gimp/app/tools/gimpcurvestool.c

/* 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 <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <gtk/gtk.h>

#include "libgimpmath/gimpmath.h"
#include "libgimpbase/gimpbase.h"
#include "libgimpwidgets/gimpwidgets.h"

#include "tools-types.h"

#include "base/gimphistogram.h"
#include "base/gimplut.h"

#include "core/gimpdrawable.h"
#include "core/gimpimage.h"

#include "widgets/gimpcursor.h"
#include "widgets/gimpwidgets-utils.h"

#include "gimpcurvestool.h"
#include "tool_manager.h"
#include "tool_options.h"

#include "app_procs.h"
#include "gdisplay.h"
#include "image_map.h"

#include "libgimp/gimpintl.h"

#define WANT_CURVES_BITS
#include "icons.h"


#define GRAPH          0x1
#define XRANGE_TOP     0x2
#define XRANGE_BOTTOM  0x4
#define YRANGE         0x8
#define DRAW          0x10
#define ALL           0xFF

/*  NB: take care when changing these values: make sure the curve[] array in
 *  curves.h is large enough.
 */
#define GRAPH_WIDTH    256
#define GRAPH_HEIGHT   256
#define XRANGE_WIDTH   256
#define XRANGE_HEIGHT   16
#define YRANGE_WIDTH    16
#define YRANGE_HEIGHT  256
#define RADIUS           3
#define MIN_DISTANCE     8

#define RANGE_MASK  GDK_EXPOSURE_MASK | \
                    GDK_ENTER_NOTIFY_MASK

#define GRAPH_MASK  GDK_EXPOSURE_MASK | \
		    GDK_POINTER_MOTION_MASK | \
		    GDK_POINTER_MOTION_HINT_MASK | \
                    GDK_ENTER_NOTIFY_MASK | \
		    GDK_BUTTON_PRESS_MASK | \
		    GDK_BUTTON_RELEASE_MASK | \
		    GDK_BUTTON1_MOTION_MASK


typedef gdouble CRMatrix[4][4];


/*  local function prototypes  */

static void   gimp_curves_tool_class_init     (GimpCurvesToolClass *klass);
static void   gimp_curves_tool_init           (GimpCurvesTool      *bc_tool);

static void   gimp_curves_tool_destroy        (GtkObject      *object);

static void   gimp_curves_tool_initialize     (GimpTool       *tool,
					       GDisplay       *gdisp);
static void   gimp_curves_tool_control        (GimpTool       *tool,
					       ToolAction      action,
					       GDisplay       *gdisp);
static void   gimp_curves_tool_button_press   (GimpTool       *tool,
					       GdkEventButton *bevent,
					       GDisplay       *gdisp);
static void   gimp_curves_tool_button_release (GimpTool       *tool,
					       GdkEventButton *bevent,
					       GDisplay       *gdisp);
static void   gimp_curves_tool_motion         (GimpTool       *tool,
					       GdkEventMotion *mevent,
					       GDisplay       *gdisp);

static void   curves_colour_update            (GimpTool       *tool,
					       GDisplay       *gdisp,
					       GimpDrawable   *drawable,
					       gint            x,
					       gint            y);
static void   curves_add_point                (GimpDrawable   *drawable,
					       gint            x,
					       gint            y,
					       gint            cchan);

static CurvesDialog * curves_dialog_new   (void);

static void   curves_update               (CurvesDialog   *cd,
					   gint            );
static void   curves_plot_curve           (CurvesDialog   *cd,
					   gint            ,
					   gint            ,
					   gint            ,
					   gint            );
static void   curves_preview              (CurvesDialog   *cd);

static void   curves_channel_callback     (GtkWidget      *widget,
					   gpointer        data);

static void   curves_smooth_callback      (GtkWidget      *widget,
					   gpointer        data);
static void   curves_free_callback        (GtkWidget      *widget,
					   gpointer        data);

static void   curves_channel_reset        (gint            );
static void   curves_reset_callback       (GtkWidget      *widget,
					   gpointer        data);
static void   curves_ok_callback          (GtkWidget      *widget,
					   gpointer        data);
static void   curves_cancel_callback      (GtkWidget      *widget,
					   gpointer        data);
static void   curves_load_callback        (GtkWidget      *widget,
					   gpointer        data);
static void   curves_save_callback        (GtkWidget      *widget,
					   gpointer        data);
static void   curves_preview_update       (GtkWidget      *widget,
					   gpointer        data);
static gint   curves_xrange_events        (GtkWidget      *widget,
					   GdkEvent       *event,
					   CurvesDialog   *cd);
static gint   curves_yrange_events        (GtkWidget      *widget,
					   GdkEvent       *event,
					   CurvesDialog   *cd);
static gint   curves_graph_events         (GtkWidget      *widget,
					   GdkEvent       *event,
					   CurvesDialog   *cd);
static void   curves_CR_compose           (CRMatrix        ,
					   CRMatrix        ,
					   CRMatrix        );

static void   file_dialog_create          (GtkWidget      *widget);
static void   file_dialog_ok_callback     (GtkWidget      *widget,
					   gpointer        data);
static void   file_dialog_cancel_callback (GtkWidget      *widget,
					   gpointer        data);

static gboolean  curves_read_from_file    (FILE           *f);
static void      curves_write_to_file     (FILE           *f);


/*  the curves tool options  */
static GimpToolOptions  * curves_options = NULL;

/*  the curves dialog  */
static CurvesDialog * curves_dialog = NULL;

static GimpImageMapToolClass *parent_class = NULL;

/*  the curves file dialog  */
static GtkWidget *file_dlg = NULL;
static gboolean   load_save;

static GtkWidget *channel_items[5];

static CRMatrix CR_basis =
{
  { -0.5,  1.5, -1.5,  0.5 },
  {  1.0, -2.5,  2.0, -0.5 },
  { -0.5,  0.0,  0.5,  0.0 },
  {  0.0,  1.0,  0.0,  0.0 },
};


/*  functions  */

void
gimp_curves_tool_register (Gimp *gimp)
{
  tool_manager_register_tool (gimp,
			      GIMP_TYPE_CURVES_TOOL,
                              FALSE,
			      "gimp:curves_tool",
			      _("Curves"),
			      _("Adjust color curves"),
			      N_("/Image/Colors/Curves..."), NULL,
			      NULL, "tools/curves.html",
			      (const gchar **) curves_bits);
}

GtkType
gimp_curves_tool_get_type (void)
{
  static GtkType tool_type = 0;

  if (! tool_type)
    {
      GtkTypeInfo tool_info =
      {
        "GimpCurvesTool",
        sizeof (GimpCurvesTool),
        sizeof (GimpCurvesToolClass),
        (GtkClassInitFunc) gimp_curves_tool_class_init,
        (GtkObjectInitFunc) gimp_curves_tool_init,
        /* reserved_1 */ NULL,
        /* reserved_2 */ NULL,
        (GtkClassInitFunc) NULL,
      };

      tool_type = gtk_type_unique (GIMP_TYPE_IMAGE_MAP_TOOL, &tool_info);
    }

  return tool_type;
}

static void
gimp_curves_tool_class_init (GimpCurvesToolClass *klass)
{
  GtkObjectClass    *object_class;
  GimpToolClass     *tool_class;

  object_class = (GtkObjectClass *) klass;
  tool_class   = (GimpToolClass *) klass;

  parent_class = gtk_type_class (GIMP_TYPE_IMAGE_MAP_TOOL);

  object_class->destroy  = gimp_curves_tool_destroy;

