Make image credits discoverable

This adds a fourth topbar button, to the left of the minimize button,
that is invisible by default. When you mouse over the space where it
would be, it appears. When you click on it, it activates the image
credits dialog.

[endlessm/eos-sdk#2934]

4 files changed, 234 insertions, 5 deletions

diff --git a/endless/eosapplication.c b/endless/eosapplication.c
index 91dbd73..510ff3b 100644
--- a/endless/eosapplication.c
+++ b/endless/eosapplication.c
@@ -612,6 +612,16 @@ eos_application_class_init (EosApplicationClass *klass)
 }
 
 static void
+set_image_credits_action_enabled (EosApplication *self,
+                                  gboolean        enabled)
+{
+  GAction *action = g_action_map_lookup_action (G_ACTION_MAP (self),
+                                                "image-credits");
+  g_simple_action_set_enabled (G_SIMPLE_ACTION (action), enabled);
+  /* action map owns action */
+}
+
+static void
 eos_application_init (EosApplication *self)
 {
   EosApplicationPrivate *priv = eos_application_get_instance_private (self);
@@ -623,6 +633,7 @@ eos_application_init (EosApplication *self)
   };
   g_action_map_add_action_entries (G_ACTION_MAP (self), actions,
                                    G_N_ELEMENTS (actions), self);
+  set_image_credits_action_enabled (self, FALSE);
 
   g_signal_connect (self, "notify::application-id",
                     G_CALLBACK (on_app_id_set), self);
@@ -734,11 +745,8 @@ eos_application_set_image_attribution_file (EosApplication *self,
 
   if (priv->image_attribution_file == NULL || file == NULL)
     {
-      GAction *action = g_action_map_lookup_action (G_ACTION_MAP (self),
-                                                    "image-credits");
-      gboolean enabled = (file == NULL);
-      g_simple_action_set_enabled (G_SIMPLE_ACTION (self), enabled);
-      /* action map owns action */
+      gboolean enabled = (file != NULL);
+      set_image_credits_action_enabled (self, enabled);
     }
 
   g_clear_object (&priv->image_attribution_file);
diff --git a/endless/eostopbar-private.h b/endless/eostopbar-private.h
index 3d0f4a7..aa6e44b 100644
--- a/endless/eostopbar-private.h
+++ b/endless/eostopbar-private.h
@@ -57,6 +57,11 @@ void       eos_top_bar_set_center_widget       (EosTopBar *self,
 void       eos_top_bar_update_window_maximized (EosTopBar *self,
                                                 gboolean   is_maximized);
 
+gboolean   eos_top_bar_get_show_credits_button (EosTopBar *self);
+
+void       eos_top_bar_set_show_credits_button (EosTopBar *self,
+                                                gboolean   show_credits_button);
+
 G_END_DECLS
 
 #endif /* EOS_TOP_BAR_H */
diff --git a/endless/eostopbar.c b/endless/eostopbar.c
index 9d7f276..3c1596d 100644
--- a/endless/eostopbar.c
+++ b/endless/eostopbar.c
@@ -29,6 +29,7 @@
 #define _EOS_TOP_BAR_MAXIMIZE_ICON_NAME "window-maximize-symbolic"
 #define _EOS_TOP_BAR_UNMAXIMIZE_ICON_NAME "window-unmaximize-symbolic"
 #define _EOS_TOP_BAR_CLOSE_ICON_NAME "window-close-symbolic"
+#define _EOS_TOP_BAR_CREDITS_ICON_NAME "user-info-symbolic"
 
 typedef struct {
   GtkWidget *actions_grid;
@@ -44,6 +45,13 @@ typedef struct {
   GtkWidget *maximize_icon;
   GtkWidget *close_button;
   GtkWidget *close_icon;
+  GtkWidget *credits_button;
+  GtkWidget *credits_icon;
+  GtkWidget *credits_stack;
+
+  gboolean show_credits_button;
+  guint credits_enter_handler;
+  guint credits_leave_handler;
 } EosTopBarPrivate;
 
