tor-browser

hb-cairo.cc (33285B)

---

/*
* Copyright © 2022  Red Hat, Inc.
*
*  This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Red Hat Author(s): Matthias Clasen
*/

#include "hb.hh"

#ifdef HAVE_CAIRO

#include "hb-cairo.h"

#include "hb-cairo-utils.hh"

#include "hb-machinery.hh"
#include "hb-utf.hh"


/**
* SECTION:hb-cairo
* @title: hb-cairo
* @short_description: Cairo integration
* @include: hb-cairo.h
*
* Functions for using HarfBuzz with the cairo library.
*
* HarfBuzz supports using cairo for rendering.
**/

static void
hb_cairo_move_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
	  void *draw_data,
	  hb_draw_state_t *st HB_UNUSED,
	  float to_x, float to_y,
	  void *user_data HB_UNUSED)
{
 cairo_t *cr = (cairo_t *) draw_data;

 cairo_move_to (cr, (double) to_x, (double) to_y);
}

static void
hb_cairo_line_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
	  void *draw_data,
	  hb_draw_state_t *st HB_UNUSED,
	  float to_x, float to_y,
	  void *user_data HB_UNUSED)
{
 cairo_t *cr = (cairo_t *) draw_data;

 cairo_line_to (cr, (double) to_x, (double) to_y);
}

static void
hb_cairo_cubic_to (hb_draw_funcs_t *dfuncs HB_UNUSED,
	   void *draw_data,
	   hb_draw_state_t *st HB_UNUSED,
	   float control1_x, float control1_y,
	   float control2_x, float control2_y,
	   float to_x, float to_y,
	   void *user_data HB_UNUSED)
{
 cairo_t *cr = (cairo_t *) draw_data;

 cairo_curve_to (cr,
                 (double) control1_x, (double) control1_y,
                 (double) control2_x, (double) control2_y,
                 (double) to_x, (double) to_y);
}

static void
hb_cairo_close_path (hb_draw_funcs_t *dfuncs HB_UNUSED,
	     void *draw_data,
	     hb_draw_state_t *st HB_UNUSED,
	     void *user_data HB_UNUSED)
{
 cairo_t *cr = (cairo_t *) draw_data;

 cairo_close_path (cr);
}

static inline void free_static_cairo_draw_funcs ();

static struct hb_cairo_draw_funcs_lazy_loader_t : hb_draw_funcs_lazy_loader_t<hb_cairo_draw_funcs_lazy_loader_t>
{
 static hb_draw_funcs_t *create ()
 {
   hb_draw_funcs_t *funcs = hb_draw_funcs_create ();

   hb_draw_funcs_set_move_to_func (funcs, hb_cairo_move_to, nullptr, nullptr);
   hb_draw_funcs_set_line_to_func (funcs, hb_cairo_line_to, nullptr, nullptr);
   hb_draw_funcs_set_cubic_to_func (funcs, hb_cairo_cubic_to, nullptr, nullptr);
   hb_draw_funcs_set_close_path_func (funcs, hb_cairo_close_path, nullptr, nullptr);

   hb_draw_funcs_make_immutable (funcs);

   hb_atexit (free_static_cairo_draw_funcs);

   return funcs;
 }
} static_cairo_draw_funcs;

static inline
void free_static_cairo_draw_funcs ()
{
 static_cairo_draw_funcs.free_instance ();
}

static hb_draw_funcs_t *
hb_cairo_draw_get_funcs ()
{
 return static_cairo_draw_funcs.get_unconst ();
}


#ifdef HAVE_CAIRO_USER_FONT_FACE_SET_RENDER_COLOR_GLYPH_FUNC

static void
hb_cairo_push_transform (hb_paint_funcs_t *pfuncs HB_UNUSED,
		 void *paint_data,
		 float xx, float yx,
		 float xy, float yy,
		 float dx, float dy,
		 void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_matrix_t m;

 cairo_save (cr);
 cairo_matrix_init (&m, (double) xx, (double) yx,
                        (double) xy, (double) yy,
                        (double) dx, (double) dy);
 cairo_transform (cr, &m);
}

static void
hb_cairo_pop_transform (hb_paint_funcs_t *pfuncs HB_UNUSED,
	        void *paint_data,
	        void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_restore (cr);
}

static hb_bool_t
hb_cairo_paint_color_glyph (hb_paint_funcs_t *pfuncs HB_UNUSED,
		    void *paint_data,
		    hb_codepoint_t glyph,
		    hb_font_t *font,
		    void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_save (cr);

 hb_position_t x_scale, y_scale;
 hb_font_get_scale (font, &x_scale, &y_scale);
 cairo_scale (cr, x_scale, -y_scale);