  tool_class->initialize     = gimp_curves_tool_initialize;
  tool_class->control        = gimp_curves_tool_control;
  tool_class->button_press   = gimp_curves_tool_button_press;
  tool_class->button_release = gimp_curves_tool_button_release;
  tool_class->motion         = gimp_curves_tool_motion;
}

static void
gimp_curves_tool_init (GimpCurvesTool *bc_tool)
{
  GimpTool *tool;

  tool = GIMP_TOOL (bc_tool);

  if (! curves_options)
    {
      curves_options = tool_options_new ();

      tool_manager_register_tool_options (GIMP_TYPE_CURVES_TOOL,
					  (GimpToolOptions *) curves_options);
    }
}

static void
gimp_curves_tool_destroy (GtkObject *object)
{
  curves_dialog_hide ();

  if (GTK_OBJECT_CLASS (parent_class)->destroy)
    GTK_OBJECT_CLASS (parent_class)->destroy (object);
}

static void
gimp_curves_tool_initialize (GimpTool *tool,
			     GDisplay *gdisp)
{
  gint i, j;

  if (! gdisp)
    {
      curves_dialog_hide ();
      return;
    }

  if (gimp_drawable_is_indexed (gimp_image_active_drawable (gdisp->gimage)))
    {
      g_message (_("Curves for indexed drawables cannot be adjusted."));
      return;
    }

  /*  The curves dialog  */
  if (!curves_dialog)
    {
      curves_dialog = curves_dialog_new ();
    }
     
  /*  Initialize the values  */
  curves_dialog->channel = GIMP_HISTOGRAM_VALUE;
  for (i = 0; i < 5; i++)
    for (j = 0; j < 256; j++)
      curves_dialog->curve[i][j] = j;
  
  for (i = 0; i < 5; i++)
    {
      curves_channel_reset (i);
    }

  curves_dialog->drawable  = gimp_image_active_drawable (gdisp->gimage);
  curves_dialog->color     = gimp_drawable_is_rgb (curves_dialog->drawable);
  curves_dialog->image_map = image_map_create (gdisp, curves_dialog->drawable);

  /* check for alpha channel */
  if (gimp_drawable_has_alpha (curves_dialog->drawable))
    gtk_widget_set_sensitive (channel_items[4], TRUE);
  else 
    gtk_widget_set_sensitive (channel_items[4], FALSE);
  
  /*  hide or show the channel menu based on image type  */
  if (curves_dialog->color)
    for (i = 0; i < 4; i++) 
       gtk_widget_set_sensitive (channel_items[i], TRUE);
  else 
    for (i = 1; i < 4; i++) 
      gtk_widget_set_sensitive (channel_items[i], FALSE);

  /* set the current selection */
  gtk_option_menu_set_history (GTK_OPTION_MENU (curves_dialog->channel_menu),
			       curves_dialog->channel);

  gimp_lut_setup (curves_dialog->lut, 
		  (GimpLutFunc) curves_lut_func,
                  (gpointer) curves_dialog, 
		  gimp_drawable_bytes (curves_dialog->drawable));

  if (!GTK_WIDGET_VISIBLE (curves_dialog->shell))
    gtk_widget_show (curves_dialog->shell);

  curves_update (curves_dialog, GRAPH | DRAW);
}

static void
gimp_curves_tool_control (GimpTool   *tool,
			  ToolAction  action,
			  GDisplay   *gdisp)
{
  switch (action)
    {
    case PAUSE:
      break;

    case RESUME:
      break;

    case HALT:
      curves_dialog_hide ();
      break;

    default:
      break;
    }

  if (GIMP_TOOL_CLASS (parent_class)->control)
    GIMP_TOOL_CLASS (parent_class)->control (tool, action, gdisp);
}

static void
gimp_curves_tool_button_press (GimpTool       *tool,
			       GdkEventButton *bevent,
			       GDisplay       *gdisp)
{
  gint          x, y;
  GimpDrawable *drawable;

  drawable = gimp_image_active_drawable (gdisp->gimage);

  tool->gdisp = gdisp;

  if (drawable != tool->drawable)
    {
      tool->preserve = TRUE;
      image_map_abort (curves_dialog->image_map);
      tool->preserve = FALSE;

      tool->drawable = drawable;

      curves_dialog->drawable = drawable;
      curves_dialog->color = gimp_drawable_is_rgb (drawable);
      curves_dialog->image_map = image_map_create (gdisp, drawable);
    }

  tool->state = ACTIVE;

  gdisplay_untransform_coords (gdisp, bevent->x, bevent->y, &x, &y,
			       FALSE, FALSE);
  curves_colour_update (tool, gdisp, drawable, x, y);
  curves_update (curves_dialog, GRAPH | DRAW);
}

static void
gimp_curves_tool_button_release (GimpTool       *tool,
				 GdkEventButton *bevent,
				 GDisplay       *gdisp)
{
  gint          x, y;
  GimpDrawable *drawable;

  if (! curves_dialog || 
      ! gdisp || 
      ! (drawable = gimp_image_active_drawable (gdisp->gimage)))
     return;

  gdisplay_untransform_coords (gdisp, bevent->x, bevent->y, &x, &y,
			       FALSE, FALSE);
  curves_colour_update (tool, gdisp, drawable, x, y);

  if (bevent->state & GDK_SHIFT_MASK)
    {
      curves_add_point (drawable, x, y, curves_dialog->channel);
      curves_calculate_curve (curves_dialog);
    }
  else if (bevent->state & GDK_CONTROL_MASK)
    {
      curves_add_point (drawable, x, y, GIMP_HISTOGRAM_VALUE);
      curves_add_point (drawable, x, y, GIMP_HISTOGRAM_RED);
      curves_add_point (drawable, x, y, GIMP_HISTOGRAM_GREEN);
      curves_add_point (drawable, x, y, GIMP_HISTOGRAM_BLUE);
      curves_add_point (drawable, x, y, GIMP_HISTOGRAM_ALPHA);
      curves_calculate_curve (curves_dialog);
    }

  curves_update (curves_dialog, GRAPH | DRAW);
}

static void
gimp_curves_tool_motion (GimpTool       *tool,
			 GdkEventMotion *mevent,
			 GDisplay       *gdisp)
{
  gint          x, y;
  GimpDrawable *drawable;

  if (! curves_dialog ||
      ! gdisp || 
      ! (drawable = gimp_image_active_drawable (gdisp->gimage)))
     return;

  gdisplay_untransform_coords (gdisp, mevent->x, mevent->y, &x, &y,
			       FALSE, FALSE);
  curves_colour_update (tool, gdisp, drawable, x, y);
  curves_update (curves_dialog, GRAPH | DRAW);
}


/*  curves machinery  */

gfloat
curves_lut_func (CurvesDialog *cd,
		 gint          nchannels,
		 gint          channel,
		 gfloat        value)
{
  gfloat  f;
  gint    index;
  gdouble inten;
  gint    j;

  if (nchannels == 1)
    j = 0;
  else
    j = channel + 1;

  inten = value;

