path: root/a11y/e-table/gal-a11y-e-table-item.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Authors: 
 *   Christopher James Lahey <clahey@ximian.com>
 *   Bolian Yin <bolian.yin@sun.com>
 *
 * Copyright (C) 2002 Ximian, Inc.
 */

#include <config.h>
#include <string.h>
#include "gal-a11y-e-table-item.h"
#include "gal-a11y-e-cell-registry.h"
#include "gal-a11y-e-cell.h"
#include "gal-a11y-util.h"
#include <gal/e-table/e-table-subset.h>
#include <gal/e-table/e-table.h>
#include <gal/e-table/e-tree.h>

#include <atk/atkobject.h>
#include <atk/atktable.h>
#include <atk/atkcomponent.h>
#include <atk/atkobjectfactory.h>
#include <atk/atkregistry.h>
#include <atk/atkgobjectaccessible.h>

#define CS_CLASS(a11y) (G_TYPE_INSTANCE_GET_CLASS ((a11y), C_TYPE_STREAM, GalA11yETableItemClass))
static GObjectClass *parent_class;
static AtkComponentIface *component_parent_iface;
static GType parent_type;
static gint priv_offset;
static GQuark       quark_accessible_object = 0;
#define GET_PRIVATE(object) ((GalA11yETableItemPrivate *) (((char *) object) + priv_offset))
#define PARENT_TYPE (parent_type)

struct _GalA11yETableItemPrivate {
    AtkObject *parent;
    gint index_in_parent;
    gint cols;
    gint rows;
    gpointer *cell_data;
    int selection_change_id;
    int cursor_change_id;
    ETableCol ** columns;
    ESelectionModel *selection;
    GtkWidget *widget;
};

static gboolean gal_a11y_e_table_item_ref_selection (GalA11yETableItem *a11y,
                             ESelectionModel *selection);
static gboolean gal_a11y_e_table_item_unref_selection (GalA11yETableItem *a11y);

static gpointer *eti_reinit_data (AtkTable *table, ETableItem *item);

#if 0
static void
unref_accessible (gpointer user_data, GObject *obj_loc)
{
    GalA11yETableItem *a11y = GAL_A11Y_E_TABLE_ITEM (user_data);
    GET_PRIVATE (a11y)->item = NULL;
    g_object_unref (a11y);
}
#endif

inline static gint
view_to_model_row(ETableItem *eti, int row)
{
    if (eti->uses_source_model) {
        ETableSubset *etss = E_TABLE_SUBSET(eti->table_model);
        if (row >= 0 && row < etss->n_map) {
            eti->row_guess = row;
            return etss->map_table[row];
        } else
            return -1;
    } else
        return row;
}

inline static gint
view_to_model_col(ETableItem *eti, int col)
{
    ETableCol *ecol = e_table_header_get_column (eti->header, col);
    return ecol ? ecol->col_idx : -1;
}

inline static gint
model_to_view_row(ETableItem *eti, int row)
{
    int i;
    if (row == -1)
        return -1;
    if (eti->uses_source_model) {
        ETableSubset *etss = E_TABLE_SUBSET(eti->table_model);
        if (eti->row_guess >= 0 && eti->row_guess < etss->n_map) {
            if (etss->map_table[eti->row_guess] == row) {
                return eti->row_guess;
            }
        }
        for (i = 0; i < etss->n_map; i++) {
            if (etss->map_table[i] == row)
                return i;
        }
        return -1;
    } else
        return row;
}

inline static gint
model_to_view_col(ETableItem *eti, int col)
{
    int i;
    if (col == -1)
        return -1;
    for (i = 0; i < eti->cols; i++) {
        ETableCol *ecol = e_table_header_get_column (eti->header, i);
        if (ecol->col_idx == col)
            return i;
    }
    return -1;
}

inline static GObject *
eti_a11y_get_gobject (AtkObject *accessible)
{
    return atk_gobject_accessible_get_object (ATK_GOBJECT_ACCESSIBLE (accessible));
}

static void
eti_dispose (GObject *object)
{
    GalA11yETableItem *a11y = GAL_A11Y_E_TABLE_ITEM (object);
    GalA11yETableItemPrivate *priv = GET_PRIVATE (a11y);

    priv->parent = NULL;

    if ( priv->cell_data != NULL ) {
        g_free(priv->cell_data);
        priv->cell_data = NULL;
    }

    if (priv->columns) {
        g_free(priv->columns);
        priv->columns = NULL;
    }

    if (parent_class->dispose)
        parent_class->dispose (object);
    if (priv->selection)
        gal_a11y_e_table_item_unref_selection (a11y);
}

/* Static functions */
static AtkObject *
eti_get_parent (AtkObject *accessible)
{
    GalA11yETableItem *a11y;

    g_return_val_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (accessible), NULL);
    if (!eti_a11y_get_gobject (accessible))
        /* defunct */
        return NULL;

    a11y = GAL_A11Y_E_TABLE_ITEM (accessible);
    return GET_PRIVATE (a11y)->parent;
}

static gint
eti_get_n_children (AtkObject *accessible)
{
    g_return_val_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (accessible), 0);
    if (!eti_a11y_get_gobject (accessible))
        return 0;

    return atk_table_get_n_columns (ATK_TABLE (accessible)) *
        atk_table_get_n_rows (ATK_TABLE (accessible));
}

static AtkObject*
eti_ref_child (AtkObject *accessible, gint index)
{
    ETableItem *item;
    gint col, row;

    g_return_val_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (accessible), NULL);
    item = E_TABLE_ITEM (eti_a11y_get_gobject (accessible));
    if (!item)
        return NULL;

    if (index < item->cols) {
        AtkObject *child;

