gimp/app/display/gimpcanvas.c

/* GIMP - The GNU 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 3 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/>.
 */

#include "config.h"

#include <gtk/gtk.h>

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

#include "display-types.h"

#include "config/gimpdisplayconfig.h"

#include "widgets/gimpcairo-wilber.h"
#include "widgets/gimpwidgets-utils.h"

#include "gimpcanvas.h"

#include "gimp-intl.h"


enum
{
  PROP_0,
  PROP_CONFIG
};


/*  local function prototypes  */

static void    gimp_canvas_set_property  (GObject         *object,
                                          guint            property_id,
                                          const GValue    *value,
                                          GParamSpec      *pspec);
static void    gimp_canvas_get_property  (GObject         *object,
                                          guint            property_id,
                                          GValue          *value,
                                          GParamSpec      *pspec);

static void    gimp_canvas_realize       (GtkWidget       *widget);
static void    gimp_canvas_unrealize     (GtkWidget       *widget);
static void    gimp_canvas_size_allocate (GtkWidget       *widget,
                                          GtkAllocation   *allocation);
static void    gimp_canvas_style_set     (GtkWidget       *widget,
                                          GtkStyle        *prev_style);

static GdkGC * gimp_canvas_gc_new       (GimpCanvas      *canvas,
                                         GimpCanvasStyle  style);


G_DEFINE_TYPE (GimpCanvas, gimp_canvas, GTK_TYPE_CONTAINER)

#define parent_class gimp_canvas_parent_class


static const guchar stipples[GIMP_CANVAS_NUM_STIPPLES][8] =
{
  {
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
  },
  {
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
  },
  {
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
  },
  {
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
  },
  {
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
  },
  {
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
  },
  {
    0x3C,    /*  --####--  */
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
  },
  {
    0x78,    /*  -####---  */
    0xF0,    /*  ####----  */
    0xE1,    /*  ###----#  */
    0xC3,    /*  ##----##  */
    0x87,    /*  #----###  */
    0x0F,    /*  ----####  */
    0x1E,    /*  ---####-  */
    0x3C,    /*  --####--  */
  },
};


static void
gimp_canvas_class_init (GimpCanvasClass *klass)
{
  GObjectClass   *object_class = G_OBJECT_CLASS (klass);
  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);

  object_class->set_property  = gimp_canvas_set_property;
  object_class->get_property  = gimp_canvas_get_property;

  widget_class->realize       = gimp_canvas_realize;
  widget_class->unrealize     = gimp_canvas_unrealize;
  widget_class->size_allocate = gimp_canvas_size_allocate;
  widget_class->style_set     = gimp_canvas_style_set;

  g_object_class_install_property (object_class, PROP_CONFIG,
                                   g_param_spec_object ("config", NULL, NULL,
                                                        GIMP_TYPE_DISPLAY_CONFIG,
                                                        GIMP_PARAM_READWRITE |
                                                        G_PARAM_CONSTRUCT_ONLY));
}

static void
gimp_canvas_init (GimpCanvas *canvas)
{
  GtkWidget *widget = GTK_WIDGET (canvas);
  gint       i;

  GTK_WIDGET_SET_FLAGS (widget, GTK_CAN_FOCUS);

  gtk_widget_set_extension_events (widget, GDK_EXTENSION_EVENTS_ALL);

  for (i = 0; i < GIMP_CANVAS_NUM_STYLES; i++)
    canvas->gc[i] = NULL;

  for (i = 0; i < GIMP_CANVAS_NUM_STIPPLES; i++)
    canvas->stipple[i] = NULL;
}

static void
gimp_canvas_set_property (GObject      *object,
                           guint         property_id,
                           const GValue *value,
                           GParamSpec   *pspec)
{
  GimpCanvas *canvas = GIMP_CANVAS (object);

  switch (property_id)
    {
    case PROP_CONFIG:
      canvas->config = g_value_get_object (value); /* don't dup */
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
      break;
    }
}

