gecko-dev/gfx/thebes/gfxFT2Utils.h
Jonathan Kew 6bbbf58763 Bug 1756468 - Add locking to gfxFont, to allow worker threads to do text shaping. r=lsalzman
We protect the shaped-word cache in each font with a RWLock, so that multiple threads can
shape in parallel using cached data; only when a new entry needs to be cached will we need
to take a write lock.

(To improve clarity, this patch also constifys a bunch of methods that do not mutate the
font instance.)

Differential Revision: https://phabricator.services.mozilla.com/D141473
2022-03-24 18:58:00 +00:00

77 lines
2.5 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef GFX_FT2UTILS_H
#define GFX_FT2UTILS_H
#include "cairo-ft.h"
#include "gfxFT2FontBase.h"
#include "mozilla/Likely.h"
// Rounding and truncation functions for a FreeType fixed point number
// (FT26Dot6) stored in a 32bit integer with high 26 bits for the integer
// part and low 6 bits for the fractional part.
#define FLOAT_FROM_26_6(x) ((x) / 64.0)
#define FLOAT_FROM_16_16(x) ((x) / 65536.0)
#define ROUND_26_6_TO_INT(x) ((x) >= 0 ? ((32 + (x)) >> 6) : -((32 - (x)) >> 6))
typedef struct FT_FaceRec_* FT_Face;
/**
* BEWARE: Recursively locking with gfxFT2LockedFace is not supported.
* Do not instantiate gfxFT2LockedFace within the scope of another instance.
* Do not attempt to call into Cairo within the scope of gfxFT2LockedFace,
* as that may accidentally try to re-lock the face within Cairo itself
* and thus deadlock.
*/
class MOZ_STACK_CLASS gfxFT2LockedFace {
public:
explicit gfxFT2LockedFace(const gfxFT2FontBase* aFont)
: mGfxFont(aFont), mFace(aFont->LockFTFace()) {}
~gfxFT2LockedFace() {
if (mFace) {
mGfxFont->UnlockFTFace();
}
}
FT_Face get() { return mFace; };
/**
* Get the glyph id for a Unicode character representable by a single
* glyph, or return zero if there is no such glyph. This does no caching,
* so you probably want gfxFcFont::GetGlyph.
*/
uint32_t GetGlyph(uint32_t aCharCode);
/**
* Returns 0 if there is no variation selector cmap subtable.
*/
uint32_t GetUVSGlyph(uint32_t aCharCode, uint32_t aVariantSelector);
protected:
typedef FT_UInt (*CharVariantFunction)(FT_Face face, FT_ULong charcode,
FT_ULong variantSelector);
CharVariantFunction FindCharVariantFunction();
const gfxFT2FontBase* MOZ_NON_OWNING_REF mGfxFont; // owned by caller
FT_Face mFace;
};
// A couple of FreeType-based utilities shared by gfxFontconfigFontEntry
// and FT2FontEntry.
typedef struct FT_MM_Var_ FT_MM_Var;
class gfxFT2Utils {
public:
static void GetVariationAxes(const FT_MM_Var* aMMVar,
nsTArray<gfxFontVariationAxis>& aAxes);
static void GetVariationInstances(
gfxFontEntry* aFontEntry, const FT_MM_Var* aMMVar,
nsTArray<gfxFontVariationInstance>& aInstances);
};
#endif /* GFX_FT2UTILS_H */