cairo-ft-font.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2000 Keith Packard
 * Copyright © 2005 Red Hat, Inc
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is Red Hat, Inc.
 *
 * Contributor(s):
 *      Graydon Hoare <[e-mail]>
 *	Owen Taylor <[e-mail]>
 *      Keith Packard <[e-mail]>
 *      Carl Worth <[e-mail]>
 */

#include <float.h>

#include "cairo-ft-private.h"

#include <fontconfig/fontconfig.h>
#include <fontconfig/fcfreetype.h>

#include <ft2build.h>
#include FT_FREETYPE_H
#include FT_OUTLINE_H
#include FT_IMAGE_H
#if HAVE_FT_GLYPHSLOT_EMBOLDEN
#include FT_SYNTHESIS_H
#endif

#define DOUBLE_TO_26_6(d) ((FT_F26Dot6)((d) * 64.0))
#define DOUBLE_FROM_26_6(t) ((double)(t) / 64.0)
#define DOUBLE_TO_16_16(d) ((FT_Fixed)((d) * 65536.0))
#define DOUBLE_FROM_16_16(t) ((double)(t) / 65536.0)

/* This is the max number of FT_face objects we keep open at once
 */
#define MAX_OPEN_FACES 10

/*
 * The simple 2x2 matrix is converted into separate scale and shape
 * factors so that hinting works right
 */

typedef struct _cairo_ft_font_transform {
    double  x_scale, y_scale;
    double  shape[2][2];
} cairo_ft_font_transform_t;

/*
 * We create an object that corresponds to a single font on the disk;
 * (identified by a filename/id pair) these are shared between all
 * fonts using that file.  For cairo_ft_font_face_create_for_ft_face(), we
 * just create a one-off version with a permanent face value.
 */

typedef struct _cairo_ft_font_face cairo_ft_font_face_t;

struct _cairo_ft_unscaled_font {
    cairo_unscaled_font_t base;

    cairo_bool_t from_face; /* from cairo_ft_font_face_create_for_ft_face()? */
    FT_Face face;	    /* provided or cached face */

    /* only set if from_face is false */
    char *filename;
    int id;

    /* We temporarily scale the unscaled font as needed */
    cairo_bool_t have_scale;
    cairo_matrix_t current_scale;
    double x_scale;		/* Extracted X scale factor */
    double y_scale;             /* Extracted Y scale factor */
    cairo_bool_t have_shape;	/* true if the current scale has a non-scale component*/
    cairo_matrix_t current_shape;

    int lock;		/* count of how many times this font has been locked */

    cairo_ft_font_face_t *faces;	/* Linked list of faces for this font */
};

static int
_cairo_ft_unscaled_font_keys_equal (const void *key_a,
				    const void *key_b);

static void
_cairo_ft_unscaled_font_fini (cairo_ft_unscaled_font_t *unscaled);

typedef enum _cairo_ft_extra_flags {
    CAIRO_FT_OPTIONS_HINT_METRICS = (1 << 0),
    CAIRO_FT_OPTIONS_EMBOLDEN = (1 << 1)
} cairo_ft_extra_flags_t;

typedef struct _cairo_ft_options {
    cairo_font_options_t    base;
    int			    load_flags;	 /* flags for FT_Load_Glyph */
    cairo_ft_extra_flags_t  extra_flags; /* other flags that affect results */
} cairo_ft_options_t;

struct _cairo_ft_font_face {
    cairo_font_face_t base;
    cairo_ft_unscaled_font_t *unscaled;
    cairo_ft_options_t ft_options;
    cairo_ft_font_face_t *next;
};

static const cairo_unscaled_font_backend_t cairo_ft_unscaled_font_backend;

/*
 * We maintain a hash table to map file/id => cairo_ft_unscaled_font_t.
 * The hash table itself isn't limited in size. However, we limit the
 * number of FT_Face objects we keep around; when we've exceeeded that
 * limit and need to create a new FT_Face, we dump the FT_Face from a
 * random cairo_ft_unscaled_font_t which has an unlocked FT_Face, (if
 * there are any).
 */

typedef struct _cairo_ft_unscaled_font_map {
    cairo_hash_table_t *hash_table;
    FT_Library ft_library;
    int num_open_faces;
} cairo_ft_unscaled_font_map_t;

static cairo_ft_unscaled_font_map_t *cairo_ft_unscaled_font_map = NULL;

CAIRO_MUTEX_DECLARE(cairo_ft_unscaled_font_map_mutex);

static void
_font_map_release_face_lock_held (cairo_ft_unscaled_font_map_t *font_map,
				  cairo_ft_unscaled_font_t *unscaled)
{
    if (unscaled->face) {
	FT_Done_Face (unscaled->face);
	unscaled->face = NULL;
	unscaled->have_scale = FALSE;

	font_map->num_open_faces--;
    }
}

static void
_cairo_ft_unscaled_font_map_create (void)
{
    cairo_ft_unscaled_font_map_t *font_map;

