[nautilus/wip/antoniof/flow-box-preparation: 8/20] view-icon-controller: Implement single-click mode

[António Fernandes <antoniof src gnome org>]

commit 5b80d092559895af47124c3f2cad117407a51460
Author: António Fernandes <antoniof gnome org>
Date:   Wed Dec 8 22:47:40 2021 +0000

    view-icon-controller: Implement single-click mode
    
    GtkFlowBox:activate-on-single-click is not fit for our purpose, as it
    introduces changes to selection modification which don't fit our desired
    behavior.
    
    Introduce our own mechanism to activate children on single click.

 src/nautilus-view-icon-controller.c | 53 +++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
---
diff --git a/src/nautilus-view-icon-controller.c b/src/nautilus-view-icon-controller.c
index dd8016ec2..b0b512068 100644
--- a/src/nautilus-view-icon-controller.c
+++ b/src/nautilus-view-icon-controller.c
@@ -20,6 +20,8 @@ struct _NautilusViewIconController
     GActionGroup *action_group;
     gint zoom_level;
 
+    gboolean single_click_mode;
+    gboolean activate_on_release;
     GtkGesture *multi_press_gesture;
 };
 
@@ -673,9 +675,22 @@ real_reveal_for_selection_context_menu (NautilusFilesView *files_view)
     return get_rectangle_for_item_ui (self, item_ui);
 }
 
+static void
+set_click_mode_from_settings (NautilusViewIconController *self)
+{
+    int click_policy;
+
+    click_policy = g_settings_get_enum (nautilus_preferences,
+                                        NAUTILUS_PREFERENCES_CLICK_POLICY);
+
+    self->single_click_mode = (click_policy == NAUTILUS_CLICK_POLICY_SINGLE);
+}
+
 static void
 real_click_policy_changed (NautilusFilesView *files_view)
 {
+    NautilusViewIconController *self = NAUTILUS_VIEW_ICON_CONTROLLER (files_view);
+    set_click_mode_from_settings (self);
 }
 
 static void
@@ -730,6 +745,10 @@ on_button_press_event (GtkGestureMultiPress *gesture,
         gboolean selection_mode;
 
         selection_mode = (modifiers & (GDK_CONTROL_MASK | GDK_SHIFT_MASK));
+        self->activate_on_release = (self->single_click_mode &&
+                                     button == GDK_BUTTON_PRIMARY &&
+                                     n_press == 1 &&
+                                     !selection_mode);
 
         /* GtkFlowBox changes selection only with the primary button, but we
          * need that to happen with all buttons, otherwise e.g. opening context
@@ -758,6 +777,7 @@ on_button_press_event (GtkGestureMultiPress *gesture,
         {
             activate_selection_on_click (self, modifiers & GDK_SHIFT_MASK);
             gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
+            self->activate_on_release = FALSE;
         }
         else if (button == GDK_BUTTON_MIDDLE && n_press == 1 && !selection_mode)
         {
@@ -781,6 +801,32 @@ on_button_press_event (GtkGestureMultiPress *gesture,
     }
 }
 
+static void
+on_click_released (GtkGestureMultiPress *gesture,
+                   gint                  n_press,
+                   gdouble               x,
+                   gdouble               y,
+                   gpointer              user_data)
+{
+    NautilusViewIconController *self = NAUTILUS_VIEW_ICON_CONTROLLER (user_data);
+
+    if (self->activate_on_release)
+    {
+        activate_selection_on_click (self, FALSE);
+        gtk_gesture_set_state (GTK_GESTURE (gesture), GTK_EVENT_SEQUENCE_CLAIMED);
+    }
+    self->activate_on_release = FALSE;
+}
+
+static void
+on_click_stopped (GtkGestureMultiPress *gesture,
+                  gpointer              user_data)
+{
+    NautilusViewIconController *self = NAUTILUS_VIEW_ICON_CONTROLLER (user_data);
+
+    self->activate_on_release = FALSE;
+}
+
 static void
 on_longpress_gesture_pressed_callback (GtkGestureLongPress *gesture,
                                        gdouble              x,
@@ -1056,6 +1102,8 @@ create_view_ui (NautilusViewIconController *self)
     gtk_widget_set_valign (widget, GTK_ALIGN_START);
 
     flowbox = GTK_FLOW_BOX (widget);
+    /* We don't use GtkFlowBox's single click mode because it doesn't match our
+     * expected behavior. Instead, we roll our own self->single_click_mode. */
     gtk_flow_box_set_activate_on_single_click (flowbox, FALSE);
     gtk_flow_box_set_max_children_per_line (flowbox, 20);
     gtk_flow_box_set_selection_mode (flowbox, GTK_SELECTION_MULTIPLE);
@@ -1108,6 +1156,10 @@ constructed (GObject *object)
                                    0);
     g_signal_connect (self->multi_press_gesture, "pressed",
                       G_CALLBACK (on_button_press_event), self);
+    g_signal_connect (self->multi_press_gesture, "stopped",
+                      G_CALLBACK (on_click_stopped), self);
+    g_signal_connect (self->multi_press_gesture, "released",
+                      G_CALLBACK (on_click_released), self);
 
     longpress_gesture = gtk_gesture_long_press_new (GTK_WIDGET (self->view_ui));
     gtk_event_controller_set_propagation_phase (GTK_EVENT_CONTROLLER (longpress_gesture),
@@ -1188,6 +1240,7 @@ nautilus_view_icon_controller_class_init (NautilusViewIconControllerClass *klass
 static void
 nautilus_view_icon_controller_init (NautilusViewIconController *self)
 {
+    set_click_mode_from_settings (self);
 }
 
 NautilusViewIconController *