/* Dia -- an diagram creation/manipulation program
 * Copyright (C) 1998 Alexander Larsson
 *
 * diacairo.c -- Cairo based export plugin for dia
 * Copyright (C) 2004, Hans Breuer, <Hans@Breuer.Org>
 *   based on wpg.c 
 *
 * 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 <string.h>
#include <math.h>

#include <errno.h>
#define G_LOG_DOMAIN "DiaCairo"
#include <glib.h>
#include <glib/gstdio.h>

/*
 * To me the following looks rather suspicious. Why do we need to compile
 * the Cairo plug-in at all if we don't have Cairo? As a result we'll
 * show it in the menus/plugin details and the user expects something
 * although there isn't any functionality behind it. Urgh.
 *
 * With Gtk+-2.7.x cairo must be available so this becomes even more ugly
 * when the user has choosen to not build the diacairo plug-in. If noone
 * can come up with a convincing reason to do it this way I'll probably
 * go back to the dont-build-at-all approach when it breaks the next time.
 *                                                                    --hb 
 */
#ifdef HAVE_CAIRO
#  include <cairo.h>
/* some backend headers, win32 missing in official Cairo */
#  ifdef CAIRO_HAS_PNG_SURFACE_FEATURE
#  include <cairo-png.h>
#  endif
#  ifdef  CAIRO_HAS_PS_SURFACE
#  include <cairo-ps.h>
#  endif
#  ifdef  CAIRO_HAS_PDF_SURFACE
#  include <cairo-pdf.h>
#  endif
#  ifdef CAIRO_HAS_SVG_SURFACE
#  include <cairo-svg.h>
#  endif
#endif

#include "intl.h"
#include "message.h"
#include "geometry.h"
#include "dia_image.h"
#include "diarenderer.h"
#include "filter.h"
#include "plug-ins.h"

#ifdef HAVE_CAIRO
/* --- the renderer --- */
G_BEGIN_DECLS

#define DIA_CAIRO_TYPE_RENDERER           (dia_cairo_renderer_get_type ())
#define DIA_CAIRO_RENDERER(obj)           (G_TYPE_CHECK_INSTANCE_CAST ((obj), DIA_CAIRO_TYPE_RENDERER, DiaCairoRenderer))
#define DIA_CAIRO_RENDERER_CLASS(klass)   (G_TYPE_CHECK_CLASS_CAST ((klass), DIA_CAIRO_TYPE_RENDERER, DiaCairoRendererClass))
#define DIA_CAIRO_IS_RENDERER(obj)        (G_TYPE_CHECK_INSTANCE_TYPE ((obj), DIA_CAIRO_TYPE_RENDERER))
#define DIA_CAIRO_RENDERER_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), DIA_CAIRO_TYPE_RENDERER, DiaCairoRendererClass))

GType dia_cairo_renderer_get_type (void) G_GNUC_CONST;

typedef struct _DiaCairoRenderer DiaCairoRenderer;
typedef struct _DiaCairoRendererClass DiaCairoRendererClass;

struct _DiaCairoRenderer
{
  DiaRenderer parent_instance;

  cairo_t *cr;
  cairo_surface_t *surface;
 
  double dash_length;
  DiagramData *dia;

  real scale;
  gboolean with_alpha;
};

struct _DiaCairoRendererClass
{
  DiaRendererClass parent_class;
};

G_END_DECLS

/*
#define DEBUG_CAIRO
 */
#ifdef DEBUG_CAIRO
#  define DIAG_NOTE(action) action
#  define DIAG_STATE(cr) { if (cairo_status (cr) != CAIRO_STATUS_SUCCESS) g_print ("%s:%d, %s\n", __FILE__, __LINE__, cairo_status_string (cr)); }
#else
#  define DIAG_NOTE(action)
#  define DIAG_STATE(cr)
#endif

/* 
 * render functions 
 */ 
static void
begin_render(DiaRenderer *self)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  renderer->cr = cairo_create (renderer->surface);
  cairo_scale (renderer->cr, renderer->scale, renderer->scale);
  cairo_translate (renderer->cr, -renderer->dia->extents.left, -renderer->dia->extents.top);

  /* clear background */
  if (renderer->with_alpha)
    {
      cairo_set_operator (renderer->cr, CAIRO_OPERATOR_SOURCE);
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             0.0);
    }
  else
    {
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             1.0);
    }
  cairo_rectangle (renderer->cr, 
                   renderer->dia->extents.left, renderer->dia->extents.top,
                   renderer->dia->extents.right, renderer->dia->extents.bottom);
  cairo_fill (renderer->cr);
  if (renderer->with_alpha)
    {
      /* restore to default drawing */
      cairo_set_operator (renderer->cr, CAIRO_OPERATOR_OVER);
      cairo_set_source_rgba (renderer->cr,
                             renderer->dia->bg_color.red, 
                             renderer->dia->bg_color.green, 
                             renderer->dia->bg_color.blue,
                             1.0);
    }
  DIAG_STATE(renderer->cr)
}

