harfbuzz/src/hb-ft.h

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/*
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* Copyright © 2009 Red Hat, Inc.
* Copyright © 2015 Google, Inc.
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*
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* This is part of HarfBuzz, a text shaping library.
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*
* 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.
*
* Red Hat Author(s): Behdad Esfahbod
* Google Author(s): Behdad Esfahbod
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*/
#ifndef HB_FT_H
#define HB_FT_H
#include "hb.h"
#include <ft2build.h>
#include FT_FREETYPE_H
HB_BEGIN_DECLS
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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/*
* Note: FreeType is not thread-safe.
* Hence, these functions are not either.
*/
/*
* hb-face from ft-face.
*/
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[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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/* This one creates a new hb-face for given ft-face.
* When the returned hb-face is destroyed, the destroy
* callback is called (if not NULL), with the ft-face passed
* to it.
*
* The client is responsible to make sure that ft-face is
* destroyed after hb-face is destroyed.
*
* Most often you don't want this function. You should use either
* hb_ft_face_create_cached(), or hb_ft_face_create_referenced().
* In particular, if you are going to pass NULL as destroy, you
* probably should use (the more recent) hb_ft_face_create_referenced()
* instead.
*/
HB_EXTERN hb_face_t *
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hb_ft_face_create (FT_Face ft_face,
hb_destroy_func_t destroy);
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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/* This version is like hb_ft_face_create(), except that it caches
* the hb-face using the generic pointer of the ft-face. This means
* that subsequent calls to this function with the same ft-face will
* return the same hb-face (correctly referenced).
*
* Client is still responsible for making sure that ft-face is destroyed
* after hb-face is.
*/
HB_EXTERN hb_face_t *
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hb_ft_face_create_cached (FT_Face ft_face);
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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/* This version is like hb_ft_face_create(), except that it calls
* FT_Reference_Face() on ft-face, as such keeping ft-face alive
* as long as the hb-face is.
*
* This is the most convenient version to use. Use it unless you have
* very good reasons not to.
*/
HB_EXTERN hb_face_t *
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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hb_ft_face_create_referenced (FT_Face ft_face);
/*
* hb-font from ft-face.
*/
/*
* Note:
*
* Set face size on ft-face before creating hb-font from it.
* Otherwise hb-ft would NOT pick up the font size correctly.
*/
/* See notes on hb_ft_face_create(). Same issues re lifecycle-management
* apply here. Use hb_ft_font_create_referenced() if you can. */
HB_EXTERN hb_font_t *
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hb_ft_font_create (FT_Face ft_face,
hb_destroy_func_t destroy);
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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/* See notes on hb_ft_face_create_referenced() re lifecycle-management
* issues. */
HB_EXTERN hb_font_t *
[ft] Add hb_ft_face_create_referenced() and hb_ft_font_create_referenced() When I originally wrote hb-ft, FreeType objects did not support reference counting. As such, hb_ft_face_create() and hb_ft_font_create() had a "destroy" callback and client was responsible for making sure FT_Face is kept around as long as the hb-font/face are alive. However, since this was not clearly documented, some clienets didn't correctly did that. In particular, some clients assumed that it's safe to destroy FT_Face and then hb_face_t. This, indeed, used to work, until 45fd9424c723f115ca98995b8f8a25185a6fc71d, which make face destroy access font tables. Now, I fixed that issue in 395b35903e052aecc97d0807e4f813c64c0d2b0b since the access was not needed, but the problem remains that not all clients handle this correctly. See: https://bugs.freedesktop.org/show_bug.cgi?id=86300 Fortunately, FT_Reference_Face() was added to FreeType in 2010, and so we can use it now. Originally I wanted to change hb_ft_face_create() and hb_ft_font_create() to reference the face if destroy==NULL was passed in. That would improve pretty much all clients, with little undesired effects. Except that FreeType itself, when compiled with HarfBuzz support, calls hb_ft_font_create() with destroy==NULL and saves the resulting hb-font on the ft-face (why does it not free it immediately?). Making hb-face reference ft-face causes a cycling reference there. At least, that's my current understanding. At any rate, a cleaner approach, even if it means all clients will need a change, is to introduce brand new API. Which this commit does. Some comments added to hb-ft.h, hoping to make future clients make better choices. Fixes https://bugs.freedesktop.org/show_bug.cgi?id=75299
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hb_ft_font_create_referenced (FT_Face ft_face);
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HB_EXTERN FT_Face
hb_ft_font_get_face (hb_font_t *font);
HB_EXTERN FT_Face
hb_ft_font_lock_face (hb_font_t *font);
HB_EXTERN void
hb_ft_font_unlock_face (hb_font_t *font);
HB_EXTERN void
hb_ft_font_set_load_flags (hb_font_t *font, int load_flags);
HB_EXTERN int
hb_ft_font_get_load_flags (hb_font_t *font);
/* Call when size or variations settings on underlying FT_Face changed,
* and you want to update the hb_font_t from it. */
HB_EXTERN void
hb_ft_font_changed (hb_font_t *font);
/* Call when size or variations settings on underlying hb_font_t may have
* changed, and you want to update the FT_Face from it. This call is fast
* if nothing changed on hb_font_t. Returns true if changed. */
HB_EXTERN hb_bool_t
hb_ft_hb_font_changed (hb_font_t *font);
/* Makes an hb_font_t use FreeType internally to implement font functions.
* Note: this internally creates an FT_Face. Use it when you create your
* hb_face_t using hb_face_create(). */
HB_EXTERN void
hb_ft_font_set_funcs (hb_font_t *font);
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HB_END_DECLS
#endif /* HB_FT_H */