        /* A column header is required */
        child = atk_table_get_column_header (ATK_TABLE (accessible), index);
        if (child)
            g_object_ref (child);
        return child;
    }

    index -= item->cols;
    col = index % item->cols;
    row = index / item->cols;

    return atk_table_ref_at (ATK_TABLE (accessible), row, col);
}

static gint
eti_get_index_in_parent (AtkObject *accessible)
{
    GalA11yETableItem *a11y;

    g_return_val_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (accessible), -1);
    if (!eti_a11y_get_gobject (accessible))
        return -1;

    a11y = GAL_A11Y_E_TABLE_ITEM (accessible);
    return GET_PRIVATE (a11y)->index_in_parent;
}

static void
eti_get_extents (AtkComponent *component,
         gint *x,
         gint *y,
         gint *width,
         gint *height,
         AtkCoordType coord_type)
{
    ETableItem *item;
    double real_width;
    double real_height;
    int fake_width;
    int fake_height;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (component)));
    if (!item)
        return;

    if (component_parent_iface &&
        component_parent_iface->get_extents)
        component_parent_iface->get_extents (component,
                             x,
                             y,
                             &fake_width,
                             &fake_height,
                             coord_type);

    gtk_object_get (GTK_OBJECT (item),
            "width", &real_width,
            "height", &real_height,
            NULL);

    if (width)
        *width = real_width;
    if (height) 
        *height = real_height;
}

static AtkObject*
eti_ref_accessible_at_point (AtkComponent *component,
                 gint x,
                 gint y,
                 AtkCoordType coord_type)
{
    int row = -1;
    int col = -1;
    int x_origin, y_origin;
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (component)));
    if (!item)
        return NULL;

    atk_component_get_position (component,
                    &x_origin,
                    &y_origin,
                    coord_type);
    x -= x_origin;
    y -= y_origin;

    e_table_item_compute_location (item, &x, &y,
                       &row, &col);

    if (row != -1 && col != -1) {
        return atk_table_ref_at (ATK_TABLE (component), row, col);
    } else {
        return NULL;
    }
}


static void
cell_destroyed (gpointer data)
{
    gint index;
    GalA11yETableItem * item;
    GalA11yECell * cell;

    g_return_if_fail (GAL_A11Y_IS_E_CELL (data));
    cell = GAL_A11Y_E_CELL (data);
        
    item = GAL_A11Y_E_TABLE_ITEM (atk_gobject_accessible_for_object (G_OBJECT (GAL_A11Y_E_CELL(data)->item)));

    g_return_if_fail (item && GAL_A11Y_IS_E_TABLE_ITEM (item));

    g_return_if_fail (cell->row < GET_PRIVATE(item)->rows && cell->view_col < GET_PRIVATE(item)->cols);

    index = cell->row * cell->item->cols + cell->view_col;
                                                                   
    if (GET_PRIVATE (item)->cell_data && GET_PRIVATE (item)->cell_data [index] == data)
        GET_PRIVATE (item)->cell_data [index] = NULL;
}

/* atk table */
static AtkObject*
eti_ref_at (AtkTable *table, gint row, gint column)
{
    ETableItem *item;
    AtkObject* ret;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return NULL;

    if (column >= 0 &&
        column < item->cols &&
        row >= 0 &&
        row < item->rows &&
        item->cell_views_realized) {
        ECellView *cell_view = item->cell_views[column];
        ETableCol *ecol = e_table_header_get_column (item->header, column);
        gpointer * cell_data;

        cell_data = eti_reinit_data (table, item);
        if (cell_data == NULL) 
            return NULL;

        if (cell_data[row*item->cols + column] == NULL) {
            ret = gal_a11y_e_cell_registry_get_object (NULL,
                                item,
                                cell_view,
                                ATK_OBJECT (table),
                                ecol->col_idx,
                                column,
                                row);
            cell_data[row*item->cols + column] = ret;
            if (ATK_IS_OBJECT (ret)) {
                gal_a11y_e_cell_add_state(ret, ATK_STATE_SHOWING, FALSE);
                gal_a11y_e_cell_add_state(ret, ATK_STATE_VISIBLE, FALSE);
                g_object_weak_ref (G_OBJECT (ret),
                           (GWeakNotify) cell_destroyed,
                           ret);
            } else
                ret = NULL;
        } else {
            ret = (AtkObject *) cell_data[row*item->cols + column];
            if (ATK_IS_OBJECT (ret)) {
                g_object_ref (ret);
            } else { 
                ret = NULL;
            }
        }


        return ret;
    }

    return NULL;
}

static gint
eti_get_index_at (AtkTable *table, gint row, gint column)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    return column + row * item->cols;
}

static gint
eti_get_column_at_index (AtkTable *table, gint index)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    return index % item->cols;
}

static gint
eti_get_row_at_index (AtkTable *table, gint index)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    return index / item->cols;
}

static gint
eti_get_n_columns (AtkTable *table)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    return item->cols;
}

static gint
eti_get_n_rows (AtkTable *table)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    return item->rows;
}

