skia2/include/core/SkTextBlob.h
Mike Klein 475c5e93fe turn on alignment sanitizer
This sanitizer checks for overaligned reads and writes,
or put another way, use of underaligned pointers.

This usually happens when you cast, e.g. char* to int*
without checking that the char* is 4-byte aligned.  Each
of the changes under src/ fixes something just like that.

The unusual setup for tools/xsan.blacklist is there to
force a rebuild whenever tools/xsan.blacklist changes.
I spent a good few minutes debugging rebuilds not happening
this morning, perhaps from some strange ccache interaction.

Align SkTextBlobs as void* (today they're just 4-byte) so the
SkTextBlob::RunRecords we put after them in SkTextBlobBuilder
buffers are properly aligned (for the SkTypeface* inside).

There's no obvious error in void SkRRect::computeType(),
but one bot seems to have seen some sort of issue with

    SK_AT_SCOPE_EXIT(SkASSERT(this->isValid()));

I can't reproduce it locally, so I'm just going to unroll it.

Change-Id: I904d94f65f695e1b626b684c32216a4930b72b0c
Reviewed-on: https://skia-review.googlesource.com/146104
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
2018-08-09 21:13:15 +00:00

239 lines
8.7 KiB
C++

/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkTextBlob_DEFINED
#define SkTextBlob_DEFINED
#include "../private/SkTemplates.h"
#include "../private/SkAtomics.h"
#include "SkPaint.h"
#include "SkString.h"
#include "SkRefCnt.h"
struct SkSerialProcs;
struct SkDeserialProcs;
/** \class SkTextBlob
SkTextBlob combines multiple text runs into an immutable, ref-counted structure.
*/
class SK_API alignas(void*) SkTextBlob final : public SkNVRefCnt<SkTextBlob> {
public:
/**
* Returns a conservative blob bounding box.
*/
const SkRect& bounds() const { return fBounds; }
/**
* Return a non-zero, unique value representing the text blob.
*/
uint32_t uniqueID() const { return fUniqueID; }
static sk_sp<SkTextBlob> MakeFromText(
const void* text, size_t byteLength, const SkPaint& paint);
static sk_sp<SkTextBlob> MakeFromString(const char* string, const SkPaint& paint) {
if (!string) {
return nullptr;
}
return MakeFromText(string, strlen(string), paint);
}
/**
* Similar to serialize above, but writes directly into |memory|. Returns bytes written or 0u
* if serialization failed due to insufficient size.
*/
size_t serialize(const SkSerialProcs& procs, void* memory, size_t memory_size) const;
sk_sp<SkData> serialize(const SkSerialProcs& procs) const;
static sk_sp<SkTextBlob> Deserialize(const void* data, size_t size,
const SkDeserialProcs& procs);
private:
friend class SkNVRefCnt<SkTextBlob>;
class RunRecord;
enum GlyphPositioning : uint8_t;
explicit SkTextBlob(const SkRect& bounds);
~SkTextBlob();
// Memory for objects of this class is created with sk_malloc rather than operator new and must
// be freed with sk_free.
void operator delete(void* p);
void* operator new(size_t);
void* operator new(size_t, void* p);
static unsigned ScalarsPerGlyph(GlyphPositioning pos);
// Call when this blob is part of the key to a cache entry. This allows the cache
// to know automatically those entries can be purged when this SkTextBlob is deleted.
void notifyAddedToCache(uint32_t cacheID) const {
fCacheID.store(cacheID);
}
friend class SkGlyphRunList;
friend class GrTextBlobCache;
friend class SkTextBlobBuilder;
friend class SkTextBlobPriv;
friend class SkTextBlobRunIterator;
const SkRect fBounds;
const uint32_t fUniqueID;
mutable SkAtomic<uint32_t> fCacheID;
SkDEBUGCODE(size_t fStorageSize;)
// The actual payload resides in externally-managed storage, following the object.
// (see the .cpp for more details)
typedef SkRefCnt INHERITED;
};
/** \class SkTextBlobBuilder
Helper class for constructing SkTextBlobs.
*/
class SK_API SkTextBlobBuilder {
public:
SkTextBlobBuilder();
~SkTextBlobBuilder();
/**
* Returns an immutable SkTextBlob for the current runs/glyphs,
* or nullptr if no runs were allocated.
*
* The builder is reset and can be reused.
*/
sk_sp<SkTextBlob> make();
/**
* Glyph and position buffers associated with a run.
*
* A run is a sequence of glyphs sharing the same font metrics
* and positioning mode.
