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skia / skia / c7ed7e6fde2929c871be90a2da9d1e9399d62bbc / . / src / core / SkScalerContext.cpp
blob: a2df87c3ef62790353b8fac8169d83bc657db3d4 [file] [log] [blame]
/*
* 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.
*/
#include "include/core/SkPaint.h"
#include "src/core/SkScalerContext.h"
#include "include/core/SkFontMetrics.h"
#include "include/core/SkMaskFilter.h"
#include "include/core/SkPathEffect.h"
#include "include/core/SkStrokeRec.h"
#include "include/private/SkColorData.h"
#include "include/private/SkTo.h"
#include "src/core/SkAutoMalloc.h"
#include "src/core/SkAutoPixmapStorage.h"
#include "src/core/SkDescriptor.h"
#include "src/core/SkDraw.h"
#include "src/core/SkFontPriv.h"
#include "src/core/SkGlyph.h"
#include "src/core/SkMaskGamma.h"
#include "src/core/SkMatrixProvider.h"
#include "src/core/SkPaintPriv.h"
#include "src/core/SkPathPriv.h"
#include "src/core/SkRasterClip.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkRectPriv.h"
#include "src/core/SkStroke.h"
#include "src/core/SkSurfacePriv.h"
#include "src/core/SkTextFormatParams.h"
#include "src/core/SkWriteBuffer.h"
#include "src/utils/SkMatrix22.h"
#include <new>
///////////////////////////////////////////////////////////////////////////////
#ifdef SK_DEBUG
#define DUMP_RECx
#endif
SkScalerContextRec SkScalerContext::PreprocessRec(const SkTypeface& typeface,
const SkScalerContextEffects& effects,
const SkDescriptor& desc) {
SkScalerContextRec rec =
*static_cast<const SkScalerContextRec*>(desc.findEntry(kRec_SkDescriptorTag, nullptr));
// Allow the typeface to adjust the rec.
typeface.onFilterRec(&rec);
if (effects.fMaskFilter) {
// Pre-blend is not currently applied to filtered text.
// The primary filter is blur, for which contrast makes no sense,
// and for which the destination guess error is more visible.
// Also, all existing users of blur have calibrated for linear.
rec.ignorePreBlend();
}
SkColor lumColor = rec.getLuminanceColor();
if (rec.fMaskFormat == SkMask::kA8_Format) {
U8CPU lum = SkComputeLuminance(SkColorGetR(lumColor),
SkColorGetG(lumColor),
SkColorGetB(lumColor));
lumColor = SkColorSetRGB(lum, lum, lum);
}
// TODO: remove CanonicalColor when we to fix up Chrome layout tests.
rec.setLuminanceColor(lumColor);
return rec;
}
SkScalerContext::SkScalerContext(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
const SkDescriptor* desc)
: fRec(PreprocessRec(*typeface, effects, *desc))
, fTypeface(std::move(typeface))
, fPathEffect(sk_ref_sp(effects.fPathEffect))
, fMaskFilter(sk_ref_sp(effects.fMaskFilter))
// Initialize based on our settings. Subclasses can also force this.
, fGenerateImageFromPath(fRec.fFrameWidth > 0 || fPathEffect != nullptr)
, fPreBlend(fMaskFilter ? SkMaskGamma::PreBlend() : SkScalerContext::GetMaskPreBlend(fRec))
{
#ifdef DUMP_REC
SkDebugf("SkScalerContext checksum %x count %d length %d\n",
desc->getChecksum(), desc->getCount(), desc->getLength());
SkDebugf("%s", fRec.dump().c_str());
SkDebugf(" effects %x\n", desc->findEntry(kEffects_SkDescriptorTag, nullptr));
#endif
}
SkScalerContext::~SkScalerContext() {}
/**
* In order to call cachedDeviceLuminance, cachedPaintLuminance, or
* cachedMaskGamma the caller must hold the mask_gamma_cache_mutex and continue
* to hold it until the returned pointer is refed or forgotten.
*/
static SkMutex& mask_gamma_cache_mutex() {
static SkMutex& mutex = *(new SkMutex);
return mutex;
}
static SkMaskGamma* gLinearMaskGamma = nullptr;
static SkMaskGamma* gMaskGamma = nullptr;
static SkScalar gContrast = SK_ScalarMin;
static SkScalar gPaintGamma = SK_ScalarMin;
static SkScalar gDeviceGamma = SK_ScalarMin;
/**
* The caller must hold the mask_gamma_cache_mutex() and continue to hold it until
* the returned SkMaskGamma pointer is refed or forgotten.
*/
static const SkMaskGamma& cached_mask_gamma(SkScalar contrast, SkScalar paintGamma,
SkScalar deviceGamma) {
mask_gamma_cache_mutex().assertHeld();
if (0 == contrast && SK_Scalar1 == paintGamma && SK_Scalar1 == deviceGamma) {
if (nullptr == gLinearMaskGamma) {
gLinearMaskGamma = new SkMaskGamma;
}
return *gLinearMaskGamma;
}
if (gContrast != contrast || gPaintGamma != paintGamma || gDeviceGamma != deviceGamma) {
SkSafeUnref(gMaskGamma);
gMaskGamma = new SkMaskGamma(contrast, paintGamma, deviceGamma);
gContrast = contrast;
gPaintGamma = paintGamma;
gDeviceGamma = deviceGamma;
}
return *gMaskGamma;
}
/**
* Expands fDeviceGamma, fPaintGamma, fContrast, and fLumBits into a mask pre-blend.