static void
gimp_canvas_get_property (GObject    *object,
                          guint       property_id,
                          GValue     *value,
                          GParamSpec *pspec)
{
  GimpCanvas *canvas = GIMP_CANVAS (object);

  switch (property_id)
    {
    case PROP_CONFIG:
      g_value_set_object (value, canvas->config);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
      break;
    }
}

static void
gimp_canvas_realize (GtkWidget *widget)
{
  GimpCanvas    *canvas = GIMP_CANVAS (widget);
  GdkWindowAttr  attributes;
  gint           attributes_mask;

  GTK_WIDGET_SET_FLAGS (widget, GTK_REALIZED);

  attributes.x           = widget->allocation.x;
  attributes.y           = widget->allocation.y;
  attributes.width       = widget->allocation.width;
  attributes.height      = widget->allocation.height;
  attributes.window_type = GDK_WINDOW_CHILD;
  attributes.wclass      = GDK_INPUT_OUTPUT;
  attributes.visual      = gtk_widget_get_visual (widget);
  attributes.colormap    = gtk_widget_get_colormap (widget);
  attributes.event_mask  = (gtk_widget_get_events (widget) |
                            GIMP_CANVAS_EVENT_MASK);

  attributes_mask = GDK_WA_X | GDK_WA_Y | GDK_WA_VISUAL | GDK_WA_COLORMAP;

  widget->window = gdk_window_new (gtk_widget_get_parent_window (widget),
                                   &attributes, attributes_mask);
  gdk_window_set_user_data (gtk_widget_get_window (widget), widget);

  widget->style = gtk_style_attach (widget->style, widget->window);
  gtk_style_set_background (widget->style, gtk_widget_get_window (widget),
                            GTK_STATE_NORMAL);

  canvas->stipple[0] =
    gdk_bitmap_create_from_data (gtk_widget_get_window (widget),
                                 (const gchar *) stipples[0], 8, 8);
}

static void
gimp_canvas_unrealize (GtkWidget *widget)
{
  GimpCanvas *canvas = GIMP_CANVAS (widget);
  gint        i;

  for (i = 0; i < GIMP_CANVAS_NUM_STYLES; i++)
    {
      if (canvas->gc[i])
        {
          g_object_unref (canvas->gc[i]);
          canvas->gc[i] = NULL;
        }
    }

  for (i = 0; i < GIMP_CANVAS_NUM_STIPPLES; i++)
    {
      if (canvas->stipple[i])
        {
          g_object_unref (canvas->stipple[i]);
          canvas->stipple[i] = NULL;
        }
    }

  if (canvas->layout)
    {
      g_object_unref (canvas->layout);
      canvas->layout = NULL;
    }

  GTK_WIDGET_CLASS (parent_class)->unrealize (widget);
}

static void
gimp_canvas_size_allocate (GtkWidget     *widget,
                           GtkAllocation *allocation)
{
  widget->allocation = *allocation;

  if (GTK_WIDGET_REALIZED (widget))
    gdk_window_move_resize (gtk_widget_get_window (widget),
                            allocation->x, allocation->y,
                            allocation->width, allocation->height);
}

static void
gimp_canvas_style_set (GtkWidget *widget,
                       GtkStyle  *prev_style)
{
  GimpCanvas *canvas = GIMP_CANVAS (widget);

  GTK_WIDGET_CLASS (parent_class)->style_set (widget, prev_style);

  if (canvas->layout)
    {
      g_object_unref (canvas->layout);
      canvas->layout = NULL;
    }
}

