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* Copyright 2006 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkGlyph_DEFINED
#define SkGlyph_DEFINED
#include "include/core/SkPath.h"
#include "include/core/SkTypes.h"
#include "include/private/SkChecksum.h"
#include "include/private/SkFixed.h"
#include "include/private/SkTo.h"
#include "src/core/SkMask.h"
class SkArenaAlloc;
class SkStrike;
class SkScalerContext;
// needs to be != to any valid SkMask::Format
// A combination of SkGlyphID and sub-pixel position information.
struct SkPackedGlyphID {
static constexpr uint32_t kImpossibleID = ~0u;
enum {
// Lengths
kGlyphIDLen = 16u,
kSubPixelPosLen = 2u,
// Bit positions
kGlyphID = 0u,
kSubPixelY = kGlyphIDLen,
kSubPixelX = kGlyphIDLen + kSubPixelPosLen,
kEndData = kGlyphIDLen + 2 * kSubPixelPosLen,
// Masks
kGlyphIDMask = (1u << kGlyphIDLen) - 1,
kSubPixelPosMask = (1u << kSubPixelPosLen) - 1,
kMaskAll = (1u << kEndData) - 1,
// Location of sub pixel info in a fixed pointer number.
kFixedPointBinaryPointPos = 16u,
kFixedPointSubPixelPosBits = kFixedPointBinaryPointPos - kSubPixelPosLen,
constexpr explicit SkPackedGlyphID(SkGlyphID glyphID)
: fID{glyphID} { }
constexpr SkPackedGlyphID(SkGlyphID glyphID, SkFixed x, SkFixed y)
: fID {PackIDXY(glyphID, x, y)} {
SkASSERT(fID != kImpossibleID);
constexpr SkPackedGlyphID(SkGlyphID code, SkIPoint pt)
: SkPackedGlyphID(code, pt.fX, pt.fY) { }
constexpr SkPackedGlyphID() : fID{kImpossibleID} {}
bool operator==(const SkPackedGlyphID& that) const {
return fID == that.fID;
bool operator!=(const SkPackedGlyphID& that) const {
return !(*this == that);
bool operator<(SkPackedGlyphID that) const {
return this->fID < that.fID;
uint32_t code() const {
return fID & kGlyphIDMask;
uint32_t value() const {
return fID;
SkFixed getSubXFixed() const {
return this->subToFixed(kSubPixelX);
SkFixed getSubYFixed() const {
return this->subToFixed(kSubPixelY);
uint32_t hash() const {
return SkChecksum::CheapMix(fID);
SkString dump() const {
SkString str;
str.appendf("code: %d, x: %d, y:%d", code(), getSubXFixed(), getSubYFixed());
return str;
static constexpr uint32_t PackIDXY(SkGlyphID glyphID, SkFixed x, SkFixed y) {
return (FixedToSub(x) << kSubPixelX)
| (FixedToSub(y) << kSubPixelY)
| glyphID;
static constexpr uint32_t FixedToSub(SkFixed n) {
return ((uint32_t)n >> kFixedPointSubPixelPosBits) & kSubPixelPosMask;
constexpr SkFixed subToFixed(uint32_t subPixelPosBit) const {
uint32_t subPixelPosition = (fID >> subPixelPosBit) & kSubPixelPosMask;
return subPixelPosition << kFixedPointSubPixelPosBits;
uint32_t fID;
struct SkGlyphPrototype;
class SkGlyph {
static constexpr SkFixed kSubpixelRound = SK_FixedHalf >> SkPackedGlyphID::kSubPixelPosLen;
// SkGlyph() is used for testing.
constexpr SkGlyph() : fID{SkPackedGlyphID()} { }
constexpr explicit SkGlyph(SkPackedGlyphID id) : fID{id} { }
explicit SkGlyph(const SkGlyphPrototype& p);
SkVector advanceVector() const { return SkVector{fAdvanceX, fAdvanceY}; }
SkScalar advanceX() const { return fAdvanceX; }
SkScalar advanceY() const { return fAdvanceY; }
SkGlyphID getGlyphID() const { return fID.code(); }
SkPackedGlyphID getPackedID() const { return fID; }
SkFixed getSubXFixed() const { return fID.getSubXFixed(); }
SkFixed getSubYFixed() const { return fID.getSubYFixed(); }
size_t rowBytes() const;
size_t rowBytesUsingFormat(SkMask::Format format) const;
// Call this to set all of the metrics fields to 0 (e.g. if the scaler
// encounters an error measuring a glyph). Note: this does not alter the
// fImage, fPath, fID, fMaskFormat fields.
void zeroMetrics();
SkMask mask() const;
SkMask mask(SkPoint position) const;
// Image
// If we haven't already tried to associate an image with this glyph
// (i.e. setImageHasBeenCalled() returns false), then use the
// SkScalerContext or const void* argument to set the image.
bool setImage(SkArenaAlloc* alloc, SkScalerContext* scalerContext);
bool setImage(SkArenaAlloc* alloc, const void* image);
// Merge the from glyph into this glyph using alloc to allocate image data. Return true if
// image data was allocated. If the image for this glyph has not been initialized, then copy
// the width, height, top, left, format, and image into this glyph making a copy of the image
// using the alloc.
bool setMetricsAndImage(SkArenaAlloc* alloc, const SkGlyph& from);
// Returns true if the image has been set.
bool setImageHasBeenCalled() const {
return fImage != nullptr || this->isEmpty() || this->imageTooLarge();
// Return a pointer to the path if the image exists, otherwise return nullptr.
const void* image() const { SkASSERT(this->setImageHasBeenCalled()); return fImage; }
// Return the size of the image.
size_t imageSize() const;
// Path
// If we haven't already tried to associate a path to this glyph
// (i.e. setPathHasBeenCalled() returns false), then use the
// SkScalerContext or SkPath argument to try to do so. N.B. this
// may still result in no path being associated with this glyph,
// e.g. if you pass a null SkPath or the typeface is bitmap-only.