 cairo_glyph_t cairo_glyph = { glyph, 0, 0 };
 cairo_set_scaled_font (cr, c->scaled_font);
 cairo_set_font_size (cr, 1);
 cairo_show_glyphs (cr, &cairo_glyph, 1);

 cairo_restore (cr);

 return true;
}

static void
hb_cairo_push_clip_glyph (hb_paint_funcs_t *pfuncs HB_UNUSED,
		  void *paint_data,
		  hb_codepoint_t glyph,
		  hb_font_t *font,
		  void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_save (cr);
 cairo_new_path (cr);

 hb_font_draw_glyph (font, glyph, hb_cairo_draw_get_funcs (), cr);

 cairo_close_path (cr);
 cairo_clip (cr);
}

static void
hb_cairo_push_clip_rectangle (hb_paint_funcs_t *pfuncs HB_UNUSED,
		      void *paint_data,
		      float xmin, float ymin, float xmax, float ymax,
		      void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_save (cr);
 cairo_rectangle (cr,
                  (double) xmin, (double) ymin,
                  (double) (xmax - xmin), (double) (ymax - ymin));
 cairo_clip (cr);
}

static void
hb_cairo_pop_clip (hb_paint_funcs_t *pfuncs HB_UNUSED,
	   void *paint_data,
	   void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_restore (cr);
}

static void
hb_cairo_push_group (hb_paint_funcs_t *pfuncs HB_UNUSED,
	     void *paint_data,
	     void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_save (cr);
 cairo_push_group (cr);
}

static void
hb_cairo_pop_group (hb_paint_funcs_t *pfuncs HB_UNUSED,
	    void *paint_data,
	    hb_paint_composite_mode_t mode,
	    void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 cairo_pop_group_to_source (cr);
 cairo_set_operator (cr, _hb_paint_composite_mode_to_cairo (mode));
 cairo_paint (cr);

 cairo_restore (cr);
}

static void
hb_cairo_paint_color (hb_paint_funcs_t *pfuncs HB_UNUSED,
	      void *paint_data,
	      hb_bool_t use_foreground,
	      hb_color_t color,
	      void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

 if (use_foreground)
 {
#ifdef HAVE_CAIRO_USER_SCALED_FONT_GET_FOREGROUND_SOURCE
   double r, g, b, a;
   cairo_pattern_t *foreground = cairo_user_scaled_font_get_foreground_source (c->scaled_font);
   if (cairo_pattern_get_rgba (foreground, &r, &g, &b, &a) == CAIRO_STATUS_SUCCESS)
     cairo_set_source_rgba (cr, r, g, b, a * hb_color_get_alpha (color) / 255.);
   else
#endif
     cairo_set_source_rgba (cr, 0, 0, 0, hb_color_get_alpha (color) / 255.);
 }
 else
   cairo_set_source_rgba (cr,
		   hb_color_get_red (color) / 255.,
		   hb_color_get_green (color) / 255.,
		   hb_color_get_blue (color) / 255.,
		   hb_color_get_alpha (color) / 255.);
 cairo_paint (cr);
}

static hb_bool_t
hb_cairo_paint_image (hb_paint_funcs_t *pfuncs HB_UNUSED,
	      void *paint_data,
	      hb_blob_t *blob,
	      unsigned width,
	      unsigned height,
	      hb_tag_t format,
	      float slant,
	      hb_glyph_extents_t *extents,
	      void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;

 return _hb_cairo_paint_glyph_image (c, blob, width, height, format, slant, extents);
}

static void
hb_cairo_paint_linear_gradient (hb_paint_funcs_t *pfuncs HB_UNUSED,
			void *paint_data,
			hb_color_line_t *color_line,
			float x0, float y0,
			float x1, float y1,
			float x2, float y2,
			void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;

 _hb_cairo_paint_linear_gradient (c, color_line, x0, y0, x1, y1, x2, y2);
}

static void
hb_cairo_paint_radial_gradient (hb_paint_funcs_t *pfuncs HB_UNUSED,
			void *paint_data,
			hb_color_line_t *color_line,
			float x0, float y0, float r0,
			float x1, float y1, float r1,
			void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;

 _hb_cairo_paint_radial_gradient (c, color_line, x0, y0, r0, x1, y1, r1);
}

static void
hb_cairo_paint_sweep_gradient (hb_paint_funcs_t *pfuncs HB_UNUSED,
		       void *paint_data,
		       hb_color_line_t *color_line,
		       float x0, float y0,
		       float start_angle, float end_angle,
		       void *user_data HB_UNUSED)
{
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;