static gint
eti_get_column_extent_at (AtkTable *table,
              gint row,
              gint column)
{
    ETableItem *item;
    int width;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    e_table_item_get_cell_geometry (item,
                    &row, 
                    &column,
                    NULL,
                    NULL,
                    &width,
                    NULL);

    return width;
}

static gint
eti_get_row_extent_at (AtkTable *table,
               gint row,
               gint column)
{
    ETableItem *item;
    int height;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return -1;

    e_table_item_get_cell_geometry (item,
                    &row, 
                    &column,
                    NULL,
                    NULL,
                    NULL,
                    &height);

    return height;
}

static AtkObject *
eti_get_caption (AtkTable *table)
{
    /* Unimplemented */
    return NULL;
}

static G_CONST_RETURN gchar *
eti_get_column_description (AtkTable *table,
                gint column)
{
    ETableItem *item;
    ETableCol *ecol;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return NULL;

    ecol = e_table_header_get_column (item->header, column);

    return ecol->text;
}

static AtkObject *
eti_get_column_header (AtkTable *table, gint column)
{
    ETableItem *item;
    ETableCol *ecol;
    AtkObject *atk_obj = NULL;
    ECell *ecell;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return NULL;

    ecol = e_table_header_get_column (item->header, column);
    ecell = ecol->ecell;
    if (ecell)
        atk_obj = atk_gobject_accessible_for_object (G_OBJECT (ecell));
    return atk_obj;
}

static G_CONST_RETURN gchar *
eti_get_row_description (AtkTable *table,
             gint row)
{
    /* Unimplemented */
    return NULL;
}

static AtkObject *
eti_get_row_header (AtkTable *table,
            gint row)
{
    /* Unimplemented */
    return NULL;
}

static AtkObject *
eti_get_summary (AtkTable *table)
{
    /* Unimplemented */
    return NULL;
}

static gboolean 
table_is_row_selected (AtkTable *table, gint row)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return FALSE;

    return e_selection_model_is_row_selected(item->selection, row);
}

static gboolean 
table_is_selected (AtkTable *table, gint row, gint column)
{
    return table_is_row_selected (table, row);
}

static gint
table_get_selected_rows (AtkTable *table, gint **rows_selected)
{
    ETableItem *item;
    gint n_selected, row, index_selected;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return 0;

    n_selected = e_selection_model_selected_count (item->selection);
    if (rows_selected) {
        *rows_selected = (gint *) g_malloc (n_selected * sizeof (gint));

        index_selected = 0;
        for (row = 0; row < item->rows && index_selected < n_selected; ++row) {
            if (atk_table_is_row_selected (table, row)) {
                (*rows_selected)[index_selected] = row;
                ++index_selected;
            }
        }
    }
    return n_selected;
}

static gboolean 
table_add_row_selection (AtkTable *table, gint row)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return FALSE;

    if (table_is_row_selected (table, row))
        return TRUE;
    e_selection_model_toggle_single_row (item->selection,
                         view_to_model_row (item, row));

    return TRUE;
}

static gboolean 
table_remove_row_selection (AtkTable *table, gint row)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (table)));
    if (!item)
        return FALSE;

    if (!atk_table_is_row_selected (table, row))
        return TRUE;
    e_selection_model_toggle_single_row (item->selection, row);
    return TRUE;
}

static void
eti_atk_table_iface_init (AtkTableIface *iface)
{
    iface->ref_at = eti_ref_at;
    iface->get_index_at = eti_get_index_at;
    iface->get_column_at_index = eti_get_column_at_index;
    iface->get_row_at_index = eti_get_row_at_index;
    iface->get_n_columns = eti_get_n_columns;
    iface->get_n_rows = eti_get_n_rows;
    iface->get_column_extent_at = eti_get_column_extent_at;
    iface->get_row_extent_at = eti_get_row_extent_at;
    iface->get_caption = eti_get_caption;
    iface->get_column_description = eti_get_column_description;
    iface->get_column_header = eti_get_column_header;
    iface->get_row_description = eti_get_row_description;
    iface->get_row_header = eti_get_row_header;
    iface->get_summary = eti_get_summary;

    iface->is_row_selected = table_is_row_selected;
    iface->is_selected = table_is_selected;
    iface->get_selected_rows = table_get_selected_rows;
    iface->add_row_selection = table_add_row_selection;
    iface->remove_row_selection = table_remove_row_selection;
}

static void
eti_atk_component_iface_init (AtkComponentIface *iface)
{
    component_parent_iface         = g_type_interface_peek_parent (iface);

    iface->ref_accessible_at_point = eti_ref_accessible_at_point;
    iface->get_extents             = eti_get_extents;
}

static void
eti_rows_inserted (ETableModel * model, int row, int count, 
           AtkObject * table_item)
{
    gint n_cols,n_rows,i,j;
    gpointer *cell_data;
    GalA11yETableItem * item_a11y;
    gint old_nrows;

    g_return_if_fail (table_item);
    item_a11y = GAL_A11Y_E_TABLE_ITEM (table_item);

        n_cols = atk_table_get_n_columns (ATK_TABLE(table_item));
    n_rows = atk_table_get_n_rows (ATK_TABLE(table_item));

    old_nrows = GET_PRIVATE(item_a11y)->rows;
    
    g_return_if_fail (n_cols > 0 && n_rows > 0);
    g_return_if_fail (old_nrows == n_rows - count);

    cell_data = GET_PRIVATE(table_item)->cell_data;
    GET_PRIVATE(table_item)->cell_data = g_realloc (cell_data, (n_rows*n_cols) * sizeof(gpointer));
    cell_data = GET_PRIVATE(table_item)->cell_data;