*/
SkMaskGamma::PreBlend SkScalerContext::GetMaskPreBlend(const SkScalerContextRec& rec) {
SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
const SkMaskGamma& maskGamma = cached_mask_gamma(rec.getContrast(),
rec.getPaintGamma(),
rec.getDeviceGamma());
// TODO: remove CanonicalColor when we to fix up Chrome layout tests.
return maskGamma.preBlend(rec.getLuminanceColor());
}
size_t SkScalerContext::GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma,
SkScalar deviceGamma, int* width, int* height) {
SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
const SkMaskGamma& maskGamma = cached_mask_gamma(contrast,
paintGamma,
deviceGamma);
maskGamma.getGammaTableDimensions(width, height);
size_t size = (*width)*(*height)*sizeof(uint8_t);
return size;
}
bool SkScalerContext::GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
uint8_t* data) {
SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
const SkMaskGamma& maskGamma = cached_mask_gamma(contrast,
paintGamma,
deviceGamma);
const uint8_t* gammaTables = maskGamma.getGammaTables();
if (!gammaTables) {
return false;
}
int width, height;
maskGamma.getGammaTableDimensions(&width, &height);
size_t size = width*height * sizeof(uint8_t);
memcpy(data, gammaTables, size);
return true;
}
void SkScalerContext::getAdvance(SkGlyph* glyph) {
if (generateAdvance(glyph)) {
glyph->fMaskFormat = MASK_FORMAT_JUST_ADVANCE;
} else {
this->getMetrics(glyph);
SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
}
}
void SkScalerContext::getMetrics(SkGlyph* glyph) {
bool generatingImageFromPath = fGenerateImageFromPath;
if (!generatingImageFromPath) {
generateMetrics(glyph);
SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
} else {
SkPath devPath;
generatingImageFromPath = this->internalGetPath(glyph->getPackedID(), &devPath);
if (!generatingImageFromPath) {
generateMetrics(glyph);
SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
} else {
uint8_t originMaskFormat = glyph->fMaskFormat;
if (!generateAdvance(glyph)) {
generateMetrics(glyph);
}
if (originMaskFormat != MASK_FORMAT_UNKNOWN) {
glyph->fMaskFormat = originMaskFormat;
} else {
glyph->fMaskFormat = fRec.fMaskFormat;
}
// If we are going to create the mask, then we cannot keep the color
if (SkMask::kARGB32_Format == glyph->fMaskFormat) {
glyph->fMaskFormat = SkMask::kA8_Format;
}
const SkIRect ir = devPath.getBounds().roundOut();
if (ir.isEmpty() || !SkRectPriv::Is16Bit(ir)) {
goto SK_ERROR;
}
glyph->fLeft = ir.fLeft;
glyph->fTop = ir.fTop;
glyph->fWidth = SkToU16(ir.width());
glyph->fHeight = SkToU16(ir.height());
if (glyph->fWidth > 0) {
switch (glyph->fMaskFormat) {
case SkMask::kLCD16_Format:
if (fRec.fFlags & SkScalerContext::kLCD_Vertical_Flag) {
glyph->fHeight += 2;
glyph->fTop -= 1;
} else {
glyph->fWidth += 2;
glyph->fLeft -= 1;
}
break;
default:
break;
}
}
}
}
// if either dimension is empty, zap the image bounds of the glyph
if (0 == glyph->fWidth || 0 == glyph->fHeight) {
glyph->fWidth = 0;
glyph->fHeight = 0;
glyph->fTop = 0;
glyph->fLeft = 0;
glyph->fMaskFormat = 0;
return;
}
if (fMaskFilter) {
SkMask src = glyph->mask(),
dst;
SkMatrix matrix;
fRec.getMatrixFrom2x2(&matrix);
src.fImage = nullptr; // only want the bounds from the filter
if (as_MFB(fMaskFilter)->filterMask(&dst, src, matrix, nullptr)) {
if (dst.fBounds.isEmpty() || !SkRectPriv::Is16Bit(dst.fBounds)) {
goto SK_ERROR;
}
SkASSERT(dst.fImage == nullptr);
glyph->fLeft = dst.fBounds.fLeft;
glyph->fTop = dst.fBounds.fTop;
glyph->fWidth = SkToU16(dst.fBounds.width());
glyph->fHeight = SkToU16(dst.fBounds.height());
glyph->fMaskFormat = dst.fFormat;
}
}
return;
SK_ERROR:
// draw nothing 'cause we failed
glyph->fLeft = 0;
glyph->fTop = 0;
glyph->fWidth = 0;
glyph->fHeight = 0;
// put a valid value here, in case it was earlier set to
// MASK_FORMAT_JUST_ADVANCE
glyph->fMaskFormat = fRec.fMaskFormat;
}
#define SK_SHOW_TEXT_BLIT_COVERAGE 0
static void applyLUTToA8Mask(const SkMask& mask, const uint8_t* lut) {
uint8_t* SK_RESTRICT dst = (uint8_t*)mask.fImage;
unsigned rowBytes = mask.fRowBytes;
for (int y = mask.fBounds.height() - 1; y >= 0; --y) {
for (int x = mask.fBounds.width() - 1; x >= 0; --x) {
dst[x] = lut[dst[x]];
}
dst += rowBytes;
}
}
static void pack4xHToLCD16(const SkPixmap& src, const SkMask& dst,
const SkMaskGamma::PreBlend& maskPreBlend,
const bool doBGR, const bool doVert) {
#define SAMPLES_PER_PIXEL 4
#define LCD_PER_PIXEL 3
SkASSERT(kAlpha_8_SkColorType == src.colorType());
SkASSERT(SkMask::kLCD16_Format == dst.fFormat);
// doVert in this function means swap x and y when writing to dst.
if (doVert) {
SkASSERT(src.width() == (dst.fBounds.height() - 2) * 4);
SkASSERT(src.height() == dst.fBounds.width());
} else {
SkASSERT(src.width() == (dst.fBounds.width() - 2) * 4);
SkASSERT(src.height() == dst.fBounds.height());
}
const int sample_width = src.width();
const int height = src.height();
uint16_t* dstImage = (uint16_t*)dst.fImage;
size_t dstRB = dst.fRowBytes;
// An N tap FIR is defined by
// out[n] = coeff[0]*x[n] + coeff[1]*x[n-1] + ... + coeff[N]*x[n-N]
// or
// out[n] = sum(i, 0, N, coeff[i]*x[n-i])
// The strategy is to use one FIR (different coefficients) for each of r, g, and b.