 _hb_cairo_paint_sweep_gradient (c, color_line, x0, y0, start_angle, end_angle);
}

static const cairo_user_data_key_t color_cache_key = {0};

static void
_hb_cairo_destroy_map (void *p)
{
 hb_map_destroy ((hb_map_t *) p);
}

static hb_bool_t
hb_cairo_paint_custom_palette_color (hb_paint_funcs_t *funcs,
                                    void *paint_data,
                                    unsigned int color_index,
                                    hb_color_t *color,
                                    void *user_data HB_UNUSED)
{
#ifdef HAVE_CAIRO_FONT_OPTIONS_GET_CUSTOM_PALETTE_COLOR
 hb_cairo_context_t *c = (hb_cairo_context_t *) paint_data;
 cairo_t *cr = c->cr;

#define HB_DEADBEEF HB_TAG(0xDE,0xAD,0xBE,0xEF)

 hb_map_t *color_cache = c->color_cache;
 hb_codepoint_t *v;
 if (likely (color_cache && color_cache->has (color_index, &v)))
 {
   if (*v == HB_DEADBEEF)
     return false;
   *color = *v;
   return true;
 }

 cairo_font_options_t *options;
 double red, green, blue, alpha;

 options = cairo_font_options_create ();
 cairo_get_font_options (cr, options);
 if (CAIRO_STATUS_SUCCESS ==
     cairo_font_options_get_custom_palette_color (options, color_index,
                                                  &red, &green, &blue, &alpha))
 {
   cairo_font_options_destroy (options);
   *color = HB_COLOR (round (255 * blue),
	       round (255 * green),
	       round (255 * red),
	       round (255 * alpha));

   if (likely (color_cache && *color != HB_DEADBEEF))
     color_cache->set (color_index, *color);

   return true;
 }
 cairo_font_options_destroy (options);

 if (likely (color_cache))
   color_cache->set (color_index, HB_DEADBEEF);

#undef HB_DEADBEEF

#endif

 return false;
}

static inline void free_static_cairo_paint_funcs ();

static struct hb_cairo_paint_funcs_lazy_loader_t : hb_paint_funcs_lazy_loader_t<hb_cairo_paint_funcs_lazy_loader_t>
{
 static hb_paint_funcs_t *create ()
 {
   hb_paint_funcs_t *funcs = hb_paint_funcs_create ();

   hb_paint_funcs_set_push_transform_func (funcs, hb_cairo_push_transform, nullptr, nullptr);
   hb_paint_funcs_set_pop_transform_func (funcs, hb_cairo_pop_transform, nullptr, nullptr);
   hb_paint_funcs_set_color_glyph_func (funcs, hb_cairo_paint_color_glyph, nullptr, nullptr);
   hb_paint_funcs_set_push_clip_glyph_func (funcs, hb_cairo_push_clip_glyph, nullptr, nullptr);
   hb_paint_funcs_set_push_clip_rectangle_func (funcs, hb_cairo_push_clip_rectangle, nullptr, nullptr);
   hb_paint_funcs_set_pop_clip_func (funcs, hb_cairo_pop_clip, nullptr, nullptr);
   hb_paint_funcs_set_push_group_func (funcs, hb_cairo_push_group, nullptr, nullptr);
   hb_paint_funcs_set_pop_group_func (funcs, hb_cairo_pop_group, nullptr, nullptr);
   hb_paint_funcs_set_color_func (funcs, hb_cairo_paint_color, nullptr, nullptr);
   hb_paint_funcs_set_image_func (funcs, hb_cairo_paint_image, nullptr, nullptr);
   hb_paint_funcs_set_linear_gradient_func (funcs, hb_cairo_paint_linear_gradient, nullptr, nullptr);
   hb_paint_funcs_set_radial_gradient_func (funcs, hb_cairo_paint_radial_gradient, nullptr, nullptr);
   hb_paint_funcs_set_sweep_gradient_func (funcs, hb_cairo_paint_sweep_gradient, nullptr, nullptr);
   hb_paint_funcs_set_custom_palette_color_func (funcs, hb_cairo_paint_custom_palette_color, nullptr, nullptr);

   hb_paint_funcs_make_immutable (funcs);

   hb_atexit (free_static_cairo_paint_funcs);

   return funcs;
 }
} static_cairo_paint_funcs;

static inline
void free_static_cairo_paint_funcs ()
{
 static_cairo_paint_funcs.free_instance ();
}

static hb_paint_funcs_t *
hb_cairo_paint_get_funcs ()
{
 return static_cairo_paint_funcs.get_unconst ();
}
#endif

