src/ftcrfont.c

   1 /* ftcrfont.c -- FreeType font driver on cairo.
   2    Copyright (C) 2015 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
   9 (at 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 "dispextern.h"
  26 #include "xterm.h"
  27 #include "frame.h"
  28 #include "blockinput.h"
  29 #include "character.h"
  30 #include "charset.h"
  31 #include "fontset.h"
  32 #include "font.h"
  33 #include "ftfont.h"
  34
  35 /* FTCR font driver.  */
  36
  37 /* The actual structure for ftcr font that can be casted to struct
  38    font.  */
  39
  40 struct ftcrfont_info
  41 {
  42   struct font font;
  43   /* The following six members must be here in this order to be
  44      compatible with struct ftfont_info (in ftfont.c).  */
  45 #ifdef HAVE_LIBOTF
  46   bool maybe_otf;         /* Flag to tell if this may be OTF or not.  */
  47   OTF *otf;
  48 #endif  /* HAVE_LIBOTF */
  49   FT_Size ft_size;
  50   int index;
  51   FT_Matrix matrix;
  52
  53   cairo_font_face_t *cr_font_face;
  54   /* To prevent cairo from cluttering the activated FT_Size maintained
  55      in ftfont.c, we activate this special FT_Size before drawing.  */
  56   FT_Size ft_size_draw;
  57   /* Font metrics cache.  */
  58   struct font_metrics **metrics;
  59   short metrics_nrows;
  60 };
  61
  62 #define METRICS_NCOLS_PER_ROW   (128)
  63
  64 enum metrics_status
  65   {
  66     METRICS_INVALID = -1,    /* metrics entry is invalid */
  67   };
  68
  69 #define METRICS_STATUS(metrics) ((metrics)->ascent + (metrics)->descent)
  70 #define METRICS_SET_STATUS(metrics, status) \
  71   ((metrics)->ascent = 0, (metrics)->descent = (status))
  72
  73 struct font_driver ftcrfont_driver;
  74
  75 static int
  76 ftcrfont_glyph_extents (struct font *font,
  77                         unsigned glyph,
  78                         struct font_metrics *metrics)
  79 {
  80   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
  81   int row, col;
  82   struct font_metrics *cache;
  83
  84   row = glyph / METRICS_NCOLS_PER_ROW;
  85   col = glyph % METRICS_NCOLS_PER_ROW;
  86   if (row >= ftcrfont_info->metrics_nrows)
  87     {
  88       ftcrfont_info->metrics =
  89         xrealloc (ftcrfont_info->metrics,
  90                   sizeof (struct font_metrics *) * (row + 1));
  91       bzero (ftcrfont_info->metrics + ftcrfont_info->metrics_nrows,
  92              (sizeof (struct font_metrics *)
  93               * (row + 1 - ftcrfont_info->metrics_nrows)));
  94       ftcrfont_info->metrics_nrows = row + 1;
  95     }
  96   if (ftcrfont_info->metrics[row] == NULL)
  97     {
  98       struct font_metrics *new;
  99       int i;
 100
 101       new = xmalloc (sizeof (struct font_metrics) * METRICS_NCOLS_PER_ROW);
 102       for (i = 0; i < METRICS_NCOLS_PER_ROW; i++)
 103         METRICS_SET_STATUS (new + i, METRICS_INVALID);
 104       ftcrfont_info->metrics[row] = new;
 105     }
 106   cache = ftcrfont_info->metrics[row] + col;
 107
 108   if (METRICS_STATUS (cache) == METRICS_INVALID)
 109     ftfont_driver.text_extents (font, &glyph, 1, cache);
 110
 111   if (metrics)
 112     *metrics = *cache;
 113
 114   return cache->width;
 115 }
 116
 117 static Lisp_Object
 118 ftcrfont_list (struct frame *f, Lisp_Object spec)
 119 {
 120   Lisp_Object list = ftfont_driver.list (f, spec), tail;
 121
 122   for (tail = list; CONSP (tail); tail = XCDR (tail))
 123     ASET (XCAR (tail), FONT_TYPE_INDEX, Qftcr);
 124   return list;
 125 }
 126
 127 static Lisp_Object
 128 ftcrfont_match (struct frame *f, Lisp_Object spec)
 129 {
 130   Lisp_Object entity = ftfont_driver.match (f, spec);
 131
 132   if (VECTORP (entity))
 133     ASET (entity, FONT_TYPE_INDEX, Qftcr);
 134   return entity;
 135 }
 136
 137 extern FT_Face ftfont_get_ft_face (Lisp_Object);
 138
 139 static Lisp_Object
 140 ftcrfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 141 {
 142   Lisp_Object font_object;
 143   struct font *font;
 144   struct ftcrfont_info *ftcrfont_info;
 145   FT_Face ft_face;
 146   FT_UInt size;
 147
 148   block_input ();
 149   size = XINT (AREF (entity, FONT_SIZE_INDEX));
 150   if (size == 0)
 151     size = pixel_size;
 152   font_object = font_build_object (VECSIZE (struct ftcrfont_info),
 153                                    Qftcr, entity, size);
 154   font_object = ftfont_open2 (f, entity, pixel_size, font_object);
 155   if (NILP (font_object)) return Qnil;
 156
 157   font = XFONT_OBJECT (font_object);
 158   font->driver = &ftcrfont_driver;
 159   ftcrfont_info = (struct ftcrfont_info *) font;
 160   ft_face = ftcrfont_info->ft_size->face;
 161   FT_New_Size (ft_face, &ftcrfont_info->ft_size_draw);