    GET_PRIVATE(table_item)->rows = n_rows; 

    /* If rows are insert in the middle of a table. */
    if (row + count < n_rows ) {
        memmove(&cell_data[(row+count)*n_cols], &cell_data[row*n_cols],
            (old_nrows-row)*n_cols*sizeof(gpointer));

        /* Update cell's index. */
        for (i = row + count; i < n_rows; i ++) {
            for (j = 0; j < n_cols; j ++)
                if (cell_data[i*n_cols + j] != NULL) {
                    AtkObject * a11y;

                    a11y = ATK_OBJECT(cell_data[i*n_cols + j]);
                                        GAL_A11Y_E_CELL(a11y)->row = i;
                }
        }
    }

    /* Clear cache for the new added rows. */
    for (i = row ; i < row+count; i ++)
        for (j = 0 ;  j < n_cols; j ++)
            cell_data [i*n_cols + j] = NULL;

    g_signal_emit_by_name (table_item, "row-inserted", row,
                   count, NULL);

        for (i = row; i < (row + count); i ++) {
                for (j = 0; j < n_cols; j ++) {
            g_signal_emit_by_name (table_item,
                           "children_changed::add",
                                               ( (i*n_cols) + j), NULL, NULL);
        }
        }

    g_signal_emit_by_name (table_item, "visible-data-changed");
}

/* 
 * reinit the eti's private data
 * make sure it is synchronized with the gal-e-table-item
 */
static gpointer *
eti_reinit_data (AtkTable *table, ETableItem *item)
{
    gpointer * cell_data;

    int oldsize, newsize;
    cell_data = GET_PRIVATE (table)->cell_data;
    if (GET_PRIVATE (table)->rows != item->rows 
        || GET_PRIVATE (table)->cols != item->cols ) { /* reinit cell_data */
        oldsize = GET_PRIVATE (table)->cols * GET_PRIVATE (table)->rows;
        newsize = item->cols*item->rows;
        GET_PRIVATE (table)->cols = item->cols;
        GET_PRIVATE (table)->rows = item->rows;

        cell_data = g_realloc(cell_data, newsize*sizeof(gpointer));
        if (newsize > oldsize)
            memset(&cell_data[oldsize], 0, (newsize-oldsize)*sizeof(gpointer));
        
        GET_PRIVATE (table)->cell_data = cell_data;
    }
    return cell_data;
}

/* 
 * clear all the AtkObjects stored in the cell_data
 * doesn't free the cell_data or resize it.
 */
static void
eti_clear_rows (ETableModel * model, AtkObject * table_item, int row, int count)
{
    gint i,j, n_rows, n_cols;
    gpointer *cell_data;

    g_return_if_fail (model && table_item);

    cell_data = GET_PRIVATE (table_item)->cell_data;
    g_return_if_fail (cell_data);

    n_rows = GET_PRIVATE (table_item)->rows;
    n_cols = GET_PRIVATE (table_item)->cols;

    g_return_if_fail( row >= 0 && count > 0 && row+count <= n_rows);

    /* DEFUNCT the deleted cells. */
    for (i = row; i < row+count; i ++) {
        for (j = 0; j < n_cols; j ++) {
            if (cell_data[i*n_cols + j] != NULL) {
                AtkObject * a11y;

                a11y = ATK_OBJECT(cell_data[i*n_cols + j]);
                gal_a11y_e_cell_add_state (GAL_A11Y_E_CELL(a11y), ATK_STATE_DEFUNCT, TRUE);
                cell_data[i*n_cols + j] = NULL;
            }
        }
    }

    g_signal_emit_by_name (table_item, "row-deleted", row,
                   count, NULL);

    for (i = row; i < row+count; i ++) {
        for (j = 0; j < n_cols; j ++) {
            g_signal_emit_by_name (table_item,
                "children_changed::remove",
                ( (i*n_cols) + j), NULL, NULL);
        }
        }
    g_signal_emit_by_name (table_item, "visible-data-changed");
}

static void
eti_rows_deleted (ETableModel * model, int row, int count, 
          AtkObject * table_item)
{
    gint i,j, n_rows, n_cols, old_nrows;
    gpointer *cell_data;
    
    n_rows = atk_table_get_n_rows (ATK_TABLE(table_item));
        n_cols = atk_table_get_n_columns (ATK_TABLE(table_item));

    cell_data = GET_PRIVATE(table_item)->cell_data;
    old_nrows = GET_PRIVATE(table_item)->rows;

    g_return_if_fail ( row+count <= old_nrows);
    g_return_if_fail (old_nrows == n_rows + count);
    GET_PRIVATE(table_item)->rows = n_rows;

    /* DEFUNCT the deleted cells. */
    for (i = row; i < row+count; i ++) {
        for (j = 0; j < n_cols; j ++) {
            if (cell_data[i*n_cols + j] != NULL) {
                AtkObject * a11y;

                a11y = ATK_OBJECT(cell_data[i*n_cols + j]);
                gal_a11y_e_cell_add_state (GAL_A11Y_E_CELL(a11y), ATK_STATE_DEFUNCT, TRUE);
                cell_data[i*n_cols + j] = NULL;
            }
        }
    }