static const cairo_user_data_key_t hb_cairo_face_user_data_key = {0};
static const cairo_user_data_key_t hb_cairo_font_user_data_key = {0};
static const cairo_user_data_key_t hb_cairo_font_init_func_user_data_key = {0};
static const cairo_user_data_key_t hb_cairo_font_init_user_data_user_data_key = {0};
static const cairo_user_data_key_t hb_cairo_scale_factor_user_data_key = {0};

static void hb_cairo_face_destroy (void *p) { hb_face_destroy ((hb_face_t *) p); }
static void hb_cairo_font_destroy (void *p) { hb_font_destroy ((hb_font_t *) p); }

static cairo_status_t
hb_cairo_init_scaled_font (cairo_scaled_font_t  *scaled_font,
		   cairo_t              *cr HB_UNUSED,
		   cairo_font_extents_t *extents)
{
 cairo_font_face_t *font_face = cairo_scaled_font_get_font_face (scaled_font);

 hb_font_t *font = (hb_font_t *) cairo_font_face_get_user_data (font_face,
							 &hb_cairo_font_user_data_key);

 if (!font)
 {
   hb_face_t *face = (hb_face_t *) cairo_font_face_get_user_data (font_face,
							   &hb_cairo_face_user_data_key);
   font = hb_font_create (face);

#if !defined(HB_NO_VAR) && CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1,16,0)
   cairo_font_options_t *font_options = cairo_font_options_create ();

   // Set variations
   cairo_scaled_font_get_font_options (scaled_font, font_options);
   const char *variations = cairo_font_options_get_variations (font_options);
   hb_vector_t<hb_variation_t> vars;
   const char *p = variations;
   while (p && *p)
   {
     const char *end = strpbrk ((char *) p, ", ");
     hb_variation_t var;
     if (hb_variation_from_string (p, end ? end - p : -1, &var))
vars.push (var);
     p = end ? end + 1 : nullptr;
   }
   hb_font_set_variations (font, &vars[0], vars.length);

   cairo_font_options_destroy (font_options);
#endif

   // Set scale; Note: should NOT set slant, or we'll double-slant.
   unsigned scale_factor = hb_cairo_font_face_get_scale_factor (font_face);
   if (scale_factor)
   {
     cairo_matrix_t font_matrix;
     cairo_scaled_font_get_scale_matrix (scaled_font, &font_matrix);
     hb_font_set_scale (font,
		 round (font_matrix.xx * scale_factor),
		 round (font_matrix.yy * scale_factor));
   }

   auto *init_func = (hb_cairo_font_init_func_t)
	      cairo_font_face_get_user_data (font_face,
					     &hb_cairo_font_init_func_user_data_key);
   if (init_func)
   {
     void *user_data = cairo_font_face_get_user_data (font_face,
					       &hb_cairo_font_init_user_data_user_data_key);
     font = init_func (font, scaled_font, user_data);
   }

   hb_font_make_immutable (font);
 }

 cairo_scaled_font_set_user_data (scaled_font,
			   &hb_cairo_font_user_data_key,
			   (void *) hb_font_reference (font),
			   hb_cairo_font_destroy);

 hb_position_t x_scale, y_scale;
 hb_font_get_scale (font, &x_scale, &y_scale);

 hb_font_extents_t hb_extents;
 hb_font_get_h_extents (font, &hb_extents);

 extents->ascent  = (double)  hb_extents.ascender  / y_scale;
 extents->descent = (double) -hb_extents.descender / y_scale;
 extents->height  = extents->ascent + extents->descent;

#ifdef HAVE_CAIRO_USER_FONT_FACE_SET_RENDER_COLOR_GLYPH_FUNC
 hb_map_t *color_cache = hb_map_create ();
 if (unlikely (CAIRO_STATUS_SUCCESS != cairo_scaled_font_set_user_data (scaled_font,
								 &color_cache_key,
								 color_cache,
								 _hb_cairo_destroy_map)))
   hb_map_destroy (color_cache);
#endif

 return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
hb_cairo_text_to_glyphs (cairo_scaled_font_t        *scaled_font,
		 const char	            *utf8,
		 int		             utf8_len,
		 cairo_glyph_t	           **glyphs,
		 int		            *num_glyphs,
		 cairo_text_cluster_t      **clusters,
		 int		            *num_clusters,
		 cairo_text_cluster_flags_t *cluster_flags)
{
 hb_font_t *font = (hb_font_t *) cairo_scaled_font_get_user_data (scaled_font,
							   &hb_cairo_font_user_data_key);

 hb_buffer_t *buffer = hb_buffer_create ();
 hb_buffer_add_utf8 (buffer, utf8, utf8_len, 0, utf8_len);
 hb_buffer_guess_segment_properties (buffer);
 hb_shape (font, buffer, nullptr, 0);

