src/ftcrfont.c

   1 /* ftcrfont.c -- FreeType font driver on cairo.
   2    Copyright (C) 2015-2017 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software: you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation, either version 3 of the License, or (at
   9 your option) any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19
  20 #include <config.h>
  21 #include <stdio.h>
  22 #include <cairo-ft.h>
  23
  24 #include "lisp.h"
  25 #include "xterm.h"
  26 #include "blockinput.h"
  27 #include "font.h"
  28 #include "ftfont.h"
  29
  30 /* FTCR font driver.  */
  31
  32 /* The actual structure for FTCR font.  A pointer to this structure
  33    can be cast to struct font *.  */
  34
  35 struct ftcrfont_info
  36 {
  37   struct font font;
  38   /* The following six members must be here in this order to be
  39      compatible with struct ftfont_info (in ftfont.c).  */
  40 #ifdef HAVE_LIBOTF
  41   bool maybe_otf;         /* Flag to tell if this may be OTF or not.  */
  42   OTF *otf;
  43 #endif  /* HAVE_LIBOTF */
  44   FT_Size ft_size;
  45   int index;
  46   FT_Matrix matrix;
  47
  48   cairo_font_face_t *cr_font_face;
  49   /* To prevent cairo from cluttering the activated FT_Size maintained
  50      in ftfont.c, we activate this special FT_Size before drawing.  */
  51   FT_Size ft_size_draw;
  52   /* Font metrics cache.  */
  53   struct font_metrics **metrics;
  54   short metrics_nrows;
  55 };
  56
  57 #define METRICS_NCOLS_PER_ROW   (128)
  58
  59 enum metrics_status
  60   {
  61     METRICS_INVALID = -1,    /* metrics entry is invalid */
  62   };
  63
  64 #define METRICS_STATUS(metrics) ((metrics)->ascent + (metrics)->descent)
  65 #define METRICS_SET_STATUS(metrics, status) \
  66   ((metrics)->ascent = 0, (metrics)->descent = (status))
  67
  68 static int
  69 ftcrfont_glyph_extents (struct font *font,
  70                         unsigned glyph,
  71                         struct font_metrics *metrics)
  72 {
  73   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
  74   int row, col;
  75   struct font_metrics *cache;
  76
  77   row = glyph / METRICS_NCOLS_PER_ROW;
  78   col = glyph % METRICS_NCOLS_PER_ROW;
  79   if (row >= ftcrfont_info->metrics_nrows)
  80     {
  81       ftcrfont_info->metrics =
  82         xrealloc (ftcrfont_info->metrics,
  83                   sizeof (struct font_metrics *) * (row + 1));
  84       bzero (ftcrfont_info->metrics + ftcrfont_info->metrics_nrows,
  85              (sizeof (struct font_metrics *)
  86               * (row + 1 - ftcrfont_info->metrics_nrows)));
  87       ftcrfont_info->metrics_nrows = row + 1;
  88     }
  89   if (ftcrfont_info->metrics[row] == NULL)
  90     {
  91       struct font_metrics *new;
  92       int i;
  93
  94       new = xmalloc (sizeof (struct font_metrics) * METRICS_NCOLS_PER_ROW);
  95       for (i = 0; i < METRICS_NCOLS_PER_ROW; i++)
  96         METRICS_SET_STATUS (new + i, METRICS_INVALID);
  97       ftcrfont_info->metrics[row] = new;
  98     }
  99   cache = ftcrfont_info->metrics[row] + col;
 100
 101   if (METRICS_STATUS (cache) == METRICS_INVALID)
 102     ftfont_text_extents (font, &glyph, 1, cache);
 103
 104   if (metrics)
 105     *metrics = *cache;
 106
 107   return cache->width;
 108 }
 109
 110 static Lisp_Object
 111 ftcrfont_list (struct frame *f, Lisp_Object spec)
