/* The GIMP -- an image manipulation program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <gtk/gtk.h>

#include "libgimpmath/gimpmath.h"

#include "apptypes.h"

#include "gimage.h"
#include "gimage_mask.h"
#include "gimphistogram.h"
#include "histogramwidget.h"
#include "tile_manager.h"


#define WAITING 0
#define WORKING 1

#define WORK_DELAY 1

#define HISTOGRAM_MASK GDK_EXPOSURE_MASK | \
                       GDK_BUTTON_PRESS_MASK | \
                       GDK_BUTTON_RELEASE_MASK | \
		       GDK_BUTTON1_MOTION_MASK

#define HISTOGRAM 0x1
#define RANGE     0x2
#define ALL       0xF


enum
{
  RANGE_CHANGED,
  LAST_SIGNAL
};

static guint histogram_widget_signals[LAST_SIGNAL];

static void   histogram_widget_class_init (HistogramWidgetClass *klass);
static void   histogram_widget_init       (HistogramWidget      *histogram);


/**************************/
/*  Function definitions  */

GtkType
histogram_widget_get_type (void)
{
  static GtkType histogram_widet_type = 0;

  if (! histogram_widet_type)
    {
      static const GtkTypeInfo info =
      {
	"HistogramWidget",
	sizeof (HistogramWidget),
	sizeof (HistogramWidgetClass),
	(GtkClassInitFunc) histogram_widget_class_init,
	(GtkObjectInitFunc) histogram_widget_init,
	NULL, NULL
      };

      histogram_widet_type =
	gtk_type_unique (gtk_drawing_area_get_type (), &info);
    }

  return histogram_widet_type;
}

static void
histogram_widget_class_init (HistogramWidgetClass *klass)
{
  GtkObjectClass *object_class;

  object_class = GTK_OBJECT_CLASS (klass);

  histogram_widget_signals[RANGE_CHANGED] =
    gtk_signal_new ("range_changed",
		    GTK_RUN_FIRST,
		    object_class->type,
		    GTK_SIGNAL_OFFSET (HistogramWidgetClass, range_changed),
		    gtk_marshal_NONE__INT_INT,
		    GTK_TYPE_NONE, 2,
		    GTK_TYPE_INT,
		    GTK_TYPE_INT);

  gtk_object_class_add_signals (GTK_OBJECT_CLASS (klass),
				histogram_widget_signals, LAST_SIGNAL);

  klass->range_changed = NULL;
}

static void 
histogram_widget_init (HistogramWidget *histogram)
{
  histogram->histogram = NULL;
  histogram->channel   = GIMP_HISTOGRAM_VALUE;
  histogram->start     = 0;
  histogram->end       = 255;
}

static void
histogram_widget_draw (HistogramWidget *histogram,
		       gint             update)
{
  gdouble max;
  gdouble v;
  gint    i, x, y;
  gint    x1, x2;
  gint    width, height;

  width  = GTK_WIDGET (histogram)->allocation.width - 2;
  height = GTK_WIDGET (histogram)->allocation.height - 2;

  if (update & HISTOGRAM)
    {
      /*  find the maximum value  */
      max = gimp_histogram_get_maximum (histogram->histogram,
					histogram->channel);

      if (max > 0.0)
	max = log (max);
      else
	max = 1.0;

      /*  clear the histogram  */
      gdk_window_clear (GTK_WIDGET (histogram)->window);

      /*  Draw the axis  */
      gdk_draw_line (GTK_WIDGET (histogram)->window,
		     GTK_WIDGET (histogram)->style->black_gc,
		     1, height + 1, width, height + 1);

      /*  Draw the spikes  */
      for (i = 0; i < 256; i++)
	{
	  x = (width * i) / 256 + 1;
	  v = gimp_histogram_get_value (histogram->histogram,
					histogram->channel, i);
	  if (v > 0.0)
	    y = (int) ((height * log (v)) / max);
	  else
	    y = 0;
	  gdk_draw_line (GTK_WIDGET (histogram)->window,
			 GTK_WIDGET (histogram)->style->black_gc,
			 x, height + 1,
			 x, height + 1 - y);
	}
    }