  /* For color images this runs through the loop with j = channel +1
     the first time and j = 0 the second time */
  /* For bw images this runs through the loop with j = 0 the first and
     only time  */
  for (; j >= 0; j -= (channel + 1))
  {
    /* don't apply the overall curve to the alpha channel */
    if (j == 0 && (nchannels == 2 || nchannels == 4)
	&& channel == nchannels -1)
      return inten;

    if (inten < 0.0)
      inten = cd->curve[j][0]/255.0;
    else if (inten >= 1.0)
      inten = cd->curve[j][255]/255.0;
    else /* interpolate the curve */
    {
      index = floor(inten * 255.0);
      f = inten*255.0 - index;
      inten = ((1.0 - f) * cd->curve[j][index    ] + 
	       (      f) * cd->curve[j][index + 1] ) / 255.0;
    }
  }
  return inten;
}

static void
curves_colour_update (GimpTool       *tool,
		      GDisplay       *gdisp,
		      GimpDrawable   *drawable,
		      gint            x,
		      gint            y)
{
  guchar        *color;
  gint           offx;
  gint           offy;
  gint           maxval;
  gboolean       has_alpha;
  gboolean       is_indexed;
  GimpImageType  sample_type;

  if (!tool || tool->state != ACTIVE)
    return;

  gimp_drawable_offsets (drawable, &offx, &offy);

  x -= offx;
  y -= offy;

  if (!(color = image_map_get_color_at (curves_dialog->image_map, x, y)))
    return;

  sample_type = gimp_drawable_type (drawable);
  is_indexed  = gimp_drawable_is_indexed (drawable);
  has_alpha   = GIMP_IMAGE_TYPE_HAS_ALPHA (sample_type);

  curves_dialog->col_value[GIMP_HISTOGRAM_RED] = color[RED_PIX];
  curves_dialog->col_value[GIMP_HISTOGRAM_GREEN] = color[GREEN_PIX];
  curves_dialog->col_value[GIMP_HISTOGRAM_BLUE] = color[BLUE_PIX];

  if (has_alpha)
    {
      curves_dialog->col_value [GIMP_HISTOGRAM_ALPHA] = color[3];
    }

  if (is_indexed)
    curves_dialog->col_value [GIMP_HISTOGRAM_ALPHA] = color[4];

  maxval = MAX (color[RED_PIX], color[GREEN_PIX]);
  curves_dialog->col_value[GIMP_HISTOGRAM_VALUE] = MAX (maxval, color[BLUE_PIX]);

  g_free (color);
}

static void
curves_add_point (GimpDrawable *drawable,
		  gint          x,
		  gint          y,
		  gint          cchan)
{
  /* Add point onto the curve */
  gint closest_point = 0;
  gint distance;
  gint curvex;
  gint i;

  switch (curves_dialog->curve_type[cchan])
    {
    case SMOOTH:
      curvex = curves_dialog->col_value[cchan];
      distance = G_MAXINT;
      for (i = 0; i < 17; i++)
	{
	  if (curves_dialog->points[cchan][i][0] != -1)
	    if (abs (curvex - curves_dialog->points[cchan][i][0]) < distance)
	      {
		distance = abs (curvex - curves_dialog->points[cchan][i][0]);
		closest_point = i;
	      }
	}
      
      if (distance > MIN_DISTANCE)
	closest_point = (curvex + 8) / 16;
      
      curves_dialog->points[cchan][closest_point][0] = curvex;
      curves_dialog->points[cchan][closest_point][1] = curves_dialog->curve[cchan][curvex];
      break;
      
    case GFREE:
      curves_dialog->curve[cchan][x] = 255 - y;
      break;
    }
}

void
curves_dialog_hide (void)
{
  if (curves_dialog)
    curves_cancel_callback (NULL, (gpointer) curves_dialog);
}

void
curves_free (void)
{
  GimpTool *active_tool;

  if (curves_dialog)
    {
      if (curves_dialog->image_map)
	{
	  active_tool = tool_manager_get_active (the_gimp);

	  active_tool->preserve = TRUE;
	  image_map_abort (curves_dialog->image_map);
	  active_tool->preserve = FALSE;

	  curves_dialog->image_map = NULL;
	}

      if (curves_dialog->pixmap)
	gdk_drawable_unref (curves_dialog->pixmap);

      gtk_widget_destroy (curves_dialog->shell);
    }
}

/*******************/
/*  Curves dialog  */
/*******************/

static CurvesDialog *
curves_dialog_new (void)
{
  CurvesDialog *cd;
  GtkWidget *vbox;
  GtkWidget *hbox;
  GtkWidget *hbbox;
  GtkWidget *label;
  GtkWidget *frame;
  GtkWidget *toggle;
  GtkWidget *channel_hbox;
  GtkWidget *table;
  GtkWidget *button;
  gint i, j;

  cd = g_new (CurvesDialog, 1);
  cd->cursor_ind_height = -1;
  cd->cursor_ind_width  = -1;
  cd->preview           = TRUE;
  cd->pixmap            = NULL;
  cd->channel           = GIMP_HISTOGRAM_VALUE;

  for (i = 0; i < 5; i++)
    cd->curve_type[i] = SMOOTH;

  for (i = 0; i < 5; i++)
    for (j = 0; j < 256; j++)
      cd->curve[i][j] = j;

  for (i = 0; i < (sizeof (cd->col_value) / sizeof (cd->col_value[0])); i++)
    cd->col_value[i] = 0;

  cd->lut = gimp_lut_new ();

  /*  The shell and main vbox  */
  cd->shell = gimp_dialog_new (_("Curves"), "curves",
			       tool_manager_help_func, NULL,
			       GTK_WIN_POS_NONE,
			       FALSE, TRUE, FALSE,

			       _("OK"), curves_ok_callback,
			       cd, NULL, NULL, TRUE, FALSE,
			       _("Reset"), curves_reset_callback,
			       cd, NULL, NULL, FALSE, FALSE,
			       _("Cancel"), curves_cancel_callback,
			       cd, NULL, NULL, FALSE, TRUE,

			       NULL);

  vbox = gtk_vbox_new (FALSE, 4);
  gtk_container_set_border_width (GTK_CONTAINER (vbox), 4);
  gtk_container_add (GTK_CONTAINER (GTK_DIALOG (cd->shell)->vbox), vbox);

  /*  The option menu for selecting channels  */
  channel_hbox = gtk_hbox_new (FALSE, 4);
  gtk_box_pack_start (GTK_BOX (vbox), channel_hbox, FALSE, FALSE, 0);

  label = gtk_label_new (_("Modify Curves for Channel:"));
  gtk_box_pack_start (GTK_BOX (channel_hbox), label, FALSE, FALSE, 0);

  cd->channel_menu = gimp_option_menu_new2
    (FALSE,
     G_CALLBACK (curves_channel_callback),
     cd,
     GINT_TO_POINTER (cd->channel),

     _("Value"), GINT_TO_POINTER (GIMP_HISTOGRAM_VALUE), &channel_items[0],
     _("Red"),   GINT_TO_POINTER (GIMP_HISTOGRAM_RED),   &channel_items[1],
     _("Green"), GINT_TO_POINTER (GIMP_HISTOGRAM_GREEN), &channel_items[2],
     _("Blue"),  GINT_TO_POINTER (GIMP_HISTOGRAM_BLUE),  &channel_items[3],
     _("Alpha"), GINT_TO_POINTER (GIMP_HISTOGRAM_ALPHA), &channel_items[4],

     NULL);

  gtk_box_pack_start (GTK_BOX (channel_hbox), cd->channel_menu, FALSE, FALSE, 2);

  gtk_widget_show (label);
  gtk_widget_show (cd->channel_menu);
  gtk_widget_show (channel_hbox);

  /*  The table for the yrange and the graph  */
  table = gtk_table_new (2, 2, FALSE);
  gtk_table_set_col_spacings (GTK_TABLE (table), 2);
  gtk_table_set_row_spacings (GTK_TABLE (table), 2);
  gtk_box_pack_start (GTK_BOX (vbox), table, FALSE, FALSE, 0);