 G_DEFINE_TYPE_WITH_PRIVATE (EosTopBar, eos_top_bar, GTK_TYPE_EVENT_BOX)
@@ -52,11 +60,58 @@ enum {
   CLOSE_CLICKED,
   MINIMIZE_CLICKED,
   MAXIMIZE_CLICKED,
+  CREDITS_CLICKED,
   LAST_SIGNAL
 };
 
 static guint top_bar_signals[LAST_SIGNAL] = { 0 };
 
+enum {
+  PROP_0,
+  PROP_SHOW_CREDITS_BUTTON,
+  NPROPS
+};
+
+static GParamSpec *eos_top_bar_props[NPROPS] = { NULL, };
+
+static void
+eos_top_bar_get_property (GObject    *object,
+                          guint       property_id,
+                          GValue     *value,
+                          GParamSpec *pspec)
+{
+  EosTopBar *self = EOS_TOP_BAR (object);
+
+  switch (property_id)
+    {
+    case PROP_SHOW_CREDITS_BUTTON:
+      g_value_set_boolean (value, eos_top_bar_get_show_credits_button (self));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
+static void
+eos_top_bar_set_property (GObject      *object,
+                          guint         property_id,
+                          const GValue *value,
+                          GParamSpec   *pspec)
+{
+  EosTopBar *self = EOS_TOP_BAR (object);
+
+  switch (property_id)
+    {
+    case PROP_SHOW_CREDITS_BUTTON:
+      eos_top_bar_set_show_credits_button (self, g_value_get_boolean (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+    }
+}
+
 static void
 eos_top_bar_get_preferred_height (GtkWidget *widget,
                                   int *minimum,
@@ -98,6 +153,8 @@ eos_top_bar_class_init (EosTopBarClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
+  object_class->get_property = eos_top_bar_get_property;
+  object_class->set_property = eos_top_bar_set_property;
   widget_class->get_preferred_height = eos_top_bar_get_preferred_height;
   widget_class->draw = eos_top_bar_draw;
 
@@ -133,6 +190,19 @@ eos_top_bar_class_init (EosTopBarClass *klass)
                     0,
                     NULL, NULL, NULL,
                     G_TYPE_NONE, 0);
+
+  top_bar_signals[CREDITS_CLICKED] =
+    g_signal_new ("credits-clicked", G_OBJECT_CLASS_TYPE (object_class),
+                  G_SIGNAL_RUN_FIRST | G_SIGNAL_ACTION, 0, NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+
+  eos_top_bar_props[PROP_SHOW_CREDITS_BUTTON] =
+    g_param_spec_boolean ("show-credits-button", "Show credits button",
+                         "Whether the credits button is discoverable",
+                         FALSE,
+                         G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, NPROPS, eos_top_bar_props);
 }
 
 static void
@@ -159,6 +229,23 @@ on_close_clicked_cb (GtkButton *button,
   g_signal_emit (self, top_bar_signals[CLOSE_CLICKED], 0);
 }
 
+static gboolean
+on_stack_hover (GtkStack *stack,
+                GdkEvent *event,
+                gpointer  data)
+{
+  gboolean show = GPOINTER_TO_INT (data);
+  gtk_stack_set_visible_child_name (stack, show ? "button" : "blank");
+  return GDK_EVENT_PROPAGATE;
+}
+
+static void
+on_credits_clicked (GtkButton *button,
+                    EosTopBar *self)
+{
+  g_signal_emit (self, top_bar_signals[CREDITS_CLICKED], 0);
+}
+
 static void
 eos_top_bar_init (EosTopBar *self)
 {
@@ -236,10 +323,36 @@ eos_top_bar_init (EosTopBar *self)
   gtk_container_add (GTK_CONTAINER (priv->close_button),
                      priv->close_icon);
 
