[gnome-software: 5/29] gs-shell: Refactor mode change code to be event-based

[Philip Withnall <pwithnall src gnome org>]

commit ab853e3d709813c72533566e45df8232858dd53f
Author: Philip Withnall <pwithnall endlessos org>
Date:   Wed Jan 20 23:16:58 2021 +0000

    gs-shell: Refactor mode change code to be event-based
    
    Rather than making a load of changes to the shell widget state when
    `gs_shell_change_mode()` is called, instead make the changes when the
    shell’s stack changes page. `gs_shell_change_mode()` changes the page of
    the stack, so this is equivalent to before.
    
    This will allow (after further refactoring) for the shell’s stack to
    have its page changed through other sources (by binding the
    `visible-child-name` property to other controller widgets, for example)
    and still have the UI work.
    
    Signed-off-by: Philip Withnall <pwithnall endlessos org>

 src/gs-shell.c | 95 +++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 64 insertions(+), 31 deletions(-)
---
diff --git a/src/gs-shell.c b/src/gs-shell.c
index 083630b18..d7616d44b 100644
--- a/src/gs-shell.c
+++ b/src/gs-shell.c
@@ -73,6 +73,7 @@ typedef struct
        gulong                   search_changed_id;
        gchar                   *events_info_uri;
        gboolean                 in_mode_change;
+       GtkStack                *stack_main;
        GsPage                  *page;
 
 #ifdef HAVE_MOGWAI
@@ -411,20 +412,27 @@ gs_shell_clean_back_entry_stack (GsShell *shell)
        }
 }
 
-void
-gs_shell_change_mode (GsShell *shell,
-                     GsShellMode mode,
-                     gpointer data,
-                     gboolean scroll_up)
+static void
+stack_notify_visible_child_cb (GObject    *object,
+                               GParamSpec *pspec,
+                               gpointer    user_data)
 {
+       GsShell *shell = GS_SHELL (user_data);
        GsShellPrivate *priv = gs_shell_get_instance_private (shell);
-       GsApp *app;
        GsPage *page;
        GtkWidget *widget;
        GtkStyleContext *context;
+       GsShellMode mode;
+       gsize i;
 
-       if (priv->ignore_primary_buttons)
-               return;
+       /* Work out the mode for this child. */
+       for (i = 0; i < G_N_ELEMENTS (page_name); i++) {
+               if (g_strcmp0 (page_name[i], gtk_stack_get_visible_child_name (priv->stack_main)) == 0) {
+                       mode = i;
+                       break;
+               }
+       }
+       g_assert (i < G_N_ELEMENTS (page_name));
 
        widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "header"));
        gtk_header_bar_set_show_close_button (GTK_HEADER_BAR (widget), TRUE);
@@ -475,10 +483,6 @@ gs_shell_change_mode (GsShell *shell,
 
        priv->ignore_primary_buttons = FALSE;
 
-       /* switch page */
-       widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "stack_main"));
-       gtk_stack_set_visible_child_name (GTK_STACK (widget), page_name[mode]);
-
        /* do action for mode */
        priv->mode = mode;
        switch (mode) {
@@ -498,32 +502,16 @@ gs_shell_change_mode (GsShell *shell,
                break;
        case GS_SHELL_MODE_SEARCH:
                page = GS_PAGE (g_hash_table_lookup (priv->pages, "search"));
-               widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "entry_search"));
-               gs_search_page_set_text (GS_SEARCH_PAGE (page), data);
-               gtk_entry_set_text (GTK_ENTRY (widget), data);
-               gtk_editable_set_position (GTK_EDITABLE (widget), -1);
                break;
        case GS_SHELL_MODE_UPDATES:
                gs_shell_clean_back_entry_stack (shell);
                page = GS_PAGE (g_hash_table_lookup (priv->pages, "updates"));
                break;
        case GS_SHELL_MODE_DETAILS:
-               app = GS_APP (data);
                page = GS_PAGE (g_hash_table_lookup (priv->pages, "details"));
-               if (gs_app_get_local_file (app) != NULL) {
-                       gs_details_page_set_local_file (GS_DETAILS_PAGE (page),
-                                                       gs_app_get_local_file (app));
-               } else if (gs_app_get_metadata_item (app, "GnomeSoftware::from-url") != NULL) {
-                       gs_details_page_set_url (GS_DETAILS_PAGE (page),
-                                                gs_app_get_metadata_item (app, "GnomeSoftware::from-url"));
-               } else {
-                       gs_details_page_set_app (GS_DETAILS_PAGE (page), data);
-               }
                break;
        case GS_SHELL_MODE_CATEGORY:
                page = GS_PAGE (g_hash_table_lookup (priv->pages, "category"));
-               gs_category_page_set_category (GS_CATEGORY_PAGE (page),
-                                              GS_CATEGORY (data));
                break;
        case GS_SHELL_MODE_EXTRAS:
                page = GS_PAGE (g_hash_table_lookup (priv->pages, "extras"));
@@ -544,8 +532,6 @@ gs_shell_change_mode (GsShell *shell,
                gs_page_switch_from (priv->page);
        g_set_object (&priv->page, page);
        gs_page_switch_to (page);
-       if (scroll_up)
-               gs_page_scroll_up (page);
        priv->in_mode_change = FALSE;
 
