path: root/widgets/table/e-cell-tree.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* 
 * e-cell-tree.c - Tree cell object.
 * Copyright 1999, 2000, 2001, Ximian, Inc.
 *
 * Authors:
 *   Chris Toshok <toshok@ximian.com>
 *
 * A majority of code taken from:
 *
 * the ECellText renderer.
 * Copyright 1998, The Free Software Foundation
 * Copyright 1999, 2000, Ximian, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License, version 2, as published by the Free Software Foundation.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <config.h>

#include <ctype.h>
#include <math.h>
#include <stdio.h>

#include <gdk/gdkx.h> /* for BlackPixel */
#include <gtk/gtkenums.h>
#include <gtk/gtkentry.h>
#include <gtk/gtkwindow.h>
#include <gtk/gtkinvisible.h>
#include <gtk/gtksignal.h>
#include <gdk/gdkkeysyms.h>
#include <libgnomeui/gnome-canvas.h>

#include "e-tree-table-adapter.h"
#include "e-tree-model.h"
#include "gal/util/e-util.h"
#include "e-table-item.h"
#include "e-cell-tree.h"

#include "tree-expanded.xpm"
#include "tree-unexpanded.xpm"

#define PARENT_TYPE e_cell_get_type ()

typedef struct {
    ECellView    cell_view;
    ECellView   *subcell_view;
    GdkGC       *gc;

    GnomeCanvas *canvas;

} ECellTreeView;

static ECellClass *parent_class;

#define INDENT_AMOUNT 16

static ETreePath
e_cell_tree_get_node (ETableModel *table_model, int row)
{
    return e_table_model_value_at (table_model, -1, row);
}

static ETreeModel*
e_cell_tree_get_tree_model (ETableModel *table_model, int row)
{
    return e_table_model_value_at (table_model, -2, row);
}

static ETreeTableAdapter *
e_cell_tree_get_tree_table_adapter (ETableModel *table_model, int row)
{
    return e_table_model_value_at (table_model, -3, row);
}

static int
visible_depth_of_node (ETableModel *model, int row)
{
    ETreeModel *tree_model = e_cell_tree_get_tree_model(model, row);
    ETreeTableAdapter *adapter = e_cell_tree_get_tree_table_adapter(model, row);
    ETreePath path = e_cell_tree_get_node(model, row);
    return (e_tree_model_node_depth (tree_model, path)
        - (e_tree_table_adapter_root_node_is_visible (adapter) ? 0 : 1));
}

static gint
offset_of_node (ETableModel *table_model, int row)
{
    ETreeModel *tree_model = e_cell_tree_get_tree_model(table_model, row);
    ETreePath path = e_cell_tree_get_node(table_model, row);

    if (visible_depth_of_node (table_model, row) > 0 ||
        e_tree_model_node_is_expandable(tree_model, path)) {
        return (visible_depth_of_node(table_model, row) + 1) * INDENT_AMOUNT;
    } else {
        return 0;
    }
}

/*
 * ECell::new_view method
 */
static ECellView *
ect_new_view (ECell *ecell, ETableModel *table_model, void *e_table_item_view)
{
    ECellTree *ect = E_CELL_TREE (ecell);
    ECellTreeView *tree_view = g_new0 (ECellTreeView, 1);
    GnomeCanvas *canvas = GNOME_CANVAS_ITEM (e_table_item_view)->canvas;
    
    tree_view->cell_view.ecell = ecell;
    tree_view->cell_view.e_table_model = table_model;
    tree_view->cell_view.e_table_item_view = e_table_item_view;
    
    /* create our subcell view */
    tree_view->subcell_view = e_cell_new_view (ect->subcell, table_model, e_table_item_view /* XXX */);

    tree_view->canvas = canvas;

    return (ECellView *)tree_view;
}

/*
 * ECell::kill_view method
 */
static void
ect_kill_view (ECellView *ecv)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecv;