static void
end_render(DiaRenderer *self)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message( "end_render"));
 
  cairo_show_page (renderer->cr);
  DIAG_STATE(renderer->cr)
  cairo_surface_destroy (renderer->surface);
  DIAG_STATE(renderer->cr)
}

static void
set_linewidth(DiaRenderer *self, real linewidth)
{  
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("set_linewidth %f", linewidth));

  cairo_set_line_width (renderer->cr, linewidth);
  DIAG_STATE(renderer->cr)
}

static void
set_linecaps(DiaRenderer *self, LineCaps mode)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("set_linecaps %d", mode));

  switch(mode) {
  case LINECAPS_BUTT:
    cairo_set_line_cap (renderer->cr, CAIRO_LINE_CAP_BUTT);
    break;
  case LINECAPS_ROUND:
    cairo_set_line_cap (renderer->cr, CAIRO_LINE_CAP_ROUND);
    break;
  case LINECAPS_PROJECTING:
    cairo_set_line_cap (renderer->cr, CAIRO_LINE_CAP_SQUARE); /* ?? */
    break;
  default:
    message_error("DiaCairoRenderer : Unsupported fill mode specified!\n");
  }
  DIAG_STATE(renderer->cr)
}

static void
set_linejoin(DiaRenderer *self, LineJoin mode)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("set_join %d", mode));

  switch(mode) {
  case LINEJOIN_MITER:
    cairo_set_line_join (renderer->cr, CAIRO_LINE_JOIN_MITER);
    break;
  case LINEJOIN_ROUND:
    cairo_set_line_join (renderer->cr, CAIRO_LINE_JOIN_ROUND);
    break;
  case LINEJOIN_BEVEL:
    cairo_set_line_join (renderer->cr, CAIRO_LINE_JOIN_BEVEL);
    break;
  default:
    message_error("DiaCairoRenderer : Unsupported fill mode specified!\n");
  }
  DIAG_STATE(renderer->cr)
}

static void
set_linestyle(DiaRenderer *self, LineStyle mode)
{
  /* dot = 10% of len */
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  double dash[6];

  DIAG_NOTE(g_message("set_linestyle %d", mode));

  /* line type */
  switch (mode) {
  case LINESTYLE_SOLID:
    cairo_set_dash (renderer->cr, NULL, 0, 0);
    break;
  case LINESTYLE_DASHED:
    dash[0] = renderer->dash_length;
    dash[1] = renderer->dash_length;
    cairo_set_dash (renderer->cr, dash, 2, 0);
    break;
  case LINESTYLE_DASH_DOT:
    dash[0] = renderer->dash_length;
    dash[1] = renderer->dash_length * 0.45;
    dash[2] = renderer->dash_length * 0.1;
    dash[3] = renderer->dash_length * 0.45;
    cairo_set_dash (renderer->cr, dash, 4, 0);
    break;
  case LINESTYLE_DASH_DOT_DOT:
    dash[0] = renderer->dash_length;
    dash[1] = renderer->dash_length * (0.8/3);
    dash[2] = renderer->dash_length * 0.1;
    dash[3] = renderer->dash_length * (0.8/3);
    dash[4] = renderer->dash_length * 0.1;
    dash[5] = renderer->dash_length * (0.8/3);
    cairo_set_dash (renderer->cr, dash, 6, 0);
    break;
  case LINESTYLE_DOTTED:
    dash[0] = renderer->dash_length * 0.1;
    dash[1] = renderer->dash_length * 0.1;
    cairo_set_dash (renderer->cr, dash, 2, 0);
    break;
  default:
    message_error("DiaCairoRenderer : Unsupported fill mode specified!\n");
  }
  DIAG_STATE(renderer->cr)
}

static void
set_dashlength(DiaRenderer *self, real length)
{  
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("set_dashlength %f", length));

  renderer->dash_length = length;
}

static void
set_fillstyle(DiaRenderer *self, FillStyle mode)
{
  DIAG_NOTE(g_message("set_fillstyle %d", mode));

  switch(mode) {
  case FILLSTYLE_SOLID:
    /* FIXME: how to set _no_ pattern ?
      * cairo_set_pattern (renderer->cr, NULL);
      */
    break;
  default:
    message_error("DiaCairoRenderer : Unsupported fill mode specified!\n");
  }
  DIAG_STATE(renderer->cr)
}

static void
set_font(DiaRenderer *self, DiaFont *font, real height)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  DiaFontStyle style = dia_font_get_style (font);

  const char *family_name;
  DIAG_NOTE(g_message("set_font %f %s", height, dia_font_get_family(font)));

  family_name = dia_font_get_family(font);

  cairo_select_font_face (
      renderer->cr,
      family_name,
      DIA_FONT_STYLE_GET_SLANT(style) == DIA_FONT_NORMAL ? CAIRO_FONT_SLANT_NORMAL : CAIRO_FONT_SLANT_ITALIC,
      DIA_FONT_STYLE_GET_WEIGHT(style) < DIA_FONT_MEDIUM ? CAIRO_FONT_WEIGHT_NORMAL : CAIRO_FONT_WEIGHT_BOLD); 
  cairo_set_font_size (renderer->cr, height * 0.7); /* same magic factor as in lib/font.c */

