source: trunk/third/bonobo/bonobo/bonobo-ui-state-cache.c @ 17169

/* bonobo-ui-state-cache.h: Image state cache for the Bonobo UI engine
 *
 * Copyright (C) 2001 Ximian, Inc.
 *
 * Author: Federico Mena-Quintero <federico@ximian.com>
 *
 * This library 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 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.
 */

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

#include "bonobo-ui-state-cache.h"
#include "bonobo-ui-icon-modify.h"



/* Structure to hold image modification parameters for the different widget states */
typedef struct {
        double saturation;
        gboolean pixelate;
        double pixelate_dark_factor;
} Modifiers;

/* A provided pixbuf and its modifiers; used as keys in the cache hash table */
typedef struct {
        GdkPixbuf *pixbuf;
        Modifiers mods;
} PixbufModifiers;

/* Defaults for icon desaturation/pixelation */
const static Modifiers defaults[] = {
        { 1.0, FALSE, 1.0 },    /* GTK_STATE_NORMAL */
        { 1.0, FALSE, 1.0 },    /* GTK_STATE_ACTIVE */
        { 1.0, FALSE, 1.0 },    /* GTK_STATE_PRELIGHT */
        { 1.0, FALSE, 1.0 },    /* GTK_STATE_SELECTED */
        { 0.8, TRUE, 0.7 },     /* GTK_STATE_INSENSITIVE */
};



/* Number of GdkStateType values */
#define NUM_STATES 5

/* Mapping of PixbufModfier structures to modified pixbufs */
static GHashTable *pixbuf_modifier_hash = NULL;



/* Hash function for a PixbufModifiers key. */
static guint
pixbuf_modifier_hash_fn (gconstpointer key)
{
        const PixbufModifiers *pm;
        int saturation, pixelate_dark_factor;
        guint hash;

        pm = key;

        /* Convert the doubles to reasonable ints for hashing */
        saturation = G_MAXINT * pm->mods.saturation;
        pixelate_dark_factor = G_MAXINT * pm->mods.pixelate_dark_factor;

        hash = GPOINTER_TO_UINT (pm->pixbuf) ^ saturation ^ pixelate_dark_factor;

        if (pm->mods.pixelate)
                hash = ~hash;

        return hash;
}

/* Comparison function for the PixbufModifiers hash table */
static gint
pixbuf_modifier_equal_fn (gconstpointer a, gconstpointer b)
{
        const PixbufModifiers *pma, *pmb;

        pma = a;
        pmb = b;

        return (pma->pixbuf == pmb->pixbuf
                && pma->mods.saturation == pmb->mods.saturation
                && pma->mods.pixelate == pmb->mods.pixelate
                && pma->mods.pixelate_dark_factor == pmb->mods.pixelate_dark_factor);
}

/* Ensures that the pixbuf->set hash table has been created */
static void
ensure_hash_table (void)
{
        if (pixbuf_modifier_hash)
                return;

        pixbuf_modifier_hash = g_hash_table_new (pixbuf_modifier_hash_fn, pixbuf_modifier_equal_fn);
}

/* Generates a pixbuf out of the specified one by modifying it as appropriate
 * for a widget state.
 */
static GdkPixbuf *
make_pixbuf_for_state (GdkPixbuf *source, GtkStateType state)
{
        return bonobo_ui_icon_modify (source,
                                      defaults[state].saturation,
                                      defaults[state].pixelate,
                                      defaults[state].pixelate_dark_factor);
}

/**
 * bonobo_ui_state_cache_get:
 * @source: Source pixbuf.
 * @state: Widget state for the result.
 *
 * Takes a @source pixbuf and modifies it as appropriate for display in the
 * specified widget @state.  For example, an image could be grayed out for
 * insensitive widgets.  The returned pixbuf comes from a cache; you should
 * unref it with gdk_pixbuf_unref() when you are done with it.
 *
 * Return value: A pixbuf, or NULL if the modified image could not be created.
 **/
GdkPixbuf *
bonobo_ui_state_cache_get (GdkPixbuf *source, GtkStateType state)
{
        PixbufModifiers pm;
        GdkPixbuf *modified;

        g_return_val_if_fail (source != NULL, NULL);
        g_return_val_if_fail (state >= GTK_STATE_NORMAL && state <= GTK_STATE_INSENSITIVE, NULL);

        ensure_hash_table ();

        pm.pixbuf = source;
        pm.mods = defaults[state];

        modified = g_hash_table_lookup (pixbuf_modifier_hash, &pm);

        if (!modified) {
                PixbufModifiers *pm_copy;

                modified = make_pixbuf_for_state (source, state);
                if (!modified)
                        return NULL;

                pm_copy = g_new (PixbufModifiers, 1);
                *pm_copy = pm;
                gdk_pixbuf_ref (source);

                g_hash_table_insert (pixbuf_modifier_hash, pm_copy, modified);
        }

        g_assert (modified != NULL);

        gdk_pixbuf_ref (modified);

        return modified;
}