harfbuzz/src/hb-shaper.hh

135 lines
5.7 KiB
C++

/*
* Copyright © 2012 Google, 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.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_SHAPER_HH
#define HB_SHAPER_HH
#include "hb.hh"
typedef hb_bool_t hb_shape_func_t (hb_shape_plan_t *shape_plan,
hb_font_t *font,
hb_buffer_t *buffer,
const hb_feature_t *features,
unsigned int num_features);
#define HB_SHAPER_IMPLEMENT(name) \
extern "C" HB_INTERNAL hb_shape_func_t _hb_##name##_shape;
#include "hb-shaper-list.hh"
#undef HB_SHAPER_IMPLEMENT
struct hb_shaper_pair_t {
char name[16];
hb_shape_func_t *func;
};
HB_INTERNAL const hb_shaper_pair_t *
_hb_shapers_get (void);
/* Means: succeeded, but don't need to keep any data. */
#define HB_SHAPER_DATA_SUCCEEDED ((void *) +1)
/* Means: tried but failed to create. */
#define HB_SHAPER_DATA_INVALID ((void *) -1)
#define HB_SHAPER_DATA_TYPE_NAME(shaper, object) hb_##shaper##_##object##_data_t
#define HB_SHAPER_DATA_TYPE(shaper, object) struct HB_SHAPER_DATA_TYPE_NAME(shaper, object)
#define HB_SHAPER_DATA_INSTANCE(shaper, object, instance) (* reinterpret_cast<hb_atomic_ptr_t<HB_SHAPER_DATA_TYPE(shaper, object) *> *> (&(instance)->shaper_data.shaper))
#define HB_SHAPER_DATA(shaper, object) HB_SHAPER_DATA_INSTANCE(shaper, object, object)
#define HB_SHAPER_DATA_CREATE_FUNC(shaper, object) _hb_##shaper##_shaper_##object##_data_create
#define HB_SHAPER_DATA_DESTROY_FUNC(shaper, object) _hb_##shaper##_shaper_##object##_data_destroy
#define HB_SHAPER_DATA_ENSURE_FUNC(shaper, object) hb_##shaper##_shaper_##object##_data_ensure
#define HB_SHAPER_DATA_PROTOTYPE(shaper, object) \
HB_SHAPER_DATA_TYPE (shaper, object); /* Type forward declaration. */ \
extern "C" HB_INTERNAL HB_SHAPER_DATA_TYPE (shaper, object) * \
HB_SHAPER_DATA_CREATE_FUNC (shaper, object) (hb_##object##_t *object HB_SHAPER_DATA_CREATE_FUNC_EXTRA_ARGS); \
extern "C" HB_INTERNAL void \
HB_SHAPER_DATA_DESTROY_FUNC (shaper, object) (HB_SHAPER_DATA_TYPE (shaper, object) *data); \
extern "C" HB_INTERNAL bool \
HB_SHAPER_DATA_ENSURE_FUNC (shaper, object) (hb_##object##_t *object)
#define HB_SHAPER_DATA_DESTROY(shaper, object) \
if (HB_SHAPER_DATA_TYPE (shaper, object) *data = HB_SHAPER_DATA (shaper, object).get ()) \
if (data != HB_SHAPER_DATA_INVALID && data != HB_SHAPER_DATA_SUCCEEDED) \
HB_SHAPER_DATA_DESTROY_FUNC (shaper, object) (data);
#define HB_SHAPER_DATA_ENSURE_DEFINE(shaper, object) \
HB_SHAPER_DATA_ENSURE_DEFINE_WITH_CONDITION(shaper, object, true)
#define HB_SHAPER_DATA_ENSURE_DEFINE_WITH_CONDITION(shaper, object, condition) \
bool \
HB_SHAPER_DATA_ENSURE_FUNC(shaper, object) (hb_##object##_t *object) \
{\
retry: \
HB_SHAPER_DATA_TYPE (shaper, object) *data = HB_SHAPER_DATA (shaper, object).get (); \
if (likely (data) && !(condition)) { \
/* XXX-MT-bug \
* Note that evaluating condition above can be dangerous if another thread \
* got here first and destructed data. That's, as always, bad use pattern. \
* If you modify the font (change font size), other threads must not be \
* using it at the same time. However, since this check is delayed to \
* when one actually tries to shape something, this is a XXX race condition \
* (and the only know we have that I know of) right now. Ie. you modify the \
* font size in one thread, then (supposedly safely) try to use it from two \
* or more threads and BOOM! I'm not sure how to fix this. We want RCU. \
* Maybe when it doesn't matter when we finally implement AAT shaping, as
* this (condition) is currently only used by hb-coretext. */ \
/* Drop and recreate. */ \
/* If someone dropped it in the mean time, throw it away and don't touch it. \
* Otherwise, destruct it. */ \
if (likely (HB_SHAPER_DATA (shaper, object).cmpexch (data, nullptr))) \
{ \
HB_SHAPER_DATA_DESTROY_FUNC (shaper, object) (data); \
} \
goto retry; \
} \
if (unlikely (!data)) { \
data = HB_SHAPER_DATA_CREATE_FUNC (shaper, object) (object); \
if (unlikely (!data)) \
data = (HB_SHAPER_DATA_TYPE (shaper, object) *) HB_SHAPER_DATA_INVALID; \
if (unlikely (!HB_SHAPER_DATA (shaper, object).cmpexch (nullptr, data))) { \
if (data && \
data != HB_SHAPER_DATA_INVALID && \
data != HB_SHAPER_DATA_SUCCEEDED) \
HB_SHAPER_DATA_DESTROY_FUNC (shaper, object) (data); \
goto retry; \
} \
} \
return data != nullptr && (void *) data != HB_SHAPER_DATA_INVALID; \
}
/* For embedding in face / font / ... */
struct hb_shaper_data_t {
#define HB_SHAPER_IMPLEMENT(shaper) hb_atomic_ptr_t<void *> shaper;
#include "hb-shaper-list.hh"
#undef HB_SHAPER_IMPLEMENT
};
#define HB_SHAPERS_COUNT (sizeof (hb_shaper_data_t) / sizeof (void *))
#endif /* HB_SHAPER_HH */