/* Returns: %TRUE if the XOR color is not white */
static gboolean
gimp_canvas_get_xor_color (GimpCanvas *canvas,
                           GdkColor   *color)
{
  guchar r, g, b;

  gimp_rgb_get_uchar (&canvas->config->xor_color, &r, &g, &b);

  color->red   = (r << 8) | r;
  color->green = (g << 8) | g;
  color->blue  = (b << 8) | b;

  return (r != 255 || g != 255 || b != 255);
}

static GdkGC *
gimp_canvas_gc_new (GimpCanvas      *canvas,
                    GimpCanvasStyle  style)
{
  GdkGC           *gc;
  GdkGCValues      values;
  GdkGCValuesMask  mask = 0;
  GdkColor         fg   = { 0, 0, 0, 0 };
  GdkColor         bg   = { 0, 0, 0, 0 };

  if (! GTK_WIDGET_REALIZED (canvas))
    return NULL;

  switch (style)
    {
    case GIMP_CANVAS_STYLE_BLACK:
    case GIMP_CANVAS_STYLE_WHITE:
    case GIMP_CANVAS_STYLE_SAMPLE_POINT_NORMAL:
    case GIMP_CANVAS_STYLE_SAMPLE_POINT_ACTIVE:
      break;

    case GIMP_CANVAS_STYLE_RENDER:
      mask |= GDK_GC_EXPOSURES;
      values.graphics_exposures = TRUE;
      break;

    case GIMP_CANVAS_STYLE_XOR_DOTTED:
    case GIMP_CANVAS_STYLE_XOR_DASHED:
      mask |= GDK_GC_LINE_STYLE;
      values.line_style = GDK_LINE_ON_OFF_DASH;
      /*  fallthrough  */

    case GIMP_CANVAS_STYLE_XOR:
      mask |= GDK_GC_FUNCTION | GDK_GC_CAP_STYLE | GDK_GC_JOIN_STYLE;

      if (gimp_canvas_get_xor_color (canvas, &fg))
        values.function = GDK_XOR;
      else
        values.function = GDK_INVERT;

      values.cap_style  = GDK_CAP_NOT_LAST;
      values.join_style = GDK_JOIN_MITER;
      break;

    case GIMP_CANVAS_STYLE_SELECTION_IN:
    case GIMP_CANVAS_STYLE_SELECTION_OUT:
    case GIMP_CANVAS_STYLE_LAYER_BOUNDARY:
    case GIMP_CANVAS_STYLE_LAYER_GROUP_BOUNDARY:
    case GIMP_CANVAS_STYLE_GUIDE_NORMAL:
    case GIMP_CANVAS_STYLE_GUIDE_ACTIVE:
    case GIMP_CANVAS_STYLE_LAYER_MASK_ACTIVE:
      mask |= GDK_GC_CAP_STYLE | GDK_GC_FILL | GDK_GC_STIPPLE;
      values.cap_style = GDK_CAP_NOT_LAST;
      values.fill      = GDK_OPAQUE_STIPPLED;
      values.stipple   = canvas->stipple[0];
      break;

    case GIMP_CANVAS_STYLE_CUSTOM:
    default:
      return NULL;
    }

  gc = gdk_gc_new_with_values (gtk_widget_get_window (GTK_WIDGET (canvas)),
                               &values, mask);

  if (style == GIMP_CANVAS_STYLE_XOR_DOTTED)
    {
      gint8 one = 1;
      gdk_gc_set_dashes (gc, 0, &one, 1);
    }

  switch (style)
    {
    default:
      return gc;

    case GIMP_CANVAS_STYLE_XOR_DOTTED:
    case GIMP_CANVAS_STYLE_XOR_DASHED:
    case GIMP_CANVAS_STYLE_XOR:
      break;

    case GIMP_CANVAS_STYLE_WHITE:
      fg.red   = 0xffff;
      fg.green = 0xffff;
      fg.blue  = 0xffff;
      break;

    case GIMP_CANVAS_STYLE_BLACK:
    case GIMP_CANVAS_STYLE_SELECTION_IN:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0xffff;
      bg.green = 0xffff;
      bg.blue  = 0xffff;
      break;

    case GIMP_CANVAS_STYLE_SELECTION_OUT:
      fg.red   = 0xffff;
      fg.green = 0xffff;
      fg.blue  = 0xffff;