  DIAG_STATE(renderer->cr)
}

static void
draw_line(DiaRenderer *self, 
          Point *start, Point *end, 
          Color *color)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("draw_line %f,%f -> %f, %f", 
            start->x, start->y, end->x, end->y));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);
  cairo_move_to (renderer->cr, start->x, start->y);
  cairo_line_to (renderer->cr, end->x, end->y);
  cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
draw_polyline(DiaRenderer *self, 
              Point *points, int num_points, 
              Color *color)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  int i;

  DIAG_NOTE(g_message("draw_polyline n:%d %f,%f ...", 
            num_points, points->x, points->y));

  g_return_if_fail(1 < num_points);

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);

  cairo_new_path (renderer->cr);
  /* point data */
  cairo_move_to (renderer->cr, points[0].x, points[0].y);
  for (i = 1; i < num_points; i++)
    {
      cairo_line_to (renderer->cr, points[i].x, points[i].y);
    }
  cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
_polygon(DiaRenderer *self, 
         Point *points, int num_points, 
         Color *color,
         gboolean fill)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  int i;

  DIAG_NOTE(g_message("%s_polygon n:%d %f,%f ...",
            fill ? "fill" : "draw",
            num_points, points->x, points->y));

  g_return_if_fail(1 < num_points);

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);

  cairo_new_path (renderer->cr);
  /* point data */
  cairo_move_to (renderer->cr, points[0].x, points[0].y);
  for (i = 1; i < num_points; i++)
    {
      cairo_line_to (renderer->cr, points[i].x, points[i].y);
    }
  cairo_line_to (renderer->cr, points[0].x, points[0].y);
  cairo_close_path (renderer->cr);
  if (fill)
    cairo_fill (renderer->cr);
  else
    cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
draw_polygon(DiaRenderer *self, 
             Point *points, int num_points, 
             Color *color)
{
  _polygon (self, points, num_points, color, FALSE);
}

static void
fill_polygon(DiaRenderer *self, 
             Point *points, int num_points, 
             Color *color)
{
  _polygon (self, points, num_points, color, TRUE);
}

static void
_rect(DiaRenderer *self, 
      Point *ul_corner, Point *lr_corner,
      Color *color,
      gboolean fill)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);

  DIAG_NOTE(g_message("%s_rect %f,%f -> %f,%f", 
            fill ? "fill" : "draw",
            ul_corner->x, ul_corner->y, lr_corner->x, lr_corner->y));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);
  
  cairo_rectangle (renderer->cr, 
                   ul_corner->x, ul_corner->y, 
                   lr_corner->x - ul_corner->x, lr_corner->y - ul_corner->y);

  if (fill)
    cairo_fill (renderer->cr);
  else
    cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
draw_rect(DiaRenderer *self, 
          Point *ul_corner, Point *lr_corner,
          Color *color)
{
  _rect (self, ul_corner, lr_corner, color, FALSE);
}

static void
fill_rect(DiaRenderer *self, 
          Point *ul_corner, Point *lr_corner,
          Color *color)
{
  _rect (self, ul_corner, lr_corner, color, TRUE);
}

static void
draw_arc(DiaRenderer *self, 
	 Point *center,
	 real width, real height,
	 real angle1, real angle2,
	 Color *color)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  Point start;
  double a1, a2;

  DIAG_NOTE(g_message("draw_arc %fx%f <%f,<%f", 
            width, height, angle1, angle2));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);

  /* Dia and Cairo don't agree on arc definitions, so it needs
   * to be converted, i.e. mirrored at the x axis
   */
  cairo_new_path (renderer->cr);
  start.x = center->x + (width / 2.0)  * cos((M_PI / 180.0) * angle1);
  start.y = center->y - (height / 2.0) * sin((M_PI / 180.0) * angle1);
  cairo_move_to (renderer->cr, start.x, start.y);
  a1 = - (angle1 / 180.0) * G_PI;
  a2 = - (angle2 / 180.0) * G_PI;
  /* FIXME: to handle width != height some cairo_scale/cairo_translate would be needed */
  cairo_arc_negative (renderer->cr, center->x, center->y, 
                      width > height ? height / 2.0 : width / 2.0, /* FIXME 2nd radius */
                      a1, a2);
  cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
fill_arc(DiaRenderer *self, 
         Point *center,
         real width, real height,
         real angle1, real angle2,
         Color *color)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  Point start;
  double a1, a2;