    /* kill our subcell view */
    e_cell_kill_view (tree_view->subcell_view);

    g_free (tree_view);
}

/*
 * ECell::realize method
 */
static void
ect_realize (ECellView *ecell_view)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    /* realize our subcell view */
    e_cell_realize (tree_view->subcell_view);

    tree_view->gc = gdk_gc_new (GTK_WIDGET (tree_view->canvas)->window);

    gdk_gc_set_line_attributes (tree_view->gc, 1, 
                    GDK_LINE_ON_OFF_DASH, None, None);
    gdk_gc_set_dashes (tree_view->gc, 0, "\1\1", 2);

    if (parent_class->realize)
        (* parent_class->realize) (ecell_view);
}

/*
 * ECell::unrealize method
 */
static void
ect_unrealize (ECellView *ecv)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecv;

    /* unrealize our subcell view. */
    e_cell_unrealize (tree_view->subcell_view);

    gdk_gc_unref (tree_view->gc);
    tree_view->gc = NULL;

    if (parent_class->unrealize)
        (* parent_class->unrealize) (ecv);
}

/*
 * ECell::draw method
 */
static void
ect_draw (ECellView *ecell_view, GdkDrawable *drawable,
      int model_col, int view_col, int row, ECellFlags flags,
      int x1, int y1, int x2, int y2)
{
    ECellTreeView *tree_view = (ECellTreeView *)ecell_view;
    ETreeModel *tree_model = e_cell_tree_get_tree_model(ecell_view->e_table_model, row);
    ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter(ecell_view->e_table_model, row);
    ETreePath node;
    GdkRectangle rect, *clip_rect;
    GtkWidget *canvas = GTK_WIDGET (tree_view->canvas);
    GdkGC *fg_gc = canvas->style->fg_gc[GTK_STATE_ACTIVE];
    GdkColor *foreground;
    gboolean selected;

    int offset, subcell_offset;

    selected = flags & E_CELL_SELECTED;

    /* only draw the tree effects if we're the active sort */
    if (/* XXX */ TRUE) {
        GdkPixbuf *node_image;
        int node_image_width = 0, node_image_height = 0;
        ETreePath parent_node;

        node = e_cell_tree_get_node (ecell_view->e_table_model, row);

        offset = offset_of_node (ecell_view->e_table_model, row);
        subcell_offset = offset;

        node_image = e_tree_model_icon_at (tree_model, node);

        if (node_image) {
            node_image_width = gdk_pixbuf_get_width (node_image);
            node_image_height = gdk_pixbuf_get_height (node_image);
        }

        /*
         * Be a nice citizen: clip to the region we are supposed to draw on
         */
        rect.x = x1;
        rect.y = y1;
        rect.width = subcell_offset + node_image_width;
        rect.height = y2 - y1;
    
        gdk_gc_set_clip_rectangle (tree_view->gc, &rect);
        gdk_gc_set_clip_rectangle (fg_gc, &rect);
        clip_rect = &rect;

        if (selected) {
            foreground = &canvas->style->text [GTK_STATE_SELECTED];
        } else {
            foreground = &canvas->style->text [GTK_STATE_NORMAL];
        }

        gdk_gc_set_foreground (tree_view->gc, foreground);

        /* draw our lines */
        if (E_CELL_TREE(tree_view->cell_view.ecell)->draw_lines) {

            int depth;

            if (visible_depth_of_node (ecell_view->e_table_model, row) > 0
                || e_tree_model_node_get_children (tree_model, node, NULL) > 0)
                gdk_draw_line (drawable, tree_view->gc,
                           rect.x + offset - INDENT_AMOUNT / 2 + 1,
                           rect.y + rect.height / 2,
                           rect.x + offset,
                           rect.y + rect.height / 2);

            if (visible_depth_of_node (ecell_view->e_table_model, row) != 0) {
                gdk_draw_line (drawable, tree_view->gc,
                           rect.x + offset - INDENT_AMOUNT / 2,
                           rect.y,
                           rect.x + offset - INDENT_AMOUNT / 2,
                           (e_tree_model_node_get_next (tree_model, node)
                        ? rect.y + rect.height
                        : rect.y + rect.height / 2));
            }

