[gnome-software/wip/installed_updates: 8/10] update dialog: Use a more generic way for storing back button state

[Kalev Lember <klember src gnome org>]

commit 789895f59a831cc38a4aecdda1451f564082ce18
Author: Kalev Lember <kalevlember gmail com>
Date:   Tue Apr 29 21:41:17 2014 +0200

    update dialog: Use a more generic way for storing back button state
    
    Currently, the dialog only has two possible states and the back button can only
    ever go back to the first one. This makes the back button handling very simple.
    However, if we want to add more states in the future, we'll also need a more
    sophisticated back button handling.
    
    This commit adds a GQueue based stack for keeping track of the previous state.

 src/gs-update-dialog.c |   55 +++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 47 insertions(+), 8 deletions(-)
---
diff --git a/src/gs-update-dialog.c b/src/gs-update-dialog.c
index 598745c..93c2878 100644
--- a/src/gs-update-dialog.c
+++ b/src/gs-update-dialog.c
@@ -28,8 +28,14 @@
 #include "gs-markdown.h"
 #include "gs-utils.h"
 
+typedef struct {
+       gchar           *title;
+       gchar           *stack_page;
+} BackEntry;
+
 struct _GsUpdateDialogPrivate
 {
+       GQueue          *back_entry_stack;
        GsApp           *app;
        GtkWidget       *box_header;
        GtkWidget       *button_back;
@@ -46,6 +52,27 @@ struct _GsUpdateDialogPrivate
 G_DEFINE_TYPE_WITH_PRIVATE (GsUpdateDialog, gs_update_dialog, GTK_TYPE_DIALOG)
 
 static void
+save_back_entry (GsUpdateDialog *dialog)
+{
+       GsUpdateDialogPrivate *priv = gs_update_dialog_get_instance_private (dialog);
+       BackEntry *entry;
+
+       entry = g_slice_new0 (BackEntry);
+       entry->stack_page = g_strdup (gtk_stack_get_visible_child_name (GTK_STACK (priv->stack)));
+       entry->title = g_strdup (gtk_window_get_title (GTK_WINDOW (dialog)));
+
+       g_queue_push_head (priv->back_entry_stack, entry);
+}
+
+static void
+back_entry_free (BackEntry *entry)
+{
+       g_free (entry->stack_page);
+       g_free (entry->title);
+       g_slice_free (BackEntry, entry);
+}
+
+static void
 set_updates_description_ui (GsUpdateDialog *dialog, GsApp *app)
 {
        GsUpdateDialogPrivate *priv = gs_update_dialog_get_instance_private (dialog);
@@ -86,6 +113,9 @@ set_updates_description_ui (GsUpdateDialog *dialog, GsApp *app)
        gtk_label_set_label (GTK_LABEL (priv->label_name), gs_app_get_name (app));
        gtk_label_set_label (GTK_LABEL (priv->label_summary), gs_app_get_summary (app));
        g_free (update_desc);
+
+       /* show the back button if needed */
+       gtk_widget_set_visible (priv->button_back, !g_queue_is_empty (priv->back_entry_stack));
 }
 
 static void
@@ -97,10 +127,13 @@ row_activated_cb (GtkListBox *list_box,
        GsApp *app = NULL;
 
        app = GS_APP (g_object_get_data (G_OBJECT (gtk_bin_get_child (GTK_BIN (row))), "app"));
+
+       /* save the current stack state for the back button */
+       save_back_entry (dialog);
+
        /* setup package view */
        gtk_stack_set_visible_child_name (GTK_STACK (priv->stack), "package-details");
        set_updates_description_ui (dialog, app);
-       gtk_widget_show (priv->button_back);
 }
 
 void
@@ -119,9 +152,6 @@ gs_update_dialog_set_app (GsUpdateDialog *dialog, GsApp *app)
        /* set update header */
        set_updates_description_ui (dialog, app);
 
-       /* only OS updates can go back, and only on selection */
-       gtk_widget_hide (priv->button_back);
-
        /* set update description */
        if (kind == GS_APP_KIND_OS_UPDATE) {
                GPtrArray *related;
@@ -201,12 +231,15 @@ static void
 button_back_cb (GtkWidget *widget, GsUpdateDialog *dialog)
 {
        GsUpdateDialogPrivate *priv = gs_update_dialog_get_instance_private (dialog);
+       BackEntry *entry;
 
-       /* return to the list view */
-       gtk_widget_hide (priv->button_back);
-       gtk_stack_set_visible_child_name (GTK_STACK (priv->stack), "os-updates-list");
+       /* return to the previous view */
+       entry = g_queue_pop_head (priv->back_entry_stack);
+       gtk_stack_set_visible_child_name (GTK_STACK (priv->stack), entry->stack_page);
+       gtk_window_set_title (GTK_WINDOW (dialog), entry->title);
+       back_entry_free (entry);
 
-       gtk_window_set_title (GTK_WINDOW (dialog), gs_app_get_name (priv->app));
+       gtk_widget_set_visible (priv->button_back, !g_queue_is_empty (priv->back_entry_stack));
 }
 
 static void
@@ -233,6 +266,10 @@ gs_update_dialog_finalize (GObject *object)
        GsUpdateDialog *dialog = GS_UPDATE_DIALOG (object);
        GsUpdateDialogPrivate *priv = gs_update_dialog_get_instance_private (dialog);
 
+       if (priv->back_entry_stack != NULL) {
+               g_queue_free_full (priv->back_entry_stack, (GDestroyNotify) back_entry_free);
+               priv->back_entry_stack = NULL;
+       }
        g_clear_object (&priv->app);
 
        G_OBJECT_CLASS (gs_update_dialog_parent_class)->finalize (object);
@@ -246,6 +283,8 @@ gs_update_dialog_init (GsUpdateDialog *dialog)
 
        gtk_widget_init_template (GTK_WIDGET (dialog));
 
+       priv->back_entry_stack = g_queue_new ();
+
        g_signal_connect (GTK_LIST_BOX (priv->list_box), "row-activated",
                          G_CALLBACK (row_activated_cb), dialog);
        gtk_list_box_set_header_func (GTK_LIST_BOX (priv->list_box),