// This means using every 4th FIR output value of each FIR and discarding the rest.
// The FIRs are aligned, and the coefficients reach 5 samples to each side of their 'center'.
// (For r and b this is technically incorrect, but the coeffs outside round to zero anyway.)
// These are in some fixed point repesentation.
// Adding up to more than one simulates ink spread.
// For implementation reasons, these should never add up to more than two.
// Coefficients determined by a gausian where 5 samples = 3 std deviations (0x110 'contrast').
// Calculated using tools/generate_fir_coeff.py
// With this one almost no fringing is ever seen, but it is imperceptibly blurry.
// The lcd smoothed text is almost imperceptibly different from gray,
// but is still sharper on small stems and small rounded corners than gray.
// This also seems to be about as wide as one can get and only have a three pixel kernel.
// TODO: calculate these at runtime so parameters can be adjusted (esp contrast).
static const unsigned int coefficients[LCD_PER_PIXEL][SAMPLES_PER_PIXEL*3] = {
//The red subpixel is centered inside the first sample (at 1/6 pixel), and is shifted.
{ 0x03, 0x0b, 0x1c, 0x33, 0x40, 0x39, 0x24, 0x10, 0x05, 0x01, 0x00, 0x00, },
//The green subpixel is centered between two samples (at 1/2 pixel), so is symetric
{ 0x00, 0x02, 0x08, 0x16, 0x2b, 0x3d, 0x3d, 0x2b, 0x16, 0x08, 0x02, 0x00, },
//The blue subpixel is centered inside the last sample (at 5/6 pixel), and is shifted.
{ 0x00, 0x00, 0x01, 0x05, 0x10, 0x24, 0x39, 0x40, 0x33, 0x1c, 0x0b, 0x03, },
};
for (int y = 0; y < height; ++y) {
uint16_t* dstP;
size_t dstPDelta;
if (doVert) {
dstP = dstImage + y;
dstPDelta = dstRB;
} else {
dstP = SkTAddOffset<uint16_t>(dstImage, dstRB * y);
dstPDelta = sizeof(uint16_t);
}
const uint8_t* srcP = src.addr8(0, y);
// TODO: this fir filter implementation is straight forward, but slow.
// It should be possible to make it much faster.
for (int sample_x = -4; sample_x < sample_width + 4; sample_x += 4) {
int fir[LCD_PER_PIXEL] = { 0 };
for (int sample_index = std::max(0, sample_x - 4), coeff_index = sample_index - (sample_x - 4)
; sample_index < std::min(sample_x + 8, sample_width)
; ++sample_index, ++coeff_index)
{
int sample_value = srcP[sample_index];
for (int subpxl_index = 0; subpxl_index < LCD_PER_PIXEL; ++subpxl_index) {
fir[subpxl_index] += coefficients[subpxl_index][coeff_index] * sample_value;
}
}
for (int subpxl_index = 0; subpxl_index < LCD_PER_PIXEL; ++subpxl_index) {
fir[subpxl_index] /= 0x100;
fir[subpxl_index] = std::min(fir[subpxl_index], 255);
}
U8CPU r, g, b;
if (doBGR) {
r = fir[2];
g = fir[1];
b = fir[0];
} else {
r = fir[0];
g = fir[1];
b = fir[2];
}
if (maskPreBlend.isApplicable()) {
r = maskPreBlend.fR[r];
g = maskPreBlend.fG[g];
b = maskPreBlend.fB[b];
}
#if SK_SHOW_TEXT_BLIT_COVERAGE
r = std::max(r, 10); g = std::max(g, 10); b = std::max(b, 10);
#endif
*dstP = SkPack888ToRGB16(r, g, b);
dstP = SkTAddOffset<uint16_t>(dstP, dstPDelta);
}
}
}
static inline int convert_8_to_1(unsigned byte) {
SkASSERT(byte <= 0xFF);
return byte >> 7;
}
static uint8_t pack_8_to_1(const uint8_t alpha[8]) {
unsigned bits = 0;
for (int i = 0; i < 8; ++i) {
bits <<= 1;
bits |= convert_8_to_1(alpha[i]);
}
return SkToU8(bits);
}
static void packA8ToA1(const SkMask& mask, const uint8_t* src, size_t srcRB) {
const int height = mask.fBounds.height();
const int width = mask.fBounds.width();
const int octs = width >> 3;
const int leftOverBits = width & 7;
uint8_t* dst = mask.fImage;
const int dstPad = mask.fRowBytes - SkAlign8(width)/8;
SkASSERT(dstPad >= 0);
SkASSERT(width >= 0);
SkASSERT(srcRB >= (size_t)width);
const size_t srcPad = srcRB - width;
for (int y = 0; y < height; ++y) {
for (int i = 0; i < octs; ++i) {
*dst++ = pack_8_to_1(src);
src += 8;
}
if (leftOverBits > 0) {
unsigned bits = 0;
int shift = 7;
for (int i = 0; i < leftOverBits; ++i, --shift) {
bits |= convert_8_to_1(*src++) << shift;
}
*dst++ = bits;
}
src += srcPad;
dst += dstPad;
}
}
static void generateMask(const SkMask& mask, const SkPath& path,