  /*  The range drawing area  */
  frame = gtk_frame_new (NULL);
  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_ETCHED_IN);
  gtk_table_attach (GTK_TABLE (table), frame, 0, 1, 0, 1,
		    GTK_EXPAND, GTK_EXPAND, 0, 0);

  cd->yrange = gtk_preview_new (GTK_PREVIEW_COLOR);
  gtk_preview_size (GTK_PREVIEW (cd->yrange), YRANGE_WIDTH, YRANGE_HEIGHT);
  gtk_widget_set_events (cd->yrange, RANGE_MASK);
  gtk_container_add (GTK_CONTAINER (frame), cd->yrange);

  g_signal_connect (G_OBJECT (cd->yrange), "event",
		    G_CALLBACK (curves_yrange_events),
		    cd);

  gtk_widget_show (cd->yrange);
  gtk_widget_show (frame);

  /*  The curves graph  */
  frame = gtk_frame_new (NULL);
  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_ETCHED_IN);
  gtk_table_attach (GTK_TABLE (table), frame, 1, 2, 0, 1,
		    GTK_SHRINK | GTK_FILL,
		    GTK_SHRINK | GTK_FILL, 0, 0);

  cd->graph = gtk_drawing_area_new ();
  gtk_drawing_area_size (GTK_DRAWING_AREA (cd->graph),
			 GRAPH_WIDTH + RADIUS * 2,
			 GRAPH_HEIGHT + RADIUS * 2);
  gtk_widget_set_events (cd->graph, GRAPH_MASK);
  gtk_container_add (GTK_CONTAINER (frame), cd->graph);

  g_signal_connect (G_OBJECT (cd->graph), "event",
		    G_CALLBACK (curves_graph_events),
		    cd);

  gtk_widget_show (cd->graph);
  gtk_widget_show (frame);

  /*  The range drawing area  */
  frame = gtk_frame_new (NULL);
  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_ETCHED_IN);
  gtk_table_attach (GTK_TABLE (table), frame, 1, 2, 1, 2,
		    GTK_EXPAND, GTK_EXPAND, 0, 0);

  cd->xrange = gtk_preview_new (GTK_PREVIEW_COLOR);
  gtk_preview_size (GTK_PREVIEW (cd->xrange), XRANGE_WIDTH, XRANGE_HEIGHT);
  gtk_widget_set_events (cd->xrange, RANGE_MASK);
  gtk_container_add (GTK_CONTAINER (frame), cd->xrange);

  g_signal_connect (G_OBJECT (cd->xrange), "event",
		    G_CALLBACK (curves_xrange_events),
		    cd);

  gtk_widget_show (cd->xrange);
  gtk_widget_show (frame);
  gtk_widget_show (table);

  /*  Horizontal box for preview  */
  hbox = gtk_hbox_new (FALSE, 4);
  gtk_box_pack_end (GTK_BOX (vbox), hbox, FALSE, FALSE, 0);

  /*  The option menu for selecting the drawing method  */
  label = gtk_label_new (_("Curve Type:"));
  gtk_box_pack_start (GTK_BOX (hbox), label, FALSE, FALSE, 0);
  gtk_widget_show (label);

  cd->curve_type_menu = gimp_option_menu_new
    (FALSE,

     _("Smooth"), curves_smooth_callback, cd, NULL, NULL, TRUE,
     _("Free"),   curves_free_callback,   cd, NULL, NULL, FALSE,

     NULL);
  gtk_box_pack_start (GTK_BOX (hbox), cd->curve_type_menu, FALSE, FALSE, 2);
  gtk_widget_show (cd->curve_type_menu);

  gtk_widget_show (hbox);

  /*  The preview toggle  */
  toggle = gtk_check_button_new_with_label (_("Preview"));
  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle), cd->preview);
  gtk_box_pack_end (GTK_BOX (hbox), toggle, FALSE, FALSE, 0);

  g_signal_connect (G_OBJECT (toggle), "toggled",
		    G_CALLBACK (curves_preview_update),
		    cd);

  gtk_widget_show (toggle);
  gtk_widget_show (hbox);

  /*  Horizontal button box for load / save  */
  hbbox = gtk_hbutton_box_new ();
  gtk_button_box_set_spacing (GTK_BUTTON_BOX (hbbox), 4);
  gtk_button_box_set_layout (GTK_BUTTON_BOX (hbbox), GTK_BUTTONBOX_SPREAD);
  gtk_box_pack_end (GTK_BOX (vbox), hbbox, FALSE, FALSE, 0);

  button = gtk_button_new_with_label (_("Load"));
  GTK_WIDGET_SET_FLAGS (button, GTK_CAN_DEFAULT);
  gtk_box_pack_start (GTK_BOX (hbbox), button, FALSE, FALSE, 0);
  gtk_widget_show (button);

  g_signal_connect (G_OBJECT (button), "clicked",
		    G_CALLBACK (curves_load_callback),
		    cd->shell);

  button = gtk_button_new_with_label (_("Save"));
  GTK_WIDGET_SET_FLAGS (button, GTK_CAN_DEFAULT);
  gtk_box_pack_start (GTK_BOX (hbbox), button, FALSE, FALSE, 0);
  gtk_widget_show (button);

  g_signal_connect (G_OBJECT (button), "clicked",
		    G_CALLBACK (curves_save_callback),
		    cd->shell);

  gtk_widget_show (hbbox);
  gtk_widget_show (vbox);

  return cd;
}

static void
curve_print_loc (CurvesDialog *cd,
		 gint          xpos,
		 gint          ypos)
{
  gchar buf[32];
  gint  width;
  gint  ascent;
  gint  descent;

  if (cd->cursor_ind_width < 0)
    {
      /* Calc max extents */
      gdk_string_extents (cd->graph->style->font,
			  "x:888 y:888",
			  NULL,
			  NULL,
			  &width,
			  &ascent,
			  &descent);
	
      cd->cursor_ind_width = width;
      cd->cursor_ind_height = ascent + descent;
      cd->cursor_ind_ascent = ascent;
    }
  
  if (xpos >= 0 && xpos <= 255 && ypos >=0 && ypos <= 255)
    {
      g_snprintf (buf, sizeof (buf), "x:%d y:%d",xpos,ypos);

      gdk_draw_rectangle (cd->graph->window, 
			  cd->graph->style->bg_gc[GTK_STATE_ACTIVE],
			  TRUE, RADIUS*2 + 2 , RADIUS*2 + 2, 
			  cd->cursor_ind_width+4, 
			  cd->cursor_ind_height+5);

      gdk_draw_rectangle (cd->graph->window, 
			  cd->graph->style->black_gc,
			  FALSE, RADIUS*2 + 2 , RADIUS*2 + 2, 
			  cd->cursor_ind_width+3, 
			  cd->cursor_ind_height+4);

      gdk_draw_string (cd->graph->window,
		       cd->graph->style->font,
		       cd->graph->style->black_gc,
		       RADIUS*2 + 4,
		       RADIUS*2 + 5 + cd->cursor_ind_ascent,
		       buf);
    }
}

