/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*-

   eel-background.h: Object for the background of a widget.

   Copyright (C) 2000 Eazel, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library 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
   Library General Public License for more details.
  
   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the
   Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.
  
   Authors: Darin Adler <darin@eazel.com>
*/

#ifndef EEL_BACKGROUND_H
#define EEL_BACKGROUND_H

/* Windows for Eel can contain backgrounds that are either tiled
   with an image, a solid color, or a color gradient. This class manages
   the process of loading the image if necessary and parsing the string
   that specifies either a color or color gradient.

   The color or gradient is always present, even if there's a tiled image
   on top of it. This is used when the tiled image can't be loaded for
   some reason (or just has not been loaded yet).

   The EelBackground object is easier to modify than a GtkStyle.
   You can just call eel_get_window_background and modify the
   returned background directly, unlike a style, which must be copied,
   modified and then set.
*/

#include <gdk/gdk.h>
#include <gtk/gtk.h>

#include <gdk-pixbuf/gdk-pixbuf.h>

typedef struct EelBackground EelBackground;
typedef struct EelBackgroundClass EelBackgroundClass;

#define EEL_TYPE_BACKGROUND \
	(eel_background_get_type ())
#define EEL_BACKGROUND(obj) \
	(GTK_CHECK_CAST ((obj), EEL_TYPE_BACKGROUND, EelBackground))
#define EEL_BACKGROUND_CLASS(klass) \
	(GTK_CHECK_CLASS_CAST ((klass), EEL_TYPE_BACKGROUND, EelBackgroundClass))
#define EEL_IS_BACKGROUND(obj) \
	(GTK_CHECK_TYPE ((obj), EEL_TYPE_BACKGROUND))
#define EEL_IS_BACKGROUND_CLASS(klass) \
	(GTK_CHECK_CLASS_TYPE ((klass), EEL_TYPE_BACKGROUND))

typedef enum {
	EEL_BACKGROUND_TILED = 0, /* zero makes this the default placement */
	EEL_BACKGROUND_CENTERED,
	EEL_BACKGROUND_SCALED,
	EEL_BACKGROUND_SCALED_ASPECT,
	EEL_BACKGROUND_ZOOM
} EelBackgroundImagePlacement;

GtkType                     eel_background_get_type                         (void);
EelBackground *             eel_background_new                              (void);


/* Calls to change a background. */
void                        eel_background_set_use_base                     (EelBackground               *background,
									     gboolean                     use_base);
void                        eel_background_set_color                        (EelBackground               *background,
									     const char                  *color_or_gradient);
void                        eel_background_set_image_uri                    (EelBackground               *background,
									     const char                  *image_uri);

void                        eel_background_reset                            (EelBackground               *background);
void                        eel_background_set_image_placement              (EelBackground               *background,
									     EelBackgroundImagePlacement  placement);

/* Should be TRUE for desktop background */
void			    eel_background_set_desktop 			    (EelBackground              *background,
									     GtkWidget *widget, 
									     gboolean is_desktop);
gboolean		    eel_background_is_desktop 			    (EelBackground              *background);

/* Calls to interrogate the current state of a background. */
char *                      eel_background_get_color                        (EelBackground               *background);
char *                      eel_background_get_image_uri                    (EelBackground               *background);
EelBackgroundImagePlacement eel_background_get_image_placement              (EelBackground               *background);
gboolean                    eel_background_is_dark                          (EelBackground               *background);
gboolean                    eel_background_is_set                           (EelBackground               *background);

/* Helper function for widgets using EelBackground */
void                        eel_background_expose                           (GtkWidget                   *widget,
									     GdkEventExpose              *event);

/* Handles a dragged color being dropped on a widget to change the background color. */
void                        eel_background_receive_dropped_color            (EelBackground               *background,
									     GtkWidget                   *widget,
									     GdkDragAction                action,
									     int                          drop_location_x,
									     int                          drop_location_y,
									     const GtkSelectionData      *dropped_color);

/* Handles a special-case image name that means "reset to default background" too. */
void                        eel_background_receive_dropped_background_image (EelBackground               *background,
									     GdkDragAction                action,
									     const char                  *image_uri);

/* Gets or creates a background so that it's attached to a widget. */
EelBackground *             eel_get_widget_background                       (GtkWidget                   *widget);
void			    eel_background_save_to_gconf                    (EelBackground               *background);

typedef struct EelBackgroundDetails EelBackgroundDetails;

struct EelBackground
{
	GtkObject object;
	EelBackgroundDetails *details;
};

struct EelBackgroundClass
{
	GtkObjectClass parent_class;

	/* This signal is emitted whenever the background settings are
	 * changed.
	 */
	void (* settings_changed) (EelBackground *);

	/* This signal is emitted whenever the appearance of the
	 * background has changed, like when the background settings are
	 * altered or when an image is loaded.
	 */
	void (* appearance_changed) (EelBackground *);

	/* This signal is emitted when image loading is over - whether it
	 * was successfully loaded or not.
	 */
	void (* image_loading_done) (EelBackground *background, gboolean successful_load);

	/* This signal is emitted when the background is reset by receiving
	   the reset property from a drag
	 */
	void (* reset) (EelBackground *);

};

#endif /* EEL_BACKGROUND_H */