const SkMaskGamma::PreBlend& maskPreBlend,
bool doBGR, bool doVert) {
SkPaint paint;
int srcW = mask.fBounds.width();
int srcH = mask.fBounds.height();
int dstW = srcW;
int dstH = srcH;
int dstRB = mask.fRowBytes;
SkMatrix matrix;
matrix.setTranslate(-SkIntToScalar(mask.fBounds.fLeft),
-SkIntToScalar(mask.fBounds.fTop));
paint.setAntiAlias(SkMask::kBW_Format != mask.fFormat);
switch (mask.fFormat) {
case SkMask::kBW_Format:
dstRB = 0; // signals we need a copy
break;
case SkMask::kA8_Format:
break;
case SkMask::kLCD16_Format:
if (doVert) {
dstW = 4*dstH - 8;
dstH = srcW;
matrix.setAll(0, 4, -SkIntToScalar(mask.fBounds.fTop + 1) * 4,
1, 0, -SkIntToScalar(mask.fBounds.fLeft),
0, 0, 1);
} else {
dstW = 4*dstW - 8;
matrix.setAll(4, 0, -SkIntToScalar(mask.fBounds.fLeft + 1) * 4,
0, 1, -SkIntToScalar(mask.fBounds.fTop),
0, 0, 1);
}
dstRB = 0; // signals we need a copy
break;
default:
SkDEBUGFAIL("unexpected mask format");
}
SkRasterClip clip;
clip.setRect(SkIRect::MakeWH(dstW, dstH));
const SkImageInfo info = SkImageInfo::MakeA8(dstW, dstH);
SkAutoPixmapStorage dst;
if (0 == dstRB) {
if (!dst.tryAlloc(info)) {
// can't allocate offscreen, so empty the mask and return
sk_bzero(mask.fImage, mask.computeImageSize());
return;
}
} else {
dst.reset(info, mask.fImage, dstRB);
}
sk_bzero(dst.writable_addr(), dst.computeByteSize());
SkDraw draw;
SkSimpleMatrixProvider matrixProvider(matrix);
draw.fDst = dst;
draw.fRC = &clip;
draw.fMatrixProvider = &matrixProvider;
draw.drawPath(path, paint);
switch (mask.fFormat) {
case SkMask::kBW_Format:
packA8ToA1(mask, dst.addr8(0, 0), dst.rowBytes());
break;
case SkMask::kA8_Format:
if (maskPreBlend.isApplicable()) {
applyLUTToA8Mask(mask, maskPreBlend.fG);
}
break;
case SkMask::kLCD16_Format:
pack4xHToLCD16(dst, mask, maskPreBlend, doBGR, doVert);
break;
default:
break;
}
}
void SkScalerContext::getImage(const SkGlyph& origGlyph) {
const SkGlyph* glyph = &origGlyph;
SkGlyph tmpGlyph{origGlyph.getPackedID()};
// in case we need to call generateImage on a mask-format that is different
// (i.e. larger) than what our caller allocated by looking at origGlyph.
SkAutoMalloc tmpGlyphImageStorage;
if (fMaskFilter) { // restore the prefilter bounds
// need the original bounds, sans our maskfilter
sk_sp<SkMaskFilter> mf = std::move(fMaskFilter);
this->getMetrics(&tmpGlyph);
fMaskFilter = std::move(mf);
// we need the prefilter bounds to be <= filter bounds
SkASSERT(tmpGlyph.fWidth <= origGlyph.fWidth);
SkASSERT(tmpGlyph.fHeight <= origGlyph.fHeight);
if (tmpGlyph.fMaskFormat == origGlyph.fMaskFormat) {
tmpGlyph.fImage = origGlyph.fImage;
} else {
tmpGlyphImageStorage.reset(tmpGlyph.imageSize());
tmpGlyph.fImage = tmpGlyphImageStorage.get();
}
glyph = &tmpGlyph;
}
if (!fGenerateImageFromPath) {
generateImage(*glyph);
} else {
SkPath devPath;
SkMask mask = glyph->mask();
if (!this->internalGetPath(glyph->getPackedID(), &devPath)) {
generateImage(*glyph);
} else {
SkASSERT(SkMask::kARGB32_Format != origGlyph.fMaskFormat);
SkASSERT(SkMask::kARGB32_Format != mask.fFormat);
const bool doBGR = SkToBool(fRec.fFlags & SkScalerContext::kLCD_BGROrder_Flag);
const bool doVert = SkToBool(fRec.fFlags & SkScalerContext::kLCD_Vertical_Flag);
generateMask(mask, devPath, fPreBlend, doBGR, doVert);
}
}
if (fMaskFilter) {
// the src glyph image shouldn't be 3D
SkASSERT(SkMask::k3D_Format != glyph->fMaskFormat);
SkMask srcM = glyph->mask(),
dstM;
SkMatrix matrix;
fRec.getMatrixFrom2x2(&matrix);
if (as_MFB(fMaskFilter)->filterMask(&dstM, srcM, matrix, nullptr)) {
int width = std::min<int>(origGlyph.fWidth, dstM.fBounds.width());
int height = std::min<int>(origGlyph.fHeight, dstM.fBounds.height());
int dstRB = origGlyph.rowBytes();
int srcRB = dstM.fRowBytes;
const uint8_t* src = (const uint8_t*)dstM.fImage;
uint8_t* dst = (uint8_t*)origGlyph.fImage;
if (SkMask::k3D_Format == dstM.fFormat) {
// we have to copy 3 times as much
height *= 3;
}
// clean out our glyph, since it may be larger than dstM
//sk_bzero(dst, height * dstRB);
while (--height >= 0) {
memcpy(dst, src, width);
src += srcRB;
