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skia2/src/core/SkScalerContext.cpp
reed 1e7f5e708e remove 'deprecated' region from SkDraw 
Most call-sites that used it just took its bounds, so it was trivial to convert them
to get the bounds of the RasterClip. Two clients wanted the actual region:
1. layeriter for android
2. pdf

Android already only has BW clips, so should be safe.
PDF now overrides its clip methods to ensure that all clips are BW.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1925693002

Review URL: https://codereview.chromium.org/1925693002
2016-04-27 07:49:17 -07:00

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30 KiB
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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.
*/
#include "SkScalerContext.h"
#include "SkAutoPixmapStorage.h"
#include "SkColorPriv.h"
#include "SkDescriptor.h"
#include "SkDraw.h"
#include "SkGlyph.h"
#include "SkMaskFilter.h"
#include "SkMaskGamma.h"
#include "SkMatrix22.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#include "SkPathEffect.h"
#include "SkRasterizer.h"
#include "SkRasterClip.h"
#include "SkStroke.h"
#include "SkStrokeRec.h"
#define ComputeBWRowBytes(width) (((unsigned)(width) + 7) >> 3)
void SkGlyph::toMask(SkMask* mask) const {
SkASSERT(mask);
mask->fImage = (uint8_t*)fImage;
mask->fBounds.set(fLeft, fTop, fLeft + fWidth, fTop + fHeight);
mask->fRowBytes = this->rowBytes();
mask->fFormat = static_cast<SkMask::Format>(fMaskFormat);
}
size_t SkGlyph::computeImageSize() const {
const size_t size = this->rowBytes() * fHeight;
switch (fMaskFormat) {
case SkMask::k3D_Format:
return 3 * size;
default:
return size;
}
}
void SkGlyph::zeroMetrics() {
fAdvanceX = 0;
fAdvanceY = 0;
fWidth = 0;
fHeight = 0;
fTop = 0;
fLeft = 0;
fRsbDelta = 0;
fLsbDelta = 0;
}
///////////////////////////////////////////////////////////////////////////////
#ifdef SK_DEBUG
#define DUMP_RECx
#endif
SkScalerContext::SkScalerContext(SkTypeface* typeface, const SkScalerContextEffects& effects,
const SkDescriptor* desc)
: fRec(*static_cast<const Rec*>(desc->findEntry(kRec_SkDescriptorTag, nullptr)))
, fTypeface(sk_ref_sp(typeface))
, fPathEffect(sk_ref_sp(effects.fPathEffect))
, fMaskFilter(sk_ref_sp(effects.fMaskFilter))
, fRasterizer(sk_ref_sp(effects.fRasterizer))
// Initialize based on our settings. Subclasses can also force this.
, fGenerateImageFromPath(fRec.fFrameWidth > 0 || fPathEffect != nullptr || fRasterizer != nullptr)
, fPreBlend(fMaskFilter ? SkMaskGamma::PreBlend() : SkScalerContext::GetMaskPreBlend(fRec))
, fPreBlendForFilter(fMaskFilter ? SkScalerContext::GetMaskPreBlend(fRec)
: SkMaskGamma::PreBlend())
{
#ifdef DUMP_REC
desc->assertChecksum();
SkDebugf("SkScalerContext checksum %x count %d length %d\n",
desc->getChecksum(), desc->getCount(), desc->getLength());
SkDebugf(" textsize %g prescale %g preskew %g post [%g %g %g %g]\n",
rec->fTextSize, rec->fPreScaleX, rec->fPreSkewX, rec->fPost2x2[0][0],
rec->fPost2x2[0][1], rec->fPost2x2[1][0], rec->fPost2x2[1][1]);
SkDebugf(" frame %g miter %g hints %d framefill %d format %d join %d cap %d\n",
rec->fFrameWidth, rec->fMiterLimit, rec->fHints, rec->fFrameAndFill,
rec->fMaskFormat, rec->fStrokeJoin, rec->fStrokeCap);
SkDebugf(" pathEffect %x maskFilter %x\n",
desc->findEntry(kPathEffect_SkDescriptorTag, nullptr),
desc->findEntry(kMaskFilter_SkDescriptorTag, nullptr));
#endif
}
SkScalerContext::~SkScalerContext() {}
void SkScalerContext::getAdvance(SkGlyph* glyph) {
// mark us as just having a valid advance
glyph->fMaskFormat = MASK_FORMAT_JUST_ADVANCE;
// we mark the format before making the call, in case the impl
// internally ends up calling its generateMetrics, which is OK
// albeit slower than strictly necessary
generateAdvance(glyph);
}
void SkScalerContext::getMetrics(SkGlyph* glyph) {
generateMetrics(glyph);
// for now we have separate cache entries for devkerning on and off
// in the future we might share caches, but make our measure/draw
// code make the distinction. Thus we zap the values if the caller
// has not asked for them.
