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listitemmanager: Remove section when adding at its end

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We are failing to go from this:

    [ BLUE ] [ RED ]

...to this:

    [ BLUE GREEN YELLOW ] [ RED ]

...where '[' and ']' represent section header and footer.

Instead, the result is...

    [ BLUE ] [ GREEN YELLOW ] [ RED ]

... despite the first 3 items belonging to the same section according
to the section model. This leaves the view in an inconsistent state
and, ultimately, to crashes the non-removed footer.

Indeed, when receiving items-changed(1,0,2), we call `append_items()`
which inserts a new tile before the tile at `1` (which was RED), and
then notices there is a HEADER right befo-re it, so it flags both it
and the corresponding FOOTER as unmatched:

    [ BLUE ] ( GREEN-YELLOW RED )

... where '(' and ')' represent unmatched header and footer.

Problem is subsequent code in `release_items()` doesn't even touch
the section boundary footer-header pair ('] ('), because they are
belong in the tracked interval (visible items). And `ensure_items()`
proceeds to match the header with a new footer, producing the result
described above.

To handle this correctly, `append_items()` must delete the section
boundary, and flag as unmatched both the HEADER of the section before
and the FOOTER of section after (whose respective footer and header
has been marked for removal):

    ( BLUE . . GREEN-YELLOW RED )

... where '.' represents tiles marked for removal.

This way, `release_items()` will release the removed footer-header
section boundary, and `ensure_items()` is going to reinstate new
section remove the section boundary at the correct place, resulting
in the expected behavior:

    [ BLUE GREEN YELLOW ] [ RED ]
This commit is contained in:
António Fernandes 2024-01-24 17:17:54 +00:00
parent 4b45adaf39
commit b05000d8bd
1 changed files with 17 additions and 1 deletions
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18
gtk/gtklistitemmanager.c
View File

@ -968,10 +968,26 @@ gtk_list_item_manager_add_items (GtkListItemManager *self,
if (section != NULL && section->type == GTK_LIST_TILE_HEADER)
{
guint start, end;
GtkListTile *footer = gtk_list_tile_get_footer (self, section);
GtkListTile *previous_footer = gtk_list_tile_get_previous_skip (section);
gtk_section_model_get_section (GTK_SECTION_MODEL (self->model), position, &start, &end);
if (previous_footer != NULL && previous_footer->type == GTK_LIST_TILE_FOOTER &&
position > start && position < end)
{
gtk_list_item_change_clear_header (change, &section->widget);
gtk_list_tile_set_type (section, GTK_LIST_TILE_REMOVED);
gtk_list_tile_set_type (previous_footer, GTK_LIST_TILE_REMOVED);
section = gtk_list_tile_get_header (self, previous_footer);
}
gtk_list_item_change_clear_header (change, &section->widget);
gtk_list_tile_set_type (section,
GTK_LIST_TILE_UNMATCHED_HEADER);
gtk_list_tile_set_type (gtk_list_tile_get_footer (self, section),
gtk_list_tile_set_type (footer,
GTK_LIST_TILE_UNMATCHED_FOOTER);
}
}