dst += dstRB;
}
SkMask::FreeImage(dstM.fImage);
}
}
}
bool SkScalerContext::getPath(SkPackedGlyphID glyphID, SkPath* path) {
return this->internalGetPath(glyphID, path);
}
void SkScalerContext::getFontMetrics(SkFontMetrics* fm) {
SkASSERT(fm);
this->generateFontMetrics(fm);
}
///////////////////////////////////////////////////////////////////////////////
bool SkScalerContext::internalGetPath(SkPackedGlyphID glyphID, SkPath* devPath) {
SkPath path;
if (!generatePath(glyphID.glyphID(), &path)) {
return false;
}
if (fRec.fFlags & SkScalerContext::kSubpixelPositioning_Flag) {
SkFixed dx = glyphID.getSubXFixed();
SkFixed dy = glyphID.getSubYFixed();
if (dx | dy) {
path.offset(SkFixedToScalar(dx), SkFixedToScalar(dy));
}
}
if (fRec.fFrameWidth > 0 || fPathEffect != nullptr) {
// need the path in user-space, with only the point-size applied
// so that our stroking and effects will operate the same way they
// would if the user had extracted the path themself, and then
// called drawPath
SkPath localPath;
SkMatrix matrix, inverse;
fRec.getMatrixFrom2x2(&matrix);
if (!matrix.invert(&inverse)) {
// assume devPath is already empty.
return true;
}
path.transform(inverse, &localPath);
// now localPath is only affected by the paint settings, and not the canvas matrix
SkStrokeRec rec(SkStrokeRec::kFill_InitStyle);
if (fRec.fFrameWidth > 0) {
rec.setStrokeStyle(fRec.fFrameWidth,
SkToBool(fRec.fFlags & kFrameAndFill_Flag));
// glyphs are always closed contours, so cap type is ignored,
// so we just pass something.
rec.setStrokeParams((SkPaint::Cap)fRec.fStrokeCap,
(SkPaint::Join)fRec.fStrokeJoin,
fRec.fMiterLimit);
}
if (fPathEffect) {
SkPath effectPath;
if (fPathEffect->filterPath(&effectPath, localPath, &rec, nullptr)) {
localPath.swap(effectPath);
}
}
if (rec.needToApply()) {
SkPath strokePath;
if (rec.applyToPath(&strokePath, localPath)) {
localPath.swap(strokePath);
}
}
// now return stuff to the caller
if (devPath) {
localPath.transform(matrix, devPath);
}
} else { // nothing tricky to do
if (devPath) {
devPath->swap(path);
}
}
if (devPath) {
devPath->updateBoundsCache();
}
return true;
}
void SkScalerContextRec::getMatrixFrom2x2(SkMatrix* dst) const {
dst->setAll(fPost2x2[0][0], fPost2x2[0][1], 0,
fPost2x2[1][0], fPost2x2[1][1], 0,
0, 0, 1);
}
void SkScalerContextRec::getLocalMatrix(SkMatrix* m) const {
*m = SkFontPriv::MakeTextMatrix(fTextSize, fPreScaleX, fPreSkewX);
}
void SkScalerContextRec::getSingleMatrix(SkMatrix* m) const {
this->getLocalMatrix(m);
// now concat the device matrix
SkMatrix deviceMatrix;
this->getMatrixFrom2x2(&deviceMatrix);
m->postConcat(deviceMatrix);
}
bool SkScalerContextRec::computeMatrices(PreMatrixScale preMatrixScale, SkVector* s, SkMatrix* sA,
SkMatrix* GsA, SkMatrix* G_inv, SkMatrix* A_out)
{
// A is the 'total' matrix.
SkMatrix A;
this->getSingleMatrix(&A);
// The caller may find the 'total' matrix useful when dealing directly with EM sizes.
if (A_out) {
*A_out = A;
}
// GA is the matrix A with rotation removed.
SkMatrix GA;
bool skewedOrFlipped = A.getSkewX() || A.getSkewY() || A.getScaleX() < 0 || A.getScaleY() < 0;
if (skewedOrFlipped) {
// QR by Givens rotations. G is Q^T and GA is R. G is rotational (no reflections).
// h is where A maps the horizontal baseline.
SkPoint h = SkPoint::Make(SK_Scalar1, 0);
A.mapPoints(&h, 1);
// G is the Givens Matrix for A (rotational matrix where GA[0][1] == 0).
SkMatrix G;
SkComputeGivensRotation(h, &G);
GA = G;
GA.preConcat(A);
// The 'remainingRotation' is G inverse, which is fairly simple since G is 2x2 rotational.
if (G_inv) {
G_inv->setAll(
G.get(SkMatrix::kMScaleX), -G.get(SkMatrix::kMSkewX), G.get(SkMatrix::kMTransX),
-G.get(SkMatrix::kMSkewY), G.get(SkMatrix::kMScaleY), G.get(SkMatrix::kMTransY),
G.get(SkMatrix::kMPersp0), G.get(SkMatrix::kMPersp1), G.get(SkMatrix::kMPersp2));
}
} else {
GA = A;
if (G_inv) {
G_inv->reset();
}
}
// If the 'total' matrix is singular, set the 'scale' to something finite and zero the matrices.
// All underlying ports have issues with zero text size, so use the matricies to zero.
