path: root/e-util/e-table-header.c

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with the program; if not, see <http://www.gnu.org/licenses/>
 *
 *
 * Authors:
 *      Chris Lahey <clahey@ximian.com>
 *      Miguel de Icaza <miguel@ximian.com>
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <string.h>

#include <gtk/gtk.h>

#include "e-marshal.h"
#include "e-table-defines.h"
#include "e-table-header.h"

enum {
    PROP_0,
    PROP_SORT_INFO,
    PROP_WIDTH,
    PROP_WIDTH_EXTRAS
};

enum {
    STRUCTURE_CHANGE,
    DIMENSION_CHANGE,
    EXPANSION_CHANGE,
    REQUEST_WIDTH,
    LAST_SIGNAL
};

static void eth_set_size (ETableHeader *eth, gint idx, gint size);
static void eth_calc_widths (ETableHeader *eth);

static guint eth_signals[LAST_SIGNAL] = { 0, };

G_DEFINE_TYPE (ETableHeader, e_table_header, G_TYPE_OBJECT)

struct two_ints {
    gint column;
    gint width;
};

static void
eth_set_width (ETableHeader *eth,
               gint width)
{
    eth->width = width;
}

static void
dequeue (ETableHeader *eth,
         gint *column,
         gint *width)
{
    GSList *head;
    struct two_ints *store;
    head = eth->change_queue;
    eth->change_queue = eth->change_queue->next;
    if (!eth->change_queue)
        eth->change_tail = NULL;
    store = head->data;
    g_slist_free_1 (head);
    if (column)
        *column = store->column;
    if (width)
        *width = store->width;
    g_free (store);
}

static gboolean
dequeue_idle (ETableHeader *eth)
{
    gint column, width;

    dequeue (eth, &column, &width);
    while (eth->change_queue && ((struct two_ints *)
        eth->change_queue->data)->column == column)
        dequeue (eth, &column, &width);

    if (column == -1)
        eth_set_width (eth, width);
    else if (column < eth->col_count)
        eth_set_size (eth, column, width);
    if (eth->change_queue)
        return TRUE;
    else {
        eth_calc_widths (eth);
        eth->idle = 0;
        return FALSE;
    }
}

static void
enqueue (ETableHeader *eth,
         gint column,
         gint width)
{
    struct two_ints *store;
    store = g_new (struct two_ints, 1);
    store->column = column;
    store->width = width;

    eth->change_tail = g_slist_last (g_slist_append (eth->change_tail, store));
    if (!eth->change_queue)
        eth->change_queue = eth->change_tail;

    if (!eth->idle) {
        eth->idle = g_idle_add_full (
            G_PRIORITY_LOW, (GSourceFunc)
            dequeue_idle, eth, NULL);
    }
}

void
e_table_header_set_size (ETableHeader *eth,
                         gint idx,
                         gint size)
{
    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));

    enqueue (eth, idx, size);
}

static void
eth_do_remove (ETableHeader *eth,
               gint idx,
               gboolean do_unref)
{
    if (do_unref)
        g_object_unref (eth->columns[idx]);

    memmove (
        &eth->columns[idx], &eth->columns[idx + 1],
        sizeof (ETableCol *) * (eth->col_count - idx - 1));
    eth->col_count--;
}

static void
eth_finalize (GObject *object)
{
    ETableHeader *eth = E_TABLE_HEADER (object);
    const gint cols = eth->col_count;
    gint i;

    if (eth->sort_info) {
        if (eth->sort_info_group_change_id)
            g_signal_handler_disconnect (
                eth->sort_info,
                eth->sort_info_group_change_id);
        g_object_unref (eth->sort_info);
        eth->sort_info = NULL;
    }

    if (eth->idle)
        g_source_remove (eth->idle);
    eth->idle = 0;

    if (eth->change_queue) {
        g_slist_foreach (eth->change_queue, (GFunc) g_free, NULL);
        g_slist_free (eth->change_queue);
        eth->change_queue = NULL;
    }

