[nautilus/wip/antoniof/new-list-view: 13/19] view-icon-controller: Select single item on specific cases

[António Fernandes <antoniof src gnome org>]

commit d6c3368dafbf03a3fb6e0a53ed2302ea577359e9
Author: António Fernandes <antoniof gnome org>
Date:   Sun May 22 17:52:33 2022 +0100

    view-icon-controller: Select single item on specific cases
    
    We've been changing the selection to the clicked item (if unselected) in
    all cases except when SHIFT or CTRL are pressed, because the default
    GtkGridView behavior does it only for primary click and only after
    release.
    
    But this causes duplicate selection events in some cases, interferes
    with drag-and-drop (work in progress in another branch) and misses some
    corner cases (e.g. middle click while holding CTRL).
    
    Instead, factor out that block into a helper function to be called in
    the specific situations where we need it:
    
        - before activating with middle click;
        - before opening context menu;
        - before activating with single click.
    
    Double-click doesn't need it because the item is selected by the release
    handler of the first click.
    
    Single-click activation enforces single-item selection for consistency
    with double-click activation. Multi-item activation still possible with
    middle click, accelerators and context menu.

 src/nautilus-view-icon-controller.c | 57 +++++++++++++++++++++++--------------
 1 file changed, 36 insertions(+), 21 deletions(-)
---
diff --git a/src/nautilus-view-icon-controller.c b/src/nautilus-view-icon-controller.c
index eae7584cf..20aba99d0 100644
--- a/src/nautilus-view-icon-controller.c
+++ b/src/nautilus-view-icon-controller.c
@@ -760,6 +760,24 @@ real_click_policy_changed (NautilusFilesView *files_view)
     set_click_mode_from_settings (self);
 }
 
+/* GtkListBase changes selection only with the primary button, and only after
+ * release. But we need to antecipate selection earlier if we are to activate it
+ * or open its context menu. This helper should be used in these situations if
+ * it's desirable to act on a multi-item selection, because it preserves it. */
+static void
+select_single_item_if_not_selected (NautilusViewIconController *self,
+                                    NautilusViewItemModel      *item)
+{
+    GtkSelectionModel *selection_model = GTK_SELECTION_MODEL (self->model);
+    guint position;
+
+    position = nautilus_view_model_get_index (self->model, item);
+    if (!gtk_selection_model_is_selected (selection_model, position))
+    {
+        gtk_selection_model_select_item (selection_model, position, TRUE);
+    }
+}
+
 static void
 activate_selection_on_click (NautilusViewIconController *self,
                              gboolean                    open_in_new_tab)
@@ -786,6 +804,7 @@ on_item_click_pressed (GtkGestureClick *gesture,
 {
     NautilusViewIconController *self;
     GtkWidget *event_widget;
+    NautilusViewItemModel *item_model;
     guint button;
     GdkModifierType modifiers;
     gboolean selection_mode;
@@ -794,6 +813,7 @@ on_item_click_pressed (GtkGestureClick *gesture,
 
     self = NAUTILUS_VIEW_ICON_CONTROLLER (user_data);
     event_widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (gesture));
+    item_model = nautilus_view_icon_item_ui_get_model (NAUTILUS_VIEW_ICON_ITEM_UI (event_widget));
     button = gtk_gesture_single_get_current_button (GTK_GESTURE_SINGLE (gesture));
     modifiers = gtk_event_controller_get_current_event_state (GTK_EVENT_CONTROLLER (gesture));
 
@@ -809,27 +829,6 @@ on_item_click_pressed (GtkGestureClick *gesture,
                                  n_press == 1 &&
                                  !selection_mode);
 
-    /* GtkGridView changes selection only with the primary button, but we
-     * need that to happen with all buttons, otherwise e.g. opening context
-     * menus would require two clicks: a primary click to select the item,
-     * followed by a secondary click to open the menu.
-     * When holding Ctrl and Shift, GtkGridView does a good job, let's not
-     * interfere in that case. */
-    if (!selection_mode)
-    {
-        GtkSelectionModel *selection_model = GTK_SELECTION_MODEL (self->model);
-        NautilusViewItemModel *item_model;
-        guint position;
-
-        item_model = nautilus_view_icon_item_ui_get_model (NAUTILUS_VIEW_ICON_ITEM_UI (event_widget));
-        position = nautilus_view_model_get_index (self->model, item_model);
-
-        if (!gtk_selection_model_is_selected (selection_model, position))
-        {
-            gtk_selection_model_select_item (selection_model, position, TRUE);
-        }
-    }
-
     /* It's safe to claim event sequence on press in the following cases because
      * they don't interfere with touch scrolling. */
     if (button == GDK_BUTTON_PRIMARY && n_press == 2 && !self->single_click_mode)
@@ -840,11 +839,15 @@ on_item_click_pressed (GtkGestureClick *gesture,
     }
     else if (button == GDK_BUTTON_MIDDLE && n_press == 1)
     {
+        /* Antecipate selection, if necessary, to activate it. */
+        select_single_item_if_not_selected (self, item_model);
         activate_selection_on_click (self, TRUE);
         gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
     }
     else if (button == GDK_BUTTON_SECONDARY && n_press == 1)
     {
+        /* Antecipate selection, if necessary, for the context menu. */
+        select_single_item_if_not_selected (self, item_model);
         nautilus_files_view_pop_up_selection_context_menu (NAUTILUS_FILES_VIEW (self),
                                                            view_x, view_y);
         gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
@@ -862,9 +865,21 @@ on_item_click_released (GtkGestureClick *gesture,
 
     if (self->activate_on_release)
     {
+        GtkWidget *event_widget;
+        NautilusViewItemModel *item_model;
+        guint i;
+
+        event_widget = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (gesture));
+        item_model = nautilus_view_icon_item_ui_get_model (NAUTILUS_VIEW_ICON_ITEM_UI (event_widget));
+        i = nautilus_view_model_get_index (self->model, item_model);
+
+        /* Antecipate selection, enforcing single selection of target item. */
+        gtk_selection_model_select_item (GTK_SELECTION_MODEL (self->model), i, TRUE);
+
         activate_selection_on_click (self, FALSE);
         gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
     }
+
     self->activate_on_release = FALSE;
     self->deny_background_click = FALSE;
 }