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/*
* 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 "SkPaint.h"
#include "SkRefCnt.h"
class SkReadBuffer;
class SkWriteBuffer;
/** \class SkTextBlob
SkTextBlob combines multiple text runs into an immutable, ref-counted structure.
*/
class SK_API SkTextBlob : public SkRefCnt {
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; }
/**
* Serialize to a buffer.
*/
void flatten(SkWriteBuffer&) const;
/**
* Recreate an SkTextBlob that was serialized into a buffer.
*
* @param SkReadBuffer Serialized blob data.
* @return A new SkTextBlob representing the serialized data, or NULL if the buffer is
* invalid.
*/
static const SkTextBlob* CreateFromBuffer(SkReadBuffer&);
enum GlyphPositioning {
kDefault_Positioning = 0, // Default glyph advances -- zero scalars per glyph.
kHorizontal_Positioning = 1, // Horizontal positioning -- one scalar per glyph.
kFull_Positioning = 2 // Point positioning -- two scalars per glyph.
};
private:
class RunRecord;
SkTextBlob(int runCount, const SkRect& bounds);
virtual ~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) { sk_free(p); }
void* operator new(size_t) {
SkFAIL("All blobs are created by placement new.");
return sk_malloc_throw(0);
}
void* operator new(size_t, void* p) { return p; }
static unsigned ScalarsPerGlyph(GlyphPositioning pos);
friend class SkTextBlobBuilder;
friend class SkTextBlobRunIterator;
const int fRunCount;
const SkRect fBounds;
const uint32_t fUniqueID;
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. The builder is reset and
* can be reused.
*/
const SkTextBlob* build();
/**
* Glyph and position buffers associated with a run.
*
* A run is a sequence of glyphs sharing the same font metrics and positioning mode.
*/
struct RunBuffer {
uint16_t* glyphs;
SkScalar* pos;
};
/**
* 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 = NULL);
/**
* 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 = NULL);
/**
* 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 = NULL);
private:
void reserve(size_t size);
void allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
int count, SkPoint offset, const SkRect* bounds);
bool mergeRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
int count, SkPoint offset);
void updateDeferredBounds();
static SkRect ConservativeRunBounds(const SkTextBlob::RunRecord&);
static SkRect TightRunBounds(const SkTextBlob::RunRecord&);
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
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