  DIAG_NOTE(g_message("draw_arc %fx%f <%f,<%f", 
            width, height, angle1, angle2));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);
  
  cairo_new_path (renderer->cr);
  start.x = center->x + (width / 2.0)  * cos((M_PI / 180.0) * angle1);
  start.y = center->y - (height / 2.0) * sin((M_PI / 180.0) * angle1);
  cairo_move_to (renderer->cr, center->x, center->y);
  cairo_line_to (renderer->cr, start.x, start.y);
  a1 = - (angle1 / 180.0) * G_PI;
  a2 = - (angle2 / 180.0) * G_PI;
  /* FIXME: to handle width != height some cairo_scale/cairo_translate would be needed */
  cairo_arc_negative (renderer->cr, center->x, center->y, 
                      width > height ? height / 2.0 : width / 2.0, /* FIXME 2nd radius */
                      a1, a2);
  cairo_line_to (renderer->cr, center->x, center->y);
  cairo_close_path (renderer->cr);
  cairo_fill (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
_ellipse(DiaRenderer *self, 
         Point *center,
         real width, real height,
         Color *color,
         gboolean fill)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  double co;

  DIAG_NOTE(g_message("%s_ellipse %fx%f center @ %f,%f", 
            fill ? "fill" : "draw", width, height, center->x, center->y));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);
  
  /* FIXME: how to make a perfect ellipse from a bezier ? */
  co = sqrt(pow(width,2)/4 + pow(height,2)/4);

  cairo_new_path (renderer->cr);
  cairo_move_to (renderer->cr,
                 center->x, center->y - height/2);
  cairo_curve_to (renderer->cr,
                  center->x + co, center->y - height/2,
                  center->x + co, center->y + height/2,
                  center->x, center->y + height/2);
  cairo_curve_to (renderer->cr,
                  center->x - co, center->y + height/2,
                  center->x - co, center->y - height/2,
                  center->x, center->y - height/2);
  if (fill)
    cairo_fill (renderer->cr);
  else
    cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
draw_ellipse(DiaRenderer *self, 
             Point *center,
             real width, real height,
             Color *color)
{
  _ellipse (self, center, width, height, color, FALSE);
}

static void
fill_ellipse(DiaRenderer *self, 
             Point *center,
             real width, real height,
             Color *color)
{
  _ellipse (self, center, width, height, color, TRUE);
}

static void
_bezier(DiaRenderer *self, 
        BezPoint *points,
        int numpoints,
        Color *color,
        gboolean fill)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  int i;

  DIAG_NOTE(g_message("%s_bezier n:%d %fx%f ...", 
            fill ? "fill" : "draw", numpoints, points->p1.x, points->p1.y));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);

  cairo_new_path (renderer->cr);
  for (i = 0; i < numpoints; i++)
  {
    switch (points[i].type)
    {
    case BEZ_MOVE_TO:
      cairo_move_to (renderer->cr, points[i].p1.x, points[i].p1.y);
      break;
    case BEZ_LINE_TO:
      cairo_line_to (renderer->cr, points[i].p1.x, points[i].p1.y);
      break;
    case BEZ_CURVE_TO:
      cairo_curve_to (renderer->cr, 
                      points[i].p1.x, points[i].p1.y,
                      points[i].p2.x, points[i].p2.y,
                      points[i].p3.x, points[i].p3.y);
      break;
    default :
      g_assert_not_reached ();
    }
  }

  if (fill)
    cairo_fill (renderer->cr);
  else
    cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void
draw_bezier(DiaRenderer *self, 
            BezPoint *points,
            int numpoints,
            Color *color)
{
  _bezier (self, points, numpoints, color, FALSE);
}

static void
fill_bezier(DiaRenderer *self, 
            BezPoint *points,
            int numpoints,
            Color *color)
{
  _bezier (self, points, numpoints, color, TRUE);
}

static void
draw_string(DiaRenderer *self,
            const char *text,
            Point *pos, Alignment alignment,
            Color *color)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  cairo_text_extents_t extents;
  double x = 0, y = 0;
  int len = strlen(text);

  DIAG_NOTE(g_message("draw_string(%d) %f,%f %s", 
            len, pos->x, pos->y, text));

  if (len < 1) return; /* shouldn't this be handled by Dia's core ? */

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);
  cairo_text_extents (renderer->cr,
                      text,
                      &extents);

  y = pos->y; /* ?? */

  switch (alignment) {
  case ALIGN_LEFT:
    x = pos->x;
    break;
  case ALIGN_CENTER:
    x = pos->x - extents.width / 2 + +extents.x_bearing;
    break;
  case ALIGN_RIGHT:
    x = pos->x - extents.width + extents.x_bearing;
    break;
  }

  cairo_move_to (renderer->cr, x, y);
  cairo_show_text (renderer->cr, text);
  DIAG_STATE(renderer->cr)
}

static void
draw_image(DiaRenderer *self,
           Point *point,
           real width, real height,
           DiaImage image)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  cairo_surface_t *surface;
  guint8 *data;
  int w = dia_image_width(image);
  int h = dia_image_height(image);
  int rs = dia_image_rowstride(image);