    /*
     * Destroy columns
     */
    for (i = cols - 1; i >= 0; i--) {
        eth_do_remove (eth, i, TRUE);
    }
    g_free (eth->columns);

    eth->col_count = 0;
    eth->columns = NULL;

    /* Chain up to parent's finalize() method. */
    G_OBJECT_CLASS (e_table_header_parent_class)->finalize (object);
}

static void
eth_group_info_changed (ETableSortInfo *info,
                        ETableHeader *eth)
{
    enqueue (eth, -1, eth->nominal_width);
}

static void
eth_set_property (GObject *object,
                  guint property_id,
                  const GValue *val,
                  GParamSpec *pspec)
{
    ETableHeader *eth = E_TABLE_HEADER (object);

    switch (property_id) {
    case PROP_WIDTH:
        eth->nominal_width = g_value_get_double (val);
        enqueue (eth, -1, eth->nominal_width);
        break;
    case PROP_WIDTH_EXTRAS:
        eth->width_extras = g_value_get_double (val);
        enqueue (eth, -1, eth->nominal_width);
        break;
    case PROP_SORT_INFO:
        if (eth->sort_info) {
            if (eth->sort_info_group_change_id)
                g_signal_handler_disconnect (
                    eth->sort_info,
                    eth->sort_info_group_change_id);
            g_object_unref (eth->sort_info);
        }
        eth->sort_info = E_TABLE_SORT_INFO (g_value_get_object (val));
        if (eth->sort_info) {
            g_object_ref (eth->sort_info);
            eth->sort_info_group_change_id = g_signal_connect (
                eth->sort_info, "group_info_changed",
                G_CALLBACK (eth_group_info_changed), eth);
        }
        enqueue (eth, -1, eth->nominal_width);
        break;
    default:
        break;
    }
}

static void
eth_get_property (GObject *object,
                  guint property_id,
                  GValue *val,
                  GParamSpec *pspec)
{
    ETableHeader *eth = E_TABLE_HEADER (object);

    switch (property_id) {
    case PROP_SORT_INFO:
        g_value_set_object (val, eth->sort_info);
        break;
    case PROP_WIDTH:
        g_value_set_double (val, eth->nominal_width);
        break;
    case PROP_WIDTH_EXTRAS:
        g_value_set_double (val, eth->width_extras);
        break;
    default:
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
        break;
    }
}

static void
e_table_header_class_init (ETableHeaderClass *class)
{
    GObjectClass *object_class = G_OBJECT_CLASS (class);

    object_class->finalize = eth_finalize;
    object_class->set_property = eth_set_property;
    object_class->get_property = eth_get_property;

    g_object_class_install_property (
        object_class,
        PROP_WIDTH,
        g_param_spec_double (
            "width", "Width", "Width",
            0.0, G_MAXDOUBLE, 0.0,
            G_PARAM_READWRITE));

    g_object_class_install_property (
        object_class,
        PROP_WIDTH_EXTRAS,
        g_param_spec_double (
            "width_extras",
            "Width of Extras",
            "Width of Extras",
            0.0, G_MAXDOUBLE, 0.0,
            G_PARAM_READWRITE));

    g_object_class_install_property (
        object_class,
        PROP_SORT_INFO,
        g_param_spec_object (
            "sort_info",
            "Sort Info",
            "Sort Info",
            E_TYPE_TABLE_SORT_INFO,
            G_PARAM_READWRITE));

    eth_signals[STRUCTURE_CHANGE] = g_signal_new (
        "structure_change",
        G_TYPE_FROM_CLASS (object_class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ETableHeaderClass, structure_change),
        (GSignalAccumulator) NULL, NULL,
        g_cclosure_marshal_VOID__VOID,
        G_TYPE_NONE, 0);