            /* now traverse back up to the root of the tree, checking at
               each level if the node has siblings, and drawing the
               correct vertical pipe for it's configuration. */
            parent_node = e_tree_model_node_get_parent (tree_model, node);
            offset -= INDENT_AMOUNT;
            depth = visible_depth_of_node (ecell_view->e_table_model, row) - 1;
            while (parent_node && depth != 0) {
                if (e_tree_model_node_get_next(tree_model, parent_node)) {
                    gdk_draw_line (drawable, tree_view->gc,
                               rect.x + offset - INDENT_AMOUNT / 2,
                               rect.y,
                               rect.x + offset - INDENT_AMOUNT / 2,
                               rect.y + rect.height);
                }
                parent_node = e_tree_model_node_get_parent (tree_model, parent_node);
                depth --;
                offset -= INDENT_AMOUNT;
            }
        }

        /* now draw our icon if we're expandable */
        if (e_tree_model_node_is_expandable (tree_model, node)) {
            GdkPixbuf *image;
            int image_width, image_height;

            image = (e_tree_table_adapter_node_is_expanded (tree_table_adapter, node)
                 ? E_CELL_TREE(tree_view->cell_view.ecell)->open_pixbuf
                 : E_CELL_TREE(tree_view->cell_view.ecell)->closed_pixbuf);

            image_width = gdk_pixbuf_get_width(image);
            image_height = gdk_pixbuf_get_height(image);

            gdk_pixbuf_render_to_drawable_alpha (image,
                                 drawable,
                                 0, 0,
                                 x1 + subcell_offset - INDENT_AMOUNT / 2 - image_width / 2,
                                 y1 + (y2 - y1) / 2 - image_height / 2,
                                 image_width, image_height,
                                 GDK_PIXBUF_ALPHA_BILEVEL,
                                 128,
                                 GDK_RGB_DITHER_NORMAL,
                                 image_width, 0);
        }

        if (node_image) {
            gdk_pixbuf_render_to_drawable_alpha (node_image,
                                 drawable,
                                 0, 0,
                                 x1 + subcell_offset,
                                 y1 + (y2 - y1) / 2 - node_image_height / 2,
                                 node_image_width, node_image_height,
                                 GDK_PIXBUF_ALPHA_BILEVEL,
                                 128,
                                 GDK_RGB_DITHER_NORMAL,
                                 node_image_width, 0);
            subcell_offset += node_image_width;
        }
    }

    /* Now cause our subcell to draw its contents, shifted by
       subcell_offset pixels */
    e_cell_draw (tree_view->subcell_view, drawable,
             model_col, view_col, row, flags,
             x1 + subcell_offset, y1, x2, y2);
}

/*
 * ECell::event method
 */
static gint
ect_event (ECellView *ecell_view, GdkEvent *event, int model_col, int view_col, int row, ECellFlags flags, ECellActions *actions)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;
    ETreeModel *tree_model = e_cell_tree_get_tree_model (ecell_view->e_table_model, row);
    ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter(ecell_view->e_table_model, row);
    ETreePath node = e_cell_tree_get_node (ecell_view->e_table_model, row);
    int offset = offset_of_node (ecell_view->e_table_model, row);

    switch (event->type) {
    case GDK_BUTTON_PRESS: {
        /* if the event happened in our area of control (and
                   we care about it), handle it. */

        /* only activate the tree control if the click/release happens in the icon's area. */
        if (event->button.x > (offset - INDENT_AMOUNT) && event->button.x < offset) {
            if (e_tree_model_node_is_expandable (tree_model, node)) {
                e_tree_table_adapter_node_set_expanded (tree_table_adapter,
                                    node,
                                    !e_tree_table_adapter_node_is_expanded(tree_table_adapter, node));
                return TRUE;
            }
        }
        else if (event->button.x < (offset - INDENT_AMOUNT))
            return FALSE;
    }
    default: {
        gint return_value;

        /* modify the event and pass it off to our subcell_view */
        switch (event->type) {
        case GDK_BUTTON_PRESS:
        case GDK_BUTTON_RELEASE:
        case GDK_2BUTTON_PRESS:
        case GDK_3BUTTON_PRESS:
            event->button.x -= offset;
            break;
        case GDK_MOTION_NOTIFY:
            event->motion.x -= offset;
            break;
        default:
            /* nada */
            break;
        }

        return_value = e_cell_event(tree_view->subcell_view, event, model_col, view_col, row, flags, actions);