  DIAG_NOTE(g_message("draw_image %fx%f [%d(%d),%d] @%f,%f", 
            width, height, w, rs, h, point->x, point->y));

  if (dia_image_rgba_data (image))
    {
      const guint8 *p1 = dia_image_rgba_data (image);
      /* we need to make a copy to rearrange channels 
       * (also need to use malloc, cause Cairo insists to free() it)
       */
      guint8 *p2 = data = g_malloc (h * rs);
      int i;

      for (i = 0; i < (h * rs) / 4; i++)
        {
#  if G_BYTE_ORDER == G_LITTLE_ENDIAN
          p2[0] = p1[2]; /* b */
          p2[1] = p1[1]; /* g */
          p2[2] = p1[0]; /* r */
          p2[3] = p1[3]; /* a */
#  else
          p2[3] = p1[2]; /* b */
          p2[2] = p1[1]; /* g */
          p2[1] = p1[0]; /* r */
          p2[0] = p1[3]; /* a */
#  endif
          p1+=4;
          p2+=4;
        }

      surface = cairo_image_surface_create_for_data (data, CAIRO_FORMAT_ARGB32, w, h, rs);
    }
  else
    {
      guint8 *p, *p2;
      guint8 *p1 = data = dia_image_rgb_data (image);
      /* need to copy to be owned by cairo/pixman, urgh.
       * Also cairo wants RGB24 32 bit aligned
       */
      int x, y;

      p = p2 = g_malloc(h*w*4);
      for (y = 0; y < h; y++)
        {
          for (x = 0; x < w; x++)
            {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
              /* apparently BGR is required */
              p2[x*4  ] = p1[x*3+2];
              p2[x*4+1] = p1[x*3+1];
              p2[x*4+2] = p1[x*3  ];
              p2[x*4+3] = 0x80; /* should not matter */
#else
              p2[x*4+3] = p1[x*3+2];
              p2[x*4+2] = p1[x*3+1];
              p2[x*4+1] = p1[x*3  ];
              p2[x*4+0] = 0x80; /* should not matter */
#endif
            }
          p2 += (w*4);
          p1 += rs;
        }
      surface = cairo_image_surface_create_for_data (p, CAIRO_FORMAT_RGB24, w, h, w*4);
      g_free (data);
      data = p;
    }
  cairo_save (renderer->cr);
  cairo_translate (renderer->cr, point->x, point->y);
  cairo_scale (renderer->cr, width/w, height/h);
  cairo_move_to (renderer->cr, 0.0, 0.0);
  /* maybe just the second set_filter is required */
#if 0
  cairo_surface_set_filter (renderer->surface, CAIRO_FILTER_BEST);
  cairo_surface_set_filter (surface, CAIRO_FILTER_BEST);
#endif
  cairo_set_source_surface (renderer->cr, surface, point->x, point->y);
  cairo_paint (renderer->cr);
  cairo_restore (renderer->cr);
  cairo_surface_destroy (surface);

  g_free (data);

  DIAG_STATE(renderer->cr);
}

static void 
_rounded_rect (DiaRenderer *self,
               Point *topleft, Point *bottomright,
               Color *color, real radius,
               gboolean fill)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (self);
  real r2;

  radius = MIN(radius, (bottomright->x - topleft->x)/2);
  radius = MIN(radius, (bottomright->y - topleft->y)/2);
  r2 = radius/2;

  DIAG_NOTE(g_message("%s_rounded_rect %f,%f -> %f,%f, %f", 
            fill ? "fill" : "draw",
            topleft->x, topleft->y, bottomright->x, bottomright->y, radius));

  cairo_set_source_rgba (renderer->cr, color->red, color->green, color->blue, 1.0);

  cairo_new_path (renderer->cr);
  cairo_move_to (renderer->cr,
                 topleft->x + radius, topleft->y);

  /* corners are _not_ control points, but halfway */
  cairo_line_to  (renderer->cr,
                  bottomright->x - radius, topleft->y);
  cairo_curve_to (renderer->cr,
                  bottomright->x - r2, topleft->y, bottomright->x, topleft->y + r2,
                  bottomright->x, topleft->y + radius);
  cairo_line_to  (renderer->cr,
                  bottomright->x, bottomright->y - radius);
  cairo_curve_to (renderer->cr,
                  bottomright->x, bottomright->y - r2, bottomright->x - r2, bottomright->y,
                  bottomright->x - radius, bottomright->y);
  cairo_line_to  (renderer->cr,
                  topleft->x + radius, bottomright->y);
  cairo_curve_to (renderer->cr,
                  topleft->x + r2, bottomright->y, topleft->x, bottomright->y - r2,
                  topleft->x, bottomright->y - radius);
  cairo_line_to  (renderer->cr,
                  topleft->x, topleft->y + radius); 
  cairo_curve_to (renderer->cr,
                  topleft->x, topleft->y + r2, topleft->x + r2, topleft->y,
                  topleft->x + radius, topleft->y);
  if (fill)
    cairo_fill (renderer->cr);
  else
    cairo_stroke (renderer->cr);
  DIAG_STATE(renderer->cr)
}

static void 
draw_rounded_rect (DiaRenderer *renderer,
                   Point *topleft, Point *bottomright,
                   Color *color, real radius)
{
  _rounded_rect (renderer, topleft, bottomright, color, radius, FALSE);
}

static void 
fill_rounded_rect (DiaRenderer *renderer,
                   Point *topleft, Point *bottomright,
                   Color *color, real radius)
{
  _rounded_rect (renderer, topleft, bottomright, color, radius, TRUE);
}