    eth_signals[DIMENSION_CHANGE] = g_signal_new (
        "dimension_change",
        G_TYPE_FROM_CLASS (object_class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ETableHeaderClass, dimension_change),
        (GSignalAccumulator) NULL, NULL,
        g_cclosure_marshal_VOID__INT,
        G_TYPE_NONE, 1,
        G_TYPE_INT);

    eth_signals[EXPANSION_CHANGE] = g_signal_new (
        "expansion_change",
        G_TYPE_FROM_CLASS (object_class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ETableHeaderClass, expansion_change),
        (GSignalAccumulator) NULL, NULL,
        g_cclosure_marshal_VOID__VOID,
        G_TYPE_NONE, 0);

    eth_signals[REQUEST_WIDTH] = g_signal_new (
        "request_width",
        G_TYPE_FROM_CLASS (object_class),
        G_SIGNAL_RUN_LAST,
        G_STRUCT_OFFSET (ETableHeaderClass, request_width),
        (GSignalAccumulator) NULL, NULL,
        e_marshal_INT__INT,
        G_TYPE_INT, 1,
        G_TYPE_INT);

    class->structure_change = NULL;
    class->dimension_change = NULL;
    class->expansion_change = NULL;
    class->request_width = NULL;
}

static void
e_table_header_init (ETableHeader *eth)
{
    eth->col_count                 = 0;
    eth->width                     = 0;

    eth->sort_info                 = NULL;
    eth->sort_info_group_change_id = 0;

    eth->columns                   = NULL;

    eth->change_queue              = NULL;
    eth->change_tail               = NULL;

    eth->width_extras              = 0;
}

/**
 * e_table_header_new:
 *
 * Returns: A new @ETableHeader object.
 */
ETableHeader *
e_table_header_new (void)
{

    return g_object_new (E_TYPE_TABLE_HEADER, NULL);
}

static void
eth_update_offsets (ETableHeader *eth)
{
    gint i;
    gint x = 0;

    for (i = 0; i < eth->col_count; i++) {
        ETableCol *etc = eth->columns[i];

        etc->x = x;
        x += etc->width;
    }
}

static void
eth_do_insert (ETableHeader *eth,
               gint pos,
               ETableCol *val)
{
    memmove (
        &eth->columns[pos + 1], &eth->columns[pos],
        sizeof (ETableCol *) * (eth->col_count - pos));
    eth->columns[pos] = val;
    eth->col_count++;
}

/**
 * e_table_header_add_column:
 * @eth: the table header to add the column to.
 * @tc: the ETableCol definition
 * @pos: position where the ETableCol will go.
 *
 * This function adds the @tc ETableCol definition into the @eth ETableHeader
 * at position @pos.  This is the way you add new ETableCols to the
 * ETableHeader.  The header will assume ownership of the @tc; you should not
 * unref it after you add it.
 *
 * This function will emit the "structure_change" signal on the @eth object.
 * The ETableCol is assumed
 */
void
e_table_header_add_column (ETableHeader *eth,
                           ETableCol *tc,
                           gint pos)
{
    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));
    g_return_if_fail (tc != NULL);
    g_return_if_fail (E_IS_TABLE_COL (tc));
    g_return_if_fail (pos >= -1 && pos <= eth->col_count);

    if (pos == -1)
        pos = eth->col_count;
    eth->columns = g_realloc (
        eth->columns, sizeof (ETableCol *) * (eth->col_count + 1));

    /*
     * We are the primary owners of the column
     */
    g_object_ref (tc);

    eth_do_insert (eth, pos, tc);

    enqueue (eth, -1, eth->nominal_width);
    g_signal_emit (eth, eth_signals[STRUCTURE_CHANGE], 0);
}