// If one of the scale factors is less than 1/256 then an EM filling square will
// never affect any pixels.
// If there are any nonfinite numbers in the matrix, bail out and set the matrices to zero.
if (SkScalarAbs(GA.get(SkMatrix::kMScaleX)) <= SK_ScalarNearlyZero ||
SkScalarAbs(GA.get(SkMatrix::kMScaleY)) <= SK_ScalarNearlyZero ||
!GA.isFinite())
{
s->fX = SK_Scalar1;
s->fY = SK_Scalar1;
sA->setScale(0, 0);
if (GsA) {
GsA->setScale(0, 0);
}
if (G_inv) {
G_inv->reset();
}
return false;
}
// At this point, given GA, create s.
switch (preMatrixScale) {
case kFull_PreMatrixScale:
s->fX = SkScalarAbs(GA.get(SkMatrix::kMScaleX));
s->fY = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
break;
case kVertical_PreMatrixScale: {
SkScalar yScale = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
s->fX = yScale;
s->fY = yScale;
break;
}
case kVerticalInteger_PreMatrixScale: {
SkScalar realYScale = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
SkScalar intYScale = SkScalarRoundToScalar(realYScale);
if (intYScale == 0) {
intYScale = SK_Scalar1;
}
s->fX = intYScale;
s->fY = intYScale;
break;
}
}
// The 'remaining' matrix sA is the total matrix A without the scale.
if (!skewedOrFlipped && (
(kFull_PreMatrixScale == preMatrixScale) ||
(kVertical_PreMatrixScale == preMatrixScale && A.getScaleX() == A.getScaleY())))
{
// If GA == A and kFull_PreMatrixScale, sA is identity.
// If GA == A and kVertical_PreMatrixScale and A.scaleX == A.scaleY, sA is identity.
sA->reset();
} else if (!skewedOrFlipped && kVertical_PreMatrixScale == preMatrixScale) {
// If GA == A and kVertical_PreMatrixScale, sA.scaleY is SK_Scalar1.
sA->reset();
sA->setScaleX(A.getScaleX() / s->fY);
} else {
// TODO: like kVertical_PreMatrixScale, kVerticalInteger_PreMatrixScale with int scales.
*sA = A;
sA->preScale(SkScalarInvert(s->fX), SkScalarInvert(s->fY));
}
// The 'remainingWithoutRotation' matrix GsA is the non-rotational part of A without the scale.
if (GsA) {
*GsA = GA;
// G is rotational so reorders with the scale.
GsA->preScale(SkScalarInvert(s->fX), SkScalarInvert(s->fY));
}
return true;
}
SkAxisAlignment SkScalerContext::computeAxisAlignmentForHText() const {
return fRec.computeAxisAlignmentForHText();
}
SkAxisAlignment SkScalerContextRec::computeAxisAlignmentForHText() const {
// Why fPost2x2 can be used here.
// getSingleMatrix multiplies in getLocalMatrix, which consists of
// * fTextSize (a scale, which has no effect)
// * fPreScaleX (a scale in x, which has no effect)
// * fPreSkewX (has no effect, but would on vertical text alignment).
// In other words, making the text bigger, stretching it along the
// horizontal axis, or fake italicizing it does not move the baseline.
if (!SkToBool(fFlags & SkScalerContext::kBaselineSnap_Flag)) {
return kNone_SkAxisAlignment;
}
if (0 == fPost2x2[1][0]) {
// The x axis is mapped onto the x axis.
return kX_SkAxisAlignment;
}
if (0 == fPost2x2[0][0]) {
// The x axis is mapped onto the y axis.
return kY_SkAxisAlignment;
}
return kNone_SkAxisAlignment;
}
void SkScalerContextRec::setLuminanceColor(SkColor c) {
fLumBits = SkMaskGamma::CanonicalColor(
SkColorSetRGB(SkColorGetR(c), SkColorGetG(c), SkColorGetB(c)));
}
extern SkScalerContext* SkCreateColorScalerContext(const SkDescriptor* desc);
std::unique_ptr<SkScalerContext> SkTypeface::createScalerContext(
const SkScalerContextEffects& effects, const SkDescriptor* desc) const {
auto answer = std::unique_ptr<SkScalerContext>{this->onCreateScalerContext(effects, desc)};
SkASSERT(answer != nullptr);
return answer;
}
/*
* Return the scalar with only limited fractional precision. Used to consolidate matrices
* that vary only slightly when we create our key into the font cache, since the font scaler
* typically returns the same looking resuts for tiny changes in the matrix.
*/
static SkScalar sk_relax(SkScalar x) {
SkScalar n = SkScalarRoundToScalar(x * 1024);
return n / 1024.0f;
}
static SkMask::Format compute_mask_format(const SkFont& font) {
switch (font.getEdging()) {
case SkFont::Edging::kAlias:
return SkMask::kBW_Format;
case SkFont::Edging::kAntiAlias:
return SkMask::kA8_Format;
case SkFont::Edging::kSubpixelAntiAlias:
return SkMask::kLCD16_Format;
}
SkASSERT(false);
return SkMask::kA8_Format;
}
// Beyond this size, LCD doesn't appreciably improve quality, but it always
// cost more RAM and draws slower, so we set a cap.