      bg.red   = 0x7f7f;
      bg.green = 0x7f7f;
      bg.blue  = 0x7f7f;
      break;

    case GIMP_CANVAS_STYLE_LAYER_BOUNDARY:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0xffff;
      bg.green = 0xffff;
      bg.blue  = 0x0;
      break;

    case GIMP_CANVAS_STYLE_LAYER_GROUP_BOUNDARY:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0x0;
      bg.green = 0xffff;
      bg.blue  = 0xffff;
      break;

    case GIMP_CANVAS_STYLE_GUIDE_NORMAL:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0x0;
      bg.green = 0x7f7f;
      bg.blue  = 0xffff;
      break;

    case GIMP_CANVAS_STYLE_GUIDE_ACTIVE:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0xffff;
      bg.green = 0x0;
      bg.blue  = 0x0;
      break;

    case GIMP_CANVAS_STYLE_LAYER_MASK_ACTIVE:
      fg.red   = 0x0;
      fg.green = 0x0;
      fg.blue  = 0x0;

      bg.red   = 0x0;
      bg.green = 0xffff;
      bg.blue  = 0x0;
      break;

    case GIMP_CANVAS_STYLE_SAMPLE_POINT_NORMAL:
      fg.red   = 0x0;
      fg.green = 0x7f7f;
      fg.blue  = 0xffff;
      break;

    case GIMP_CANVAS_STYLE_SAMPLE_POINT_ACTIVE:
      fg.red   = 0xffff;
      fg.green = 0x0;
      fg.blue  = 0x0;
      break;
    }

  gdk_gc_set_rgb_fg_color (gc, &fg);
  gdk_gc_set_rgb_bg_color (gc, &bg);

  return gc;
}

static inline gboolean
gimp_canvas_ensure_style (GimpCanvas      *canvas,
                          GimpCanvasStyle  style)
{
  return (canvas->gc[style] != NULL ||
          (canvas->gc[style] = gimp_canvas_gc_new (canvas, style)) != NULL);
}


/*  public functions  */

/**
 * gimp_canvas_new:
 *
 * Creates a new #GimpCanvas widget.
 *
 * The #GimpCanvas widget is a #GtkDrawingArea abstraction. It manages
 * a set of graphic contexts for drawing on a GIMP display. If you
 * draw using a #GimpCanvasStyle, #GimpCanvas makes sure that the
 * associated #GdkGC is created. All drawing on the canvas needs to
 * happen by means of the #GimpCanvas drawing functions. Besides from
 * not needing a #GdkGC pointer, the #GimpCanvas drawing functions
 * look and work like their #GdkDrawable counterparts. #GimpCanvas
 * gracefully handles attempts to draw on the unrealized widget.
 *
 * Return value: a new #GimpCanvas widget
 **/
GtkWidget *
gimp_canvas_new (GimpDisplayConfig *config)
{
  g_return_val_if_fail (GIMP_IS_DISPLAY_CONFIG (config), NULL);

  return g_object_new (GIMP_TYPE_CANVAS,
                       "name",   "gimp-canvas",
                       "config", config,
                       NULL);
}

/**
 * gimp_canvas_scroll:
 * @canvas: the #GimpCanvas widget to scroll.
 * @offset_x: the x scroll amount.
 * @offset_y: the y scroll amount.
 *
 * Scrolls the canvas using gdk_window_scroll() and makes sure the result
 * is displayed immediately by calling gdk_window_process_updates().
 **/
void
gimp_canvas_scroll (GimpCanvas *canvas,
                    gint        offset_x,
                    gint        offset_y)
{
  GtkWidget *widget;
  GdkWindow *window;

  g_return_if_fail (GIMP_IS_CANVAS (canvas));

  widget = GTK_WIDGET (canvas);
  window = gtk_widget_get_window (widget);

  gdk_window_scroll (window, offset_x, offset_y);

