/* This file is an image processing operation for GEGL
 *
 * GEGL 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 3 of the License, or (at your option) any later version.
 *
 * GEGL 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 GEGL; if not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright 2006 Øyvind Kolås <pippin@gimp.org>
 */

#include "config.h"
#include <glib/gi18n-lib.h>


#ifdef GEGL_CHANT_PROPERTIES

gegl_chant_multiline (string, _("Text"), "Hello",
                      _("String to display (utf8)"))
gegl_chant_string (font, _("Font family"), "Sans",
                   _("Font family (utf8)"))
gegl_chant_double (size, _("Size"), 1.0, 2048.0, 10.0,
                   _("Approximate height of text in pixels."))
gegl_chant_color  (color, _("Color"), "black",
                   _("Color for the text (defaults to 'white')"))
gegl_chant_int    (wrap, _("Wrap width"), -1, 1000000, -1,
                   _("Sets the width in pixels at which long lines will wrap. "
                     "Use -1 for no wrapping."))
gegl_chant_int    (alignment, _("Justification"), 0, 2, 0,
                   _("Alignment for multi-line text (0=Left, 1=Center, 2=Right)"))
gegl_chant_int    (width, _("Width"), 0, 1000000, 0,
                   _("Rendered width in pixels. (read only)"))
gegl_chant_int    (height, _("Height"), 0, 1000000, 0,
                   _("Rendered height in pixels. (read only)"))

#else

#include <gegl-plugin.h>
#include <cairo.h>
#include <pango/pango-attributes.h>
#include <pango/pangocairo.h>

/* XXX: this struct is unneeded and could be folded directly into
 * struct _GeglChant
 */
typedef struct {
  gchar         *string;
  gchar         *font;
  gdouble        size;
  gint           wrap;
  gint           alignment;
  GeglRectangle  defined;
} CachedExtent;

struct _GeglChant
{
  GeglOperationSource parent_instance;
  gpointer            properties;
  CachedExtent        cex;
};

typedef struct
{
  GeglOperationSourceClass parent_class;
} GeglChantClass;

#define GEGL_CHANT_C_FILE "text.c"
#include "gegl-chant.h"
GEGL_DEFINE_DYNAMIC_OPERATION (GEGL_TYPE_OPERATION_SOURCE)





static void text_layout_text (GeglChant *self,
                              cairo_t   *cr,
                              gdouble    rowstride,
                              gdouble   *width,
                              gdouble   *height)
{
  GeglChantO           *o = GEGL_CHANT_PROPERTIES (self);
  PangoFontDescription *desc;
  PangoLayout    *layout;
  PangoAttrList  *attrs;
  PangoAttribute *attr  = NULL;
  gchar          *string;
  gfloat          color[4];
  gint            alignment = 0;

  /* Create a PangoLayout, set the font and text */
  layout = pango_cairo_create_layout (cr);

  string = g_strcompress (o->string);
  pango_layout_set_text (layout, string, -1);
  g_free (string);

  desc = pango_font_description_from_string (o->font);
  pango_font_description_set_absolute_size (desc, o->size * PANGO_SCALE);
  pango_layout_set_font_description (layout, desc);

  switch (o->alignment)
  {
  case 0:
    alignment = PANGO_ALIGN_LEFT;
    break;
  case 1:
    alignment = PANGO_ALIGN_CENTER;
    break;
  case 2:
    alignment = PANGO_ALIGN_RIGHT;
    break;
  }
  pango_layout_set_alignment (layout, alignment);
  pango_layout_set_width (layout, o->wrap * PANGO_SCALE);

  attrs = pango_attr_list_new ();
  if (attrs)
  {
    gegl_color_get_pixel (o->color, babl_format ("RGBA float"), color);
    attr = pango_attr_foreground_new ((guint16) (color[0] * 65535),
                                      (guint16) (color[1] * 65535),
                                      (guint16) (color[2] * 65535));
    if (attr)
      {
        attr->start_index = 0;
        attr->end_index   = -1;
        pango_attr_list_insert (attrs, attr);
        pango_layout_set_attributes (layout, attrs);
      }
  }