/**
 * e_table_header_get_column:
 * @eth: the ETableHeader to query
 * @column: the column inside the @eth.
 *
 * Returns: The ETableCol at @column in the @eth object
 */
ETableCol *
e_table_header_get_column (ETableHeader *eth,
                           gint column)
{
    g_return_val_if_fail (eth != NULL, NULL);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), NULL);

    if (column < 0)
        return NULL;

    if (column >= eth->col_count)
        return NULL;

    return eth->columns[column];
}

/**
 * e_table_header_get_column_by_spec:
 * @eth: the ETableHeader to query
 * @spec: an #ETableColumnSpecification
 *
 * Returns the #ETableCol having @spec as the column specification, or
 * %NULL if there is no matching #ETableCol.
 *
 * Returns: an #ETableCol, or %NULL
 **/
ETableCol *
e_table_header_get_column_by_spec (ETableHeader *eth,
                                   ETableColumnSpecification *spec)
{
    gint ii;

    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), NULL);
    g_return_val_if_fail (E_IS_TABLE_COLUMN_SPECIFICATION (spec), NULL);

    for (ii = 0; ii < eth->col_count; ii++) {
        gboolean column_specs_equal;

        column_specs_equal = e_table_column_specification_equal (
            spec, eth->columns[ii]->spec);

        if (column_specs_equal)
            return eth->columns[ii];
    }

    return NULL;
}

/**
 * e_table_header_get_column_by_col_id:
 * @eth: the ETableHeader to query
 * @col_id: the col_id to search for.
 *
 * Returns: The ETableCol with col_idx = @col_idx in the @eth object
 */
ETableCol *
e_table_header_get_column_by_col_idx (ETableHeader *eth,
                                      gint col_idx)
{
    gint i;
    g_return_val_if_fail (eth != NULL, NULL);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), NULL);

    for (i = 0; i < eth->col_count; i++) {
        if (eth->columns[i]->spec->model_col == col_idx) {
            return eth->columns[i];
        }
    }

    return NULL;
}

/**
 * e_table_header_count:
 * @eth: the ETableHeader to query
 *
 * Returns: the number of columns in this ETableHeader.
 */
gint
e_table_header_count (ETableHeader *eth)
{
    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    return eth->col_count;
}

/**
 * e_table_header_index:
 * @eth: the ETableHeader to query
 * @col: the column to fetch.
 *
 * ETableHeaders contain the visual list of columns that the user will
 * view.  The visible columns will typically map to different columns
 * in the ETableModel (because the user reordered the data for
 * example).
 *
 * Returns: the column in the model that the @col column
 * in the ETableHeader points to.  */
gint
e_table_header_index (ETableHeader *eth,
                      gint col)
{
    g_return_val_if_fail (eth != NULL, -1);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), -1);
    g_return_val_if_fail (col >= 0 && col < eth->col_count, -1);

    return eth->columns[col]->spec->model_col;
}

/**
 * e_table_header_get_index_at:
 * @eth: the ETableHeader to query
 * @x_offset: a pixel count from the beginning of the ETableHeader
 *
 * This will return the ETableHeader column that would contain
 * the @x_offset pixel.
 *
 * Returns: the column that contains pixel @x_offset, or -1
 * if no column inside this ETableHeader contains that pixel.
 */
gint
e_table_header_get_index_at (ETableHeader *eth,
                             gint x_offset)
{
    gint i, total;

    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    total = 0;
    for (i = 0; i < eth->col_count; i++) {
        total += eth->columns[i]->width;

        if (x_offset < total)
            return i;
    }

    return -1;
}

/**
 * e_table_header_get_columns:
 * @eth: The ETableHeader to query
 *
 * Returns: A NULL terminated array of the ETableCols
 * contained in the ETableHeader @eth.  Note that every
 * returned ETableCol in the array has been referenced, to release
 * this information you need to g_free the buffer returned
 * and you need to g_object_unref every element returned
 */
ETableCol **
e_table_header_get_columns (ETableHeader *eth)
{
    ETableCol **ret;
    gint i;

    g_return_val_if_fail (eth != NULL, NULL);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), NULL);

    ret = g_new (ETableCol *, eth->col_count + 1);
    memcpy (ret, eth->columns, sizeof (ETableCol *) * eth->col_count);
    ret[eth->col_count] = NULL;

    for (i = 0; i < eth->col_count; i++) {
        g_object_ref (ret[i]);
    }

    return ret;
}

/**
 * e_table_header_get_selected:
 * @eth: The ETableHeader to query
 *
 * Returns: The number of selected columns in the @eth object.
 */
gint
e_table_header_get_selected (ETableHeader *eth)
{
    gint i;
    gint selected = 0;

