path: root/widgets/misc/e-canvas-utils.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/* 
 * e-canvas-utils.c
 * Copyright (C) 2000  Helix Code, Inc.
 * Author: Chris Lahey <clahey@helixcode.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU 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 "e-canvas-utils.h"

void
e_canvas_item_move_absolute (GnomeCanvasItem *item, double dx, double dy)
{
    double translate[6];

    g_return_if_fail (item != NULL);
    g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));

    art_affine_translate (translate, dx, dy);

    gnome_canvas_item_affine_absolute (item, translate);
}

static double
compute_offset(int top, int bottom, int page_top, int page_bottom)
{
    int size = bottom - top;
    int offset = 0;

    if (top <= page_top && bottom >= page_bottom)
        return 0;

    if (bottom > page_bottom)
        offset = (bottom - page_bottom);
    if (top < page_top + offset)
        offset = (top - page_top);

    if (top <= page_top + offset && bottom >= page_bottom + offset)
        return offset;

    if (top < page_top + size * 3 / 2 + offset)
        offset = top - (page_top + size * 3 / 2);
    if (bottom > page_bottom - size * 3 / 2 + offset)
        offset = bottom - (page_bottom - size * 3 / 2);
    if (top < page_top + size * 3 / 2 + offset)
        offset = top - ((page_top + page_bottom - (bottom - top)) / 2);

    return offset;
}


void
e_canvas_item_show_area (GnomeCanvasItem *item, double x1, double y1, double x2, double y2)
{
    GtkAdjustment *h, *v;
    int dx = 0, dy = 0;
    
    g_return_if_fail (item != NULL);
    g_return_if_fail (GNOME_IS_CANVAS_ITEM (item));
    
    gnome_canvas_item_i2w(item, &x1, &y1);
    gnome_canvas_item_i2w(item, &x2, &y2);

    h = gtk_layout_get_hadjustment(GTK_LAYOUT(item->canvas));
    dx = compute_offset(x1, x2, h->value, h->value + h->page_size);
    if (dx)
        gtk_adjustment_set_value(h, CLAMP(h->value + dx, h->lower, h->upper - h->page_size));

    v = gtk_layout_get_vadjustment(GTK_LAYOUT(item->canvas));
    dy = compute_offset(y1, y2, v->value, v->value + v->page_size);
    if (dy)
        gtk_adjustment_set_value(v, CLAMP(v->value + dy, v->lower, v->upper - v->page_size));
}