/* TODO: preview alpha channel stuff correctly.  -- austin, 20/May/99 */
static void
curves_update (CurvesDialog *cd,
	       gint          update)
{
  GdkRectangle area;
  gint   i, j;
  gchar  buf[32];
  gint   offset;
  gint   sel_channel;
  
  if(cd->color) {
    sel_channel = cd->channel;
  } else {
    if(cd->channel == 2)
      sel_channel = GIMP_HISTOGRAM_ALPHA;
    else
      sel_channel = GIMP_HISTOGRAM_VALUE;
  }


  if (update & XRANGE_TOP)
    {
      guchar buf[XRANGE_WIDTH * 3];

      switch (sel_channel)
	{
	case GIMP_HISTOGRAM_VALUE:
	case GIMP_HISTOGRAM_ALPHA:
	  for (i = 0; i < XRANGE_HEIGHT / 2; i++)
	    {
	      for (j = 0; j < XRANGE_WIDTH ; j++)
		{
		  buf[j*3+0] = cd->curve[sel_channel][j];
		  buf[j*3+1] = cd->curve[sel_channel][j];
		  buf[j*3+2] = cd->curve[sel_channel][j];
		}
	      gtk_preview_draw_row (GTK_PREVIEW (cd->xrange),
				    buf, 0, i, XRANGE_WIDTH);
	    }
	  break;

	case GIMP_HISTOGRAM_RED:
	case GIMP_HISTOGRAM_GREEN:
	case GIMP_HISTOGRAM_BLUE:
	  {
	    for (i = 0; i < XRANGE_HEIGHT / 2; i++)
	      {
		for (j = 0; j < XRANGE_WIDTH; j++)
		  {
		    buf[j*3+0] = cd->curve[GIMP_HISTOGRAM_RED][j];
		    buf[j*3+1] = cd->curve[GIMP_HISTOGRAM_GREEN][j];
		    buf[j*3+2] = cd->curve[GIMP_HISTOGRAM_BLUE][j];
		  }
		gtk_preview_draw_row (GTK_PREVIEW (cd->xrange),
				      buf, 0, i, XRANGE_WIDTH);
	      }
	    break;
	  }

	default:
	  g_warning ("unknown channel type %d, can't happen!?!?",
		     cd->channel);
	  break;
	}

      if (update & DRAW)
	{
	  area.x = 0;
	  area.y = 0;
	  area.width = XRANGE_WIDTH;
	  area.height = XRANGE_HEIGHT / 2;
	  gtk_widget_draw (cd->xrange, &area);
	}
    }
  if (update & XRANGE_BOTTOM)
    {
      guchar buf[XRANGE_WIDTH * 3];

      for (i = 0; i < XRANGE_WIDTH; i++)
      {
	buf[i*3+0] = i;
	buf[i*3+1] = i;
	buf[i*3+2] = i;
      }

      for (i = XRANGE_HEIGHT / 2; i < XRANGE_HEIGHT; i++)
	gtk_preview_draw_row (GTK_PREVIEW (cd->xrange), buf, 0, i, XRANGE_WIDTH);

      if (update & DRAW)
	{
	  area.x = 0;
	  area.y = XRANGE_HEIGHT / 2;
	  area.width = XRANGE_WIDTH;
	  area.height = XRANGE_HEIGHT / 2;
	  gtk_widget_draw (cd->xrange, &area);
	}
    }
  if (update & YRANGE)
    {
      guchar buf[YRANGE_WIDTH * 3];
      guchar pix[3];

      for (i = 0; i < YRANGE_HEIGHT; i++)
	{
	  switch (sel_channel)
	    {
	    case GIMP_HISTOGRAM_VALUE:
	    case GIMP_HISTOGRAM_ALPHA:
	      pix[0] = pix[1] = pix[2] = (255 - i);
	      break;

	    case GIMP_HISTOGRAM_RED:
	    case GIMP_HISTOGRAM_GREEN:
	    case GIMP_HISTOGRAM_BLUE:
	      pix[0] = pix[1] = pix[2] = 0;
	      pix[sel_channel - 1] = (255 - i);
	      break;

	    default:
	      g_warning ("unknown channel type %d, can't happen!?!?",
			 cd->channel);
	      break;
	    }

	  for (j = 0; j < YRANGE_WIDTH * 3; j++)
	    buf[j] = pix[j%3];

	  gtk_preview_draw_row (GTK_PREVIEW (cd->yrange),
				buf, 0, i, YRANGE_WIDTH);
	}

      if (update & DRAW)
	gtk_widget_draw (cd->yrange, NULL);
    }
  if ((update & GRAPH) && (update & DRAW) && cd->pixmap != NULL)
    {
      GdkPoint points[256];

      /*  Clear the pixmap  */
      gdk_draw_rectangle (cd->pixmap, cd->graph->style->bg_gc[GTK_STATE_NORMAL],
			  TRUE, 0, 0,
			  GRAPH_WIDTH + RADIUS * 2, GRAPH_HEIGHT + RADIUS * 2);

      /*  Draw the grid lines  */
      for (i = 0; i < 5; i++)
	{
	  gdk_draw_line (cd->pixmap, cd->graph->style->dark_gc[GTK_STATE_NORMAL],
			 RADIUS, i * (GRAPH_HEIGHT / 4) + RADIUS,
			 GRAPH_WIDTH + RADIUS, i * (GRAPH_HEIGHT / 4) + RADIUS);
	  gdk_draw_line (cd->pixmap, cd->graph->style->dark_gc[GTK_STATE_NORMAL],
			 i * (GRAPH_WIDTH / 4) + RADIUS, RADIUS,
			 i * (GRAPH_WIDTH / 4) + RADIUS, GRAPH_HEIGHT + RADIUS);
	}

      /*  Draw the curve  */
      for (i = 0; i < 256; i++)
	{
	  points[i].x = i + RADIUS;
	  points[i].y = 255 - cd->curve[cd->channel][i] + RADIUS;
	}
      gdk_draw_points (cd->pixmap, cd->graph->style->black_gc, points, 256);

      /*  Draw the points  */
      if (cd->curve_type[cd->channel] == SMOOTH)
	for (i = 0; i < 17; i++)
	  {
	    if (cd->points[cd->channel][i][0] != -1)
	      gdk_draw_arc (cd->pixmap, cd->graph->style->black_gc, TRUE,
			    cd->points[cd->channel][i][0],
			    255 - cd->points[cd->channel][i][1],
			    RADIUS * 2, RADIUS * 2, 0, 23040);
	  }

      /* draw the colour line */
      gdk_draw_line (cd->pixmap, cd->graph->style->black_gc,
		     cd->col_value[sel_channel]+RADIUS,RADIUS,
		     cd->col_value[sel_channel]+RADIUS,GRAPH_HEIGHT + RADIUS);

      /* and xpos indicator */
      g_snprintf (buf, sizeof (buf), "x:%d",cd->col_value[sel_channel]);
      
      if ((cd->col_value[sel_channel]+RADIUS) < 127)
	{
	  offset = RADIUS + 4;
	}
      else
	{
	  offset = - gdk_string_width (cd->graph->style->font,buf) - 2;
	}

      gdk_draw_string (cd->pixmap,
		       cd->graph->style->font,
		       cd->graph->style->black_gc,
		       cd->col_value[sel_channel]+offset,
		       GRAPH_HEIGHT,
		       buf);

      gdk_draw_pixmap (cd->graph->window, cd->graph->style->black_gc, cd->pixmap,
		       0, 0, 0, 0, GRAPH_WIDTH + RADIUS * 2, GRAPH_HEIGHT + RADIUS * 2);
      