    /* This function is only intended to be called from
     * _cairo_ft_unscaled_font_map_lock. So we'll crash if we can
     * detect some other call path. */
    assert (cairo_ft_unscaled_font_map == NULL);

    font_map = malloc (sizeof (cairo_ft_unscaled_font_map_t));
    if (font_map == NULL)
	goto FAIL;

    font_map->hash_table =
	_cairo_hash_table_create (_cairo_ft_unscaled_font_keys_equal);

    if (font_map->hash_table == NULL)
	goto FAIL;

    if (FT_Init_FreeType (&font_map->ft_library))
	goto FAIL;

    font_map->num_open_faces = 0;

    cairo_ft_unscaled_font_map = font_map;
    return;

FAIL:
    if (font_map) {
	if (font_map->hash_table)
	    _cairo_hash_table_destroy (font_map->hash_table);
	free (font_map);
    }
    cairo_ft_unscaled_font_map = NULL;
}

static void
_cairo_ft_unscaled_font_map_destroy (void)
{
    cairo_ft_unscaled_font_t *unscaled;
    cairo_ft_unscaled_font_map_t *font_map;

    CAIRO_MUTEX_LOCK (cairo_ft_unscaled_font_map_mutex);

    if (cairo_ft_unscaled_font_map) {
	font_map = cairo_ft_unscaled_font_map;

	/* This is rather inefficient, but destroying the hash table
	 * is something we only do during debugging, (during
	 * cairo_debug_reset_static_data), when efficiency is not
	 * relevant. */
        while (1) {
	    unscaled = _cairo_hash_table_random_entry (font_map->hash_table,
						       NULL);
	    if (unscaled == NULL)
		break;
	    _cairo_hash_table_remove (font_map->hash_table,
				      &unscaled->base.hash_entry);

	    _font_map_release_face_lock_held (font_map, unscaled);
	    _cairo_ft_unscaled_font_fini (unscaled);
	    free (unscaled);
	}

	assert (font_map->num_open_faces == 0);

	FT_Done_FreeType (font_map->ft_library);

	_cairo_hash_table_destroy (font_map->hash_table);

	free (font_map);

	cairo_ft_unscaled_font_map = NULL;
    }

    CAIRO_MUTEX_UNLOCK (cairo_ft_unscaled_font_map_mutex);
}

static cairo_ft_unscaled_font_map_t *
_cairo_ft_unscaled_font_map_lock (void)
{
    CAIRO_MUTEX_LOCK (cairo_ft_unscaled_font_map_mutex);

    if (cairo_ft_unscaled_font_map == NULL)
    {
	_cairo_ft_unscaled_font_map_create ();

	if (cairo_ft_unscaled_font_map == NULL) {
	    CAIRO_MUTEX_UNLOCK (cairo_ft_unscaled_font_map_mutex);
	    return NULL;
	}
    }

    return cairo_ft_unscaled_font_map;
}

static void
_cairo_ft_unscaled_font_map_unlock (void)
{
    CAIRO_MUTEX_UNLOCK (cairo_ft_unscaled_font_map_mutex);
}

static void
_cairo_ft_unscaled_font_init_key (cairo_ft_unscaled_font_t *key,
				  char			   *filename,
				  int			    id)
{
    unsigned long hash;

    key->filename = filename;
    key->id = id;

    /* 1607 is just an arbitrary prime. */
    hash = _cairo_hash_string (filename);
    hash += ((unsigned long) id) * 1607;

    key->base.hash_entry.hash = hash;
}

/**
 * _cairo_ft_unscaled_font_init:
 *
 * Initialize a cairo_ft_unscaled_font_t.
 *
 * There are two basic flavors of cairo_ft_unscaled_font_t, one
 * created from an FT_Face and the other created from a filename/id
 * pair. These two flavors are identified as from_face and !from_face.
 *
 * To initialize a from_face font, pass filename==NULL, id=0 and the
 * desired face.
 *
 * To initialize a !from_face font, pass the filename/id as desired
 * and face==NULL.
 *
 * Note that the code handles these two flavors in very distinct
 * ways. For example there is a hash_table mapping
 * filename/id->cairo_unscaled_font_t in the !from_face case, but no
 * parallel in the from_face case, (where the calling code would have
 * to do its own mapping to ensure similar sharing).
 **/
static cairo_status_t
_cairo_ft_unscaled_font_init (cairo_ft_unscaled_font_t *unscaled,
			      const char	       *filename,
			      int			id,
			      FT_Face			face)
{
    _cairo_unscaled_font_init (&unscaled->base,
			       &cairo_ft_unscaled_font_backend);

    if (face) {
	unscaled->from_face = TRUE;
	unscaled->face = face;
	unscaled->filename = NULL;
	unscaled->id = 0;
    } else {
	char *filename_copy;

	unscaled->from_face = FALSE;
	unscaled->face = NULL;

	filename_copy = strdup (filename);
	if (filename_copy == NULL)
	    return CAIRO_STATUS_NO_MEMORY;