if ((fRec.fFlags & SkScalerContext::kDevKernText_Flag) == 0) {
// no devkern, so zap the fields
glyph->fLsbDelta = glyph->fRsbDelta = 0;
}
// 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 (fGenerateImageFromPath) {
SkPath devPath, fillPath;
SkMatrix fillToDevMatrix;
this->internalGetPath(*glyph, &fillPath, &devPath, &fillToDevMatrix);
if (fRasterizer) {
SkMask mask;
if (fRasterizer->rasterize(fillPath, fillToDevMatrix, nullptr,
fMaskFilter.get(), &mask,
SkMask::kJustComputeBounds_CreateMode)) {
glyph->fLeft = mask.fBounds.fLeft;
glyph->fTop = mask.fBounds.fTop;
glyph->fWidth = SkToU16(mask.fBounds.width());
glyph->fHeight = SkToU16(mask.fBounds.height());
} else {
goto SK_ERROR;
}
} else {
// just use devPath
const SkIRect ir = devPath.getBounds().roundOut();
if (ir.isEmpty() || !ir.is16Bit()) {
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 (fRec.fMaskFormat) {
case SkMask::kLCD16_Format:
glyph->fWidth += 2;
glyph->fLeft -= 1;
break;
default:
break;
}
}
}
}
if (SkMask::kARGB32_Format != glyph->fMaskFormat) {
glyph->fMaskFormat = fRec.fMaskFormat;
}
// If we are going to create the mask, then we cannot keep the color
if ((fGenerateImageFromPath || fMaskFilter) &&
SkMask::kARGB32_Format == glyph->fMaskFormat) {
glyph->fMaskFormat = SkMask::kA8_Format;
}
if (fMaskFilter) {
SkMask src, dst;
SkMatrix matrix;
glyph->toMask(&src);
fRec.getMatrixFrom2x2(&matrix);
src.fImage = nullptr; // only want the bounds from the filter
if (fMaskFilter->filterMask(&dst, src, matrix, nullptr)) {
if (dst.fBounds.isEmpty() || !dst.fBounds.is16Bit()) {
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;
}
}
template<bool APPLY_PREBLEND>
static void pack4xHToLCD16(const SkPixmap& src, const SkMask& dst,
const SkMaskGamma::PreBlend& maskPreBlend) {
#define SAMPLES_PER_PIXEL 4
#define LCD_PER_PIXEL 3
SkASSERT(kAlpha_8_SkColorType == src.colorType());
SkASSERT(SkMask::kLCD16_Format == dst.fFormat);
const int sample_width = src.width();
const int height = src.height();
uint16_t* dstP = (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: caculate 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) {
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, pixel_x = 0; sample_x < sample_width + 4; sample_x += 4, ++pixel_x) {
int fir[LCD_PER_PIXEL] = { 0 };
for (int sample_index = SkMax32(0, sample_x - 4), coeff_index = sample_index - (sample_x - 4)
; sample_index < SkMin32(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] = SkMin32(fir[subpxl_index], 255);
}
U8CPU r = sk_apply_lut_if<APPLY_PREBLEND>(fir[0], maskPreBlend.fR);
U8CPU g = sk_apply_lut_if<APPLY_PREBLEND>(fir[1], maskPreBlend.fG);
U8CPU b = sk_apply_lut_if<APPLY_PREBLEND>(fir[2], maskPreBlend.fB);
#if SK_SHOW_TEXT_BLIT_COVERAGE
r = SkMax32(r, 10); g = SkMax32(g, 10); b = SkMax32(b, 10);
#endif
dstP[pixel_x] = SkPack888ToRGB16(r, g, b);
}
dstP = (uint16_t*)((char*)dstP + dstRB);
}
}
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) {
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:
// TODO: trigger off LCD orientation
dstW = 4*dstW - 8;
matrix.setTranslate(-SkIntToScalar(mask.fBounds.fLeft + 1),
-SkIntToScalar(mask.fBounds.fTop));
matrix.postScale(SkIntToScalar(4), SK_Scalar1);
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.getSafeSize());
