src/ftcrfont.c

   1 /* ftcrfont.c -- FreeType font driver on cairo.
   2    Copyright (C) 2015-2016 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 struct font_driver ftcrfont_driver;
  69
  70 static int
  71 ftcrfont_glyph_extents (struct font *font,
  72                         unsigned glyph,
  73                         struct font_metrics *metrics)
  74 {
  75   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
  76   int row, col;
  77   struct font_metrics *cache;
  78
  79   row = glyph / METRICS_NCOLS_PER_ROW;
  80   col = glyph % METRICS_NCOLS_PER_ROW;
  81   if (row >= ftcrfont_info->metrics_nrows)
  82     {
  83       ftcrfont_info->metrics =
  84         xrealloc (ftcrfont_info->metrics,
  85                   sizeof (struct font_metrics *) * (row + 1));
  86       bzero (ftcrfont_info->metrics + ftcrfont_info->metrics_nrows,
  87              (sizeof (struct font_metrics *)
  88               * (row + 1 - ftcrfont_info->metrics_nrows)));
  89       ftcrfont_info->metrics_nrows = row + 1;
  90     }
  91   if (ftcrfont_info->metrics[row] == NULL)
  92     {
  93       struct font_metrics *new;
  94       int i;
  95
  96       new = xmalloc (sizeof (struct font_metrics) * METRICS_NCOLS_PER_ROW);
  97       for (i = 0; i < METRICS_NCOLS_PER_ROW; i++)
  98         METRICS_SET_STATUS (new + i, METRICS_INVALID);
  99       ftcrfont_info->metrics[row] = new;
 100     }
 101   cache = ftcrfont_info->metrics[row] + col;
 102
 103   if (METRICS_STATUS (cache) == METRICS_INVALID)
 104     ftfont_driver.text_extents (font, &glyph, 1, cache);
 105
 106   if (metrics)
 107     *metrics = *cache;
 108
 109   return cache->width;
 110 }
 111
 112 static Lisp_Object
 113 ftcrfont_list (struct frame *f, Lisp_Object spec)
 114 {
 115   Lisp_Object list = ftfont_driver.list (f, spec), tail;
 116
 117   for (tail = list; CONSP (tail); tail = XCDR (tail))
 118     ASET (XCAR (tail), FONT_TYPE_INDEX, Qftcr);
 119   return list;
 120 }
 121
 122 static Lisp_Object
 123 ftcrfont_match (struct frame *f, Lisp_Object spec)
 124 {
 125   Lisp_Object entity = ftfont_driver.match (f, spec);
 126
 127   if (VECTORP (entity))
 128     ASET (entity, FONT_TYPE_INDEX, Qftcr);
 129   return entity;
 130 }
 131
 132 extern FT_Face ftfont_get_ft_face (Lisp_Object);
 133
 134 static Lisp_Object
 135 ftcrfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 136 {
 137   Lisp_Object font_object;
 138   struct font *font;
 139   struct ftcrfont_info *ftcrfont_info;
 140   FT_Face ft_face;
 141   FT_UInt size;
 142
 143   block_input ();
 144   size = XINT (AREF (entity, FONT_SIZE_INDEX));
 145   if (size == 0)
 146     size = pixel_size;
 147   font_object = font_build_object (VECSIZE (struct ftcrfont_info),
 148                                    Qftcr, entity, size);
 149   font_object = ftfont_open2 (f, entity, pixel_size, font_object);
 150   if (NILP (font_object)) return Qnil;
 151
 152   font = XFONT_OBJECT (font_object);
 153   font->driver = &ftcrfont_driver;
 154   ftcrfont_info = (struct ftcrfont_info *) font;
 155   ft_face = ftcrfont_info->ft_size->face;
 156   FT_New_Size (ft_face, &ftcrfont_info->ft_size_draw);
 157   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 158   FT_Set_Pixel_Sizes (ft_face, 0, font->pixel_size);
 159   ftcrfont_info->cr_font_face =
 160     cairo_ft_font_face_create_for_ft_face (ft_face, 0);
 161   ftcrfont_info->metrics = NULL;
 162   ftcrfont_info->metrics_nrows = 0;
 163   unblock_input ();
 164
 165   return font_object;
 166 }
 167
 168 static void
 169 ftcrfont_close (struct font *font)
 170 {
 171   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) font;
 172   int i;
 173
 174   block_input ();
 175   for (i = 0; i < ftcrfont_info->metrics_nrows; i++)
 176     if (ftcrfont_info->metrics[i])
 177       xfree (ftcrfont_info->metrics[i]);
 178   if (ftcrfont_info->metrics)
 179     xfree (ftcrfont_info->metrics);
 180   FT_Done_Size (ftcrfont_info->ft_size_draw);