+  /* This works like a revealer but it's really a GtkStack so that it takes up
+  space and presents a target even when it's not shown. */
+  priv->credits_stack = gtk_stack_new ();
+  gtk_stack_set_transition_type (GTK_STACK (priv->credits_stack),
+                                 GTK_STACK_TRANSITION_TYPE_CROSSFADE);
+  gtk_widget_add_events (priv->credits_stack,
+                         GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
+  gtk_stack_add_named (GTK_STACK (priv->credits_stack),
+                       gtk_event_box_new (), "blank");
+  priv->credits_button = g_object_new (GTK_TYPE_BUTTON,
+                                       "can-focus", FALSE,
+                                       "halign", GTK_ALIGN_END,
+                                       "valign", GTK_ALIGN_CENTER,
+                                       NULL);
+  priv->credits_icon =
+    gtk_image_new_from_icon_name (_EOS_TOP_BAR_CREDITS_ICON_NAME,
+                                  GTK_ICON_SIZE_SMALL_TOOLBAR);
+  g_object_set (priv->credits_icon,
+                "pixel-size", _EOS_TOP_BAR_ICON_SIZE_PX,
+                "margin", _EOS_TOP_BAR_BUTTON_PADDING_PX,
+                NULL);
+  gtk_container_add (GTK_CONTAINER (priv->credits_button), priv->credits_icon);
+  gtk_stack_add_named (GTK_STACK (priv->credits_stack),
+                       priv->credits_button, "button");
+
   gtk_container_add (GTK_CONTAINER (priv->actions_grid),
                      priv->left_top_bar_attach);
   gtk_container_add (GTK_CONTAINER (priv->actions_grid),
                      priv->center_top_bar_attach);
+  gtk_container_add (GTK_CONTAINER (priv->actions_grid), priv->credits_stack);
   gtk_container_add (GTK_CONTAINER (priv->actions_grid),
                      priv->minimize_button);
   gtk_container_add (GTK_CONTAINER (priv->actions_grid),
@@ -258,6 +371,16 @@ eos_top_bar_init (EosTopBar *self)
                     G_CALLBACK (on_maximize_clicked_cb), self);
   g_signal_connect (priv->close_button, "clicked",
                     G_CALLBACK (on_close_clicked_cb), self);
+  priv->credits_enter_handler =
+    g_signal_connect (priv->credits_stack, "enter-notify-event",
+                      G_CALLBACK (on_stack_hover), GINT_TO_POINTER (TRUE));
+  priv->credits_leave_handler =
+    g_signal_connect (priv->credits_stack, "leave-notify-event",
+                      G_CALLBACK (on_stack_hover), GINT_TO_POINTER (FALSE));
+  g_signal_handler_block (priv->credits_stack, priv->credits_enter_handler);
+  g_signal_handler_block (priv->credits_stack, priv->credits_leave_handler);
+  g_signal_connect (priv->credits_button, "clicked",
+                    G_CALLBACK (on_credits_clicked), self);
 }
 
