the GtkUriLauncher API for
every other URI scheme.

Fixes: #5671

gtk/gtklinkbutton.c

@@ -57,9 +57,9 @@
 #include "gtklinkbutton.h"
 
 #include "gtkdragsource.h"
+#include "gtkfilelauncher.h"
 #include "gtkgestureclick.h"
 #include "gtkgesturesingle.h"
-#include <glib/gi18n-lib.h>
 #include "gtklabel.h"
 #include "gtkmain.h"
 #include "gtkmarshalers.h"
@@ -71,6 +71,7 @@
 #include "gtkwidgetprivate.h"
 
 #include <string.h>
+#include <glib/gi18n-lib.h>
 
 typedef struct _GtkLinkButtonClass GtkLinkButtonClass;
 
@@ -230,7 +231,7 @@ gtk_link_button_class_init (GtkLinkButtonClass *klass)
   /**
    * GtkLinkButton|menu.popup:
    *
-   * Opens the context menu. 
+   * Opens the context menu.
    */
   gtk_widget_class_install_action (widget_class, "menu.popup", NULL, gtk_link_button_popup_menu);
 
@@ -303,7 +304,7 @@ gtk_link_content_get_value (GdkContentProvider  *provider,
       content->link != NULL)
     {
       char *uri;
-  
+
       uri = g_strdup_printf ("%s\r\n", content->link->uri);
       g_value_set_string (value, uri);
       g_free (uri);
@@ -381,7 +382,7 @@ gtk_link_button_get_property (GObject    *object,
 			      GParamSpec *pspec)
 {
   GtkLinkButton *link_button = GTK_LINK_BUTTON (object);
-  
+
   switch (prop_id)
     {
     case PROP_URI:
@@ -403,7 +404,7 @@ gtk_link_button_set_property (GObject      *object,
 			      GParamSpec   *pspec)
 {
   GtkLinkButton *link_button = GTK_LINK_BUTTON (object);
-  
+
   switch (prop_id)
     {
     case PROP_URI:
@@ -479,13 +480,31 @@ static gboolean
 gtk_link_button_activate_link (GtkLinkButton *link_button)
 {
   GtkWidget *toplevel;
-  GtkUriLauncher *launcher;
+  const char *uri_scheme;
 
   toplevel = GTK_WIDGET (gtk_widget_get_root (GTK_WIDGET (link_button)));
 
-  launcher = gtk_uri_launcher_new (link_button->uri);
-  gtk_uri_launcher_launch (launcher, GTK_WINDOW (toplevel), NULL, NULL, NULL);
-  g_object_unref (launcher);
+  uri_scheme = g_uri_peek_scheme (link_button->uri);
+  if (g_strcmp0 (uri_scheme, "file") == 0)
+    {
+      GFile *file = g_file_new_for_uri (link_button->uri);
+      GtkFileLauncher *launcher;
+
+      launcher = gtk_file_launcher_new (file);
+
+      gtk_file_launcher_launch (launcher, GTK_WINDOW (toplevel), NULL, NULL, NULL);
+
+      g_object_unref (launcher);
+      g_object_unref (file);
+    }
+  else
+    {
+      GtkUriLauncher *launcher = gtk_uri_launcher_new (link_button->uri);
+
+      gtk_uri_launcher_launch (launcher, GTK_WINDOW (toplevel), NULL, NULL, NULL);
+
+      g_object_unref (launcher);
+    }
 
   gtk_link_button_set_visited (link_button, TRUE);
 
@@ -521,9 +540,9 @@ gtk_link_button_new (const char *uri)
 {
   char *utf8_uri = NULL;
   GtkWidget *retval;
-  
+
   g_return_val_if_fail (uri != NULL, NULL);
-  
+
   if (g_utf8_validate (uri, -1, NULL))
     {
       utf8_uri = g_strdup (uri);
@@ -531,7 +550,7 @@ gtk_link_button_new (const char *uri)
   else
     {
       GError *conv_err = NULL;
-    
+
       utf8_uri = g_locale_to_utf8 (uri, -1, NULL, NULL, &conv_err);
       if (conv_err)
         {
@@ -540,18 +559,18 @@ gtk_link_button_new (const char *uri)
                      uri,
                      conv_err->message);
           g_error_free (conv_err);
-        
+
           utf8_uri = g_strdup (_("Invalid URI"));
         }
     }
-  
+
   retval = g_object_new (GTK_TYPE_LINK_BUTTON,
   			 "label", utf8_uri,
   			 "uri", uri,
   			 NULL);
-  
+
   g_free (utf8_uri);
-  
+
   return retval;
 }
 
@@ -569,9 +588,9 @@ gtk_link_button_new_with_label (const char *uri,
 				const char *label)
 {
   GtkWidget *retval;
-  
+
   g_return_val_if_fail (uri != NULL, NULL);
-  
+
   if (!label)
     return gtk_link_button_new (uri);
 
@@ -583,7 +602,7 @@ gtk_link_button_new_with_label (const char *uri,
   return retval;
 }
 
-static gboolean 
+static gboolean
 gtk_link_button_query_tooltip_cb (GtkWidget    *widget,
                                   int           x,
                                   int           y,