        /* modify the event and pass it off to our subcell_view */
        switch (event->type) {
        case GDK_BUTTON_PRESS:
        case GDK_BUTTON_RELEASE:
        case GDK_2BUTTON_PRESS:
        case GDK_3BUTTON_PRESS:
            event->button.x += offset;
            break;
        case GDK_MOTION_NOTIFY:
            event->motion.x += offset;
            break;
        default:
            /* nada */
            break;
        }

        return return_value;
    }
    }
}

/*
 * ECell::height method
 */
static int
ect_height (ECellView *ecell_view, int model_col, int view_col, int row) 
{
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    return (((e_cell_height (tree_view->subcell_view, model_col, view_col, row)) + 1) / 2) * 2;
}

/*
 * ECell::max_width method
 */
static int
ect_max_width (ECellView *ecell_view, int model_col, int view_col)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;
    int row;
    int number_of_rows;
    int max_width = 0;
    int width = 0;
    int subcell_max_width;

    number_of_rows = e_table_model_row_count (ecell_view->e_table_model);

    subcell_max_width = e_cell_max_width (tree_view->subcell_view, model_col, view_col);
    
    for (row = 0; row < number_of_rows; row++) {
        ETreeModel *tree_model = e_cell_tree_get_tree_model(ecell_view->e_table_model, row);
        ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter(ecell_view->e_table_model, row);
        ETreePath node;
        GdkPixbuf *node_image;
        int node_image_width = 0, node_image_height = 0;
        
        int offset, subcell_offset;
        gboolean expanded, expandable;
        
        node = e_cell_tree_get_node (ecell_view->e_table_model, row);
        
        offset = offset_of_node (ecell_view->e_table_model, row);
        expandable = e_tree_model_node_is_expandable (tree_model, node);
        expanded = e_tree_table_adapter_node_is_expanded (tree_table_adapter, node);
        subcell_offset = offset;

        node_image = e_tree_model_icon_at (tree_model, node);

        if (node_image) {
            node_image_width = gdk_pixbuf_get_width (node_image);
            node_image_height = gdk_pixbuf_get_height (node_image);
        }

        width = subcell_max_width + subcell_offset + node_image_width;

        if (expandable) {
            GdkPixbuf *image;

            image = (expanded 
                 ? E_CELL_TREE(tree_view->cell_view.ecell)->open_pixbuf
                 : E_CELL_TREE(tree_view->cell_view.ecell)->closed_pixbuf);

            width += gdk_pixbuf_get_width(image);
        }

        max_width = MAX (max_width, width);
    }

    return max_width;
}

/*
 * ECellView::show_tooltip method
 */
static void
ect_show_tooltip (ECellView *ecell_view, int model_col, int view_col, int row,
          int col_width, ETableTooltip *tooltip)
{       
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;
    ETreeModel *tree_model = e_cell_tree_get_tree_model (ecell_view->e_table_model, row);
    ETreePath node = e_cell_tree_get_node (ecell_view->e_table_model, row);
    int offset = offset_of_node (ecell_view->e_table_model, row);
    GdkPixbuf *node_image;

    node_image = e_tree_model_icon_at (tree_model, node);
    if (node_image)
        offset += gdk_pixbuf_get_width (node_image);

    tooltip->x += offset;
    e_cell_show_tooltip (tree_view->subcell_view, model_col, view_col, row, col_width - offset, tooltip);
}

/*
 * ECellView::get_bg_color method
 */
static char *
ect_get_bg_color (ECellView *ecell_view, int row)
{       
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    return e_cell_get_bg_color (tree_view->subcell_view, row);
}
        
/*
 * ECellView::enter_edit method
 */
static void *
ect_enter_edit (ECellView *ecell_view, int model_col, int view_col, int row)
{
    /* just defer to our subcell's view */
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    return e_cell_enter_edit (tree_view->subcell_view, model_col, view_col, row);
}

