/* LIBGIMP - The GIMP Library
 * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
 *
 * gimpcolorarea.c
 * Copyright (C) 2001-2002  Sven Neumann <sven@gimp.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser 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 Lesser 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.
 */

#include "config.h"

#include <gtk/gtk.h>

#include "libgimpcolor/gimpcolor.h"
#include "libgimpbase/gimpbase.h"

#include "gimpwidgetstypes.h"

#include "gimpcolorarea.h"


#define DRAG_PREVIEW_SIZE   32
#define DRAG_ICON_OFFSET    -8


enum
{
  COLOR_CHANGED,
  LAST_SIGNAL
};


static void     gimp_color_area_class_init    (GimpColorAreaClass *klass);
static void     gimp_color_area_init          (GimpColorArea      *area);

static void     gimp_color_area_finalize      (GObject            *object);

static void     gimp_color_area_size_allocate (GtkWidget          *widget,
                                               GtkAllocation      *allocation);
static gboolean gimp_color_area_expose        (GtkWidget          *widget,
                                               GdkEventExpose     *event);
static void     gimp_color_area_render        (GimpColorArea      *area);

static void  gimp_color_area_drag_begin         (GtkWidget        *widget,
						 GdkDragContext   *context);
static void  gimp_color_area_drag_end           (GtkWidget        *widget,
						 GdkDragContext   *context);
static void  gimp_color_area_drag_data_received (GtkWidget        *widget,
						 GdkDragContext   *context,
						 gint              x,
						 gint              y,
						 GtkSelectionData *selection_data,
						 guint             info,
						 guint             time);
static void  gimp_color_area_drag_data_get      (GtkWidget        *widget,
						 GdkDragContext   *context,
						 GtkSelectionData *selection_data,
						 guint             info,
						 guint             time);


static const GtkTargetEntry target = { "application/x-color", 0 };

static guint gimp_color_area_signals[LAST_SIGNAL] = { 0 };

static GtkDrawingAreaClass * parent_class = NULL;


GType
gimp_color_area_get_type (void)
{
  static GType area_type = 0;

  if (! area_type)
    {
      static const GTypeInfo area_info =
      {
        sizeof (GimpColorAreaClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc) gimp_color_area_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data     */
        sizeof (GimpColorArea),
        0,              /* n_preallocs    */
        (GInstanceInitFunc) gimp_color_area_init,
      };

      area_type = g_type_register_static (GTK_TYPE_DRAWING_AREA,
                                          "GimpColorArea",
                                          &area_info, 0);
    }

  return area_type;
}

static void
gimp_color_area_class_init (GimpColorAreaClass *klass)
{
  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);

  gimp_color_area_signals[COLOR_CHANGED] =
    g_signal_new ("color_changed",
                  G_TYPE_FROM_CLASS (klass),
                  G_SIGNAL_RUN_FIRST,
                  G_STRUCT_OFFSET (GimpColorAreaClass, color_changed),
                  NULL, NULL,
                  g_cclosure_marshal_VOID__VOID,
                  G_TYPE_NONE, 0);

  object_class->finalize           = gimp_color_area_finalize;

  widget_class->size_allocate      = gimp_color_area_size_allocate;
  widget_class->expose_event       = gimp_color_area_expose;

  widget_class->drag_begin         = gimp_color_area_drag_begin;
  widget_class->drag_end           = gimp_color_area_drag_end;
  widget_class->drag_data_received = gimp_color_area_drag_data_received;
  widget_class->drag_data_get      = gimp_color_area_drag_data_get;

  klass->color_changed             = NULL;
}

static void
gimp_color_area_init (GimpColorArea *area)
{
  area->buf       = NULL;
  area->width     = 0;
  area->height    = 0;
  area->rowstride = 0;

  area->type      = GIMP_COLOR_AREA_FLAT;
  gimp_rgba_set (&area->color, 0.0, 0.0, 0.0, 1.0);

  area->draw_border  = FALSE;
  area->needs_render = TRUE;
}

static void
gimp_color_area_finalize (GObject *object)
{
  GimpColorArea *area = GIMP_COLOR_AREA (object);

  if (area->buf)
    {
      g_free (area->buf);
      area->buf = NULL;
    }

  G_OBJECT_CLASS (parent_class)->finalize (object);
}

static void
gimp_color_area_size_allocate (GtkWidget     *widget,
			       GtkAllocation *allocation)
{
  GimpColorArea *area = GIMP_COLOR_AREA (widget);