#ifndef SK_MAX_SIZE_FOR_LCDTEXT
#define SK_MAX_SIZE_FOR_LCDTEXT 48
#endif
const SkScalar gMaxSize2ForLCDText = SK_MAX_SIZE_FOR_LCDTEXT * SK_MAX_SIZE_FOR_LCDTEXT;
static bool too_big_for_lcd(const SkScalerContextRec& rec, bool checkPost2x2) {
if (checkPost2x2) {
SkScalar area = rec.fPost2x2[0][0] * rec.fPost2x2[1][1] -
rec.fPost2x2[1][0] * rec.fPost2x2[0][1];
area *= rec.fTextSize * rec.fTextSize;
return area > gMaxSize2ForLCDText;
} else {
return rec.fTextSize > SK_MAX_SIZE_FOR_LCDTEXT;
}
}
// The only reason this is not file static is because it needs the context of SkScalerContext to
// access SkPaint::computeLuminanceColor.
void SkScalerContext::MakeRecAndEffects(const SkFont& font, const SkPaint& paint,
const SkSurfaceProps& surfaceProps,
SkScalerContextFlags scalerContextFlags,
const SkMatrix& deviceMatrix,
SkScalerContextRec* rec,
SkScalerContextEffects* effects) {
SkASSERT(!deviceMatrix.hasPerspective());
sk_bzero(rec, sizeof(SkScalerContextRec));
SkTypeface* typeface = font.getTypefaceOrDefault();
rec->fFontID = typeface->uniqueID();
rec->fTextSize = font.getSize();
rec->fPreScaleX = font.getScaleX();
rec->fPreSkewX = font.getSkewX();
bool checkPost2x2 = false;
const SkMatrix::TypeMask mask = deviceMatrix.getType();
if (mask & SkMatrix::kScale_Mask) {
rec->fPost2x2[0][0] = sk_relax(deviceMatrix.getScaleX());
rec->fPost2x2[1][1] = sk_relax(deviceMatrix.getScaleY());
checkPost2x2 = true;
} else {
rec->fPost2x2[0][0] = rec->fPost2x2[1][1] = SK_Scalar1;
}
if (mask & SkMatrix::kAffine_Mask) {
rec->fPost2x2[0][1] = sk_relax(deviceMatrix.getSkewX());
rec->fPost2x2[1][0] = sk_relax(deviceMatrix.getSkewY());
checkPost2x2 = true;
} else {
rec->fPost2x2[0][1] = rec->fPost2x2[1][0] = 0;
}
SkPaint::Style style = paint.getStyle();
SkScalar strokeWidth = paint.getStrokeWidth();
unsigned flags = 0;
if (font.isEmbolden()) {
#ifdef SK_USE_FREETYPE_EMBOLDEN
flags |= SkScalerContext::kEmbolden_Flag;
#else
SkScalar fakeBoldScale = SkScalarInterpFunc(font.getSize(),
kStdFakeBoldInterpKeys,
kStdFakeBoldInterpValues,
kStdFakeBoldInterpLength);
SkScalar extra = font.getSize() * fakeBoldScale;
if (style == SkPaint::kFill_Style) {
style = SkPaint::kStrokeAndFill_Style;
strokeWidth = extra; // ignore paint's strokeWidth if it was "fill"
} else {
strokeWidth += extra;
}
#endif
}
if (style != SkPaint::kFill_Style && strokeWidth > 0) {
rec->fFrameWidth = strokeWidth;
rec->fMiterLimit = paint.getStrokeMiter();
rec->fStrokeJoin = SkToU8(paint.getStrokeJoin());
rec->fStrokeCap = SkToU8(paint.getStrokeCap());
if (style == SkPaint::kStrokeAndFill_Style) {
flags |= SkScalerContext::kFrameAndFill_Flag;
}
} else {
rec->fFrameWidth = 0;
rec->fMiterLimit = 0;
rec->fStrokeJoin = 0;
rec->fStrokeCap = 0;
}
rec->fMaskFormat = SkToU8(compute_mask_format(font));
if (SkMask::kLCD16_Format == rec->fMaskFormat) {
if (too_big_for_lcd(*rec, checkPost2x2)) {
rec->fMaskFormat = SkMask::kA8_Format;
flags |= SkScalerContext::kGenA8FromLCD_Flag;
} else {
SkPixelGeometry geometry = surfaceProps.pixelGeometry();
switch (geometry) {
case kUnknown_SkPixelGeometry:
// eeek, can't support LCD
rec->fMaskFormat = SkMask::kA8_Format;
flags |= SkScalerContext::kGenA8FromLCD_Flag;
break;
case kRGB_H_SkPixelGeometry:
// our default, do nothing.
break;
case kBGR_H_SkPixelGeometry:
flags |= SkScalerContext::kLCD_BGROrder_Flag;
break;
case kRGB_V_SkPixelGeometry:
flags |= SkScalerContext::kLCD_Vertical_Flag;
break;
case kBGR_V_SkPixelGeometry:
flags |= SkScalerContext::kLCD_Vertical_Flag;
flags |= SkScalerContext::kLCD_BGROrder_Flag;
break;
}
}
}
if (font.isEmbeddedBitmaps()) {
flags |= SkScalerContext::kEmbeddedBitmapText_Flag;
}
if (font.isSubpixel()) {
flags |= SkScalerContext::kSubpixelPositioning_Flag;
}
if (font.isForceAutoHinting()) {
flags |= SkScalerContext::kForceAutohinting_Flag;
}
if (font.isLinearMetrics()) {
flags |= SkScalerContext::kLinearMetrics_Flag;
}
if (font.isBaselineSnap()) {
flags |= SkScalerContext::kBaselineSnap_Flag;
}
rec->fFlags = SkToU16(flags);
// these modify fFlags, so do them after assigning fFlags
rec->setHinting(font.getHinting());
rec->setLuminanceColor(SkPaintPriv::ComputeLuminanceColor(paint));
// For now always set the paint gamma equal to the device gamma.