 int x_scale, y_scale;
 hb_font_get_scale (font, &x_scale, &y_scale);

 hb_cairo_glyphs_from_buffer (buffer,
		       true,
		       x_scale, y_scale,
		       0., 0.,
		       utf8, utf8_len,
		       glyphs, (unsigned *) num_glyphs,
		       clusters, (unsigned *) num_clusters,
		       cluster_flags);

 hb_buffer_destroy (buffer);

 return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
hb_cairo_render_glyph (cairo_scaled_font_t  *scaled_font,
	       unsigned long         glyph,
	       cairo_t              *cr,
	       cairo_text_extents_t *extents)
{
 hb_font_t *font = (hb_font_t *) cairo_scaled_font_get_user_data (scaled_font,
							   &hb_cairo_font_user_data_key);

 hb_position_t x_scale, y_scale;
 hb_font_get_scale (font, &x_scale, &y_scale);
 cairo_scale (cr,
       +1. / (x_scale ? x_scale : 1),
       -1. / (y_scale ? y_scale : 1));

 if (hb_font_draw_glyph_or_fail (font, glyph, hb_cairo_draw_get_funcs (), cr))
   cairo_fill (cr);

 // If draw fails, we still return SUCCESS, as we want empty drawing, not
 // setting the cairo object into error.
 return CAIRO_STATUS_SUCCESS;
}

#ifdef HAVE_CAIRO_USER_FONT_FACE_SET_RENDER_COLOR_GLYPH_FUNC

static cairo_status_t
hb_cairo_render_color_glyph (cairo_scaled_font_t  *scaled_font,
		     unsigned long         glyph,
		     cairo_t              *cr,
		     cairo_text_extents_t *extents)
{
 hb_font_t *font = (hb_font_t *) cairo_scaled_font_get_user_data (scaled_font,
							   &hb_cairo_font_user_data_key);

 unsigned int palette = 0;
#ifdef CAIRO_COLOR_PALETTE_DEFAULT
 cairo_font_options_t *options = cairo_font_options_create ();
 cairo_scaled_font_get_font_options (scaled_font, options);
 palette = cairo_font_options_get_color_palette (options);
 cairo_font_options_destroy (options);
#endif

 hb_color_t color = HB_COLOR (0, 0, 0, 255);
 hb_position_t x_scale, y_scale;
 hb_font_get_scale (font, &x_scale, &y_scale);
 cairo_scale (cr,
       +1. / (x_scale ? x_scale : 1),
       -1. / (y_scale ? y_scale : 1));

 hb_cairo_context_t c;
 c.scaled_font = scaled_font;
 c.cr = cr;
 c.color_cache = (hb_map_t *) cairo_scaled_font_get_user_data (scaled_font, &color_cache_key);

 if (!hb_font_paint_glyph_or_fail (font, glyph, hb_cairo_paint_get_funcs (), &c, palette, color))
   return CAIRO_STATUS_USER_FONT_NOT_IMPLEMENTED;

 return CAIRO_STATUS_SUCCESS;
}

#endif

static cairo_font_face_t *
user_font_face_create (hb_face_t *face)
{
 cairo_font_face_t *cairo_face;

 cairo_face = cairo_user_font_face_create ();
 cairo_user_font_face_set_init_func (cairo_face, hb_cairo_init_scaled_font);
 cairo_user_font_face_set_text_to_glyphs_func (cairo_face, hb_cairo_text_to_glyphs);
 cairo_user_font_face_set_render_glyph_func (cairo_face, hb_cairo_render_glyph);
#ifdef HAVE_CAIRO_USER_FONT_FACE_SET_RENDER_COLOR_GLYPH_FUNC
 cairo_user_font_face_set_render_color_glyph_func (cairo_face, hb_cairo_render_color_glyph);
#endif

 if (unlikely (CAIRO_STATUS_SUCCESS != cairo_font_face_set_user_data (cairo_face,
							       &hb_cairo_face_user_data_key,
							       (void *) hb_face_reference (face),
							       hb_cairo_face_destroy)))
   hb_face_destroy (face);

 return cairo_face;
}

/**
* hb_cairo_font_face_create_for_font:
* @font: a #hb_font_t
*
* Creates a #cairo_font_face_t for rendering text according
* to @font.
*
* Note that the scale of @font does not affect the rendering,
* but the variations and slant that are set on @font do.
*
* Returns: (transfer full): a newly created #cairo_font_face_t
*
* Since: 7.0.0
*/
cairo_font_face_t *
hb_cairo_font_face_create_for_font (hb_font_t *font)
{
 hb_font_make_immutable (font);