 112 {
 113   Lisp_Object list = ftfont_list (f, spec), tail;
 114
 115   for (tail = list; CONSP (tail); tail = XCDR (tail))
 116     ASET (XCAR (tail), FONT_TYPE_INDEX, Qftcr);
 117   return list;
 118 }
 119
 120 static Lisp_Object
 121 ftcrfont_match (struct frame *f, Lisp_Object spec)
 122 {
 123   Lisp_Object entity = ftfont_match (f, spec);
 124
 125   if (VECTORP (entity))
 126     ASET (entity, FONT_TYPE_INDEX, Qftcr);
 127   return entity;
 128 }
 129
 130 static Lisp_Object
 131 ftcrfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 132 {
 133   Lisp_Object font_object;
 134   struct font *font;
 135   struct ftcrfont_info *ftcrfont_info;
 136   FT_Face ft_face;
 137   FT_UInt size;
 138
 139   block_input ();
 140   size = XINT (AREF (entity, FONT_SIZE_INDEX));
 141   if (size == 0)
 142     size = pixel_size;
 143   font_object = font_build_object (VECSIZE (struct ftcrfont_info),
 144                                    Qftcr, entity, size);
 145   font_object = ftfont_open2 (f, entity, pixel_size, font_object);
 146   if (NILP (font_object)) return Qnil;
 147
 148   font = XFONT_OBJECT (font_object);
 149   font->driver = &ftcrfont_driver;
 150   ftcrfont_info = (struct ftcrfont_info *) font;
 151   ft_face = ftcrfont_info->ft_size->face;
 152   FT_New_Size (ft_face, &ftcrfont_info->ft_size_draw);
 153   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 154   FT_Set_Pixel_Sizes (ft_face, 0, font->pixel_size);
 155   ftcrfont_info->cr_font_face =
 156     cairo_ft_font_face_create_for_ft_face (ft_face, 0);
 157   ftcrfont_info->metrics = NULL;
 158   ftcrfont_info->metrics_nrows = 0;
 159   unblock_input ();
 160
 161   return font_object;
 162 }
 163
 164 static void
 165 ftcrfont_close (struct font *font)
 166 {
 167   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
 168   int i;
 169
 170   block_input ();
 171   for (i = 0; i < ftcrfont_info->metrics_nrows; i++)
 172     if (ftcrfont_info->metrics[i])
 173       xfree (ftcrfont_info->metrics[i]);
 174   if (ftcrfont_info->metrics)
 175     xfree (ftcrfont_info->metrics);
 176   FT_Done_Size (ftcrfont_info->ft_size_draw);
 177   cairo_font_face_destroy (ftcrfont_info->cr_font_face);
 178   unblock_input ();
 179
 180   ftfont_close (font);
 181 }
 182
 183 static void
 184 ftcrfont_text_extents (struct font *font,
 185                        unsigned *code,
 186                        int nglyphs,
 187                        struct font_metrics *metrics)
 188 {
 189   int width, i;
 190
 191   block_input ();
 192   width = ftcrfont_glyph_extents (font, code[0], metrics);
 193   for (i = 1; i < nglyphs; i++)
 194     {
 195       struct font_metrics m;
 196       int w = ftcrfont_glyph_extents (font, code[i], metrics ? &m : NULL);
 197
 198       if (metrics)
 199         {
 200           if (width + m.lbearing < metrics->lbearing)
 201             metrics->lbearing = width + m.lbearing;
 202           if (width + m.rbearing > metrics->rbearing)
 203             metrics->rbearing = width + m.rbearing;
 204           if (m.ascent > metrics->ascent)
 205             metrics->ascent = m.ascent;
 206           if (m.descent > metrics->descent)
 207             metrics->descent = m.descent;
 208         }
 209       width += w;
 210     }
 211   unblock_input ();
 212
 213   if (metrics)
 214     metrics->width = width;