  /*  Make sure expose events are processed before scrolling again  */
  gdk_window_process_updates (window, FALSE);
}

/**
 * gimp_canvas_draw_cursor:
 * @canvas: the #GimpCanvas widget to draw on.
 * @x: x coordinate
 * @y: y coordinate
 *
 * Draws a plus-shaped black and white cursor, centered at the point
 * @x, @y.
 **/
void
gimp_canvas_draw_cursor (GimpCanvas *canvas,
                         gint        x,
                         gint        y)
{
  GtkWidget *widget = GTK_WIDGET (canvas);
  GdkWindow *window = gtk_widget_get_window (widget);

  if (! (gimp_canvas_ensure_style (canvas, GIMP_CANVAS_STYLE_BLACK) &&
         gimp_canvas_ensure_style (canvas, GIMP_CANVAS_STYLE_WHITE)) )
    return;

  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_WHITE],
                 x - 7, y - 1, x + 7, y - 1);
  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_BLACK],
                 x - 7, y,     x + 7, y    );
  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_WHITE],
                 x - 7, y + 1, x + 7, y + 1);
  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_WHITE],
                 x - 1, y - 7, x - 1, y + 7);
  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_BLACK],
                 x,     y - 7, x,     y + 7);
  gdk_draw_line (window, canvas->gc[GIMP_CANVAS_STYLE_WHITE],
                 x + 1, y - 7, x + 1, y + 7);
}

/**
 * gimp_canvas_draw_point:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @x:      x coordinate
 * @y:      y coordinate
 *
 * Draw a single pixel at the specified location in the specified
 * style.
 **/
void
gimp_canvas_draw_point (GimpCanvas      *canvas,
                        GimpCanvasStyle  style,
                        gint             x,
                        gint             y)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_point (gtk_widget_get_window (GTK_WIDGET (canvas)),
                  canvas->gc[style],
                  x, y);
}

/**
 * gimp_canvas_draw_points:
 * @canvas:     a #GimpCanvas widget
 * @style:      one of the enumerated #GimpCanvasStyle's.
 * @points:     an array of GdkPoint x-y pairs.
 * @num_points: the number of points in the array
 *
 * Draws a set of one-pixel points at the locations given in the
 * @points argument, in the specified style.
 **/
void
gimp_canvas_draw_points (GimpCanvas      *canvas,
                         GimpCanvasStyle  style,
                         GdkPoint        *points,
                         gint             num_points)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_points (gtk_widget_get_window (GTK_WIDGET (canvas)),
                   canvas->gc[style],
                   points, num_points);
}

/**
 * gimp_canvas_draw_line:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @x1:     X coordinate of the first point
 * @y1:     Y coordinate of the first point
 * @x2:     X coordinate of the second point
 * @y2:     Y coordinate of the second point
 *
 * Draw a line connecting the specified points, using the specified
 * style.
 **/
void
gimp_canvas_draw_line (GimpCanvas      *canvas,
                       GimpCanvasStyle  style,
                       gint             x1,
                       gint             y1,
                       gint             x2,
                       gint             y2)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_line (gtk_widget_get_window (GTK_WIDGET (canvas)),
                 canvas->gc[style],
                 x1, y1, x2, y2);
}

/**
 * gimp_canvas_draw_lines:
 * @canvas:     a #GimpCanvas widget
 * @style:      one of the enumerated #GimpCanvasStyle's.
 * @points:     a #GdkPoint array.
 * @num_points: the number of points in the array.
 *
 * Draws a set of lines connecting the specified points, in the
 * specified style.
 **/
void
gimp_canvas_draw_lines (GimpCanvas      *canvas,
                        GimpCanvasStyle  style,
                        GdkPoint        *points,
                        gint             num_points)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_lines (gtk_widget_get_window (GTK_WIDGET (canvas)),
                  canvas->gc[style],
                  points, num_points);
}

