gimp/libgimpwidgets/gimpcairo-utils.c

/* LIBGIMP - The GIMP Library
 * Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
 *
 * gimpcairo-utils.c
 * Copyright (C) 2007 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
 * Lesser 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 <cairo.h>
#include <gdk-pixbuf/gdk-pixbuf.h>

#include "libgimpcolor/gimpcolor.h"

#include "gimpcairo-utils.h"


/**
 * gimp_cairo_set_source_color:
 * @cr:    Cairo context
 * @color: GimpRGB color
 *
 * Sets the source pattern within @cr to the color described by @color.
 *
 * This function calls cairo_set_source_rgba() for you.
 *
 * Since: GIMP 2.6
 **/
void
gimp_cairo_set_source_color (cairo_t *cr,
                             GimpRGB *color)
{
  cairo_set_source_rgba (cr, color->r, color->g, color->b, color->a);
}

/**
 * gimp_cairo_create_surface_from_pixbuf:
 * @pixbuf: a GdkPixbuf
 *
 * Create a Cairo image surface from a GdkPixbuf.
 *
 * You should avoid calling this function as there are probably more
 * efficient ways of achieving the result you are looking for.
 *
 * Since: GIMP 2.6
 **/
cairo_surface_t *
gimp_cairo_create_surface_from_pixbuf (GdkPixbuf *pixbuf)
{
  cairo_surface_t *surface;
  cairo_format_t   format;
  guchar          *dest;
  const guchar    *src;
  gint             width;
  gint             height;
  gint             src_stride;
  gint             dest_stride;
  gint             y;

  g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);

  width  = gdk_pixbuf_get_width (pixbuf);
  height = gdk_pixbuf_get_height (pixbuf);

  switch (gdk_pixbuf_get_n_channels (pixbuf))
    {
    case 3:
      format = CAIRO_FORMAT_RGB24;
      break;
    case 4:
      format = CAIRO_FORMAT_ARGB32;
      break;
    default:
      g_assert_not_reached ();
      break;
    }

  surface = cairo_image_surface_create (format, width, height);

  src         = gdk_pixbuf_get_pixels (pixbuf);
  src_stride  = gdk_pixbuf_get_rowstride (pixbuf);

  dest        = cairo_image_surface_get_data (surface);
  dest_stride = cairo_image_surface_get_stride (surface);

  switch (format)
    {
    case CAIRO_FORMAT_RGB24:
      for (y = 0; y < height; y++)
        {
          const guchar *s = src;
          guchar       *d = dest;
          gint          w = width;

          while (w--)
            {
              GIMP_CAIRO_RGB24_SET_PIXEL (d, s[0], s[1], s[2]);

              s += 3;
              d += 4;
            }

          src  += src_stride;
          dest += dest_stride;
        }
      break;

    case CAIRO_FORMAT_ARGB32:
      for (y = 0; y < height; y++)
        {
          const guchar *s = src;
          guchar       *d = dest;
          gint          w = width;

          while (w--)
            {
              GIMP_CAIRO_ARGB32_SET_PIXEL (d, s[0], s[1], s[2], s[3]);

              s += 4;
              d += 4;
            }

          src  += src_stride;
          dest += dest_stride;
        }
      break;

    default:
      break;
    }

  return surface;
}