listbase: Compute rubberband region on-demand

Instead of storing the active items as we go, compute the affected items
whenever the rubberband changes and in particular when the rubberband
ends.
That way, the rubberband is guaranteed to select a rectangle even
after scrolling very far.

This is achieved by having a get_items_in_rect() vfunc that selects all
the items in the rubberbanded rectangle and returns them as a bitset.

1 files changed, 32 insertions, 0 deletions

diff --git a/gtk/gtkgridview.c b/gtk/gtkgridview.c
index ac3d49cdda..3a1b96098e 100644
--- a/gtk/gtkgridview.c
+++ b/gtk/gtkgridview.c
@@ -21,6 +21,7 @@
 
 #include "gtkgridview.h"
 
+#include "gtkbitset.h"
 #include "gtkintl.h"
 #include "gtklistbaseprivate.h"
 #include "gtklistitemfactory.h"
@@ -452,6 +453,36 @@ gtk_grid_view_get_position_from_allocation (GtkListBase           *base,
   return TRUE;
 }
 
+static GtkBitset *
+gtk_grid_view_get_items_in_rect (GtkListBase        *base,
+                                 const GdkRectangle *rect)
+{
+  GtkGridView *self = GTK_GRID_VIEW (base);
+  guint first_row, last_row, first_column, last_column, n_items;
+  GtkBitset *result;
+
+  result = gtk_bitset_new_empty ();
+
+  n_items = gtk_list_base_get_n_items (base);
+  if (n_items == 0)
+    return result;
+
+  first_column = floor (rect->x / self->column_width);
+  last_column = floor ((rect->x + rect->width) / self->column_width);
+  if (!gtk_grid_view_get_cell_at_y (self, rect->y, &first_row, NULL, NULL))
+    first_row = rect->y < 0 ? 0 : n_items - 1;
+  if (!gtk_grid_view_get_cell_at_y (self, rect->y + rect->height, &last_row, NULL, NULL))
+    last_row = rect->y < 0 ? 0 : n_items - 1;
+
+  gtk_bitset_add_rectangle (result,
+                            first_row + first_column,
+                            last_column - first_column + 1,
+                            (last_row - first_row) / self->n_columns + 1,
+                            self->n_columns);
+
+  return result;
+}
+
 static guint
 gtk_grid_view_move_focus_along (GtkListBase *base,
                                 guint        pos,
@@ -1000,6 +1031,7 @@ gtk_grid_view_class_init (GtkGridViewClass *klass)
   list_base_class->list_item_augment_func = cell_augment;
   list_base_class->get_allocation_along = gtk_grid_view_get_allocation_along;
   list_base_class->get_allocation_across = gtk_grid_view_get_allocation_across;
+  list_base_class->get_items_in_rect = gtk_grid_view_get_items_in_rect;
   list_base_class->get_position_from_allocation = gtk_grid_view_get_position_from_allocation;
   list_base_class->move_focus_along = gtk_grid_view_move_focus_along;
   list_base_class->move_focus_across = gtk_grid_view_move_focus_across;