	_cairo_ft_unscaled_font_init_key (unscaled, filename_copy, id);
    }

    unscaled->have_scale = FALSE;
    unscaled->lock = 0;

    unscaled->faces = NULL;

    return CAIRO_STATUS_SUCCESS;
}

cairo_bool_t
_cairo_unscaled_font_is_ft (cairo_unscaled_font_t *unscaled_font)
{
    return unscaled_font->backend == &cairo_ft_unscaled_font_backend;
}

/**
 * _cairo_ft_unscaled_font_fini:
 *
 * Free all data associated with a cairo_ft_unscaled_font_t.
 *
 * CAUTION: The unscaled->face field must be NULL before calling this
 * function. This is because the cairo_ft_unscaled_font_map keeps a
 * count of these faces (font_map->num_open_faces) so it maintains the
 * unscaled->face field while it has its lock held. See
 * _font_map_release_face_lock_held().
 **/
static void
_cairo_ft_unscaled_font_fini (cairo_ft_unscaled_font_t *unscaled)
{
    assert (unscaled->face == NULL);

    if (unscaled->filename) {
	free (unscaled->filename);
	unscaled->filename = NULL;
    }
}

static int
_cairo_ft_unscaled_font_keys_equal (const void *key_a,
				    const void *key_b)
{
    const cairo_ft_unscaled_font_t *unscaled_a = key_a;
    const cairo_ft_unscaled_font_t *unscaled_b = key_b;

    return (strcmp (unscaled_a->filename, unscaled_b->filename) == 0 &&
	    unscaled_a->id == unscaled_b->id);
}

/* Finds or creates a cairo_ft_unscaled_font for the filename/id from
 * pattern.  Returns a new reference to the unscaled font.
 */
static cairo_ft_unscaled_font_t *
_cairo_ft_unscaled_font_create_for_pattern (FcPattern *pattern)
{
    cairo_ft_unscaled_font_t key, *unscaled;
    cairo_ft_unscaled_font_map_t *font_map;
    cairo_status_t status;
    FcChar8 *fc_filename;
    char *filename;
    int id;

    if (FcPatternGetString (pattern, FC_FILE, 0, &fc_filename) != FcResultMatch)
	goto UNWIND;
    filename = (char *) fc_filename;

    if (FcPatternGetInteger (pattern, FC_INDEX, 0, &id) != FcResultMatch)
	goto UNWIND;

    font_map = _cairo_ft_unscaled_font_map_lock ();
    if (font_map == NULL)
	goto UNWIND;

    _cairo_ft_unscaled_font_init_key (&key, filename, id);

    /* Return existing unscaled font if it exists in the hash table. */
    if (_cairo_hash_table_lookup (font_map->hash_table, &key.base.hash_entry,
				  (cairo_hash_entry_t **) &unscaled))
    {
	_cairo_ft_unscaled_font_map_unlock ();
	_cairo_unscaled_font_reference (&unscaled->base);
	return unscaled;
    }

    /* Otherwise create it and insert into hash table. */
    unscaled = malloc (sizeof (cairo_ft_unscaled_font_t));
    if (unscaled == NULL)
	goto UNWIND_FONT_MAP_LOCK;

    status = _cairo_ft_unscaled_font_init (unscaled, filename, id, NULL);
    if (status)
	goto UNWIND_UNSCALED_MALLOC;

    status = _cairo_hash_table_insert (font_map->hash_table,
				       &unscaled->base.hash_entry);
    if (status)
	goto UNWIND_UNSCALED_FONT_INIT;

    _cairo_ft_unscaled_font_map_unlock ();

    return unscaled;

UNWIND_UNSCALED_FONT_INIT:
    _cairo_ft_unscaled_font_fini (unscaled);
UNWIND_UNSCALED_MALLOC:
    free (unscaled);
UNWIND_FONT_MAP_LOCK:
    _cairo_ft_unscaled_font_map_unlock ();
UNWIND:
    return NULL;
}

static cairo_ft_unscaled_font_t *
_cairo_ft_unscaled_font_create_from_face (FT_Face face)
{
    cairo_status_t status;
    cairo_ft_unscaled_font_t *unscaled;

    unscaled = malloc (sizeof (cairo_ft_unscaled_font_t));
    if (unscaled == NULL)
	return NULL;

    status = _cairo_ft_unscaled_font_init (unscaled, NULL, 0, face);
    if (status) {
	free (unscaled);
	return NULL;
    }

    return unscaled;
}

static void
_cairo_ft_unscaled_font_destroy (void *abstract_font)
{
    cairo_ft_unscaled_font_t *unscaled  = abstract_font;