 auto *hb_face = hb_font_get_face (font);
 auto *cairo_face =  user_font_face_create (hb_face);

 if (unlikely (CAIRO_STATUS_SUCCESS != cairo_font_face_set_user_data (cairo_face,
							       &hb_cairo_font_user_data_key,
							       (void *) hb_font_reference (font),
							       hb_cairo_font_destroy)))
   hb_font_destroy (font);

 return cairo_face;
}

/**
* hb_cairo_font_face_get_font:
* @font_face: a #cairo_font_face_t
*
* Gets the #hb_font_t that @font_face was created from.
*
* Returns: (nullable) (transfer none): the #hb_font_t that @font_face was created from
*
* Since: 7.0.0
*/
hb_font_t *
hb_cairo_font_face_get_font (cairo_font_face_t *font_face)
{
 return (hb_font_t *) cairo_font_face_get_user_data (font_face,
					      &hb_cairo_font_user_data_key);
}

/**
* hb_cairo_font_face_create_for_face:
* @face: a #hb_face_t
*
* Creates a #cairo_font_face_t for rendering text according
* to @face.
*
* Returns: (transfer full): a newly created #cairo_font_face_t
*
* Since: 7.0.0
*/
cairo_font_face_t *
hb_cairo_font_face_create_for_face (hb_face_t *face)
{
 hb_face_make_immutable (face);

 return user_font_face_create (face);
}

/**
* hb_cairo_font_face_get_face:
* @font_face: a #cairo_font_face_t
*
* Gets the #hb_face_t associated with @font_face.
*
* Returns: (nullable) (transfer none): the #hb_face_t associated with @font_face
*
* Since: 7.0.0
*/
hb_face_t *
hb_cairo_font_face_get_face (cairo_font_face_t *font_face)
{
 return (hb_face_t *) cairo_font_face_get_user_data (font_face,
					      &hb_cairo_face_user_data_key);
}

/**
* hb_cairo_font_face_set_font_init_func:
* @font_face: a #cairo_font_face_t
* @func: The virtual method to use
* @user_data: user data accompanying the method
* @destroy: function to call when @user_data is not needed anymore
*
* Set the virtual method to be called when a cairo
* face created using hb_cairo_font_face_create_for_face()
* creates an #hb_font_t for a #cairo_scaled_font_t.
*
* Since: 7.0.0
*/
void
hb_cairo_font_face_set_font_init_func (cairo_font_face_t *font_face,
			       hb_cairo_font_init_func_t func,
			       void *user_data,
			       hb_destroy_func_t destroy)
{
 cairo_font_face_set_user_data (font_face,
			 &hb_cairo_font_init_func_user_data_key,
			 (void *) func,
			 nullptr);
 if (unlikely (CAIRO_STATUS_SUCCESS != cairo_font_face_set_user_data (font_face,
							       &hb_cairo_font_init_user_data_user_data_key,
							       (void *) user_data,
							       destroy)) && destroy)
 {
   destroy (user_data);
   cairo_font_face_set_user_data (font_face,
			   &hb_cairo_font_init_func_user_data_key,
			   nullptr,
			   nullptr);
 }
}

/**
* hb_cairo_scaled_font_get_font:
* @scaled_font: a #cairo_scaled_font_t
*
* Gets the #hb_font_t associated with @scaled_font.
*
* Returns: (nullable) (transfer none): the #hb_font_t associated with @scaled_font
*
* Since: 7.0.0
*/
hb_font_t *
hb_cairo_scaled_font_get_font (cairo_scaled_font_t *scaled_font)
{
 return (hb_font_t *) cairo_scaled_font_get_user_data (scaled_font, &hb_cairo_font_user_data_key);
}