  if (GTK_WIDGET_CLASS (parent_class)->size_allocate)
    GTK_WIDGET_CLASS (parent_class)->size_allocate (widget, allocation);

  if (widget->allocation.width  != area->width ||
      widget->allocation.height != area->height)
    {
      area->width  = widget->allocation.width;
      area->height = widget->allocation.height;

      area->rowstride = (area->width * 3 + 3) & ~0x3;

      g_free (area->buf);
      area->buf = g_new (guchar, area->rowstride * area->height);

      area->needs_render = TRUE;
    }
}

static gboolean
gimp_color_area_expose (GtkWidget      *widget,
                        GdkEventExpose *event)
{
  GimpColorArea *area = GIMP_COLOR_AREA (widget);
  guchar        *buf;

  if (! area->buf || !GTK_WIDGET_DRAWABLE (widget))
    return FALSE;

  if (area->needs_render)
    gimp_color_area_render (area);

  buf = area->buf + event->area.y * area->rowstride + event->area.x * 3;

  gdk_draw_rgb_image_dithalign (widget->window,
                                widget->style->black_gc,
                                event->area.x,
                                event->area.y,
                                event->area.width,
                                event->area.height,
                                GDK_RGB_DITHER_MAX,
                                buf,
                                area->rowstride,
                                event->area.x,
                                event->area.y);

  if (area->draw_border)
    gdk_draw_rectangle (widget->window,
                        widget->style->fg_gc[widget->state],
                        FALSE,
                        0, 0,
                        area->width - 1, area->height - 1);

  return FALSE;
}

/**
 * gimp_color_area_new:
 * @color:     A pointer to a #GimpRGB struct.
 * @type:      The type of color area to create.
 * @drag_mask: The event_mask that should trigger drags.
 *
 * Creates a new #GimpColorArea widget.
 *
 * This returns a preview area showing the color. It handles color
 * DND. If the color changes, the "color_changed" signal is emitted.
 *
 * Returns: Pointer to the new #GimpColorArea widget.
 **/
GtkWidget *
gimp_color_area_new (const GimpRGB     *color,
		     GimpColorAreaType  type,
		     GdkModifierType    drag_mask)
{
  GimpColorArea *area;

  g_return_val_if_fail (color != NULL, NULL);

  area = g_object_new (GIMP_TYPE_COLOR_AREA, NULL);

  area->color = *color;
  area->type  = type;

  gtk_drag_dest_set (GTK_WIDGET (area),
                     GTK_DEST_DEFAULT_HIGHLIGHT |
                     GTK_DEST_DEFAULT_MOTION |
                     GTK_DEST_DEFAULT_DROP,
                     &target, 1,
                     GDK_ACTION_COPY);

  drag_mask &= (GDK_BUTTON1_MASK | GDK_BUTTON2_MASK | GDK_BUTTON3_MASK);

  if (drag_mask)
    gtk_drag_source_set (GTK_WIDGET (area),
			 drag_mask,
			 &target, 1,
			 GDK_ACTION_COPY | GDK_ACTION_MOVE);

  return GTK_WIDGET (area);
}

/**
 * gimp_color_area_set_color:
 * @area: Pointer to a #GimpColorArea.
 * @color: Pointer to a #GimpRGB struct that defines the new color.
 *
 * Sets @area to a different @color.
 **/
void
gimp_color_area_set_color (GimpColorArea *area,
                           const GimpRGB *color)
{
  g_return_if_fail (GIMP_IS_COLOR_AREA (area));
  g_return_if_fail (color != NULL);

  if (area->type == GIMP_COLOR_AREA_FLAT)
    {
      if (gimp_rgb_distance (&area->color, color) < 0.000001)
        return;
    }
  else
    {
      if (gimp_rgba_distance (&area->color, color) < 0.000001)
        return;
    }

  area->color = *color;

  area->needs_render = TRUE;
  gtk_widget_queue_draw (GTK_WIDGET (area));

  g_signal_emit (area, gimp_color_area_signals[COLOR_CHANGED], 0);
}

/**
 * gimp_color_area_get_color:
 * @area: Pointer to a #GimpColorArea.
 * @color: Pointer to a #GimpRGB struct that is used to return the color.
 *
 * Retrieves the current color of the @area.
 **/
void
gimp_color_area_get_color (GimpColorArea *area,
                           GimpRGB       *color)
{
  g_return_if_fail (GIMP_IS_COLOR_AREA (area));
  g_return_if_fail (color != NULL);