/**
 * gimp_canvas_draw_rectangle:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @filled: %TRUE if the rectangle is to be filled.
 * @x:      X coordinate of the upper left corner.
 * @y:      Y coordinate of the upper left corner.
 * @width:  width of the rectangle.
 * @height: height of the rectangle.
 *
 * Draws a rectangle in the specified style.
 **/
void
gimp_canvas_draw_rectangle (GimpCanvas      *canvas,
                            GimpCanvasStyle  style,
                            gboolean         filled,
                            gint             x,
                            gint             y,
                            gint             width,
                            gint             height)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_rectangle (gtk_widget_get_window (GTK_WIDGET (canvas)),
                      canvas->gc[style],
                      filled, x, y, width, height);
}

/**
 * gimp_canvas_draw_arc:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @filled: %TRUE if the arc is to be filled, producing a 'pie slice'.
 * @x:      X coordinate of the left edge of the bounding rectangle.
 * @y:      Y coordinate of the top edge of the bounding rectangle.
 * @width:  width of the bounding rectangle.
 * @height: height of the bounding rectangle.
 * @angle1: the start angle of the arc.
 * @angle2: the end angle of the arc.
 *
 * Draws an arc or pie slice, in the specified style.
 **/
void
gimp_canvas_draw_arc (GimpCanvas      *canvas,
                      GimpCanvasStyle  style,
                      gboolean         filled,
                      gint             x,
                      gint             y,
                      gint             width,
                      gint             height,
                      gint             angle1,
                      gint             angle2)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_arc (gtk_widget_get_window (GTK_WIDGET (canvas)),
                canvas->gc[style],
                filled, x, y, width, height, angle1, angle2);
}

/**
 * gimp_canvas_draw_polygon:
 * @canvas:     a #GimpCanvas widget
 * @style:      one of the enumerated #GimpCanvasStyle's.
 * @filled:     if %TRUE, fill the polygon.
 * @points:     a #GdkPoint array.
 * @num_points: the number of points in the array.
 *
 * Draws a polygon connecting the specified points, in the specified
 * style.
 **/
void
gimp_canvas_draw_polygon (GimpCanvas      *canvas,
                          GimpCanvasStyle  style,
                          gboolean         filled,
                          GdkPoint        *points,
                          gint             num_points)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_polygon (gtk_widget_get_window (GTK_WIDGET (canvas)),
                    canvas->gc[style],
                    filled, points, num_points);
}

/**
 * gimp_canvas_draw_segments:
 * @canvas:       a #GimpCanvas widget
 * @style:        one of the enumerated #GimpCanvasStyle's.
 * @segments:     a #GdkSegment array.
 * @num_segments: the number of segments in the array.
 *
 * Draws a set of line segments in the specified style.
 **/
void
gimp_canvas_draw_segments (GimpCanvas      *canvas,
                           GimpCanvasStyle  style,
                           GdkSegment      *segments,
                           gint             num_segments)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  while (num_segments >= 32000)
    {
      gdk_draw_segments (gtk_widget_get_window (GTK_WIDGET (canvas)),
                         canvas->gc[style],
                         segments, 32000);
      num_segments -= 32000;
      segments     += 32000;
    }

  gdk_draw_segments (gtk_widget_get_window (GTK_WIDGET (canvas)),
                     canvas->gc[style],
                     segments, num_segments);
}

/**
 * gimp_canvas_draw_text:
 * @canvas:  a #GimpCanvas widget
 * @style:   one of the enumerated #GimpCanvasStyle's.
 * @x:       X coordinate of the left of the layout.
 * @y:       Y coordinate of the top of the layout.
 * @format:  a standard printf() format string.
 * @Varargs: the parameters to insert into the format string.
 *
 * Draws a layout, in the specified style.
 **/
void
gimp_canvas_draw_text (GimpCanvas      *canvas,
                       GimpCanvasStyle  style,
                       gint             x,
                       gint             y,
                       const gchar     *format,
                       ...)
{
  va_list  args;
  gchar   *text;