    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    for (i = 0; i < eth->col_count; i++) {
        if (eth->columns[i]->selected)
            selected++;
    }

    return selected;
}

/**
 * e_table_header_total_width:
 * @eth: The ETableHeader to query
 *
 * Returns: the number of pixels used by the @eth object
 * when rendered on screen
 */
gint
e_table_header_total_width (ETableHeader *eth)
{
    gint total, i;

    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    total = 0;
    for (i = 0; i < eth->col_count; i++)
        total += eth->columns[i]->width;

    return total;
}

/**
 * e_table_header_min_width:
 * @eth: The ETableHeader to query
 *
 * Returns: the minimum number of pixels required by the @eth object.
 **/
gint
e_table_header_min_width (ETableHeader *eth)
{
    gint total, i;

    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    total = 0;
    for (i = 0; i < eth->col_count; i++)
        total += eth->columns[i]->min_width;

    return total;
}

/**
 * e_table_header_move:
 * @eth: The ETableHeader to operate on.
 * @source_index: the source column to move.
 * @target_index: the target location for the column
 *
 * This function moves the column @source_index to @target_index
 * inside the @eth ETableHeader.  The signals "dimension_change"
 * and "structure_change" will be emmited
 */
void
e_table_header_move (ETableHeader *eth,
                     gint source_index,
                     gint target_index)
{
    ETableCol *old;

    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));
    g_return_if_fail (source_index >= 0);
    g_return_if_fail (target_index >= 0);
    g_return_if_fail (source_index < eth->col_count);

    /* Can be moved beyond the last item. */
    g_return_if_fail (target_index < eth->col_count + 1);

    if (source_index < target_index)
        target_index--;

    old = eth->columns[source_index];
    eth_do_remove (eth, source_index, FALSE);
    eth_do_insert (eth, target_index, old);
    eth_update_offsets (eth);

    g_signal_emit (eth, eth_signals[DIMENSION_CHANGE], 0, eth->width);
    g_signal_emit (eth, eth_signals[STRUCTURE_CHANGE], 0);
}

/**
 * e_table_header_remove:
 * @eth: The ETableHeader to operate on.
 * @idx: the index to the column to be removed.
 *
 * Removes the column at @idx position in the ETableHeader @eth.
 * This emmits the "structure_change" signal on the @eth object.
 */
void
e_table_header_remove (ETableHeader *eth,
                       gint idx)
{
    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));
    g_return_if_fail (idx >= 0);
    g_return_if_fail (idx < eth->col_count);

    eth_do_remove (eth, idx, TRUE);
    enqueue (eth, -1, eth->nominal_width);
    g_signal_emit (eth, eth_signals[STRUCTURE_CHANGE], 0);
}

/*
 * FIXME: deprecated?
 */
void
e_table_header_set_selection (ETableHeader *eth,
                              gboolean allow_selection)
{
    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));
}

static void
eth_set_size (ETableHeader *eth,
              gint idx,
              gint size)
{
    gdouble expansion;
    gdouble old_expansion;
    gint min_width;
    gint left_width;
    gint total_extra;
    gint expandable_count;
    gint usable_width;
    gint i;
    g_return_if_fail (eth != NULL);
    g_return_if_fail (E_IS_TABLE_HEADER (eth));
    g_return_if_fail (idx >= 0);
    g_return_if_fail (idx < eth->col_count);

    /* If this column is not resizable, don't do anything. */
    if (!eth->columns[idx]->spec->resizable)
        return;

    expansion = 0;
    min_width = 0;
    left_width = 0;
    expandable_count = -1;