 GtkWidget *
@@ -355,3 +478,55 @@ eos_top_bar_update_window_maximized (EosTopBar *self,
   else
     gtk_style_context_remove_class (context, _EOS_STYLE_CLASS_UNMAXIMIZED);
 }
+
+/*
+ * eos_top_bar_get_show_credits_button:
+ * @self: the top bar
+ *
+ * See eos_top_bar_set_show_credits_button().
+ *
+ * Returns: %TRUE if credits button should be discoverable, %FALSE if not.
+ */
+gboolean
+eos_top_bar_get_show_credits_button (EosTopBar *self)
+{
+  EosTopBarPrivate *priv = eos_top_bar_get_instance_private (self);
+  return priv->show_credits_button;
+}
+
+/*
+ * eos_top_bar_set_show_credits_button:
+ * @self: the top bar
+ * @show_credits_button: whether the credits button should be discoverable.
+ *
+ * Gets whether the credits button should be discoverable.
+ * Note that the credits button is not visible as such, but when the mouse
+ * hovers over it, it becomes visible if this is set to %TRUE.
+ * If this is %FALSE, the button never becomes visible.
+ */
+void
+eos_top_bar_set_show_credits_button (EosTopBar *self,
+                                     gboolean   show_credits_button)
+{
+  EosTopBarPrivate *priv = eos_top_bar_get_instance_private (self);
+  if (priv->show_credits_button == show_credits_button)
+    return;
+
+  priv->show_credits_button = show_credits_button;
+  if (show_credits_button)
+    {
+      g_signal_handler_unblock (priv->credits_stack,
+                                priv->credits_enter_handler);
+      g_signal_handler_unblock (priv->credits_stack,
+                                priv->credits_leave_handler);
+    }
+  else
+    {
+      gtk_stack_set_visible_child_name (GTK_STACK (priv->credits_stack),
+                                        "blank");
+      g_signal_handler_block (priv->credits_stack, priv->credits_enter_handler);
+      g_signal_handler_block (priv->credits_stack, priv->credits_leave_handler);
+    }
+  g_object_notify_by_pspec (G_OBJECT (self),
+                            eos_top_bar_props[PROP_SHOW_CREDITS_BUTTON]);
+}
diff --git a/endless/eoswindow.c b/endless/eoswindow.c
index 0b39ffb..d128a5e 100644
--- a/endless/eoswindow.c
+++ b/endless/eoswindow.c
@@ -342,6 +342,34 @@ update_page (EosWindow *self)
 }
 
 static void
+on_image_credits_enabled_changed (GActionGroup *group,
+                                  const gchar  *action_name,
+                                  gboolean      enabled,
+                                  EosWindow    *self)
+{
+  EosWindowPrivate *priv = eos_window_get_instance_private (self);
+  eos_top_bar_set_show_credits_button (EOS_TOP_BAR (priv->top_bar), enabled);
+}
+
+static void
+eos_window_constructed (GObject *object)
+{
+  EosWindow *self = EOS_WINDOW (object);
+  EosWindowPrivate *priv = eos_window_get_instance_private (self);
+
+  G_OBJECT_CLASS (eos_window_parent_class)->constructed (object);
+
+  GtkApplication *application =
+    gtk_window_get_application (GTK_WINDOW (object));
+  GFile *credits_file =
+    eos_application_get_image_attribution_file (EOS_APPLICATION (application));
+  eos_top_bar_set_show_credits_button (EOS_TOP_BAR (priv->top_bar),
+                                       (credits_file != NULL));
+  g_signal_connect (application, "action-enabled-changed::image-credits",
+                    G_CALLBACK (on_image_credits_enabled_changed), self);
+}
+
+static void
 eos_window_get_property (GObject    *object,
                          guint       property_id,
                          GValue     *value,
@@ -510,6 +538,7 @@ eos_window_class_init (EosWindowClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
+  object_class->constructed = eos_window_constructed;
   object_class->get_property = eos_window_get_property;
   object_class->set_property = eos_window_set_property;
   object_class->finalize = eos_window_finalize;
@@ -631,6 +660,16 @@ on_close_clicked_cb (GtkWidget *top_bar,
   gtk_window_close (GTK_WINDOW (self));
 }
 
+static void
+on_credits_clicked (GtkWidget *top_bar,
+                    EosWindow *self)
+{
+  GtkApplication *application = gtk_window_get_application (GTK_WINDOW (self));
+  /* application cannot be NULL */
+  g_action_group_activate_action (G_ACTION_GROUP (application), "image-credits",
+                                  NULL);
+}
+
 static gboolean
 on_window_state_event_cb (GtkWidget           *widget,
                           GdkEventWindowState *event)
@@ -748,6 +787,8 @@ eos_window_init (EosWindow *self)
                     G_CALLBACK (on_maximize_clicked_cb), self);
   g_signal_connect (priv->top_bar, "close-clicked",
                     G_CALLBACK (on_close_clicked_cb), self);
+  g_signal_connect (priv->top_bar, "credits-clicked",
+                    G_CALLBACK (on_credits_clicked), self);
   g_signal_connect (self, "window-state-event",
                     G_CALLBACK (on_window_state_event_cb), NULL);