    }
}

static void
curves_plot_curve (CurvesDialog *cd,
		   gint          p1,
		   gint          p2,
		   gint          p3,
		   gint          p4)
{
  CRMatrix geometry;
  CRMatrix tmp1, tmp2;
  CRMatrix deltas;
  gdouble  x, dx, dx2, dx3;
  gdouble  y, dy, dy2, dy3;
  gdouble  d, d2, d3;
  gint     lastx, lasty;
  gint32   newx, newy;
  gint     i;

  /* construct the geometry matrix from the segment */
  for (i = 0; i < 4; i++)
    {
      geometry[i][2] = 0;
      geometry[i][3] = 0;
    }

  for (i = 0; i < 2; i++)
    {
      geometry[0][i] = cd->points[cd->channel][p1][i];
      geometry[1][i] = cd->points[cd->channel][p2][i];
      geometry[2][i] = cd->points[cd->channel][p3][i];
      geometry[3][i] = cd->points[cd->channel][p4][i];
    }

  /* subdivide the curve 1000 times */
  /* n can be adjusted to give a finer or coarser curve */
  d = 1.0 / 1000;
  d2 = d * d;
  d3 = d * d * d;

  /* construct a temporary matrix for determining the forward differencing deltas */
  tmp2[0][0] = 0;     tmp2[0][1] = 0;     tmp2[0][2] = 0;    tmp2[0][3] = 1;
  tmp2[1][0] = d3;    tmp2[1][1] = d2;    tmp2[1][2] = d;    tmp2[1][3] = 0;
  tmp2[2][0] = 6*d3;  tmp2[2][1] = 2*d2;  tmp2[2][2] = 0;    tmp2[2][3] = 0;
  tmp2[3][0] = 6*d3;  tmp2[3][1] = 0;     tmp2[3][2] = 0;    tmp2[3][3] = 0;

  /* compose the basis and geometry matrices */
  curves_CR_compose (CR_basis, geometry, tmp1);

  /* compose the above results to get the deltas matrix */
  curves_CR_compose (tmp2, tmp1, deltas);

  /* extract the x deltas */
  x = deltas[0][0];
  dx = deltas[1][0];
  dx2 = deltas[2][0];
  dx3 = deltas[3][0];

  /* extract the y deltas */
  y = deltas[0][1];
  dy = deltas[1][1];
  dy2 = deltas[2][1];
  dy3 = deltas[3][1];

  lastx = CLAMP (x, 0, 255);
  lasty = CLAMP (y, 0, 255);

  cd->curve[cd->channel][lastx] = lasty;

  /* loop over the curve */
  for (i = 0; i < 1000; i++)
    {
      /* increment the x values */
      x += dx;
      dx += dx2;
      dx2 += dx3;

      /* increment the y values */
      y += dy;
      dy += dy2;
      dy2 += dy3;

      newx = CLAMP0255 (ROUND (x));
      newy = CLAMP0255 (ROUND (y));

      /* if this point is different than the last one...then draw it */
      if ((lastx != newx) || (lasty != newy))
	cd->curve[cd->channel][newx] = newy;

      lastx = newx;
      lasty = newy;
    }
}

void
curves_calculate_curve (CurvesDialog *cd)
{
  gint i;
  gint points[17];
  gint num_pts;
  gint p1, p2, p3, p4;

  switch (cd->curve_type[cd->channel])
    {
    case GFREE:
      break;
    case SMOOTH:
      /*  cycle through the curves  */
      num_pts = 0;
      for (i = 0; i < 17; i++)
	if (cd->points[cd->channel][i][0] != -1)
	  points[num_pts++] = i;

      /*  Initialize boundary curve points */
      if (num_pts != 0)
	{
	  for (i = 0; i < cd->points[cd->channel][points[0]][0]; i++)
	    cd->curve[cd->channel][i] = cd->points[cd->channel][points[0]][1];
	  for (i = cd->points[cd->channel][points[num_pts - 1]][0]; i < 256; i++)
	    cd->curve[cd->channel][i] = cd->points[cd->channel][points[num_pts - 1]][1];
	}

      for (i = 0; i < num_pts - 1; i++)
	{
	  p1 = (i == 0) ? points[i] : points[(i - 1)];
	  p2 = points[i];
	  p3 = points[(i + 1)];
	  p4 = (i == (num_pts - 2)) ? points[(num_pts - 1)] : points[(i + 2)];

	  curves_plot_curve (cd, p1, p2, p3, p4);
	}
      break;
    }
  gimp_lut_setup (cd->lut, (GimpLutFunc) curves_lut_func,
		  (void *) cd, gimp_drawable_bytes (cd->drawable));

}

static void
curves_preview (CurvesDialog *cd)
{
  GimpTool *active_tool;

  if (!cd->image_map)
    {
      g_message ("curves_preview(): No image map");
      return;
    }

  active_tool = tool_manager_get_active (the_gimp);

  active_tool->preserve = TRUE;
  image_map_apply (cd->image_map,  (ImageMapApplyFunc)gimp_lut_process_2,
		   (void *) cd->lut);
  active_tool->preserve = FALSE;
}

static void
curves_channel_callback (GtkWidget *widget,
			 gpointer   data)
{
  CurvesDialog *cd;

  cd = (CurvesDialog *) data;

  gimp_menu_item_update (widget, &cd->channel);

  if(!cd->color) {
    if(cd->channel > 1)
      {
	cd->channel = 2;
      }
    else 
      {
	cd->channel = 1;
      }
  } 

  gtk_option_menu_set_history (GTK_OPTION_MENU (cd->curve_type_menu), 
			       cd->curve_type[cd->channel]);

  curves_update (cd, XRANGE_TOP | YRANGE | GRAPH | DRAW);
}

static void
curves_smooth_callback (GtkWidget *widget,
			gpointer   data)
{
  CurvesDialog *cd;
  gint   i;
  gint32 index;

  cd = (CurvesDialog *) data;

  if (cd->curve_type[cd->channel] != SMOOTH)
    {
      cd->curve_type[cd->channel] = SMOOTH;

      /*  pick representative points from the curve and make them control points  */
      for (i = 0; i <= 8; i++)
	{
	  index = CLAMP0255 (i * 32);
	  cd->points[cd->channel][i * 2][0] = index;
	  cd->points[cd->channel][i * 2][1] = cd->curve[cd->channel][index];
	}

      curves_calculate_curve (cd);
      curves_update (cd, GRAPH | DRAW);

      if (cd->preview)
	curves_preview (cd);
    }
}

static void
curves_free_callback (GtkWidget *widget,
		      gpointer   data)
{
  CurvesDialog *cd;

  cd = (CurvesDialog *) data;

  if (cd->curve_type[cd->channel] != GFREE)
    {
      cd->curve_type[cd->channel] = GFREE;
      curves_calculate_curve (cd);
      curves_update (cd, GRAPH | DRAW);

      if (cd->preview)
	curves_preview (cd);
    }
}

static void
curves_channel_reset (int i)
{
  gint j;

  curves_dialog->grab_point = -1;

  for (j = 0; j < 17; j++)
  {
    curves_dialog->points[i][j][0] = -1;
    curves_dialog->points[i][j][1] = -1;
  }
  curves_dialog->points[i][0][0] = 0;
  curves_dialog->points[i][0][1] = 0;
  curves_dialog->points[i][16][0] = 255;
  curves_dialog->points[i][16][1] = 255;
}


static void
curves_reset_callback (GtkWidget *widget,
		       gpointer   data)
{
  CurvesDialog *cd;
  gint i;

  cd = (CurvesDialog *) data;