  *color = area->color;
}

/**
 * gimp_color_area_has_alpha:
 * @area: Pointer to a #GimpColorArea.
 *
 * Checks whether the @area shows transparency information. This is determined
 * via the @area's #GimpColorAreaType.
 *
 * Returns: %TRUE if @area shows transparency information, %FALSE otherwise.
 **/
gboolean
gimp_color_area_has_alpha (GimpColorArea *area)
{
  g_return_val_if_fail (GIMP_IS_COLOR_AREA (area), FALSE);

  return area->type != GIMP_COLOR_AREA_FLAT;
}

/**
 * gimp_color_area_set_type:
 * @area: Pointer to a #GimpColorArea.
 * @type: A #GimpColorAreaType.
 *
 * Allows to change the type of @area. The #GimpColorAreaType determines
 * whether the widget shows transparency information and chooses the size of
 * the checkerboard used to do that.
 **/
void
gimp_color_area_set_type (GimpColorArea     *area,
                          GimpColorAreaType  type)
{
  g_return_if_fail (GIMP_IS_COLOR_AREA (area));

  area->type = type;

  area->needs_render = TRUE;
  gtk_widget_queue_draw (GTK_WIDGET (area));
}

/**
 * gimp_color_area_set_draw_border:
 * @area: Pointer to a #GimpColorArea.
 * @draw_border: whether to draw a border or not
 *
 * The @area can draw a thin border in the foreground color around
 * itself.  This function allows to toggle this behaviour on and
 * off. The default is not draw a border.
 **/
void
gimp_color_area_set_draw_border (GimpColorArea *area,
                                 gboolean       draw_border)
{
  g_return_if_fail (GIMP_IS_COLOR_AREA (area));

  area->draw_border = draw_border ? TRUE : FALSE;

  gtk_widget_queue_draw (GTK_WIDGET (area));
}

void
_gimp_color_area_render_buf (GimpColorAreaType  type,
                             guchar            *buf,
                             guint              width,
                             guint              height,
                             guint              rowstride,
                             GimpRGB           *color)
{
  guint    x, y;
  guint    check_size = 0;
  guchar   light[3];
  guchar   dark[3];
  guchar   opaque[3];
  guchar  *p;
  gdouble  frac;

  switch (type)
    {
    case GIMP_COLOR_AREA_FLAT:
      check_size = 0;
      break;

    case GIMP_COLOR_AREA_SMALL_CHECKS:
      check_size = GIMP_CHECK_SIZE_SM;
      break;

    case GIMP_COLOR_AREA_LARGE_CHECKS:
      check_size = GIMP_CHECK_SIZE;
      break;
    }

  gimp_rgb_get_uchar (color, opaque, opaque + 1, opaque + 2);

  if (color->a == 1.0 || !check_size)
    {
      for (y = 0; y < height; y++)
        {
          p = buf + y * rowstride;

          for (x = 0; x < width; x++)
            {
              *p++ = opaque[0];
              *p++ = opaque[1];
              *p++ = opaque[2];
            }
        }

      return;
    }

  light[0] = (GIMP_CHECK_LIGHT +
              (color->r - GIMP_CHECK_LIGHT) * color->a) * 255.999;
  dark[0]  = (GIMP_CHECK_DARK +
              (color->r - GIMP_CHECK_DARK)  * color->a) * 255.999;
  light[1] = (GIMP_CHECK_LIGHT +
              (color->g - GIMP_CHECK_LIGHT) * color->a) * 255.999;
  dark[1]  = (GIMP_CHECK_DARK +
              (color->g - GIMP_CHECK_DARK)  * color->a) * 255.999;
  light[2] = (GIMP_CHECK_LIGHT +
              (color->b - GIMP_CHECK_LIGHT) * color->a) * 255.999;
  dark[2]  = (GIMP_CHECK_DARK +
              (color->b - GIMP_CHECK_DARK)  * color->a) * 255.999;

  for (y = 0; y < height; y++)
    {
      p = buf + y * rowstride;

      for (x = 0; x < width; x++)
        {
          if ((width - x) * height > y * width)
            {
              *p++ = opaque[0];
              *p++ = opaque[1];
              *p++ = opaque[2];

              continue;
            }

          frac = y - (gdouble) ((width - x) * height) / (gdouble) width;