*
* If textByteCount is 0, utf8text and clusters will be NULL (no
* character information will be associated with the glyphs).
*
* utf8text will point to a buffer of size textByteCount bytes.
*
* clusters (if not NULL) will point to an array of size count.
* For each glyph, give the byte-offset into the text for the
* first byte in the first character in that glyph's cluster.
* Each value in the array should be an integer less than
* textByteCount. Values in the array should either be
* monotonically increasing (left-to-right text) or monotonically
* decreasing (right-to-left text). This definiton is conviently
* the same as used by Harfbuzz's hb_glyph_info_t::cluster field,
* except that Harfbuzz interleaves glyphs and clusters.
*/
struct RunBuffer {
SkGlyphID* glyphs;
SkScalar* pos;
char* utf8text;
uint32_t* clusters;
};
/**
* Allocates a new default-positioned run and returns its writable glyph buffer
* for direct manipulation.
*
* @param font The font to be used for this run.
* @param count Number of glyphs.
* @param x,y Position within the blob.
* @param bounds Optional run bounding box. If known in advance (!= NULL), it will
* be used when computing the blob bounds, to avoid re-measuring.
*
* @return A writable glyph buffer, valid until the next allocRun() or
* build() call. The buffer is guaranteed to hold @count@ glyphs.
*/
const RunBuffer& allocRun(const SkPaint& font, int count, SkScalar x, SkScalar y,
const SkRect* bounds = nullptr) {
return this->allocRunText(font, count, x, y, 0, SkString(), bounds);
}
/**
* Allocates a new horizontally-positioned run and returns its writable glyph and position
* buffers for direct manipulation.
*
* @param font The font to be used for this run.
* @param count Number of glyphs.
* @param y Vertical offset within the blob.
* @param bounds Optional run bounding box. If known in advance (!= NULL), it will
* be used when computing the blob bounds, to avoid re-measuring.
*
* @return Writable glyph and position buffers, valid until the next allocRun()
* or build() call. The buffers are guaranteed to hold @count@ elements.
*/
const RunBuffer& allocRunPosH(const SkPaint& font, int count, SkScalar y,
const SkRect* bounds = nullptr) {
return this->allocRunTextPosH(font, count, y, 0, SkString(), bounds);
}
/**
* Allocates a new fully-positioned run and returns its writable glyph and position
* buffers for direct manipulation.
*
* @param font The font to be used for this run.
* @param count Number of glyphs.
* @param bounds Optional run bounding box. If known in advance (!= NULL), it will
* be used when computing the blob bounds, to avoid re-measuring.
*
* @return Writable glyph and position buffers, valid until the next allocRun()
* or build() call. The glyph buffer and position buffer are
* guaranteed to hold @count@ and 2 * @count@ elements, respectively.
*/
const RunBuffer& allocRunPos(const SkPaint& font, int count,
const SkRect* bounds = nullptr) {
return this->allocRunTextPos(font, count, 0, SkString(), bounds);
}
private:
const RunBuffer& allocRunText(const SkPaint& font,
int count,
SkScalar x,
SkScalar y,
int textByteCount,
SkString lang,
const SkRect* bounds = nullptr);
const RunBuffer& allocRunTextPosH(const SkPaint& font, int count, SkScalar y,
int textByteCount, SkString lang,
const SkRect* bounds = nullptr);
const RunBuffer& allocRunTextPos(const SkPaint& font, int count,
int textByteCount, SkString lang,
const SkRect* bounds = nullptr);
void reserve(size_t size);
void allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
int count, int textBytes, SkPoint offset, const SkRect* bounds);
bool mergeRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
uint32_t count, SkPoint offset);
void updateDeferredBounds();
static SkRect ConservativeRunBounds(const SkTextBlob::RunRecord&);
static SkRect TightRunBounds(const SkTextBlob::RunRecord&);
friend class SkTextBlobPriv;
friend class SkTextBlobBuilderPriv;
SkAutoTMalloc<uint8_t> fStorage;
size_t fStorageSize;
size_t fStorageUsed;
SkRect fBounds;
int fRunCount;
bool fDeferredBounds;
size_t fLastRun; // index into fStorage
RunBuffer fCurrentRunBuffer;
};
#endif // SkTextBlob_DEFINED