/*
 * ECellView::leave_edit method
 */
static void
ect_leave_edit (ECellView *ecell_view, int model_col, int view_col, int row, void *edit_context)
{
    /* just defer to our subcell's view */
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    e_cell_leave_edit (tree_view->subcell_view, model_col, view_col, row, edit_context);
}

static void
ect_print (ECellView *ecell_view, GnomePrintContext *context, 
       int model_col, int view_col, int row,
       double width, double height)
{
    ECellTreeView *tree_view = (ECellTreeView *) ecell_view;

    if (/* XXX only if we're the active sort */ TRUE) {
        ETreeModel *tree_model = e_cell_tree_get_tree_model (ecell_view->e_table_model, row);
        ETreeTableAdapter *tree_table_adapter = e_cell_tree_get_tree_table_adapter(ecell_view->e_table_model, row);
        ETreePath node = e_cell_tree_get_node (ecell_view->e_table_model, row);
        int offset = offset_of_node (ecell_view->e_table_model, row);
        int subcell_offset = offset;
        gboolean expandable = e_tree_model_node_is_expandable (tree_model, node);
        gboolean expanded = e_tree_table_adapter_node_is_expanded (tree_table_adapter, node);

        /* draw our lines */
        if (E_CELL_TREE(tree_view->cell_view.ecell)->draw_lines) {
            int depth;

            if (!e_tree_model_node_is_root (tree_model, node)
                || e_tree_model_node_get_children (tree_model, node, NULL) > 0) {
                gnome_print_moveto (context,
                            offset - INDENT_AMOUNT / 2,
                            height / 2);

                gnome_print_lineto (context,
                            offset,
                            height / 2);
            }

            if (visible_depth_of_node (ecell_view->e_table_model, row) != 0) {
                gnome_print_moveto (context,
                            offset - INDENT_AMOUNT / 2,
                            height);
                gnome_print_lineto (context,
                            offset - INDENT_AMOUNT / 2,
                            (e_tree_model_node_get_next (tree_model, node)
                             ? 0
                             : height / 2));
            }

            /* now traverse back up to the root of the tree, checking at
               each level if the node has siblings, and drawing the
               correct vertical pipe for it's configuration. */
            node = e_tree_model_node_get_parent (tree_model, node);
            depth = visible_depth_of_node (ecell_view->e_table_model, row) - 1;
            offset -= INDENT_AMOUNT;
            while (node && depth != 0) {
                if (e_tree_model_node_get_next(tree_model, node)) {
                    gnome_print_moveto (context,
                                offset - INDENT_AMOUNT / 2,
                                height);
                    gnome_print_lineto (context,
                                offset - INDENT_AMOUNT / 2,
                                0);
                }
                node = e_tree_model_node_get_parent (tree_model, node);
                depth --;
                offset -= INDENT_AMOUNT;
            }
        }

        /* now draw our icon if we're expandable */
        if (expandable) {
            double image_matrix [6] = {16, 0, 0, 16, 0, 0};
            GdkPixbuf *image = (expanded 
                        ? E_CELL_TREE(tree_view->cell_view.ecell)->open_pixbuf
                        : E_CELL_TREE(tree_view->cell_view.ecell)->closed_pixbuf);
            int image_width, image_height, image_rowstride;
            guchar *image_pixels;

            image_width = gdk_pixbuf_get_width(image);
            image_height = gdk_pixbuf_get_height(image);
            image_pixels = gdk_pixbuf_get_pixels(image);
            image_rowstride = gdk_pixbuf_get_rowstride(image);

            image_matrix [4] = subcell_offset - INDENT_AMOUNT / 2 - image_width / 2;
            image_matrix [5] = height / 2 - image_height / 2;

            gnome_print_gsave (context);
            gnome_print_concat (context, image_matrix);

            gnome_print_rgbaimage (context, image_pixels, image_width, image_height, image_rowstride);
            gnome_print_grestore (context);
        }

        gnome_print_stroke (context);

        if (gnome_print_translate(context, subcell_offset, 0) == -1)
                /* FIXME */;
        width -= subcell_offset;
    }


    e_cell_print (tree_view->subcell_view, context, model_col, view_col, row, width, height);
}

static gdouble
ect_print_height (ECellView *ecell_view, GnomePrintContext *context, 
          int model_col, int view_col, int row,
          double width)
{
    return 12; /* XXX */
}