          if (((x / check_size) ^ (y / check_size)) & 1)
            {
              if ((gint) frac)
                {
                  *p++ = light[0];
                  *p++ = light[1];
                  *p++ = light[2];
                }
              else
                {
                  *p++ = ((gdouble) light[0]  * frac +
                          (gdouble) opaque[0] * (1.0 - frac));
                  *p++ = ((gdouble) light[1]  * frac +
                          (gdouble) opaque[1] * (1.0 - frac));
                  *p++ = ((gdouble) light[2]  * frac +
                          (gdouble) opaque[2] * (1.0 - frac));
                }
            }
          else
            {
              if ((gint) frac)
                {
                  *p++ = dark[0];
                  *p++ = dark[1];
                  *p++ = dark[2];
                }
              else
                {
                  *p++ = ((gdouble) dark[0] * frac +
                          (gdouble) opaque[0] * (1.0 - frac));
                  *p++ = ((gdouble) dark[1] * frac +
                          (gdouble) opaque[1] * (1.0 - frac));
                  *p++ = ((gdouble) dark[2] * frac +
                          (gdouble) opaque[2] * (1.0 - frac));
                }
            }
        }
    }
}
static void
gimp_color_area_render (GimpColorArea *area)
{
  area->needs_render = FALSE;

  if (! area->buf)
    return;

  _gimp_color_area_render_buf (area->type,
                               area->buf,
                               area->width, area->height, area->rowstride,
                               &area->color);
}

static void
gimp_color_area_drag_begin (GtkWidget      *widget,
			    GdkDragContext *context)
{
  GimpRGB    color;
  GtkWidget *window;
  GtkWidget *frame;
  GtkWidget *color_area;

  window = gtk_window_new (GTK_WINDOW_POPUP);
  gtk_widget_realize (window);

  frame = gtk_frame_new (NULL);
  gtk_frame_set_shadow_type (GTK_FRAME (frame), GTK_SHADOW_OUT);
  gtk_container_add (GTK_CONTAINER (window), frame);

  gimp_color_area_get_color (GIMP_COLOR_AREA (widget), &color);

  color_area = gimp_color_area_new (&color,
                                    GIMP_COLOR_AREA (widget)->type,
                                    0);

  gtk_widget_set_size_request (color_area,
                               DRAG_PREVIEW_SIZE, DRAG_PREVIEW_SIZE);
  gtk_container_add (GTK_CONTAINER (frame), color_area);
  gtk_widget_show (color_area);
  gtk_widget_show (frame);

  g_object_set_data_full (G_OBJECT (widget),
                          "gimp-color-area-drag-window",
                          window,
                          (GDestroyNotify) gtk_widget_destroy);

  gtk_drag_set_icon_widget (context, window,
                            DRAG_ICON_OFFSET, DRAG_ICON_OFFSET);
}

static void
gimp_color_area_drag_end (GtkWidget      *widget,
                          GdkDragContext *context)
{
  g_object_set_data (G_OBJECT (widget),
                     "gimp-color-area-drag-window", NULL);
}

static void
gimp_color_area_drag_data_received (GtkWidget        *widget,
                                    GdkDragContext   *context,
                                    gint              x,
                                    gint              y,
                                    GtkSelectionData *selection_data,
                                    guint             info,
                                    guint             time)
{
  GimpColorArea *area = GIMP_COLOR_AREA (widget);
  GimpRGB        color;
  guint16       *vals;

  if (selection_data->length < 0)
    return;

  if ((selection_data->format != 16) ||
      (selection_data->length != 8))
    {
      g_warning ("Received invalid color data");
      return;
    }

  vals = (guint16 *)selection_data->data;

  gimp_rgba_set (&color,
                 (gdouble) vals[0] / 0xffff,
                 (gdouble) vals[1] / 0xffff,
                 (gdouble) vals[2] / 0xffff,
                 (gdouble) vals[3] / 0xffff);

  gimp_color_area_set_color (area, &color);
}

static void
gimp_color_area_drag_data_get (GtkWidget        *widget,
                               GdkDragContext   *context,
                               GtkSelectionData *selection_data,
                               guint             info,
                               guint             time)
{
  GimpColorArea *area = GIMP_COLOR_AREA (widget);
  guint16        vals[4];

  vals[0] = area->color.r * 0xffff;
  vals[1] = area->color.g * 0xffff;
  vals[2] = area->color.b * 0xffff;

  if (area->type == GIMP_COLOR_AREA_FLAT)
    vals[3] = 0xffff;
  else
    vals[3] = area->color.a * 0xffff;

  gtk_selection_data_set (selection_data,
                          gdk_atom_intern ("application/x-color", FALSE),
                          16, (guchar *) vals, 8);
}