    /* If more rows left, update the a11y object. */
    if (old_nrows > row + count) {

        /* Remove the defunct cells in cache. */
        memmove (&cell_data[row*n_cols], &cell_data[(row+count)*n_cols],
            ( old_nrows-row-count)*n_cols*sizeof(gpointer));

        GET_PRIVATE(table_item)->cell_data = g_realloc (cell_data, n_rows*n_cols*sizeof(gpointer));
        cell_data = GET_PRIVATE(table_item)->cell_data;

        /* Update index of cells below the deleted rows. */
        for (i = row; i < n_rows; i ++) {
            for (j = 0; j < n_cols; j ++) {
                if (cell_data[i*n_cols + j] != NULL) {
                    AtkObject * a11y;

                    a11y = ATK_OBJECT(cell_data[i*n_cols + j]);
                    GAL_A11Y_E_CELL(a11y)->row = i;
                }
            }
        }
    }

    g_signal_emit_by_name (table_item, "row-deleted", row,
                   count, NULL);

        for (i = row; i < (row + count); i ++) {
                for (j = 0; j < n_cols; j ++) {
            g_signal_emit_by_name (table_item,
                           "children_changed::remove",
                                               ( (i*n_cols) + j), NULL, NULL);
        }
        }
    g_signal_emit_by_name (table_item, "visible-data-changed");
}

static void
eti_tree_model_node_changed_cb (ETreeModel *model, ETreePath node, ETableItem *eti)
{
    AtkObject *atk_obj;
    GalA11yETableItem *a11y;

    g_return_if_fail (E_IS_TABLE_ITEM (eti));

    atk_obj = atk_gobject_accessible_for_object (G_OBJECT (eti));
    a11y = GAL_A11Y_E_TABLE_ITEM (atk_obj);

    /* we can't figure out which rows are changed, so just clear all of them ... */
    if  (GET_PRIVATE (a11y)->rows > 0)
        eti_clear_rows (eti->table_model, atk_obj, 0, GET_PRIVATE (a11y)->rows);
}

enum {
        ETI_HEADER_UNCHANGED = 0,
        ETI_HEADER_REORDERED,
        ETI_HEADER_NEW_ADDED,
        ETI_HEADER_REMOVED,
};
                                                                                
/*
 * 1. Check what actually happened: column reorder, remove or add
 * 2. Update cache
 * 3. Emit signals
 */
static void
eti_header_structure_changed (ETableHeader *eth, AtkObject *a11y)
{
                                                                                
        gboolean reorder_found=FALSE, added_found=FALSE, removed_found=FALSE;
        GalA11yETableItem * a11y_item;
        ETableCol ** cols, **prev_cols;
        GalA11yETableItemPrivate *priv;
        gint *state = NULL, *prev_state = NULL, *reorder = NULL;
        gint i,j,n_rows,n_cols, prev_n_cols;
        gpointer * cell_data, * tmp;
                                                                                
        a11y_item = GAL_A11Y_E_TABLE_ITEM (a11y);
        priv = GET_PRIVATE (a11y_item);
                                                                                
    g_return_if_fail (priv && priv->cell_data);
    cell_data = priv->cell_data ;

    /* Assume rows do not changed. */
        n_rows = priv->rows;

        prev_n_cols = priv->cols;
        prev_cols = priv->columns;

        cols = e_table_header_get_columns (eth);
    n_cols = eth->col_count;
                                                                                
        g_return_if_fail (cols && prev_cols && n_cols > 0);
                                                                                
        /* Init to ETI_HEADER_UNCHANGED. */
        state = g_malloc0 (sizeof (gint) * n_cols);
        prev_state = g_malloc0 (sizeof (gint) * prev_n_cols);
        reorder = g_malloc0 (sizeof (gint) * n_cols);

        /* Compare with previously saved column headers. */
        for ( i = 0 ; i < n_cols && cols[i]; i ++ ) {
                for ( j = 0 ; j < prev_n_cols && prev_cols[j]; j ++ ) {
                        if ( prev_cols [j] == cols[i] && i != j ) {

                                reorder_found = TRUE;
                                state [i] = ETI_HEADER_REORDERED;
                reorder [i] = j;

                                break;
                        } else if (prev_cols[j] == cols[i]) {
                                /* OK, this column is not changed. */
                                break;
                        }
                }
                                                                                
                /* cols[i] is new added column. */
                if ( j == prev_n_cols ) {
            added_found = TRUE;
                        state[i] = ETI_HEADER_NEW_ADDED;
                }
        }

        /* Now try to find if there are removed columns. */
        for (i = 0 ; i < prev_n_cols && prev_cols[i]; i ++) {
                for (j = 0 ; j < n_cols && cols[j]; j ++)
                        if ( prev_cols [j] == cols[i] )
                break;
                                                                                
                /* Removed columns found. */
                if ( j == n_cols ) {
            removed_found = TRUE;
            prev_state[j] = ETI_HEADER_REMOVED;
                }
        }

    /* If nothing interesting just return. */
    if (!reorder_found && !added_found && !removed_found)
        return;