  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  if (! canvas->layout)
    canvas->layout = gtk_widget_create_pango_layout (GTK_WIDGET (canvas),
                                                     NULL);

  va_start (args, format);
  text = g_strdup_vprintf (format, args);
  va_end (args);

  pango_layout_set_text (canvas->layout, text, -1);
  g_free (text);

  gdk_draw_layout (gtk_widget_get_window (GTK_WIDGET (canvas)),
                   canvas->gc[style],
                   x, y, canvas->layout);
}

/**
 * gimp_canvas_draw_rgb:
 * @canvas:    a #GimpCanvas widget
 * @style:     one of the enumerated #GimpCanvasStyle's.
 * @x:         X coordinate of the upper left corner.
 * @y:         Y coordinate of the upper left corner.
 * @width:     width of the rectangle to be drawn.
 * @height:    height of the rectangle to be drawn.
 * @rgb_buf:   pixel data for the image to be drawn.
 * @rowstride: the rowstride in @rgb_buf.
 * @xdith:     x offset for dither alignment.
 * @ydith:     y offset for dither alignment.
 *
 * Draws an RGB image on the canvas in the specified style.
 **/
void
gimp_canvas_draw_rgb (GimpCanvas      *canvas,
                      GimpCanvasStyle  style,
                      gint             x,
                      gint             y,
                      gint             width,
                      gint             height,
                      guchar          *rgb_buf,
                      gint             rowstride,
                      gint             xdith,
                      gint             ydith)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  gdk_draw_rgb_image_dithalign (gtk_widget_get_window (GTK_WIDGET (canvas)),
                                canvas->gc[style],
                                x, y, width, height,
                                GDK_RGB_DITHER_MAX,
                                rgb_buf, rowstride, xdith, ydith);
}

void
gimp_canvas_draw_drop_zone (GimpCanvas *canvas,
                            cairo_t    *cr)
{
  GtkWidget *widget = GTK_WIDGET (canvas);
  GtkStyle  *style  = gtk_widget_get_style (widget);
  gdouble    wilber_width;
  gdouble    wilber_height;
  gdouble    width;
  gdouble    height;
  gdouble    side;
  gdouble    factor;

  gimp_cairo_wilber_get_size (cr, &wilber_width, &wilber_height);

  wilber_width  /= 2;
  wilber_height /= 2;

  side = MIN (MIN (widget->allocation.width, widget->allocation.height),
              MAX (widget->allocation.width, widget->allocation.height) / 2);

  width  = MAX (wilber_width,  side);
  height = MAX (wilber_height, side);

  factor = MIN (width / wilber_width, height / wilber_height);

  cairo_scale (cr, factor, factor);

  /*  magic factors depend on the image used, everything else is generic
   */
  gimp_cairo_wilber (cr,
                     - wilber_width * 0.6,
                     widget->allocation.height / factor - wilber_height * 1.1);

  cairo_set_source_rgba (cr,
                         style->fg[widget->state].red   / 65535.0,
                         style->fg[widget->state].green / 65535.0,
                         style->fg[widget->state].blue  / 65535.0,
                         0.15);
  cairo_fill (cr);
}

/**
 * gimp_canvas_set_clip_rect:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @rect:   a #GdkRectangle to set the bounds of the clipping area.
 *
 * Sets a rectangular clipping area for the specified style.
 **/
void
gimp_canvas_set_clip_rect (GimpCanvas      *canvas,
                           GimpCanvasStyle  style,
                           GdkRectangle    *rect)
{
  if (! canvas->gc[style])
    {
      if (! rect)
        return;