/**
* hb_cairo_font_face_set_scale_factor:
* @scale_factor: The scale factor to use. See below
* @font_face: a #cairo_font_face_t
*
* Sets the scale factor of the @font_face. Default scale
* factor is zero.
*
* When a #cairo_font_face_t is created from a #hb_face_t using
* hb_cairo_font_face_create_for_face(), such face will create
* #hb_font_t objects during scaled-font creation.  The scale
* factor defines how the scale set on such #hb_font_t objects
* relates to the font-matrix (as such font size) of the cairo
* scaled-font.
*
* If the scale-factor is zero (default), then the scale of the
* #hb_font_t object will be left at default, which is the UPEM
* value of the respective #hb_face_t.
*
* If the scale-factor is set to non-zero, then the X and Y scale
* of the #hb_font_t object will be respectively set to the
* @scale_factor times the xx and yy elements of the scale-matrix
* of the cairo scaled-font being created.
*
* When using the hb_cairo_glyphs_from_buffer() API to convert the
* HarfBuzz glyph buffer that resulted from shaping with such a #hb_font_t,
* if the scale-factor was non-zero, you can pass it directly to
* that API as both X and Y scale factors.
*
* If the scale-factor was zero however, or the cairo face was
* created using the alternative constructor
* hb_cairo_font_face_create_for_font(), you need to calculate the
* correct X/Y scale-factors to pass to hb_cairo_glyphs_from_buffer()
* by dividing the #hb_font_t X/Y scale-factors by the
* cairo scaled-font's scale-matrix XX/YY components respectively
* and use those values.  Or if you know that relationship offhand
* (because you set the scale of the #hb_font_t yourself), use
* the conversion rate involved.
*
* Since: 7.0.0
*/
void
hb_cairo_font_face_set_scale_factor (cairo_font_face_t *font_face,
			     unsigned int scale_factor)
{
 cairo_font_face_set_user_data (font_face,
			 &hb_cairo_scale_factor_user_data_key,
			 (void *) (uintptr_t) scale_factor,
			 nullptr);
}

/**
* hb_cairo_font_face_get_scale_factor:
* @font_face: a #cairo_font_face_t
*
* Gets the scale factor set on the @font_face. Defaults to zero.
* See hb_cairo_font_face_set_scale_factor() for details.
*
* Returns: the scale factor of @font_face
*
* Since: 7.0.0
*/
unsigned int
hb_cairo_font_face_get_scale_factor (cairo_font_face_t *font_face)
{
 return (unsigned int) (uintptr_t)
 cairo_font_face_get_user_data (font_face,
				&hb_cairo_scale_factor_user_data_key);
}


/**
* hb_cairo_glyphs_from_buffer:
* @buffer: a #hb_buffer_t containing glyphs
* @utf8_clusters: `true` if @buffer clusters are in bytes, instead of characters
* @x_scale_factor: scale factor to divide #hb_position_t Y values by
* @y_scale_factor: scale factor to divide #hb_position_t X values by
* @x: X position to place first glyph
* @y: Y position to place first glyph
* @utf8: (nullable): the text that was shaped in @buffer
* @utf8_len: the length of @utf8 in bytes
* @glyphs: (out): return location for an array of #cairo_glyph_t
* @num_glyphs: (inout): return location for the length of @glyphs
* @clusters: (out) (nullable): return location for an array of cluster positions
* @num_clusters: (inout) (nullable): return location for the length of @clusters
* @cluster_flags: (out) (nullable): return location for cluster flags
*
* Extracts information from @buffer in a form that can be
* passed to cairo_show_text_glyphs() or cairo_show_glyphs().
* This API is modeled after cairo_scaled_font_text_to_glyphs() and
* cairo_user_scaled_font_text_to_glyphs_func_t.
*
* The @num_glyphs argument should be preset to the number of glyph entries available
* in the @glyphs buffer. If the @glyphs buffer is `NULL`, the value of
* @num_glyphs must be zero.  If the provided glyph array is too short for
* the conversion (or for convenience), a new glyph array may be allocated
* using cairo_glyph_allocate() and placed in @glyphs.  Upon return,
* @num_glyphs should contain the number of generated glyphs.  If the value
* @glyphs points at has changed after the call, the caller will free the
* allocated glyph array using cairo_glyph_free().  The caller will also free
* the original value of @glyphs, so this function shouldn't do so.
*
* If @clusters is not `NULL`, then @num_clusters and @cluster_flags
* should not be either, and @utf8 must be provided, and cluster
* mapping will be computed. The semantics of how
* cluster array allocation works is similar to the glyph array.  That is,
* if @clusters initially points to a non-`NULL` value, that array may be used
* as a cluster buffer, and @num_clusters points to the number of cluster
* entries available there.  If the provided cluster array is too short for
* the conversion (or for convenience), a new cluster array may be allocated
* using cairo_text_cluster_allocate() and placed in @clusters.  In this case,
* the original value of @clusters will still be freed by the caller.  Upon
* return, @num_clusters will contain the number of generated clusters.
* If the value @clusters points at has changed after the call, the caller
* will free the allocated cluster array using cairo_text_cluster_free().
*
* See hb_cairo_font_face_set_scale_factor() for the details of
* the @scale_factor argument.
*
* The returned @glyphs vector actually has `@num_glyphs + 1` entries in
* it and the x,y values of the extra entry at the end add up the advance
* x,y of all the glyphs in the @buffer.
*
* Since: 7.0.0
*/
void
hb_cairo_glyphs_from_buffer (hb_buffer_t *buffer,
		     hb_bool_t utf8_clusters,
		     double x_scale_factor,
		     double y_scale_factor,
		     double x,
		     double y,
		     const char *utf8,
		     int utf8_len,
		     cairo_glyph_t **glyphs,
		     unsigned int *num_glyphs,
		     cairo_text_cluster_t **clusters,
		     unsigned int *num_clusters,
		     cairo_text_cluster_flags_t *cluster_flags)
{
 if (utf8 && utf8_len < 0)
   utf8_len = strlen (utf8);