/*
 * GtkObject::destroy method
 */
static void
ect_destroy (GtkObject *object)
{
    ECellTree *ect = E_CELL_TREE (object);

    /* destroy our subcell */
    if (ect->subcell)
        gtk_object_unref (GTK_OBJECT (ect->subcell));
    ect->subcell = NULL;

    gdk_pixbuf_unref (ect->open_pixbuf);
    gdk_pixbuf_unref (ect->closed_pixbuf);

    GTK_OBJECT_CLASS (parent_class)->destroy (object);
}

static void
e_cell_tree_class_init (GtkObjectClass *object_class)
{
    ECellClass *ecc = (ECellClass *) object_class;

    object_class->destroy = ect_destroy;

    ecc->new_view         = ect_new_view;
    ecc->kill_view        = ect_kill_view;
    ecc->realize          = ect_realize;
    ecc->unrealize        = ect_unrealize;
    ecc->draw             = ect_draw;
    ecc->event            = ect_event;
    ecc->height           = ect_height;
    ecc->enter_edit       = ect_enter_edit;
    ecc->leave_edit       = ect_leave_edit;
    ecc->print            = ect_print;
    ecc->print_height     = ect_print_height;
    ecc->max_width        = ect_max_width;
    ecc->show_tooltip     = ect_show_tooltip;
    ecc->get_bg_color     = ect_get_bg_color;

    parent_class = gtk_type_class (PARENT_TYPE);
}

E_MAKE_TYPE(e_cell_tree, "ECellTree", ECellTree, e_cell_tree_class_init, NULL, PARENT_TYPE);

/**
 * e_cell_tree_construct:
 * @ect: the ECellTree we're constructing.
 * @open_pixbuf: pixbuf to be used instead of the '-' icon.
 * @closed_pixbuf: pixbuf to be used instead of the '+' icon.
 * @draw_lines: whether or not to draw the lines between parents/children/siblings.
 * @subcell: the ECell to render to the right of the tree effects.
 * 
 * Constructs an ECellTree.  used by subclasses that need to
 * initialize a nested ECellTree.  See e_cell_tree_new() for more info.
 * 
 **/
void
e_cell_tree_construct (ECellTree *ect,
               GdkPixbuf *open_pixbuf,
               GdkPixbuf *closed_pixbuf,
               gboolean draw_lines,
               ECell *subcell)
{              
    ect->subcell = subcell;
    if (subcell) {
        gtk_object_ref (GTK_OBJECT (subcell));
        gtk_object_sink (GTK_OBJECT (subcell));
    }
    if (open_pixbuf)
        ect->open_pixbuf = open_pixbuf;
    else
        ect->open_pixbuf = gdk_pixbuf_new_from_xpm_data ((const char **)tree_expanded_xpm);
    if (closed_pixbuf)
        ect->closed_pixbuf = closed_pixbuf;
    else
        ect->closed_pixbuf = gdk_pixbuf_new_from_xpm_data ((const char **)tree_unexpanded_xpm);

    ect->draw_lines = draw_lines;
}


/**
 * e_cell_tree_new:
 * @open_pixbuf: pixbuf to be used instead of the '-' icon.
 * @closed_pixbuf: pixbuf to be used instead of the '+' icon.
 * @draw_lines: whether or not to draw the lines between parents/children/siblings.
 * @subcell: the ECell to render to the right of the tree effects.
 * 
 * Creates a new ECell renderer that can be used to render tree
 * effects that come from an ETreeModel.  Various assumptions are made
 * as to the fact that the ETableModel the ETable this cell is
 * associated with is in fact an ETreeModel.  The cell uses special
 * columns to get at structural information (needed to draw the
 * lines/icons.
 * 
 * Return value: an ECell object that can be used to render trees.
 **/
ECell *
e_cell_tree_new (GdkPixbuf *open_pixbuf,
         GdkPixbuf *closed_pixbuf,
         gboolean draw_lines,
         ECell *subcell)
{
    ECellTree *ect = gtk_type_new (e_cell_tree_get_type ());

    e_cell_tree_construct (ect, open_pixbuf, closed_pixbuf, draw_lines, subcell);

    return (ECell *) ect;
}