/* gobject boiler plate */
static void cairo_renderer_init (DiaCairoRenderer *r, void *p);
static void cairo_renderer_class_init (DiaCairoRendererClass *klass);

static gpointer parent_class = NULL;

GType
dia_cairo_renderer_get_type (void)
{
  static GType object_type = 0;

  if (!object_type)
    {
      static const GTypeInfo object_info =
      {
        sizeof (DiaCairoRendererClass),
        (GBaseInitFunc) NULL,
        (GBaseFinalizeFunc) NULL,
        (GClassInitFunc) cairo_renderer_class_init,
        NULL,           /* class_finalize */
        NULL,           /* class_data */
        sizeof (DiaCairoRenderer),
        0,              /* n_preallocs */
	(GInstanceInitFunc)cairo_renderer_init /* init */
      };

      object_type = g_type_register_static (DIA_TYPE_RENDERER,
                                            "DiaCairoRenderer",
                                            &object_info, 0);
    }
  
  return object_type;
}

static void
cairo_renderer_init (DiaCairoRenderer *renderer, void *p)
{
  /*
   * Initialize fields where 0 init isn't good enough. Bug #151716
   * appears to show that we are sometimes called to render a line
   * without setting the linestyle first. Probably a bug elsewhere
   * but it's this plug-in which hangs ;)
   */
  renderer->dash_length = 1.0;
  renderer->scale = 1.0;
}

static void
cairo_renderer_finalize (GObject *object)
{
  DiaCairoRenderer *renderer = DIA_CAIRO_RENDERER (object);

  cairo_destroy (renderer->cr);

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

static void
cairo_renderer_class_init (DiaCairoRendererClass *klass)
{
  GObjectClass *object_class = G_OBJECT_CLASS (klass);
  DiaRendererClass *renderer_class = DIA_RENDERER_CLASS (klass);

  parent_class = g_type_class_peek_parent (klass);

  object_class->finalize = cairo_renderer_finalize;

  /* renderer members */
  renderer_class->begin_render = begin_render;
  renderer_class->end_render   = end_render;

  renderer_class->set_linewidth  = set_linewidth;
  renderer_class->set_linecaps   = set_linecaps;
  renderer_class->set_linejoin   = set_linejoin;
  renderer_class->set_linestyle  = set_linestyle;
  renderer_class->set_dashlength = set_dashlength;
  renderer_class->set_fillstyle  = set_fillstyle;

  renderer_class->set_font  = set_font;

  renderer_class->draw_line    = draw_line;
  renderer_class->fill_polygon = fill_polygon;
  renderer_class->draw_rect    = draw_rect;
  renderer_class->fill_rect    = fill_rect;
  renderer_class->draw_arc     = draw_arc;
  renderer_class->fill_arc     = fill_arc;
  renderer_class->draw_ellipse = draw_ellipse;
  renderer_class->fill_ellipse = fill_ellipse;

  renderer_class->draw_string  = draw_string;
  renderer_class->draw_image   = draw_image;

  /* medium level functions */
  renderer_class->draw_rect = draw_rect;
  renderer_class->draw_polyline  = draw_polyline;
  renderer_class->draw_polygon   = draw_polygon;

  renderer_class->draw_bezier   = draw_bezier;
  renderer_class->fill_bezier   = fill_bezier;

  /* highest level functions */
  renderer_class->draw_rounded_rect = draw_rounded_rect;
  renderer_class->fill_rounded_rect = fill_rounded_rect;
}

typedef enum OutputKind
{
  OUTPUT_PS = 1,
  OUTPUT_PNG,
  OUTPUT_PNGA,
  OUTPUT_PDF,
  OUTPUT_WMF,
  OUTPUT_EMF,
  OUTPUT_CB,
  OUTPUT_SVG
} OutputKind;

/* dia export funtion */
static void
export_data(DiagramData *data, const gchar *filename_utf8, 
            const gchar *diafilename, void* user_data)
{
  DiaCairoRenderer *renderer;
  FILE *file;
  real width, height;
  OutputKind kind = (OutputKind)user_data;
  gchar* filename = g_locale_from_utf8 (filename_utf8, -1, NULL, NULL, NULL);

  if (!filename) {
    message_error(_("Can't convert output filename '%s' to locale encoding.\n"
                    "Please choose a different name to save with cairo.\n"), 
		  dia_message_filename(filename_utf8), strerror(errno));
    return;
  }
  file = fopen(filename, "wb"); /* "wb" for binary! */