 unsigned orig_num_glyphs = *num_glyphs;
 *num_glyphs = hb_buffer_get_length (buffer);
 hb_glyph_info_t *hb_glyph = hb_buffer_get_glyph_infos (buffer, nullptr);
 hb_glyph_position_t *hb_position = hb_buffer_get_glyph_positions (buffer, nullptr);
 if (orig_num_glyphs < *num_glyphs + 1)
   *glyphs = cairo_glyph_allocate (*num_glyphs + 1);

 if (clusters && utf8)
 {
   unsigned orig_num_clusters = *num_clusters;
   *num_clusters = *num_glyphs ? 1 : 0;
   for (unsigned int i = 1; i < *num_glyphs; i++)
     if (hb_glyph[i].cluster != hb_glyph[i-1].cluster)
(*num_clusters)++;
   if (orig_num_clusters < *num_clusters)
     *clusters = cairo_text_cluster_allocate (*num_clusters);
 }

 double x_scale = x_scale_factor ? 1. / x_scale_factor : 0.;
 double y_scale = y_scale_factor ? 1. / y_scale_factor : 0.;
 hb_position_t hx = 0, hy = 0;
 int i;
 for (i = 0; i < (int) *num_glyphs; i++)
 {
   (*glyphs)[i].index = hb_glyph[i].codepoint;
   (*glyphs)[i].x = x + (+hb_position->x_offset + hx) * x_scale;
   (*glyphs)[i].y = y + (-hb_position->y_offset + hy) * y_scale;
   hx +=  hb_position->x_advance;
   hy += -hb_position->y_advance;

   hb_position++;
 }
 (*glyphs)[i].index = -1;
 (*glyphs)[i].x = round (hx * x_scale);
 (*glyphs)[i].y = round (hy * y_scale);

 if (clusters && *num_clusters && utf8)
 {
   hb_memset ((void *) *clusters, 0, *num_clusters * sizeof ((*clusters)[0]));
   hb_bool_t backward = HB_DIRECTION_IS_BACKWARD (hb_buffer_get_direction (buffer));
   *cluster_flags = backward ? CAIRO_TEXT_CLUSTER_FLAG_BACKWARD : (cairo_text_cluster_flags_t) 0;
   unsigned int cluster = 0;
   const char *start = utf8, *end;
   (*clusters)[cluster].num_glyphs++;
   if (backward)
   {
     for (i = *num_glyphs - 2; i >= 0; i--)
     {
if (hb_glyph[i].cluster != hb_glyph[i+1].cluster)
{
  assert (hb_glyph[i].cluster > hb_glyph[i+1].cluster);
  if (utf8_clusters)
    end = start + hb_glyph[i].cluster - hb_glyph[i+1].cluster;
  else
    end = (const char *) hb_utf_offset_to_pointer<hb_utf8_t> ((const uint8_t *) start,
							      (const uint8_t *) utf8, utf8_len,
							      (signed) (hb_glyph[i].cluster - hb_glyph[i+1].cluster));
  (*clusters)[cluster].num_bytes = end - start;
  start = end;
  cluster++;
}
(*clusters)[cluster].num_glyphs++;
     }
     (*clusters)[cluster].num_bytes = utf8 + utf8_len - start;
   }
   else
   {
     for (i = 1; i < (int) *num_glyphs; i++)
     {
if (hb_glyph[i].cluster != hb_glyph[i-1].cluster)
{
  assert (hb_glyph[i].cluster > hb_glyph[i-1].cluster);
  if (utf8_clusters)
    end = start + hb_glyph[i].cluster - hb_glyph[i-1].cluster;
  else
    end = (const char *) hb_utf_offset_to_pointer<hb_utf8_t> ((const uint8_t *) start,
							      (const uint8_t *) utf8, utf8_len,
							      (signed) (hb_glyph[i].cluster - hb_glyph[i-1].cluster));
  (*clusters)[cluster].num_bytes = end - start;
  start = end;
  cluster++;
}
(*clusters)[cluster].num_glyphs++;
     }
     (*clusters)[cluster].num_bytes = utf8 + utf8_len - start;
   }
 }
 else if (num_clusters)
   *num_clusters = 0;
}

#endif