// The math in SkMaskGamma can handle them being different,
// but it requires superluminous masks when
// Ex : deviceGamma(x) < paintGamma(x) and x is sufficiently large.
rec->setDeviceGamma(SK_GAMMA_EXPONENT);
rec->setPaintGamma(SK_GAMMA_EXPONENT);
#ifdef SK_GAMMA_CONTRAST
rec->setContrast(SK_GAMMA_CONTRAST);
#else
// A value of 0.5 for SK_GAMMA_CONTRAST appears to be a good compromise.
// With lower values small text appears washed out (though correctly so).
// With higher values lcd fringing is worse and the smoothing effect of
// partial coverage is diminished.
rec->setContrast(0.5f);
#endif
if (!SkToBool(scalerContextFlags & SkScalerContextFlags::kFakeGamma)) {
rec->ignoreGamma();
}
if (!SkToBool(scalerContextFlags & SkScalerContextFlags::kBoostContrast)) {
rec->setContrast(0);
}
new (effects) SkScalerContextEffects{paint};
}
SkDescriptor* SkScalerContext::MakeDescriptorForPaths(SkFontID typefaceID,
SkAutoDescriptor* ad) {
SkScalerContextRec rec;
memset((void*)&rec, 0, sizeof(rec));
rec.fFontID = typefaceID;
rec.fTextSize = SkFontPriv::kCanonicalTextSizeForPaths;
rec.fPreScaleX = rec.fPost2x2[0][0] = rec.fPost2x2[1][1] = SK_Scalar1;
return AutoDescriptorGivenRecAndEffects(rec, SkScalerContextEffects(), ad);
}
SkDescriptor* SkScalerContext::CreateDescriptorAndEffectsUsingPaint(
const SkFont& font, const SkPaint& paint, const SkSurfaceProps& surfaceProps,
SkScalerContextFlags scalerContextFlags, const SkMatrix& deviceMatrix, SkAutoDescriptor* ad,
SkScalerContextEffects* effects)
{
SkScalerContextRec rec;
MakeRecAndEffects(font, paint, surfaceProps, scalerContextFlags, deviceMatrix, &rec, effects);
return AutoDescriptorGivenRecAndEffects(rec, *effects, ad);
}
static size_t calculate_size_and_flatten(const SkScalerContextRec& rec,
const SkScalerContextEffects& effects,
SkBinaryWriteBuffer* effectBuffer) {
size_t descSize = sizeof(rec);
int entryCount = 1;
if (effects.fPathEffect || effects.fMaskFilter) {
if (effects.fPathEffect) { effectBuffer->writeFlattenable(effects.fPathEffect); }
if (effects.fMaskFilter) { effectBuffer->writeFlattenable(effects.fMaskFilter); }
entryCount += 1;
descSize += effectBuffer->bytesWritten();
}
descSize += SkDescriptor::ComputeOverhead(entryCount);
return descSize;
}
static void generate_descriptor(const SkScalerContextRec& rec,
const SkBinaryWriteBuffer& effectBuffer,
SkDescriptor* desc) {
desc->addEntry(kRec_SkDescriptorTag, sizeof(rec), &rec);
if (effectBuffer.bytesWritten() > 0) {
effectBuffer.writeToMemory(desc->addEntry(kEffects_SkDescriptorTag,
effectBuffer.bytesWritten(),
nullptr));
}
desc->computeChecksum();
}
SkDescriptor* SkScalerContext::AutoDescriptorGivenRecAndEffects(
const SkScalerContextRec& rec,
const SkScalerContextEffects& effects,
SkAutoDescriptor* ad)
{
SkBinaryWriteBuffer buf;
ad->reset(calculate_size_and_flatten(rec, effects, &buf));
generate_descriptor(rec, buf, ad->getDesc());
return ad->getDesc();
}
std::unique_ptr<SkDescriptor> SkScalerContext::DescriptorGivenRecAndEffects(
const SkScalerContextRec& rec,
const SkScalerContextEffects& effects)
{
SkBinaryWriteBuffer buf;
auto desc = SkDescriptor::Alloc(calculate_size_and_flatten(rec, effects, &buf));
generate_descriptor(rec, buf, desc.get());
return desc;
}
void SkScalerContext::DescriptorBufferGiveRec(const SkScalerContextRec& rec, void* buffer) {
generate_descriptor(rec, SkBinaryWriteBuffer{}, (SkDescriptor*)buffer);
}
bool SkScalerContext::CheckBufferSizeForRec(const SkScalerContextRec& rec,
const SkScalerContextEffects& effects,
size_t size) {
SkBinaryWriteBuffer buf;
return size >= calculate_size_and_flatten(rec, effects, &buf);
}
SkScalerContext* SkScalerContext::MakeEmptyContext(
sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
const SkDescriptor* desc) {
class SkScalerContext_Empty : public SkScalerContext {
public:
SkScalerContext_Empty(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
const SkDescriptor* desc)
: SkScalerContext(std::move(typeface), effects, desc) {}
protected:
unsigned generateGlyphCount() override {
return 0;
}
bool generateAdvance(SkGlyph* glyph) override {
glyph->zeroMetrics();
return true;
}
void generateMetrics(SkGlyph* glyph) override {
glyph->fMaskFormat = fRec.fMaskFormat;
glyph->zeroMetrics();
}
void generateImage(const SkGlyph& glyph) override {}
bool generatePath(SkGlyphID glyph, SkPath* path) override {
path->reset();
return false;
}
void generateFontMetrics(SkFontMetrics* metrics) override {
if (metrics) {
sk_bzero(metrics, sizeof(*metrics));
}
}
};
return new SkScalerContext_Empty{std::move(typeface), effects, desc};
}