    /* Now update our cache. */
    tmp = g_malloc0 (n_rows*n_cols*sizeof(gpointer));
    g_return_if_fail (tmp);

    for (i = 0 ; i < n_rows; i ++) {
        for ( j = 0 ; j < n_cols; j ++ ) {
            if ( state[j] == ETI_HEADER_REORDERED ) {
                tmp [i*n_cols+j] = cell_data[i*prev_n_cols+reorder[j]];
                if (tmp[i*n_cols+j] &&  ATK_IS_OBJECT(tmp[i*n_cols+j])) {
                    GAL_A11Y_E_CELL(tmp[i*n_cols+j])->view_col = j;
                }
            } else if (state[j] == ETI_HEADER_UNCHANGED) {
                tmp [i*n_cols+j] = cell_data[i*prev_n_cols+j];
            } /* else: new added, keep NULL. */
        }
    }

    g_free (cell_data);
    priv->cell_data = tmp;

    /* Emit signals */
    if (reorder_found)
            g_signal_emit_by_name (G_OBJECT(a11y_item), "column_reordered");


    if (removed_found) {
        for (i = 0; i < prev_n_cols; i ++ ) {
            if (prev_state[i] == ETI_HEADER_REMOVED) {
                g_signal_emit_by_name (G_OBJECT(a11y_item), "column-deleted", i, 1);
                for (j = 0 ; j < n_rows; j ++)
                    g_signal_emit_by_name (G_OBJECT(a11y_item), "children_changed::remove", (j*prev_n_cols+i), NULL, NULL);
            }
        }
    }

    if (added_found) {
        for ( i = 0; i < n_cols; i ++ ) {
            if (state[i] == ETI_HEADER_NEW_ADDED) {
                g_signal_emit_by_name (G_OBJECT(a11y_item), "column-inserted", i, 1);
                for (j = 0 ; j < n_rows; j ++)
                    g_signal_emit_by_name (G_OBJECT(a11y_item), "children_changed::add", (j*n_cols+i), NULL, NULL);
            }
        }
    }

    priv->cols = n_cols;

    g_free (state);
    g_free (reorder);
    g_free (prev_state);

    g_free (priv->columns);
    priv->columns = cols;
}


static void
eti_real_initialize (AtkObject *obj, 
             gpointer data)
{
    ETableItem * eti;
    ETableModel * model;

    ATK_OBJECT_CLASS (parent_class)->initialize (obj, data);
    eti = E_TABLE_ITEM (data);

    model = eti->table_model;

    g_signal_connect (model, "model-rows-inserted",
              G_CALLBACK (eti_rows_inserted),
              obj);
    g_signal_connect (model, "model-rows-deleted",
              G_CALLBACK (eti_rows_deleted),
              obj);
    g_signal_connect (G_OBJECT (eti->header), "structure_change",
              G_CALLBACK (eti_header_structure_changed), obj);

}

static void
eti_class_init (GalA11yETableItemClass *klass)
{
    AtkObjectClass *atk_object_class = ATK_OBJECT_CLASS (klass);
    GObjectClass *object_class = G_OBJECT_CLASS (klass);

    quark_accessible_object               = g_quark_from_static_string ("gtk-accessible-object");

    parent_class                          = g_type_class_ref (PARENT_TYPE);

    object_class->dispose                 = eti_dispose;

    atk_object_class->get_parent          = eti_get_parent;
    atk_object_class->get_n_children      = eti_get_n_children;
    atk_object_class->ref_child           = eti_ref_child;
    atk_object_class->get_index_in_parent = eti_get_index_in_parent;
    atk_object_class->initialize          = eti_real_initialize;
}

static void
eti_init (GalA11yETableItem *a11y)
{
    GalA11yETableItemPrivate *priv;

    priv = GET_PRIVATE (a11y);

    priv->parent = NULL;
    priv->index_in_parent = -1;
    priv->selection_change_id = 0;
    priv->cursor_change_id = 0;
    priv->selection = NULL;
}

/* atk selection */

static void             atk_selection_interface_init    (AtkSelectionIface      *iface);
static gboolean         selection_add_selection    (AtkSelection           *selection,
                            gint                   i);
static gboolean         selection_clear_selection  (AtkSelection           *selection);
static AtkObject*       selection_ref_selection    (AtkSelection           *selection,
                            gint                   i);
static gint             selection_get_selection_count (AtkSelection           *selection);
static gboolean         selection_is_child_selected (AtkSelection           *selection,
                             gint                   i);

/* callbacks */
static void eti_a11y_selection_model_removed_cb (ETableItem *eti,
                         ESelectionModel *selection,
                         gpointer data);
static void eti_a11y_selection_model_added_cb (ETableItem *eti,
                           ESelectionModel *selection,
                           gpointer data);
static void eti_a11y_selection_changed_cb (ESelectionModel *selection,
                       GalA11yETableItem *a11y);
static void eti_a11y_cursor_changed_cb (ESelectionModel *selection,
                    int row, int col,
                    GalA11yETableItem *a11y);

/**
 * gal_a11y_e_table_item_get_type:
 * @void: 
 * 
 * Registers the &GalA11yETableItem class if necessary, and returns the type ID
 * associated to it.
 * 
 * Return value: The type ID of the &GalA11yETableItem class.
 **/
GType
gal_a11y_e_table_item_get_type (void)
{
    static GType type = 0;

    if (!type) {
        AtkObjectFactory *factory;

