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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 "SkPaint.h"
#include "SkRefCnt.h"
#include "SkTArray.h"
#include "SkTDArray.h"
/** \class SkTextBlob
SkTextBlob combines multiple text runs into an immutable, ref-counted structure.
*/
class SkTextBlob : public SkRefCnt {
public:
/**
* Returns the blob bounding box.
*/
const SkRect& bounds() const { return fBounds; }
/**
* Return a non-zero, unique value representing the text blob.
*/
uint32_t uniqueID() const;
private:
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.
};
class RunIterator {
public:
RunIterator(const SkTextBlob* blob);
bool done() const;
void next();
uint32_t glyphCount() const;
const uint16_t* glyphs() const;
const SkScalar* pos() const;
const SkPoint& offset() const;
void applyFontToPaint(SkPaint*) const;
GlyphPositioning positioning() const;
private:
const SkTextBlob* fBlob;
int fIndex;
};
// A run is a sequence of glyphs sharing the same font metrics and positioning mode.
struct Run {
uint32_t count;
uint32_t glyphStart; // index into fGlyphBuffer
uint32_t posStart; // index into fPosBuffer
SkPoint offset; // run offset (unsued for fully positioned glyphs)
SkPaint font;
GlyphPositioning positioning;
};
SkTextBlob(uint16_t* glyphs, SkScalar* pos, const SkTArray<Run>* runs, const SkRect& bounds);
friend class SkCanvas;
friend class SkTextBlobBuilder;
friend class TextBlobTester;
const SkAutoTMalloc<uint16_t> fGlyphBuffer;
const SkAutoTMalloc<SkScalar> fPosBuffer;
// SkTArray required here for run font destruction.
SkAutoTDelete<const SkTArray<Run> > fRuns;
const SkRect fBounds;
mutable uint32_t fUniqueID;
typedef SkRefCnt INHERITED;
};
/** \class SkTextBlobBuilder
Helper class for constructing SkTextBlobs.
*/
class SkTextBlobBuilder {
public:
/**
* @param runs The number of runs to be added, if known. This is a storage hint and
* not a limit.
*/
SkTextBlobBuilder(unsigned runs = 0);
~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 allocInternal(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
int count, SkPoint offset, const SkRect* bounds);
void ensureRun(const SkPaint& font, SkTextBlob::GlyphPositioning positioning,
const SkPoint& offset);
void updateDeferredBounds();
SkTDArray<uint16_t> fGlyphBuffer;
SkTDArray<SkScalar> fPosBuffer;
SkTArray<SkTextBlob::Run>* fRuns;
SkRect fBounds;
bool fDeferredBounds;
RunBuffer fCurrentRunBuffer;
};
#endif // SkTextBlob_DEFINED
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