  if ((update & RANGE) && histogram->start >= 0)
    {
      x1 = (width * MIN (histogram->start, histogram->end)) / 256 + 1;
      x2 = (width * MAX (histogram->start, histogram->end)) / 256 + 1;
      gdk_gc_set_function (GTK_WIDGET (histogram)->style->black_gc, GDK_INVERT);
      gdk_draw_rectangle (GTK_WIDGET (histogram)->window,
			  GTK_WIDGET (histogram)->style->black_gc, TRUE,
			  x1, 1, (x2 - x1) + 1, height);
      gdk_gc_set_function (GTK_WIDGET (histogram)->style->black_gc, GDK_COPY);
    }
}

static gint
histogram_widget_events (HistogramWidget *histogram,
			 GdkEvent        *event)
{
  GdkEventButton *bevent;
  GdkEventMotion *mevent;
  gint            width;

  switch (event->type)
    {
    case GDK_EXPOSE:
      histogram_widget_draw (histogram, ALL);
      break;

    case GDK_BUTTON_PRESS:
      bevent = (GdkEventButton *) event;

      if (bevent->button != 1)
	break;

      gdk_pointer_grab (GTK_WIDGET (histogram)->window, FALSE, 
			GDK_BUTTON_RELEASE_MASK | GDK_BUTTON1_MOTION_MASK,
			NULL, NULL, bevent->time);

      width = GTK_WIDGET (histogram)->allocation.width - 2;

      histogram_widget_draw (histogram, RANGE);

      histogram->start = CLAMP ((((bevent->x - 1) * 256) / width), 0, 255);
      histogram->end = histogram->start;

      histogram_widget_draw (histogram, RANGE);
      break;

    case GDK_BUTTON_RELEASE:
      bevent = (GdkEventButton *) event;

      gdk_pointer_ungrab (bevent->time);

      gtk_signal_emit (GTK_OBJECT(histogram),
		       histogram_widget_signals[RANGE_CHANGED],
		       MIN (histogram->start, histogram->end),
		       MAX (histogram->start, histogram->end));
      break;

    case GDK_MOTION_NOTIFY:
      mevent = (GdkEventMotion *) event;
      width = GTK_WIDGET (histogram)->allocation.width - 2;

      histogram_widget_draw (histogram, RANGE);

      histogram->start = CLAMP ((((mevent->x - 1) * 256) / width), 0, 255);

      histogram_widget_draw (histogram, RANGE);
      break;

    default:
      break;
    }

  return FALSE;
}

HistogramWidget *
histogram_widget_new (gint width,
		      gint height)
{
  HistogramWidget *histogram;

  histogram = HISTOGRAM_WIDGET (gtk_type_new (HISTOGRAM_WIDGET_TYPE));

  gtk_drawing_area_size (GTK_DRAWING_AREA (histogram), width + 2, height + 2);
  gtk_widget_set_events (GTK_WIDGET (histogram), HISTOGRAM_MASK);

  gtk_signal_connect (GTK_OBJECT (histogram), "event",
		      GTK_SIGNAL_FUNC (histogram_widget_events),
		      histogram);

  return histogram;
}

void
histogram_widget_update (HistogramWidget *histogram_widget,
			 GimpHistogram   *hist)
{
  histogram_widget->histogram = hist;

  if (!hist)
    return;

  if (histogram_widget->channel >= gimp_histogram_nchannels (hist))
    histogram_widget_channel (histogram_widget, 0);

  /*  Make sure the histogram is updated  */
  gtk_widget_draw (GTK_WIDGET (histogram_widget), NULL);

  /*  Give a range callback  */
  gtk_signal_emit (GTK_OBJECT (histogram_widget),
		   histogram_widget_signals[RANGE_CHANGED],
		   MIN (histogram_widget->start, histogram_widget->end),
		   MAX (histogram_widget->start, histogram_widget->end));
}

void
histogram_widget_range (HistogramWidget *histogram,
			gint             start,
			gint             end)
{
  histogram_widget_draw (histogram, RANGE);

  histogram->start = start;
  histogram->end   = end;

  histogram_widget_draw (histogram, RANGE);
}

void
histogram_widget_channel (HistogramWidget *histogram,
			  int              channel)
{
  histogram->channel = channel;
  histogram_widget_draw (histogram, ALL);

  /*  Give a range callback  */
  gtk_signal_emit (GTK_OBJECT (histogram),
		   histogram_widget_signals[RANGE_CHANGED],
		   MIN (histogram->start, histogram->end),
		   MAX (histogram->start, histogram->end));
}

GimpHistogram *
histogram_widget_histogram (HistogramWidget *histogram)
{
  return histogram->histogram;
}