  /*  Initialize the values  */
  for (i = 0; i < 256; i++)
    cd->curve[cd->channel][i] = i;

  curves_channel_reset (cd->channel);

  curves_calculate_curve (cd);
  curves_update (cd, GRAPH | XRANGE_TOP | DRAW);

  if (cd->preview)
    curves_preview (cd);
}

static void
curves_ok_callback (GtkWidget *widget,
		    gpointer   data)
{
  CurvesDialog *cd;
  GimpTool     *active_tool;

  cd = (CurvesDialog *) data;

  gimp_dialog_hide (cd->shell);

  active_tool = tool_manager_get_active (the_gimp);

  active_tool->preserve = TRUE;  /* We're about to dirty... */

  if (!cd->preview)
    image_map_apply (cd->image_map, (ImageMapApplyFunc)gimp_lut_process_2,
		     (void *) cd->lut);

  if (cd->image_map)
    image_map_commit (cd->image_map);

  active_tool->preserve = FALSE;

  cd->image_map = NULL;

  active_tool->gdisp    = NULL;
  active_tool->drawable = NULL;
}

static void
curves_cancel_callback (GtkWidget *widget,
			gpointer   data)
{
  CurvesDialog *cd;
  GimpTool     *active_tool;

  cd = (CurvesDialog *) data;

  gimp_dialog_hide (cd->shell);

  active_tool = tool_manager_get_active (the_gimp);

  if (cd->image_map)
    {
      active_tool->preserve = TRUE;
      image_map_abort (cd->image_map);
      active_tool->preserve = FALSE;

      gdisplays_flush ();
      cd->image_map = NULL;
    }

  active_tool->gdisp    = NULL;
  active_tool->drawable = NULL;
}

static void
curves_load_callback (GtkWidget *widget,
		      gpointer   data)
{
  if (!file_dlg)
    file_dialog_create (GTK_WIDGET (data));
  else if (GTK_WIDGET_VISIBLE (file_dlg)) 
    return;

  load_save = TRUE;

  gtk_window_set_title (GTK_WINDOW (file_dlg), _("Load Curves"));
  gtk_widget_show (file_dlg);
}

static void
curves_save_callback (GtkWidget *widget,
		      gpointer   data)
{
  if (!file_dlg)
    file_dialog_create (GTK_WIDGET (data));
  else if (GTK_WIDGET_VISIBLE (file_dlg)) 
    return;

  load_save = FALSE;

  gtk_window_set_title (GTK_WINDOW (file_dlg), _("Save Curves"));
  gtk_widget_show (file_dlg);
}

static void
curves_preview_update (GtkWidget *widget,
		       gpointer   data)
{
  CurvesDialog *cd;
  GimpTool     *active_tool;

  cd = (CurvesDialog *) data;
  
  if (GTK_TOGGLE_BUTTON (widget)->active)
    {
      cd->preview = TRUE;
      curves_preview (cd);
    }
  else
    {
      cd->preview = FALSE;
      if (cd->image_map)
	{
	  active_tool = tool_manager_get_active (the_gimp);

	  active_tool->preserve = TRUE;
	  image_map_clear (cd->image_map);
	  active_tool->preserve = FALSE;
	  gdisplays_flush ();
	}
    }
}

static gint
curves_graph_events (GtkWidget    *widget,
		     GdkEvent     *event,
		     CurvesDialog *cd)
{
  static GdkCursorType cursor_type = GDK_TOP_LEFT_ARROW;
  GdkCursorType new_type;
  GdkEventButton *bevent;
  GdkEventMotion *mevent;
  gint i;
  gint tx, ty;
  gint x, y;
  gint closest_point;
  gint distance;
  gint x1, x2, y1, y2;

  new_type      = GDK_X_CURSOR;
  closest_point = 0;

  /*  get the pointer position  */
  gdk_window_get_pointer (cd->graph->window, &tx, &ty, NULL);
  x = CLAMP ((tx - RADIUS), 0, 255);
  y = CLAMP ((ty - RADIUS), 0, 255);

  distance = G_MAXINT;
  for (i = 0; i < 17; i++)
    {
      if (cd->points[cd->channel][i][0] != -1)
	if (abs (x - cd->points[cd->channel][i][0]) < distance)
	  {
	    distance = abs (x - cd->points[cd->channel][i][0]);
	    closest_point = i;
	  }
    }
  if (distance > MIN_DISTANCE)
    closest_point = (x + 8) / 16;

  switch (event->type)
    {
    case GDK_EXPOSE:
      if (cd->pixmap == NULL)
	cd->pixmap = gdk_pixmap_new (cd->graph->window,
				     GRAPH_WIDTH + RADIUS * 2,
				     GRAPH_HEIGHT + RADIUS * 2, -1);

      curves_update (cd, GRAPH | DRAW);
      break;

    case GDK_BUTTON_PRESS:
      bevent = (GdkEventButton *) event;
      new_type = GDK_TCROSS;

      switch (cd->curve_type[cd->channel])
	{
	case SMOOTH:
	  /*  determine the leftmost and rightmost points  */
	  cd->leftmost = -1;
	  for (i = closest_point - 1; i >= 0; i--)
	    if (cd->points[cd->channel][i][0] != -1)
	      {
		cd->leftmost = cd->points[cd->channel][i][0];
		break;
	      }
	  cd->rightmost = 256;
	  for (i = closest_point + 1; i < 17; i++)
	    if (cd->points[cd->channel][i][0] != -1)
	      {
		cd->rightmost = cd->points[cd->channel][i][0];
		break;
	      }

	  cd->grab_point = closest_point;
	  cd->points[cd->channel][cd->grab_point][0] = x;
	  cd->points[cd->channel][cd->grab_point][1] = 255 - y;

	  break;

	case GFREE:
	  cd->curve[cd->channel][x] = 255 - y;
	  cd->grab_point = x;
	  cd->last = y;
	  break;
	}
      
      curves_calculate_curve (cd);
      curves_update (cd, GRAPH | XRANGE_TOP | DRAW);
      gtk_grab_add (widget);

      break;

    case GDK_BUTTON_RELEASE:
      new_type = GDK_FLEUR;
      cd->grab_point = -1;

      if (cd->preview)
	curves_preview (cd);

      gtk_grab_remove (widget);

      break;

    case GDK_MOTION_NOTIFY:
      mevent = (GdkEventMotion *) event;

      if (mevent->is_hint)
	{
	  mevent->x = tx;
	  mevent->y = ty;
	}

      switch (cd->curve_type[cd->channel])
	{
	case SMOOTH:
	  /*  If no point is grabbed...  */
	  if (cd->grab_point == -1)
	    {
	      if (cd->points[cd->channel][closest_point][0] != -1)
		new_type = GDK_FLEUR;
	      else
		new_type = GDK_TCROSS;
	    }
	  /*  Else, drag the grabbed point  */
	  else
	    {
	      new_type = GDK_TCROSS;

	      cd->points[cd->channel][cd->grab_point][0] = -1;

	      if (x > cd->leftmost && x < cd->rightmost)
		{
		  closest_point = (x + 8) / 16;
		  if (cd->points[cd->channel][closest_point][0] == -1)
		    cd->grab_point = closest_point;
		  cd->points[cd->channel][cd->grab_point][0] = x;
		  cd->points[cd->channel][cd->grab_point][1] = 255 - y;
		}

	      curves_calculate_curve (cd);
	      curves_update (cd, GRAPH | XRANGE_TOP | DRAW);
	    }
	  break;