  if (file == NULL) {
    message_error(_("Can't open output file %s: %s\n"), 
		  dia_message_filename(filename_utf8), strerror(errno));
    return;
  }
  fclose (file);
  renderer = g_object_new (DIA_CAIRO_TYPE_RENDERER, NULL);
  renderer->dia = data; /* FIXME: not sure if this a good idea */
  renderer->scale = 1.0;

  switch (kind) {
#ifdef CAIRO_HAS_PS_SURFACE
  case OUTPUT_PS :
    width  = data->paper.width * (72.0 / 2.54);
    height = data->paper.height * (72.0 / 2.54);
    renderer->scale = data->paper.scaling * (72.0 / 2.54);
    DIAG_NOTE(g_message ("PS Surface %dx%d\n", (int)width, (int)height)); 
    renderer->surface = cairo_ps_surface_create (filename,
                                                 width, height); /*  in points? */
    /* maybe we should increase the resolution here as well */
    break;
#endif  
#if defined CAIRO_HAS_PNG_SURFACE || defined CAIRO_HAS_PNG_FUNCTIONS
  case OUTPUT_PNGA :
    renderer->with_alpha = TRUE;
    /* fall through */
  case OUTPUT_PNG :
    /* quite arbitrary, but consistent with ../pixbuf ;-) */
    renderer->scale = 20.0 * data->paper.scaling; 
    width  = (data->extents.right - data->extents.left) * renderer->scale;
    height = (data->extents.bottom - data->extents.top) * renderer->scale;

    DIAG_NOTE(g_message ("PNG Surface %dx%d\n", (int)width, (int)height));
    /* use case screwed by API shakeup. We need to special case */
    renderer->surface = cairo_image_surface_create(
						CAIRO_FORMAT_ARGB32,
						(int)width, (int)height);
    /* an extra refernce to make it survive end_render():cairo_surface_destroy() */
    cairo_surface_reference(renderer->surface);
    break;
#endif
#ifdef CAIRO_HAS_PDF_SURFACE
  case OUTPUT_PDF :
#define DPI 72.0 /* 600.0? */
    /* I just don't get how the scaling is supposed to work, dpi versus page size ? */
    renderer->scale = data->paper.scaling * (72.0 / 2.54);
    width = data->paper.width * (72.0 / 2.54);
    height = data->paper.height * (72.0 / 2.54);
    DIAG_NOTE(g_message ("PDF Surface %dx%d\n", (int)width, (int)height));
    renderer->surface = cairo_pdf_surface_create (filename,
                                                  width, height);
    cairo_surface_set_fallback_resolution (renderer->surface, DPI, DPI);
#undef DPI
    break;
#endif
#ifdef CAIRO_HAS_SVG_SURFACE
  case OUTPUT_SVG :
    /* quite arbitrary, but consistent with ../pixbuf ;-) */
    renderer->scale = 20.0 * data->paper.scaling; 
    width  = (data->extents.right - data->extents.left) * renderer->scale;
    height = (data->extents.bottom - data->extents.top) * renderer->scale;
    DIAG_NOTE(g_message ("SVG Surface %dx%d\n", (int)width, (int)height));
    /* use case screwed by API shakeup. We need to special case */
    renderer->surface = cairo_svg_surface_create(
						filename,
						(int)width, (int)height);
    break;
#endif
  /* the default Cairo/win32 surface isn't able to do such ... */
#ifdef CAIRO_HAS_WIN32X_SURFACE
  case OUTPUT_EMF :
    renderer->scale = 72.0;
    renderer->surface = cairo_win32_surface_create (filename, NULL, CAIRO_WIN32_TARGET_EMF, 0, 0);
    break;
  case OUTPUT_WMF :
    renderer->scale = 72.0;
    renderer->surface = cairo_win32_surface_create (filename, NULL, CAIRO_WIN32_TARGET_WMF, 0, 0);
    break;
  case OUTPUT_CB :
    /* just testing, does not create a file but puts content in the clpboard */
    renderer->scale = 72.0;
    renderer->surface = cairo_win32_surface_create (filename, NULL, CAIRO_WIN32_TARGET_CLIPBOARD, 0, 0);
    break;
#endif
  default :
    /* quite arbitrary, but consistent with ../pixbuf ;-) */
    renderer->scale = 20.0 * data->paper.scaling; 
    width  = (data->extents.right - data->extents.left) * renderer->scale;
    height = (data->extents.bottom - data->extents.top) * renderer->scale;
    DIAG_NOTE(g_message ("Image Surface %dx%d\n", (int)width, (int)height)); 
    renderer->surface = cairo_image_surface_create (CAIRO_FORMAT_A8, (int)width, (int)height);
  }

  /* use extents */
  DIAG_NOTE(g_message("export_data extents %f,%f -> %f,%f", 
            data->extents.left, data->extents.top, data->extents.right, data->extents.bottom));

  data_render(data, DIA_RENDERER(renderer), NULL, NULL, NULL);
#if defined CAIRO_HAS_PNG_FUNCTIONS
  if (OUTPUT_PNGA == kind || OUTPUT_PNG == kind)
    {
      cairo_surface_write_to_png(renderer->surface, filename);
      cairo_surface_destroy(renderer->surface);
    }
#endif
  g_object_unref(renderer);
}