  /* Inform Pango to re-layout the text with the new transformation */
  pango_cairo_update_layout (cr, layout);

  if (width && height)
    {
      int w, h;

      pango_layout_get_pixel_size (layout, &w, &h);
      *width = (gdouble)w;
      *height = (gdouble)h;
    }
  else
    {
      /* FIXME: This feels like a hack but it stops the rendered text  */
      /* from shifting position depending on the value of 'alignment'. */
      if (o->alignment == 1)
         cairo_move_to (cr, o->width / 2, 0);
      else
        {
          if (o->alignment == 2)
             cairo_move_to (cr, o->width, 0);
        }

      pango_cairo_show_layout (cr, layout);
    }

  pango_font_description_free (desc);
  pango_attr_list_unref (attrs);
  g_object_unref (layout);
}

static gboolean
process (GeglOperation       *operation,
         GeglBuffer          *output,
         const GeglRectangle *result,
         gint                 level)
{
  GeglChant *self = GEGL_CHANT (operation);

  guchar          *data = g_new0 (guchar, result->width * result->height * 4);
  cairo_t         *cr;
  cairo_surface_t *surface;

  surface = cairo_image_surface_create_for_data (data,
                                                 CAIRO_FORMAT_ARGB32,
                                                 result->width,
                                                 result->height,
                                                 result->width * 4);
  cr = cairo_create (surface);
  cairo_set_source_rgba (cr, 1.0, 1.0, 1.0, 1.0);
  cairo_translate (cr, -result->x, -result->y);
  text_layout_text (self, cr, 0, NULL, NULL);

  gegl_buffer_set (output, result, 0, babl_format ("B'aG'aR'aA u8"), data,
                   GEGL_AUTO_ROWSTRIDE);

  cairo_destroy (cr);
  cairo_surface_destroy (surface);
  g_free (data);

  return  TRUE;
}

static GeglRectangle
get_bounding_box (GeglOperation *operation)
{
  GeglChant *self = GEGL_CHANT (operation);
  GeglChantO           *o = GEGL_CHANT_PROPERTIES (self);
  CachedExtent *extent;
  gint status = FALSE;

  extent = (CachedExtent*)&self->cex;
  /*if (!self->priv)
    {
      self->priv = g_malloc0 (sizeof (CachedExtent));
      extent = (CachedExtent*)self->priv;
      extent->string = g_strdup ("");
      extent->font = g_strdup ("");
    }*/

  if ((extent->string && strcmp (extent->string, o->string)) ||
      (extent->font && strcmp (extent->font, o->font)) ||
      extent->size != o->size ||
      extent->wrap != o->wrap ||
      extent->alignment != o->alignment)
    { /* get extents */
      cairo_t *cr;
      gdouble width, height;

      cairo_surface_t *surface  = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
          1, 1);
      cr = cairo_create (surface);
      text_layout_text (self, cr, 0, &width, &height);
      cairo_destroy (cr);
      cairo_surface_destroy (surface);

      extent->defined.width = width;
      extent->defined.height = height;
      if (extent->string)
        g_free (extent->string);
      extent->string = g_strdup (o->string);
      if (extent->font)
        g_free (extent->font);
      extent->font = g_strdup (o->font);
      extent->size = o->size;
      extent->wrap = o->wrap;
      extent->alignment = o->alignment;

      /* store the measured size for later use */
      o->width = width;
      o->height = height;

      gegl_operation_invalidate (operation, NULL, TRUE);
    }

  if (status)
    {
      g_warning ("get defined region for text '%s' failed", o->string);
    }

  return extent->defined;
}

static void
finalize (GObject *object)
{
  GeglChant *self = GEGL_CHANT (object);

  if (self->cex.string)
    g_free (self->cex.string);
  if (self->cex.font)
    g_free (self->cex.font);

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

static void
prepare (GeglOperation *operation)
{
  gegl_operation_set_format (operation, "output", babl_format ("RaGaBaA float"));
}


static void
gegl_chant_class_init (GeglChantClass *klass)
{
  GObjectClass             *object_class;
  GeglOperationClass       *operation_class;
  GeglOperationSourceClass *operation_source_class;

  object_class    = G_OBJECT_CLASS (klass);
  operation_class = GEGL_OPERATION_CLASS (klass);
  operation_source_class = GEGL_OPERATION_SOURCE_CLASS (klass);

  object_class->finalize = finalize;
  operation_class->prepare = prepare;
  operation_class->get_bounding_box = get_bounding_box;
  operation_source_class->process = process;

  gegl_operation_class_set_keys (operation_class,
    "name"        , "gegl:text",
    "categories"  , "render",
    "description" , _("Display a string of text using pango and cairo."),
    NULL);

}


#endif