        GTypeInfo info = {
            sizeof (GalA11yETableItemClass),
            (GBaseInitFunc) NULL,
            (GBaseFinalizeFunc) NULL,
            (GClassInitFunc) eti_class_init,
            (GClassFinalizeFunc) NULL,
            NULL, /* class_data */
            sizeof (GalA11yETableItem),
            0,
            (GInstanceInitFunc) eti_init,
            NULL /* value_table_item */
        };

        static const GInterfaceInfo atk_component_info = {
            (GInterfaceInitFunc) eti_atk_component_iface_init,
            (GInterfaceFinalizeFunc) NULL,
            NULL
        };
        static const GInterfaceInfo atk_table_info = {
            (GInterfaceInitFunc) eti_atk_table_iface_init,
            (GInterfaceFinalizeFunc) NULL,
            NULL
        };

        static const GInterfaceInfo atk_selection_info = {
            (GInterfaceInitFunc) atk_selection_interface_init,
            (GInterfaceFinalizeFunc) NULL,
            NULL
        };


        factory = atk_registry_get_factory (atk_get_default_registry (), GNOME_TYPE_CANVAS_ITEM);
        parent_type = atk_object_factory_get_accessible_type (factory);

        type = gal_a11y_type_register_static_with_private (PARENT_TYPE, "GalA11yETableItem", &info, 0,
                                   sizeof (GalA11yETableItemPrivate), &priv_offset);

        g_type_add_interface_static (type, ATK_TYPE_COMPONENT, &atk_component_info);
        g_type_add_interface_static (type, ATK_TYPE_TABLE, &atk_table_info);
        g_type_add_interface_static (type, ATK_TYPE_SELECTION, &atk_selection_info);
    }

    return type;
}

AtkObject *
gal_a11y_e_table_item_new (AtkObject *parent,
               ETableItem *item,
               int index_in_parent)
{
    GalA11yETableItem *a11y;
    AtkObject *accessible;
    int n;

    g_return_val_if_fail (item && item->cols >= 0 && item->rows >= 0, NULL);
    a11y = g_object_new (gal_a11y_e_table_item_get_type (), NULL);

    atk_object_initialize (ATK_OBJECT (a11y), item);

    GET_PRIVATE (a11y)->parent = parent;
    GET_PRIVATE (a11y)->index_in_parent = index_in_parent;

    accessible  = ATK_OBJECT(a11y);
    accessible->role = ATK_ROLE_TREE_TABLE;

    /* Initialize cell data. */
    n = item->cols * item->rows;
    GET_PRIVATE (a11y)->cols = item->cols;
    GET_PRIVATE (a11y)->rows = item->rows;
    if (n > 0) {
        GET_PRIVATE (a11y)->cell_data = g_malloc0(n*sizeof(gpointer));
        /* memory error. */
        if ( GET_PRIVATE (a11y)->cell_data == NULL)
            return NULL;
    } else
        GET_PRIVATE (a11y)->cell_data = NULL;
        

        GET_PRIVATE (a11y)->columns = e_table_header_get_columns (item->header);                                                                                
        if ( GET_PRIVATE (a11y)->columns == NULL)
                return NULL;

    if (item) {
        g_signal_connect (G_OBJECT(item), "selection_model_removed",
                  G_CALLBACK (eti_a11y_selection_model_removed_cb), NULL);
        g_signal_connect (G_OBJECT(item), "selection_model_added",
                  G_CALLBACK (eti_a11y_selection_model_added_cb), NULL);
        if (item->selection)
            gal_a11y_e_table_item_ref_selection (a11y,
                                 item->selection);

        /* find the TableItem's parent: table or tree */
        GET_PRIVATE (a11y)->widget = gtk_widget_get_parent (GTK_WIDGET (item->parent.canvas));
        if (E_IS_TREE (GET_PRIVATE (a11y)->widget)) {
            ETreeModel *model;
            model = e_tree_get_model (E_TREE (GET_PRIVATE (a11y)->widget));
            g_signal_connect (G_OBJECT(model), "node_changed",
                    G_CALLBACK (eti_tree_model_node_changed_cb), item);
        } 
    }
    if (parent)
        g_object_ref (parent);

#if 0
    if (item)
        g_object_weak_ref (G_OBJECT (item),
                   unref_accessible,
                   a11y);
#endif

    return ATK_OBJECT (a11y);
}

static gboolean
gal_a11y_e_table_item_ref_selection (GalA11yETableItem *a11y,
                     ESelectionModel *selection)
{
    GalA11yETableItemPrivate *priv;

    g_return_val_if_fail (a11y && selection, FALSE);

    priv = GET_PRIVATE (a11y);
    priv->selection_change_id = g_signal_connect (
        G_OBJECT(selection), "selection_changed",
        G_CALLBACK (eti_a11y_selection_changed_cb), a11y);
    priv->cursor_change_id = g_signal_connect (
            G_OBJECT(selection), "cursor_changed",
        G_CALLBACK (eti_a11y_cursor_changed_cb), a11y);

    priv->selection = selection;
    g_object_ref (selection);

    return TRUE;
}

static gboolean
gal_a11y_e_table_item_unref_selection (GalA11yETableItem *a11y)
{
    GalA11yETableItemPrivate *priv;

    g_return_val_if_fail (a11y, FALSE);

    priv = GET_PRIVATE (a11y);

    g_return_val_if_fail (priv->selection_change_id != 0, FALSE);
    g_return_val_if_fail (priv->cursor_change_id != 0, FALSE);


