/*
 * Copyright © 2008 Alexander “weej” Jones <alex@weej.com>
 * Copyright © 2008 Thomas Perl <thp@thpinfo.com>
 * Copyright © 2009 daniel g. siegel <dgsiegel@gnome.org>
 *
 * Licensed under the GNU General Public License Version 2
 *
 * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
 */

/* This is a "flash" object that you can create and invoke a method "flash" on to
 * flood the screen with white temporarily */

#include <gtk/gtk.h>

#include "cheese-flash.h"

#ifdef GDK_WINDOWING_X11
#include <X11/Xproto.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xatom.h>
#include <gdk/gdkx.h>
#endif /* GDK_WINDOWING_X11 */

/* How long to hold the flash for */
#define FLASH_DURATION 150

/* The factor which defines how much the flash fades per frame */
#define FLASH_FADE_FACTOR 0.95

/* How many frames per second */
#define FLASH_ANIMATION_RATE 120

/* When to consider the flash finished so we can stop fading */
#define FLASH_LOW_THRESHOLD 0.01

G_DEFINE_TYPE (CheeseFlash, cheese_flash, G_TYPE_OBJECT);

#define CHEESE_FLASH_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), CHEESE_TYPE_FLASH, CheeseFlashPrivate))

typedef struct
{
  GtkWindow *window;
  guint flash_timeout_tag;
  guint fade_timeout_tag;
} CheeseFlashPrivate;

static gboolean
cheese_flash_window_draw_event_cb (GtkWidget *widget, cairo_t *cr, gpointer user_data)
{
  cairo_fill (cr);
  return TRUE;
}

static void
cheese_flash_init (CheeseFlash *self)
{
  CheeseFlashPrivate *priv = CHEESE_FLASH_GET_PRIVATE (self);
  cairo_region_t *input_region;
  GtkWindow *window;
  GdkScreen *screen;
  GdkVisual *visual;

  priv->flash_timeout_tag = 0;
  priv->fade_timeout_tag  = 0;

  window = GTK_WINDOW (gtk_window_new (GTK_WINDOW_POPUP));

  /* make it so it doesn't look like a window on the desktop (+fullscreen) */
  gtk_window_set_decorated (window, FALSE);
  gtk_window_set_skip_taskbar_hint (window, TRUE);
  gtk_window_set_skip_pager_hint (window, TRUE);
  gtk_window_set_keep_above (window, TRUE);
  gtk_window_set_type_hint (window, GDK_WINDOW_TYPE_HINT_NOTIFICATION);

  /* Don't take focus */
  gtk_window_set_accept_focus (window, FALSE);
  gtk_window_set_focus_on_map (window, FALSE);

  /* no shadow */
  screen = gtk_widget_get_screen (GTK_WIDGET (window));
  visual = gdk_screen_get_rgba_visual (screen);
  if (visual == NULL)
    visual = gdk_screen_get_system_visual (screen);

  gtk_widget_set_visual (GTK_WIDGET (window), visual);

  /* Don't consume input */
  gtk_widget_realize (GTK_WIDGET (window));

  input_region = cairo_region_create ();
  gdk_window_input_shape_combine_region (gtk_widget_get_window (GTK_WIDGET (window)), input_region, 0, 0);
  cairo_region_destroy (input_region);

  g_signal_connect (G_OBJECT (window), "draw", G_CALLBACK (cheese_flash_window_draw_event_cb), NULL);
  priv->window = window;
}

static void
cheese_flash_dispose (GObject *object)
{
  CheeseFlashPrivate *priv = CHEESE_FLASH_GET_PRIVATE (object);

  if (priv->window != NULL)
  {
    gtk_widget_destroy (GTK_WIDGET (priv->window));
    priv->window = NULL;
  }

  if (G_OBJECT_CLASS (cheese_flash_parent_class)->dispose)
    G_OBJECT_CLASS (cheese_flash_parent_class)->dispose (object);
}

static void
cheese_flash_finalize (GObject *object)
{
  if (G_OBJECT_CLASS (cheese_flash_parent_class)->finalize)
    G_OBJECT_CLASS (cheese_flash_parent_class)->finalize (object);
}

static void
cheese_flash_class_init (CheeseFlashClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  g_type_class_add_private (klass, sizeof (CheeseFlashPrivate));

  object_class->dispose      = cheese_flash_dispose;
  object_class->finalize     = cheese_flash_finalize;
}

static gboolean
cheese_flash_opacity_fade (gpointer data)
{
  CheeseFlash        *flash        = data;
  CheeseFlashPrivate *flash_priv   = CHEESE_FLASH_GET_PRIVATE (flash);
  GtkWidget          *flash_window = GTK_WIDGET (flash_priv->window);
  double              opacity      = gtk_widget_get_opacity (flash_window);

  /* exponentially decrease */
  gtk_widget_set_opacity (flash_window, opacity * FLASH_FADE_FACTOR);

  if (opacity <= FLASH_LOW_THRESHOLD)
  {
    /* the flasher has finished when we reach the quit value */
    gtk_widget_hide (flash_window);
    return FALSE;
  }

  return TRUE;
}

static gboolean
cheese_flash_start_fade (gpointer data)
{
  CheeseFlash *self = data;
  CheeseFlashPrivate *flash_priv = CHEESE_FLASH_GET_PRIVATE (self);
  GtkWindow *flash_window = flash_priv->window;

  /* If the screen is non-composited, just hide and finish up */
  if (!gdk_screen_is_composited (gtk_window_get_screen (flash_window)))
  {
    gtk_widget_hide (GTK_WIDGET (flash_window));
    return FALSE;
  }

  flash_priv->fade_timeout_tag = 
    g_timeout_add_full (G_PRIORITY_DEFAULT,
                        1000.0 / FLASH_ANIMATION_RATE,
                        cheese_flash_opacity_fade,
                        g_object_ref (self), g_object_unref);
  return FALSE;
}

void
cheese_flash_fire (CheeseFlash  *flash,
                   GdkRectangle *rect)
{
  CheeseFlashPrivate *flash_priv = CHEESE_FLASH_GET_PRIVATE (flash);
  GtkWindow *flash_window = flash_priv->window;

  if (flash_priv->flash_timeout_tag > 0)
    g_source_remove (flash_priv->flash_timeout_tag);
  if (flash_priv->fade_timeout_tag > 0)
    g_source_remove (flash_priv->fade_timeout_tag);

  gtk_window_resize (flash_window, rect->width, rect->height);
  gtk_window_move (flash_window, rect->x, rect->y);

  gtk_widget_set_opacity (GTK_WIDGET (flash_window), 0.99);
  gtk_widget_show_all (GTK_WIDGET (flash_window));
  flash_priv->flash_timeout_tag = 
    g_timeout_add_full (G_PRIORITY_DEFAULT,
                        FLASH_DURATION,
                        cheese_flash_start_fade,
                        g_object_ref (flash), g_object_unref);
}

CheeseFlash *
cheese_flash_new (void)
{
  return g_object_new (CHEESE_TYPE_FLASH, NULL);
}