#ifdef CAIRO_HAS_PS_SURFACE
static const gchar *ps_extensions[] = { "ps", NULL };
static DiaExportFilter ps_export_filter = {
    N_("Cairo PostScript"),
    ps_extensions,
    export_data,
    (void*)OUTPUT_PS,
    "cairo-ps" /* unique name */
};
#endif

#ifdef CAIRO_HAS_PDF_SURFACE
static const gchar *pdf_extensions[] = { "pdf", NULL };
static DiaExportFilter pdf_export_filter = {
    N_("Cairo Portable Document Format"),
    pdf_extensions,
    export_data,
    (void*)OUTPUT_PDF,
    "cairo-pdf"
};
#endif

#ifdef CAIRO_HAS_SVG_SURFACE
static const gchar *svg_extensions[] = { "svg", NULL };
static DiaExportFilter svg_export_filter = {
    N_("Cairo Scalable Vector Graphics"),
    svg_extensions,
    export_data,
    (void*)OUTPUT_SVG,
    "cairo-svg"
};
#endif

static const gchar *png_extensions[] = { "png", NULL };
static DiaExportFilter png_export_filter = {
    N_("Cairo PNG"),
    png_extensions,
    export_data,
    (void*)OUTPUT_PNG,
    "cairo-png"
};

static DiaExportFilter pnga_export_filter = {
    N_("Cairo PNG (with alpha)"),
    png_extensions,
    export_data,
    (void*)OUTPUT_PNGA,
    "cairo-alpha-png"
};

#ifdef CAIRO_HAS_WIN32X_SURFACE
static const gchar *emf_extensions[] = { "wmf", NULL };
static DiaExportFilter emf_export_filter = {
    N_("Cairo WMF"),
    emf_extensions,
    export_data,
    (void*)OUTPUT_EMF,
    "cairo-emf"
};

static const gchar *wmf_extensions[] = { "wmf", NULL };
static DiaExportFilter wmf_export_filter = {
    N_("Cairo old WMF"),
    wmf_extensions,
    export_data,
    (void*)OUTPUT_WMF,
    "cairo-wmf"
};

static const gchar *cb_extensions[] = { "cb", NULL };
static DiaExportFilter cb_export_filter = {
    N_("Cairo Clipboard"),
    cb_extensions,
    export_data,
    (void*)OUTPUT_CB,
    "cairo-clipboard"
};
#endif /* CAIRO_HAS_WIN32X_SURFACE */

#endif /* HAVE_CAIRO */

static gboolean
_plugin_can_unload (PluginInfo *info)
{
  return TRUE;
}

static void
_plugin_unload (PluginInfo *info)
{
#ifdef HAVE_CAIRO
#ifdef CAIRO_HAS_PS_SURFACE
  filter_unregister_export(&ps_export_filter);
#endif
#ifdef CAIRO_HAS_PDF_SURFACE
  filter_unregister_export(&pdf_export_filter);
#endif
#ifdef CAIRO_HAS_SVG_SURFACE
  filter_unregister_export(&svg_export_filter);
#endif
#if defined CAIRO_HAS_PNG_SURFACE || defined CAIRO_HAS_PNG_FUNCTIONS
  filter_unregister_export(&png_export_filter);
  filter_unregister_export(&pnga_export_filter);
#endif
#ifdef CAIRO_HAS_WIN32X_SURFACE
  filter_unregister_export(&emf_export_filter);
  filter_unregister_export(&wmf_export_filter);
  filter_unregister_export(&cb_export_filter);
#endif
#endif /* HAVE_CAIRO */
}

/* --- dia plug-in interface --- */

DIA_PLUGIN_CHECK_INIT

PluginInitResult
dia_plugin_init(PluginInfo *info)
{
  if (!dia_plugin_info_init(info, "Cairo",
                            _("Cairo based Rendering"),
                            _plugin_can_unload,
                            _plugin_unload))
    return DIA_PLUGIN_INIT_ERROR;

#ifdef HAVE_CAIRO
#ifdef CAIRO_HAS_PS_SURFACE
  filter_register_export(&ps_export_filter);
#endif
#ifdef CAIRO_HAS_PDF_SURFACE
  filter_register_export(&pdf_export_filter);
#endif
#ifdef CAIRO_HAS_SVG_SURFACE
  filter_register_export(&svg_export_filter);
#endif
#if defined CAIRO_HAS_PNG_SURFACE || defined CAIRO_HAS_PNG_FUNCTIONS
  filter_register_export(&png_export_filter);
  filter_register_export(&pnga_export_filter);
#endif
#ifdef CAIRO_HAS_WIN32X_SURFACE
  filter_register_export(&emf_export_filter);
  filter_register_export(&wmf_export_filter);
  filter_register_export(&cb_export_filter);
#endif
#endif

  return DIA_PLUGIN_INIT_OK;
}