	case GFREE:
	  if (cd->grab_point != -1)
	    {
	      if (cd->grab_point > x)
		{
		  x1 = x;
		  x2 = cd->grab_point;
		  y1 = y;
		  y2 = cd->last;
		}
	      else
		{
		  x1 = cd->grab_point;
		  x2 = x;
		  y1 = cd->last;
		  y2 = y;
		}

	      if (x2 != x1)
		for (i = x1; i <= x2; i++)
		  cd->curve[cd->channel][i] = 255 - (y1 + ((y2 - y1) * (i - x1)) / (x2 - x1));
	      else
		cd->curve[cd->channel][x] = 255 - y;

	      cd->grab_point = x;
	      cd->last = y;

	      curves_update (cd, GRAPH | XRANGE_TOP | DRAW);
	    }

	  if (mevent->state & GDK_BUTTON1_MASK)
	    new_type = GDK_TCROSS;
	  else
	    new_type = GDK_PENCIL;
	  break;
	}

      if (new_type != cursor_type)
	{
	  GdkCursor *cursor;

	  cursor_type = new_type;

	  cursor = gimp_cursor_new (cursor_type,
				    GIMP_TOOL_CURSOR_NONE,
				    GIMP_CURSOR_MODIFIER_NONE);
	  gdk_window_set_cursor (cd->graph->window, cursor);
	  gdk_cursor_destroy (cursor);
	}

      curve_print_loc (cd, x, 255 - y);

      break;

    default:
      break;
    }

  return FALSE;
}

static gint
curves_xrange_events (GtkWidget    *widget,
		      GdkEvent     *event,
		      CurvesDialog *cd)
{
  switch (event->type)
    {
    case GDK_EXPOSE:
      curves_update (cd, XRANGE_TOP | XRANGE_BOTTOM);
      break;

    case GDK_DELETE:
      break;

    default:
      break;
    }

  return FALSE;
}

static gint
curves_yrange_events (GtkWidget    *widget,
		      GdkEvent     *event,
		      CurvesDialog *cd)
{
  switch (event->type)
    {
    case GDK_EXPOSE:
      curves_update (cd, YRANGE);
      break;

    default:
      break;
    }

  return FALSE;
}

static void
curves_CR_compose (CRMatrix a,
		   CRMatrix b,
		   CRMatrix ab)
{
  gint i, j;

  for (i = 0; i < 4; i++)
    {
      for (j = 0; j < 4; j++)
        {
          ab[i][j] = (a[i][0] * b[0][j] +
                      a[i][1] * b[1][j] +
                      a[i][2] * b[2][j] +
                      a[i][3] * b[3][j]);
        }
    }
}


static void
file_dialog_create (GtkWidget *parent)
{
  gchar *temp;

  file_dlg = gtk_file_selection_new (_("Load/Save Curves"));
  gtk_window_set_wmclass (GTK_WINDOW (file_dlg), "load_save_curves", "Gimp");
  gtk_window_set_position (GTK_WINDOW (file_dlg), GTK_WIN_POS_MOUSE);

  gtk_container_set_border_width (GTK_CONTAINER (file_dlg), 2);
  gtk_container_set_border_width (GTK_CONTAINER (GTK_FILE_SELECTION (file_dlg)->button_area), 2);

  g_signal_connect (G_OBJECT (GTK_FILE_SELECTION (file_dlg)->cancel_button),
		    "clicked",
		    G_CALLBACK (file_dialog_cancel_callback),
		    NULL);
  g_signal_connect (G_OBJECT (file_dlg), "delete_event",
		    G_CALLBACK (file_dialog_cancel_callback),
		    NULL);
  g_signal_connect (G_OBJECT (GTK_FILE_SELECTION (file_dlg)->ok_button),
		    "clicked",
		    G_CALLBACK (file_dialog_ok_callback),
		    NULL);

  g_signal_connect (G_OBJECT (parent), "unmap",
		    G_CALLBACK (file_dialog_cancel_callback),
		    NULL);

  temp = g_strdup_printf ("%s" G_DIR_SEPARATOR_S "curves" G_DIR_SEPARATOR_S,
      			  gimp_directory ());
  gtk_file_selection_set_filename (GTK_FILE_SELECTION (file_dlg), temp);
  g_free (temp);

  gimp_help_connect (file_dlg, tool_manager_help_func, NULL);
}

static void
file_dialog_ok_callback (GtkWidget *widget,
			 gpointer   data)
{
  FILE        *f;
  const gchar *filename;

  filename = gtk_file_selection_get_filename (GTK_FILE_SELECTION (file_dlg));

  if (load_save)
    {
      f = fopen (filename, "rt");

      if (!f)
	{
	  g_message (_("Unable to open file %s"), filename);
	  return;
	}

      if (!curves_read_from_file (f))
	{
	  g_message (("Error in reading file %s"), filename);
	  return;
	}

      fclose (f);
    }
  else
    {
      f = fopen (filename, "wt");

      if (!f)
	{
	  g_message (_("Unable to open file %s"), filename);
	  return;
	}

      curves_write_to_file (f);

      fclose (f);
    }

  file_dialog_cancel_callback (file_dlg, NULL);
}

static void
file_dialog_cancel_callback (GtkWidget *widget,
			     gpointer   data)
{
  gimp_dialog_hide (file_dlg);
}

static gboolean
curves_read_from_file (FILE *f)
{
  gint  i, j;
  gint  fields;
  gchar buf[50];
  gint  index[5][17];
  gint  value[5][17];
  gint  current_channel;
  
  if (!fgets (buf, 50, f))
    return FALSE;

  if (strcmp (buf, "# GIMP Curves File\n") != 0)
    return FALSE;

  for (i = 0; i < 5; i++)
    {
      for (j = 0; j < 17; j++)
	{
	  fields = fscanf (f, "%d %d ", &index[i][j], &value[i][j]);
	  if (fields != 2)
	    {
	      g_print ("fields != 2");
	      return FALSE;
	    }
	}
    }

  for (i = 0; i < 5; i++)
    {
      curves_dialog->curve_type[i] = SMOOTH;
      for (j = 0; j < 17; j++)
	{
	  curves_dialog->points[i][j][0] = index[i][j];
	  curves_dialog->points[i][j][1] = value[i][j];
	}
    }

  /* this is ugly, but works ... */
  current_channel = curves_dialog->channel;
  for (i = 0; i < 5; i++)
    {
      curves_dialog->channel = i;
      curves_calculate_curve (curves_dialog);
    }
  curves_dialog->channel = current_channel;

  curves_update (curves_dialog, ALL);
  gtk_option_menu_set_history (GTK_OPTION_MENU (curves_dialog->curve_type_menu),
			       SMOOTH);

  if (curves_dialog->preview)
    curves_preview (curves_dialog);

  return TRUE;
}

static void
curves_write_to_file (FILE *f)
{
  gint   i, j;
  gint32 index;

  for (i = 0; i < 5; i++)
    if (curves_dialog->curve_type[i] == GFREE)
      {  
	/*  pick representative points from the curve and make them control points  */
	for (j = 0; j <= 8; j++)
	  {
	    index = CLAMP0255 (j * 32);
	    curves_dialog->points[i][j * 2][0] = index;
	    curves_dialog->points[i][j * 2][1] = curves_dialog->curve[i][index];
	  }      
      }
  
  fprintf (f, "# GIMP Curves File\n");

  for (i = 0; i < 5; i++)
    {
      for (j = 0; j < 17; j++)
	fprintf (f, "%d %d ", curves_dialog->points[i][j][0], 
		              curves_dialog->points[i][j][1]);
      
      fprintf (f, "\n");
    }
}