 181   cairo_font_face_destroy (ftcrfont_info->cr_font_face);
 182   unblock_input ();
 183
 184   ftfont_driver.close (font);
 185 }
 186
 187 static void
 188 ftcrfont_text_extents (struct font *font,
 189                        unsigned *code,
 190                        int nglyphs,
 191                        struct font_metrics *metrics)
 192 {
 193   int width, i;
 194
 195   block_input ();
 196   width = ftcrfont_glyph_extents (font, code[0], metrics);
 197   for (i = 1; i < nglyphs; i++)
 198     {
 199       struct font_metrics m;
 200       int w = ftcrfont_glyph_extents (font, code[i], metrics ? &m : NULL);
 201
 202       if (metrics)
 203         {
 204           if (width + m.lbearing < metrics->lbearing)
 205             metrics->lbearing = width + m.lbearing;
 206           if (width + m.rbearing > metrics->rbearing)
 207             metrics->rbearing = width + m.rbearing;
 208           if (m.ascent > metrics->ascent)
 209             metrics->ascent = m.ascent;
 210           if (m.descent > metrics->descent)
 211             metrics->descent = m.descent;
 212         }
 213       width += w;
 214     }
 215   unblock_input ();
 216
 217   if (metrics)
 218     metrics->width = width;
 219 }
 220
 221 static int
 222 ftcrfont_draw (struct glyph_string *s,
 223                int from, int to, int x, int y, bool with_background)
 224 {
 225   struct frame *f = s->f;
 226   struct face *face = s->face;
 227   struct ftcrfont_info *ftcrfont_info = (struct ftcrfont_info *) s->font;
 228   cairo_t *cr;
 229   cairo_glyph_t *glyphs;
 230   cairo_surface_t *surface;
 231   cairo_surface_type_t surface_type;
 232   int len = to - from;
 233   int i;
 234
 235   block_input ();
 236
 237   cr = x_begin_cr_clip (f, s->gc);
 238
 239   if (with_background)
 240     {
 241       x_set_cr_source_with_gc_background (f, s->gc);
 242       cairo_rectangle (cr, x, y - FONT_BASE (face->font),
 243                        s->width, FONT_HEIGHT (face->font));
 244       cairo_fill (cr);
 245     }
 246
 247   glyphs = alloca (sizeof (cairo_glyph_t) * len);
 248   for (i = 0; i < len; i++)
 249     {
 250       unsigned code = ((XCHAR2B_BYTE1 (s->char2b + from + i) << 8)
 251                        | XCHAR2B_BYTE2 (s->char2b + from + i));
 252
 253       glyphs[i].index = code;
 254       glyphs[i].x = x;
 255       glyphs[i].y = y;
 256       x += (s->padding_p ? 1 : ftcrfont_glyph_extents (s->font, code, NULL));
 257     }
 258
 259   x_set_cr_source_with_gc_foreground (f, s->gc);
 260   cairo_set_font_face (cr, ftcrfont_info->cr_font_face);
 261   cairo_set_font_size (cr, s->font->pixel_size);
 262   /* cairo_set_font_matrix */
 263   /* cairo_set_font_options */
 264
 265   FT_Activate_Size (ftcrfont_info->ft_size_draw);
 266   cairo_show_glyphs (cr, glyphs, len);
 267   surface = cairo_get_target (cr);
 268   /* XXX: It used to be necessary to flush when exporting.  It might
 269      be the case that this is no longer necessary.  */
 270   surface_type = cairo_surface_get_type (surface);
 271   if (surface_type != CAIRO_SURFACE_TYPE_XLIB
 272       && (surface_type != CAIRO_SURFACE_TYPE_IMAGE
 273           || cairo_image_surface_get_format (surface) != CAIRO_FORMAT_ARGB32))
 274     cairo_surface_flush (surface);
 275
 276   x_end_cr_clip (f);
 277
 278   unblock_input ();
 279
 280   return len;
 281 }
 282
 283 \f
 284
 285 void
 286 syms_of_ftcrfont (void)
 287 {
 288   if (ftfont_info_size != offsetof (struct ftcrfont_info, cr_font_face))
 289     abort ();
 290
 291   DEFSYM (Qftcr, "ftcr");
 292
 293   ftcrfont_driver = ftfont_driver;
 294   ftcrfont_driver.type = Qftcr;
 295   ftcrfont_driver.list = ftcrfont_list;
 296   ftcrfont_driver.match = ftcrfont_match;
 297   ftcrfont_driver.open = ftcrfont_open;
 298   ftcrfont_driver.close = ftcrfont_close;
 299   ftcrfont_driver.text_extents = ftcrfont_text_extents;
 300   ftcrfont_driver.draw = ftcrfont_draw;
 301   register_font_driver (&ftcrfont_driver, NULL);
 302 }