        /* update header bar widgets */
@@ -567,7 +553,6 @@ gs_shell_change_mode (GsShell *shell,
 
        /* destroy any existing modals */
        if (priv->modal_dialogs != NULL) {
-               gsize i = 0;
                /* block signal emission of 'unmapped' since that will
                 * call g_ptr_array_remove_index. The unmapped signal may
                 * be emitted whilst running unref handlers for
@@ -582,6 +567,51 @@ gs_shell_change_mode (GsShell *shell,
        }
 }
 
+void
+gs_shell_change_mode (GsShell *shell,
+                     GsShellMode mode,
+                     gpointer data,
+                     gboolean scroll_up)
+{
+       GsShellPrivate *priv = gs_shell_get_instance_private (shell);
+       GsApp *app;
+       GsPage *page;
+       GtkWidget *widget;
+
+       if (priv->ignore_primary_buttons)
+               return;
+
+       /* switch page */
+       gtk_stack_set_visible_child_name (GTK_STACK (priv->stack_main), page_name[mode]);
+
+       /* do any mode-specific actions */
+       page = GS_PAGE (g_hash_table_lookup (priv->pages, page_name[mode]));
+
+       if (mode == GS_SHELL_MODE_SEARCH) {
+               widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "entry_search"));
+               gs_search_page_set_text (GS_SEARCH_PAGE (page), data);
+               gtk_entry_set_text (GTK_ENTRY (widget), data);
+               gtk_editable_set_position (GTK_EDITABLE (widget), -1);
+       } else if (mode == GS_SHELL_MODE_DETAILS) {
+               app = GS_APP (data);
+               if (gs_app_get_local_file (app) != NULL) {
+                       gs_details_page_set_local_file (GS_DETAILS_PAGE (page),
+                                                       gs_app_get_local_file (app));
+               } else if (gs_app_get_metadata_item (app, "GnomeSoftware::from-url") != NULL) {
+                       gs_details_page_set_url (GS_DETAILS_PAGE (page),
+                                                gs_app_get_metadata_item (app, "GnomeSoftware::from-url"));
+               } else {
+                       gs_details_page_set_app (GS_DETAILS_PAGE (page), data);
+               }
+       } else if (mode == GS_SHELL_MODE_CATEGORY) {
+               gs_category_page_set_category (GS_CATEGORY_PAGE (page),
+                                              GS_CATEGORY (data));
+       }
+
+       if (scroll_up)
+               gs_page_scroll_up (page);
+}
+
 static void
 gs_overview_page_button_cb (GtkWidget *widget, GsShell *shell)
 {
@@ -2217,6 +2247,9 @@ gs_shell_setup (GsShell *shell, GsPluginLoader *plugin_loader, GCancellable *can
        g_signal_connect_after (priv->main_window, "button_press_event",
                                G_CALLBACK (window_button_press_event), shell);
 
+       priv->stack_main = GTK_STACK (gtk_builder_get_object (priv->builder, "stack_main"));
+       g_signal_connect (priv->stack_main, "notify::visible-child", G_CALLBACK 
(stack_notify_visible_child_cb), shell);
+
        /* show the search bar when clicking on the search button */
        widget = GTK_WIDGET (gtk_builder_get_object (priv->builder, "search_button"));
        g_signal_connect (widget, "clicked",