    g_signal_handler_disconnect (priv->selection,
                     priv->selection_change_id);
    g_signal_handler_disconnect (priv->selection,
                     priv->cursor_change_id);
    priv->cursor_change_id = 0;
    priv->selection_change_id = 0;

    g_object_unref (priv->selection);
    priv->selection = NULL;

    return TRUE;
}

/* callbacks */

static void
eti_a11y_selection_model_removed_cb (ETableItem *eti, ESelectionModel *selection,
                     gpointer data)
{
    AtkObject *atk_obj;
    GalA11yETableItem *a11y;

    g_return_if_fail (E_IS_TABLE_ITEM (eti));
    g_return_if_fail (E_IS_SELECTION_MODEL (selection));

    atk_obj = atk_gobject_accessible_for_object (G_OBJECT (eti));
    a11y = GAL_A11Y_E_TABLE_ITEM (atk_obj);

    if (selection == GET_PRIVATE (a11y)->selection)
        gal_a11y_e_table_item_unref_selection (a11y);
}

static void
eti_a11y_selection_model_added_cb (ETableItem *eti, ESelectionModel *selection,
                   gpointer data)
{
    AtkObject *atk_obj;
    GalA11yETableItem *a11y;

    g_return_if_fail (E_IS_TABLE_ITEM (eti));
    g_return_if_fail (E_IS_SELECTION_MODEL (selection));

    atk_obj = atk_gobject_accessible_for_object (G_OBJECT (eti));
    a11y = GAL_A11Y_E_TABLE_ITEM (atk_obj);

    if (GET_PRIVATE (a11y)->selection)
        gal_a11y_e_table_item_unref_selection (a11y);
    gal_a11y_e_table_item_ref_selection (a11y, selection);
}

static void
eti_a11y_selection_changed_cb (ESelectionModel *selection, GalA11yETableItem *a11y)
{
    g_return_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (a11y));

    g_signal_emit_by_name (a11y, "selection_changed");
}

static void
eti_a11y_cursor_changed_cb (ESelectionModel *selection,
                int row, int col,  GalA11yETableItem *a11y)
{
    AtkObject * cell;
    int view_row, view_col;
    ETableItem *item;

    g_return_if_fail (GAL_A11Y_IS_E_TABLE_ITEM (a11y));

    g_signal_emit_by_name (a11y, "selection_changed");

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (a11y)));

    g_return_if_fail (item);

    view_row = model_to_view_row (item, row);
    view_col = model_to_view_col (item, col);

    cell = atk_table_ref_at (ATK_TABLE (a11y), view_row, view_col);
    if (cell != NULL) {
        gal_a11y_e_cell_add_state (GAL_A11Y_E_CELL (cell), ATK_STATE_FOCUSED, FALSE);

            if (ATK_IS_OBJECT (cell))
                    g_signal_emit_by_name  (a11y,
                                        "active-descendant-changed",
                                        cell);
        atk_focus_tracker_notify (cell);
    }

}

/* atk selection */

static void atk_selection_interface_init (AtkSelectionIface *iface)
{
    g_return_if_fail (iface != NULL);
    iface->add_selection = selection_add_selection;
    iface->clear_selection = selection_clear_selection;
    iface->ref_selection = selection_ref_selection;
    iface->get_selection_count = selection_get_selection_count;
    iface->is_child_selected = selection_is_child_selected;
}

static gboolean
selection_add_selection (AtkSelection *selection, gint index)
{
    AtkTable *table;
    gint row, col;
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (selection)));
    if (!item)
        return FALSE;

    table = ATK_TABLE (selection);

    row = atk_table_get_row_at_index (table, index);
    atk_table_add_row_selection (table, row);

    col = atk_table_get_column_at_index (table, index);
    e_selection_model_change_cursor (item->selection,
                     view_to_model_row (item, row),
                     view_to_model_col (item, col));
    e_selection_model_cursor_changed (item->selection,
                      view_to_model_row (item, row),
                      view_to_model_col (item, col));
    e_selection_model_cursor_activated (item->selection,
                        view_to_model_row (item, row),
                        view_to_model_col (item, col));
    return TRUE;
}

static gboolean
selection_clear_selection (AtkSelection *selection)
{
    ETableItem *item;

    item = E_TABLE_ITEM (eti_a11y_get_gobject (ATK_OBJECT (selection)));
    if (!item)
        return FALSE;

    e_selection_model_clear (item->selection);
    return TRUE;
}

static AtkObject *
selection_ref_selection (AtkSelection *selection, gint index)
{
    AtkTable *table;
    gint row, col;

    table = ATK_TABLE (selection);
    row = atk_table_get_row_at_index (table, index);
    col = atk_table_get_column_at_index (table, index);
    if (!atk_table_is_row_selected (table, row))
        return NULL;

    return atk_table_ref_at (table, row, col);
}

static gint
selection_get_selection_count (AtkSelection *selection)
{
    AtkTable *table;
    gint n_selected;

    table = ATK_TABLE (selection);
    n_selected = atk_table_get_selected_rows (table, NULL);
    if (n_selected > 0)
        n_selected *= atk_table_get_n_columns (table);
    return n_selected;
}

static gboolean
selection_is_child_selected (AtkSelection *selection, gint i)
{
    gint row;

    row = atk_table_get_row_at_index (ATK_TABLE (selection), i);
    return atk_table_is_row_selected (ATK_TABLE (selection), row);
}