    /* Calculate usable area. */
    for (i = 0; i < idx; i++) {
        left_width += eth->columns[i]->width;
    }
    /* - 1 to account for the last pixel border. */
    usable_width = eth->width - left_width - 1;

    if (eth->sort_info)
        usable_width -= e_table_sort_info_grouping_get_count (
            eth->sort_info) * GROUP_INDENT;

    /* Calculate minimum_width of stuff on the right as well as
     * total usable expansion on the right.
     */
    for (; i < eth->col_count; i++) {
        min_width += eth->columns[i]->min_width + eth->width_extras;
        if (eth->columns[i]->spec->resizable) {
            expansion += eth->columns[i]->expansion;
            expandable_count++;
        }
    }
    /* If there's no room for anything, don't change. */
    if (expansion == 0)
        return;

    /* (1) If none of the columns to the right are expandable, use
     * all the expansion space in this column.
     */
    if (expandable_count == 0) {
        eth->columns[idx]->expansion = expansion;
        for (i = idx + 1; i < eth->col_count; i++) {
            eth->columns[i]->expansion = 0;
        }

        g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
        return;
    }

    total_extra = usable_width - min_width;
    /* If there's no extra space, set all expansions to 0. */
    if (total_extra <= 0) {
        for (i = idx; i < eth->col_count; i++) {
            eth->columns[i]->expansion = 0;
        }
        g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
        return;
    }

    /* If you try to resize smaller than the minimum width, it
     * uses the minimum. */
    if (size < eth->columns[idx]->min_width + eth->width_extras)
        size = eth->columns[idx]->min_width + eth->width_extras;

    /* If all the extra space will be used up in this column, use
     * all the expansion and set all others to 0.
     */
    if (size >= total_extra + eth->columns[idx]->min_width + eth->width_extras) {
        eth->columns[idx]->expansion = expansion;
        for (i = idx + 1; i < eth->col_count; i++) {
            eth->columns[i]->expansion = 0;
        }
        g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
        return;
    }

    /* The old_expansion used by columns to the right. */
    old_expansion = expansion;
    old_expansion -= eth->columns[idx]->expansion;
    /* Set the new expansion so that it will generate the desired size. */
    eth->columns[idx]->expansion =
        expansion * (((gdouble)(size - (eth->columns[idx]->min_width +
        eth->width_extras))) / ((gdouble) total_extra));
    /* The expansion left for the columns on the right. */
    expansion -= eth->columns[idx]->expansion;

    /* (2) If the old columns to the right didn't have any
     * expansion before, expand them evenly.  old_expansion > 0 by
     * expansion = SUM(i=idx to col_count -1,
     * columns[i]->min_width) - columns[idx]->min_width) =
     * SUM(non-negatives).
     */
    if (old_expansion == 0) {
        for (i = idx + 1; i < eth->col_count; i++) {
            if (eth->columns[idx]->spec->resizable) {
                /* expandable_count != 0 by (1) */
                eth->columns[i]->expansion = expansion / expandable_count;
            }
        }
        g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
        return;
    }

    for (i = idx + 1; i < eth->col_count; i++) {
        if (eth->columns[idx]->spec->resizable) {
            /* old_expansion != 0 by (2) */
            eth->columns[i]->expansion *= expansion / old_expansion;
        }
    }
    g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
}

