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gridview: Implement list.scroll-to action

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Benjamin Otte 2019-10-20 18:52:28 +02:00 committed by Matthias Clasen
parent ba0122fd02
commit c38e050cc7
1 changed files with 112 additions and 0 deletions
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112
gtk/gtkgridview.c
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@ -1214,6 +1214,106 @@ gtk_grid_view_select_item_action (GtkWidget *widget,
gtk_grid_view_select_item (self, pos, modify, extend);
}
static void
gtk_grid_view_compute_scroll_align (GtkGridView *self,
GtkOrientation orientation,
int cell_start,
int cell_end,
double current_align,
gboolean current_start,
double *new_align,
gboolean *new_start)
{
int visible_start, visible_size, visible_end;
int cell_size;
visible_start = gtk_adjustment_get_value (self->adjustment[orientation]);
visible_size = gtk_adjustment_get_page_size (self->adjustment[orientation]);
if (gtk_grid_view_adjustment_is_flipped (self, orientation))
visible_start = gtk_adjustment_get_upper (self->adjustment[orientation]) - visible_size - visible_start;
visible_end = visible_start + visible_size;
cell_size = cell_end - cell_start;
if (cell_size <= visible_size)
{
if (cell_start < visible_start)
{
*new_align = 0.0;
*new_start = TRUE;
}
else if (cell_end > visible_end)
{
*new_align = 1.0;
*new_start = FALSE;
}
else
{
/* XXX: start or end here? */
*new_start = TRUE;
*new_align = (double) (cell_start - visible_start) / visible_size;
}
}
else
{
/* This is the unlikely case of the cell being higher than the visible area */
if (cell_start > visible_start)
{
*new_align = 0.0;
*new_start = TRUE;
}
else if (cell_end < visible_end)
{
*new_align = 1.0;
*new_start = FALSE;
}
else
{
/* the cell already covers the whole screen */
*new_align = current_align;
*new_start = current_start;
}
}
}
static void
gtk_grid_view_scroll_to_item (GtkWidget *widget,
const char *action_name,
GVariant *parameter)
{
GtkGridView *self = GTK_GRID_VIEW (widget);
int start, end;
double xalign, yalign;
gboolean xstart, ystart;
guint pos;
if (!g_variant_check_format_string (parameter, "u", FALSE))
return;
g_variant_get (parameter, "u", &pos);
/* figure out primary orientation and if position is valid */
if (!gtk_grid_view_get_size_at_position (self, pos, &start, &end))
return;
end += start;
gtk_grid_view_compute_scroll_align (self,
self->orientation,
start, end,
self->anchor_yalign, self->anchor_ystart,
&yalign, &ystart);
/* now do the same thing with the other orientation */
start = floor (self->column_width * (pos % self->n_columns));
end = floor (self->column_width * ((pos % self->n_columns) + 1));
gtk_grid_view_compute_scroll_align (self,
OPPOSITE_ORIENTATION (self->orientation),
start, end,
self->anchor_xalign, self->anchor_xstart,
&xalign, &xstart);
gtk_grid_view_set_anchor (self, pos, xalign, xstart, yalign, ystart);
}
static void
gtk_grid_view_activate_item (GtkWidget *widget,
const char *action_name,
@ -1388,6 +1488,18 @@ gtk_grid_view_class_init (GtkGridViewClass *klass)
"(ubb)",
gtk_grid_view_select_item_action);
/**
* GtkGridView|list.scroll-to-item:
* @position: position of item to scroll to
*
* Scrolls to the item given in @position with the minimum amount
* of scrolling required. If the item is already visible, nothing happens.
*/
gtk_widget_class_install_action (widget_class,
"list.scroll-to-item",
"u",
gtk_grid_view_scroll_to_item);
gtk_widget_class_set_css_name (widget_class, I_("flowbox"));
}