 162   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 163   FT_Set_Pixel_Sizes (ft_face, 0, font->pixel_size);
 164   ftcrfont_info->cr_font_face =
 165     cairo_ft_font_face_create_for_ft_face (ft_face, 0);
 166   ftcrfont_info->metrics = NULL;
 167   ftcrfont_info->metrics_nrows = 0;
 168   unblock_input ();
 169
 170   return font_object;
 171 }
 172
 173 static void
 174 ftcrfont_close (struct font *font)
 175 {
 176   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
 177   int i;
 178
 179   block_input ();
 180   for (i = 0; i < ftcrfont_info->metrics_nrows; i++)
 181     if (ftcrfont_info->metrics[i])
 182       xfree (ftcrfont_info->metrics[i]);
 183   if (ftcrfont_info->metrics)
 184     xfree (ftcrfont_info->metrics);
 185   FT_Done_Size (ftcrfont_info->ft_size_draw);
 186   cairo_font_face_destroy (ftcrfont_info->cr_font_face);
 187   unblock_input ();
 188
 189   ftfont_driver.close (font);
 190 }
 191
 192 static void
 193 ftcrfont_text_extents (struct font *font,
 194                        unsigned *code,
 195                        int nglyphs,
 196                        struct font_metrics *metrics)
 197 {
 198   int width, i;
 199
 200   block_input ();
 201   width = ftcrfont_glyph_extents (font, code[0], metrics);
 202   for (i = 1; i < nglyphs; i++)
 203     {
 204       struct font_metrics m;
 205       int w = ftcrfont_glyph_extents (font, code[i], metrics ? &m : NULL);
 206
 207       if (metrics)
 208         {
 209           if (width + m.lbearing < metrics->lbearing)
 210             metrics->lbearing = width + m.lbearing;
 211           if (width + m.rbearing > metrics->rbearing)
 212             metrics->rbearing = width + m.rbearing;
 213           if (m.ascent > metrics->ascent)
 214             metrics->ascent = m.ascent;
 215           if (m.descent > metrics->descent)
 216             metrics->descent = m.descent;
 217         }
 218       width += w;
 219     }
 220   unblock_input ();
 221
 222   if (metrics)
 223     metrics->width = width;
 224 }
 225
 226 static int
 227 ftcrfont_draw (struct glyph_string *s,
 228                int from, int to, int x, int y, bool with_background)
 229 {
 230   struct frame *f = s->f;
 231   struct face *face = s->face;
 232   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) s->font;
 233   cairo_t *cr;
 234   cairo_glyph_t *glyphs;
 235   cairo_surface_t *surface;
 236   cairo_surface_type_t surface_type;
 237   int len = to - from;
 238   int i;
 239
 240   block_input ();
 241
 242   cr = x_begin_cr_clip (f, s->gc);
 243
 244   if (with_background)
 245     {
 246       x_set_cr_source_with_gc_background (f, s->gc);
 247       cairo_rectangle (cr, x, y - FONT_BASE (face->font),
 248                        s->width, FONT_HEIGHT (face->font));
 249       cairo_fill (cr);
 250     }
 251
 252   glyphs = alloca (sizeof (cairo_glyph_t) * len);
 253   for (i = 0; i < len; i++)
 254     {
 255       unsigned code = ((XCHAR2B_BYTE1 (s->char2b + from + i) << 8)
 256                        | XCHAR2B_BYTE2 (s->char2b + from + i));
 257
 258       glyphs[i].index = code;
 259       glyphs[i].x = x;
 260       glyphs[i].y = y;
 261       x += (s->padding_p ? 1 : ftcrfont_glyph_extents (s->font, code, NULL));
 262     }
 263
 264   x_set_cr_source_with_gc_foreground (f, s->gc);
 265   cairo_set_font_face (cr, ftcrfont_info->cr_font_face);
 266   cairo_set_font_size (cr, s->font->pixel_size);
 267   /* cairo_set_font_matrix */
 268   /* cairo_set_font_options */
 269
 270   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 271   cairo_show_glyphs (cr, glyphs, len);
 272   surface = cairo_get_target (cr);
 273   /* XXX: It used to be necessary to flush when exporting.  It might
 274      be the case that this is no longer necessary.  */
 275   surface_type = cairo_surface_get_type (surface);
 276   if (surface_type != CAIRO_SURFACE_TYPE_XLIB
 277       && (surface_type != CAIRO_SURFACE_TYPE_IMAGE
 278           || cairo_image_surface_get_format (surface) != CAIRO_FORMAT_ARGB32))
 279     cairo_surface_flush (surface);
 280
 281   x_end_cr_clip (f);
 282
 283   unblock_input ();
 284
 285   return len;
 286 }
 287
 288 \f
 289
 290 void
 291 syms_of_ftcrfont (void)
 292 {
 293   if (ftfont_info_size != offsetof (struct ftcrfont_info, cr_font_face))
 294     abort ();
 295
 296   DEFSYM (Qftcr, "ftcr");
 297
 298   ftcrfont_driver = ftfont_driver;
 299   ftcrfont_driver.type = Qftcr;
 300   ftcrfont_driver.list = ftcrfont_list;
 301   ftcrfont_driver.match = ftcrfont_match;
 302   ftcrfont_driver.open = ftcrfont_open;
 303   ftcrfont_driver.close = ftcrfont_close;
 304   ftcrfont_driver.text_extents = ftcrfont_text_extents;
 305   ftcrfont_driver.draw = ftcrfont_draw;
 306   register_font_driver (&ftcrfont_driver, NULL);
 307 }