/**
 * e_table_header_col_diff:
 * @eth: the ETableHeader to query.
 * @start_col: the starting column
 * @end_col: the ending column.
 *
 * Computes the number of pixels between the columns @start_col and
 * @end_col.
 *
 * Returns: the number of pixels between @start_col and @end_col on the
 * @eth ETableHeader object
 */
gint
e_table_header_col_diff (ETableHeader *eth,
                         gint start_col,
                         gint end_col)
{
    gint total, col;

    g_return_val_if_fail (eth != NULL, 0);
    g_return_val_if_fail (E_IS_TABLE_HEADER (eth), 0);

    if (start_col < 0)
        start_col = 0;
    if (end_col > eth->col_count)
        end_col = eth->col_count;

    total = 0;
    for (col = start_col; col < end_col; col++) {

        total += eth->columns[col]->width;
    }

    return total;
}

static void
eth_calc_widths (ETableHeader *eth)
{
    gint i;
    gint extra;
    gdouble expansion;
    gint last_position = 0;
    gdouble next_position = 0;
    gint last_resizable = -1;
    gint *widths;
    gboolean changed;

    widths = g_new (int, eth->col_count);

    /* - 1 to account for the last pixel border. */
    extra = eth->width - 1;
    expansion = 0;
    for (i = 0; i < eth->col_count; i++) {
        extra -= eth->columns[i]->min_width + eth->width_extras;
        if (eth->columns[i]->spec->resizable && eth->columns[i]->expansion > 0)
            last_resizable = i;
        expansion += eth->columns[i]->spec->resizable ? eth->columns[i]->expansion : 0;
        widths[i] = eth->columns[i]->min_width + eth->width_extras;
    }
    if (eth->sort_info)
        extra -= e_table_sort_info_grouping_get_count (eth->sort_info)
            * GROUP_INDENT;
    if (expansion != 0 && extra > 0) {
        for (i = 0; i < last_resizable; i++) {
            next_position +=
                extra * (eth->columns[i]->spec->resizable ?
                eth->columns[i]->expansion : 0) / expansion;
            widths[i] += next_position - last_position;
            last_position = next_position;
        }
        widths[i] += extra - last_position;
    }

    changed = FALSE;

    for (i = 0; i < eth->col_count; i++) {
        if (eth->columns[i]->width != widths[i]) {
            changed = TRUE;
            eth->columns[i]->width = widths[i];
        }
    }
    g_free (widths);
    if (changed)
        g_signal_emit (eth, eth_signals[DIMENSION_CHANGE], 0, eth->width);
    eth_update_offsets (eth);
}

void
e_table_header_update_horizontal (ETableHeader *eth)
{
    gint i;
    gint cols;

    cols = eth->col_count;

    for (i = 0; i < cols; i++) {
        gint width = 0;

        g_signal_emit_by_name (
            eth, "request_width", i, &width);
        eth->columns[i]->min_width = width + 10;
        eth->columns[i]->expansion = 1;
    }
    enqueue (eth, -1, eth->nominal_width);
    g_signal_emit (eth, eth_signals[EXPANSION_CHANGE], 0);
}

gint
e_table_header_prioritized_column (ETableHeader *eth)
{
    gint best_model_col = 0;
    gint best_priority;
    gint i;
    gint count;

    count = e_table_header_count (eth);
    if (count == 0)
        return -1;
    best_priority = e_table_header_get_column (eth, 0)->spec->priority;
    best_model_col = e_table_header_get_column (eth, 0)->spec->model_col;
    for (i = 1; i < count; i++) {
        gint priority = e_table_header_get_column (eth, i)->spec->priority;
        if (priority > best_priority) {
            best_priority = priority;
            best_model_col = e_table_header_get_column (eth, i)->spec->model_col;
        }
    }
    return best_model_col;
}

ETableCol *
e_table_header_prioritized_column_selected (ETableHeader *eth,
                                            ETableColCheckFunc check_func,
                                            gpointer user_data)
{
    ETableCol *best_col = NULL;
    gint best_priority = G_MININT;
    gint i;
    gint count;

    count = e_table_header_count (eth);
    if (count == 0)
        return NULL;
    for (i = 1; i < count; i++) {
        ETableCol *col = e_table_header_get_column (eth, i);
        if (col) {
            if ((best_col == NULL || col->spec->priority > best_priority)
               && check_func (col, user_data)) {
                best_priority = col->spec->priority;
                best_col = col;
            }
        }
    }
    return best_col;
}