 215 }
 216
 217 static int
 218 ftcrfont_draw (struct glyph_string *s,
 219                int from, int to, int x, int y, bool with_background)
 220 {
 221   struct frame *f = s->f;
 222   struct face *face = s->face;
 223   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) s->font;
 224   cairo_t *cr;
 225   cairo_glyph_t *glyphs;
 226   cairo_surface_t *surface;
 227   cairo_surface_type_t surface_type;
 228   int len = to - from;
 229   int i;
 230
 231   block_input ();
 232
 233   cr = x_begin_cr_clip (f, s->gc);
 234
 235   if (with_background)
 236     {
 237       x_set_cr_source_with_gc_background (f, s->gc);
 238       cairo_rectangle (cr, x, y - FONT_BASE (face->font),
 239                        s->width, FONT_HEIGHT (face->font));
 240       cairo_fill (cr);
 241     }
 242
 243   glyphs = alloca (sizeof (cairo_glyph_t) * len);
 244   for (i = 0; i < len; i++)
 245     {
 246       unsigned code = ((XCHAR2B_BYTE1 (s->char2b + from + i) << 8)
 247                        | XCHAR2B_BYTE2 (s->char2b + from + i));
 248
 249       glyphs[i].index = code;
 250       glyphs[i].x = x;
 251       glyphs[i].y = y;
 252       x += (s->padding_p ? 1 : ftcrfont_glyph_extents (s->font, code, NULL));
 253     }
 254
 255   x_set_cr_source_with_gc_foreground (f, s->gc);
 256   cairo_set_font_face (cr, ftcrfont_info->cr_font_face);
 257   cairo_set_font_size (cr, s->font->pixel_size);
 258   /* cairo_set_font_matrix */
 259   /* cairo_set_font_options */
 260
 261   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 262   cairo_show_glyphs (cr, glyphs, len);
 263   surface = cairo_get_target (cr);
 264   /* XXX: It used to be necessary to flush when exporting.  It might
 265      be the case that this is no longer necessary.  */
 266   surface_type = cairo_surface_get_type (surface);
 267   if (surface_type != CAIRO_SURFACE_TYPE_XLIB
 268       && (surface_type != CAIRO_SURFACE_TYPE_IMAGE
 269           || cairo_image_surface_get_format (surface) != CAIRO_FORMAT_ARGB32))
 270     cairo_surface_flush (surface);
 271
 272   x_end_cr_clip (f);
 273
 274   unblock_input ();
 275
 276   return len;
 277 }
 278
 279 \f
 280
 281 struct font_driver const ftcrfont_driver =
 282   {
 283   .type = LISPSYM_INITIALLY (Qftcr),
 284   .get_cache = ftfont_get_cache,
 285   .list = ftcrfont_list,
 286   .match = ftcrfont_match,
 287   .list_family = ftfont_list_family,
 288   .open = ftcrfont_open,
 289   .close = ftcrfont_close,
 290   .has_char = ftfont_has_char,
 291   .encode_char = ftfont_encode_char,
 292   .text_extents = ftcrfont_text_extents,
 293   .draw = ftcrfont_draw,
 294   .get_bitmap = ftfont_get_bitmap,
 295   .anchor_point = ftfont_anchor_point,
 296 #ifdef HAVE_LIBOTF
 297   .otf_capability = ftfont_otf_capability,
 298 #endif
 299 #if defined HAVE_M17N_FLT && defined HAVE_LIBOTF
 300   .shape = ftfont_shape,
 301 #endif
 302 #ifdef HAVE_OTF_GET_VARIATION_GLYPHS
 303   .get_variation_glyphs = ftfont_variation_glyphs,
 304 #endif
 305   .filter_properties = ftfont_filter_properties,
 306   .combining_capability = ftfont_combining_capability,
 307   };
 308
 309 void
 310 syms_of_ftcrfont (void)
 311 {
 312   if (ftfont_info_size != offsetof (struct ftcrfont_info, cr_font_face))
 313     abort ();
 314
 315   DEFSYM (Qftcr, "ftcr");
 316   register_font_driver (&ftcrfont_driver, NULL);
 317 }