      canvas->gc[style] = gimp_canvas_gc_new (canvas, style);
    }

  gdk_gc_set_clip_rectangle (canvas->gc[style], rect);
}

/**
 * gimp_canvas_set_clip_region:
 * @canvas: a #GimpCanvas widget
 * @style:  one of the enumerated #GimpCanvasStyle's.
 * @region: a #GdkRegion to set the bounds of the clipping area.
 *
 * Sets a clipping region for the specified style.
 **/
void
gimp_canvas_set_clip_region (GimpCanvas      *canvas,
                             GimpCanvasStyle  style,
                             GdkRegion       *region)
{
  if (! canvas->gc[style])
    {
      if (! region)
        return;

      canvas->gc[style] = gimp_canvas_gc_new (canvas, style);
    }

  gdk_gc_set_clip_region (canvas->gc[style], region);
}

/**
 * gimp_canvas_set_stipple_index:
 * @canvas: a #GimpCanvas widget
 * @style:  the #GimpCanvasStyle to alter
 * @index:  the new stipple index
 *
 * Some styles of the #GimpCanvas do a stipple fill. #GimpCanvas has a
 * set of %GIMP_CANVAS_NUM_STIPPLES stipple bitmaps. This function
 * allows you to change the bitmap being used. This can be used to
 * implement a marching ants effect. An older implementation used to
 * use this feature and so it is included since it might be useful in
 * the future. All stipple bitmaps but the default one are created on
 * the fly.
 */
void
gimp_canvas_set_stipple_index (GimpCanvas      *canvas,
                               GimpCanvasStyle  style,
                               guint            index)
{
  if (! gimp_canvas_ensure_style (canvas, style))
    return;

  index = index % GIMP_CANVAS_NUM_STIPPLES;

  if (! canvas->stipple[index])
    {
      canvas->stipple[index] =
        gdk_bitmap_create_from_data (gtk_widget_get_window (GTK_WIDGET (canvas)),
                                     (const gchar *) stipples[index], 8, 8);
    }

  gdk_gc_set_stipple (canvas->gc[style], canvas->stipple[index]);
}

/**
 * gimp_canvas_set_custom_gc:
 * @canvas: a #GimpCanvas widget
 * @gc:     a #GdkGC;
 *
 * The #GimpCanvas widget has an extra style for a custom #GdkGC. This
 * function allows you to set the @gc for the %GIMP_CANVAS_STYLE_CUSTOM.
 * Drawing with the custom style only works if you set a #GdkGC
 * earlier.  Since the custom #GdkGC can under certain circumstances
 * be destroyed by #GimpCanvas, you should always set the custom gc
 * before calling a #GimpCanvas drawing function with
 * %GIMP_CANVAS_STYLE_CUSTOM.
 **/
void
gimp_canvas_set_custom_gc (GimpCanvas *canvas,
                           GdkGC      *gc)
{
  if (gc)
    g_object_ref (gc);

  if (canvas->gc[GIMP_CANVAS_STYLE_CUSTOM])
    g_object_unref (canvas->gc[GIMP_CANVAS_STYLE_CUSTOM]);

  canvas->gc[GIMP_CANVAS_STYLE_CUSTOM] = gc;
}

/**
 * gimp_canvas_set_bg_color:
 * @canvas:   a #GimpCanvas widget
 * @color:    a color in #GimpRGB format
 *
 * Sets the background color of the canvas's window.  This
 * is the color the canvas is set to if it is cleared.
 **/
void
gimp_canvas_set_bg_color (GimpCanvas *canvas,
                          GimpRGB    *color)
{
  GtkWidget   *widget = GTK_WIDGET (canvas);
  GdkColormap *colormap;
  GdkColor     gdk_color;

  if (! GTK_WIDGET_REALIZED (widget))
    return;

  gimp_rgb_get_gdk_color (color, &gdk_color);

  colormap = gdk_drawable_get_colormap (gtk_widget_get_window (widget));
  g_return_if_fail (colormap != NULL);
  gdk_colormap_alloc_color (colormap, &gdk_color, FALSE, TRUE);

  gdk_window_set_background (gtk_widget_get_window (widget), &gdk_color);
}