// This setPath() call is sticky... once you call it, the glyph
// stays in its state permanently, ignoring any future calls.
// Returns true if this is the first time you called setPath()
// and there actually is a path; call path() to get it.
bool setPath(SkArenaAlloc* alloc, SkScalerContext* scalerContext);
bool setPath(SkArenaAlloc* alloc, const SkPath* path);
// Returns true if that path has been set.
bool setPathHasBeenCalled() const { return fPathData != nullptr; }
// Return a pointer to the path if it exists, otherwise return nullptr. Only works if the
// path was previously set.
const SkPath* path() const;
// Format
bool isColor() const { return fMaskFormat == SkMask::kARGB32_Format; }
SkMask::Format maskFormat() const { return static_cast<SkMask::Format>(fMaskFormat); }
size_t formatAlignment() const;
// Bounds
int maxDimension() const { return std::max(fWidth, fHeight); }
SkIRect iRect() const { return SkIRect::MakeXYWH(fLeft, fTop, fWidth, fHeight); }
SkRect rect() const { return SkRect::MakeXYWH(fLeft, fTop, fWidth, fHeight); }
int left() const { return fLeft; }
int top() const { return fTop; }
int width() const { return fWidth; }
int height() const { return fHeight; }
bool isEmpty() const {
// fHeight == 0 -> fWidth == 0;
SkASSERT(fHeight != 0 || fWidth == 0);
return fWidth == 0;
bool imageTooLarge() const { return fWidth >= kMaxGlyphWidth; }
// Make sure that the intercept information is on the glyph and return it, or return it if it
// already exists.
// * bounds - either end of the gap for the character.
// * scale, xPos - information about how wide the gap is.
// * array - accumulated gaps for many characters if not null.
// * count - the number of gaps.
void ensureIntercepts(const SkScalar bounds[2], SkScalar scale, SkScalar xPos,
SkScalar* array, int* count, SkArenaAlloc* alloc);
// There are two sides to an SkGlyph, the scaler side (things that create glyph data) have
// access to all the fields. Scalers are assumed to maintain all the SkGlyph invariants. The
// consumer side has a tighter interface.
friend class RandomScalerContext;
friend class SkScalerContext;
friend class SkScalerContextProxy;
friend class SkScalerContext_Empty;
friend class SkScalerContext_FreeType;
friend class SkScalerContext_FreeType_Base;
friend class SkScalerContext_DW;
friend class SkScalerContext_GDI;
friend class SkScalerContext_Mac;
friend class SkStrikeClient;
friend class SkStrikeServer;
friend class SkTestScalerContext;
friend class SkTestSVGScalerContext;
friend class TestSVGTypeface;
friend class TestTypeface;
static constexpr uint16_t kMaxGlyphWidth = 1u << 13u;
// Support horizontal and vertical skipping strike-through / underlines.
// The caller walks the linked list looking for a match. For a horizontal underline,
// the fBounds contains the top and bottom of the underline. The fInterval pair contains the
// beginning and end of of the intersection of the bounds and the glyph's path.
// If interval[0] >= interval[1], no intersection was found.
struct Intercept {
Intercept* fNext;
SkScalar fBounds[2]; // for horz underlines, the boundaries in Y
SkScalar fInterval[2]; // the outside intersections of the axis and the glyph
struct PathData {
Intercept* fIntercept{nullptr};
SkPath fPath;
bool fHasPath{false};
size_t allocImage(SkArenaAlloc* alloc);
// path == nullptr indicates that there is no path.
void installPath(SkArenaAlloc* alloc, const SkPath* path);
// The width and height of the glyph mask.
uint16_t fWidth = 0,
fHeight = 0;
// The offset from the glyphs origin on the baseline to the top left of the glyph mask.
int16_t fTop = 0,
fLeft = 0;
// fImage must remain null if the glyph is empty or if width > kMaxGlyphWidth.
void* fImage = nullptr;
// Path data has tricky state. If the glyph isEmpty, then fPathData should always be nullptr,
// else if fPathData is not null, then a path has been requested. The fPath field of fPathData
// may still be null after the request meaning that there is no path for this glyph.
PathData* fPathData = nullptr;
// The advance for this glyph.
float fAdvanceX = 0,
fAdvanceY = 0;
// This is a combination of SkMask::Format and SkGlyph state. The SkGlyph can be in one of two
// states, just the advances have been calculated, and all the metrics are available. The
// illegal mask format is used to signal that only the advances are available.
uint8_t fMaskFormat = MASK_FORMAT_UNKNOWN;
// Used by the DirectWrite scaler to track state.
int8_t fForceBW = 0;
const SkPackedGlyphID fID;
struct SkGlyphPrototype {
SkPackedGlyphID id;
float advanceX = 0,
advanceY = 0;
// The width and height of the glyph mask.
uint16_t width = 0,
height = 0;
// The offset from the glyphs origin on the baseline to the top left of the glyph mask.
int16_t left = 0,
top = 0;
SkMask::Format maskFormat = SkMask::kBW_Format;
bool forceBW = false;