SkDraw draw;
draw.fDst = dst;
draw.fRC = &clip;
draw.fMatrix = &matrix;
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:
if (maskPreBlend.isApplicable()) {
pack4xHToLCD16<true>(dst, mask, maskPreBlend);
} else {
pack4xHToLCD16<false>(dst, mask, maskPreBlend);
}
break;
default:
break;
}
}
static void extract_alpha(const SkMask& dst,
const SkPMColor* srcRow, size_t srcRB) {
int width = dst.fBounds.width();
int height = dst.fBounds.height();
int dstRB = dst.fRowBytes;
uint8_t* dstRow = dst.fImage;
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
dstRow[x] = SkGetPackedA32(srcRow[x]);
}
// zero any padding on each row
for (int x = width; x < dstRB; ++x) {
dstRow[x] = 0;
}
dstRow += dstRB;
srcRow = (const SkPMColor*)((const char*)srcRow + srcRB);
}
}
void SkScalerContext::getImage(const SkGlyph& origGlyph) {
const SkGlyph* glyph = &origGlyph;
SkGlyph tmpGlyph;
// 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 we are going to draw-from-path, then we cannot generate color, since
// the path only makes a mask. This case should have been caught up in
// generateMetrics().
SkASSERT(!fGenerateImageFromPath ||
SkMask::kARGB32_Format != origGlyph.fMaskFormat);
if (fMaskFilter) { // restore the prefilter bounds
tmpGlyph.initGlyphIdFrom(origGlyph);
// need the original bounds, sans our maskfilter
SkMaskFilter* mf = fMaskFilter.release(); // temp disable
this->getMetrics(&tmpGlyph);
fMaskFilter = sk_sp<SkMaskFilter>(mf); // restore
// 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.computeImageSize());
tmpGlyph.fImage = tmpGlyphImageStorage.get();
}
glyph = &tmpGlyph;
}
if (fGenerateImageFromPath) {
SkPath devPath, fillPath;
SkMatrix fillToDevMatrix;
SkMask mask;
this->internalGetPath(*glyph, &fillPath, &devPath, &fillToDevMatrix);
glyph->toMask(&mask);
if (fRasterizer) {
mask.fFormat = SkMask::kA8_Format;
sk_bzero(glyph->fImage, mask.computeImageSize());
if (!fRasterizer->rasterize(fillPath, fillToDevMatrix, nullptr,
fMaskFilter.get(), &mask,
SkMask::kJustRenderImage_CreateMode)) {
return;
}
if (fPreBlend.isApplicable()) {
applyLUTToA8Mask(mask, fPreBlend.fG);
}
} else {
SkASSERT(SkMask::kARGB32_Format != mask.fFormat);
generateMask(mask, devPath, fPreBlend);
}
} else {
generateImage(*glyph);
}
if (fMaskFilter) {
SkMask srcM, dstM;
SkMatrix matrix;
// the src glyph image shouldn't be 3D
SkASSERT(SkMask::k3D_Format != glyph->fMaskFormat);
SkAutoSMalloc<32*32> a8storage;
glyph->toMask(&srcM);
if (SkMask::kARGB32_Format == srcM.fFormat) {
// now we need to extract the alpha-channel from the glyph's image
// and copy it into a temp buffer, and then point srcM at that temp.
srcM.fFormat = SkMask::kA8_Format;
srcM.fRowBytes = SkAlign4(srcM.fBounds.width());
size_t size = srcM.computeImageSize();
a8storage.reset(size);
srcM.fImage = (uint8_t*)a8storage.get();
extract_alpha(srcM,
(const SkPMColor*)glyph->fImage, glyph->rowBytes());
}
fRec.getMatrixFrom2x2(&matrix);
if (fMaskFilter->filterMask(&dstM, srcM, matrix, nullptr)) {
int width = SkFastMin32(origGlyph.fWidth, dstM.fBounds.width());
int height = SkFastMin32(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);
if (fPreBlendForFilter.isApplicable()) {
applyLUTToA8Mask(srcM, fPreBlendForFilter.fG);
}
}
}
}
void SkScalerContext::getPath(const SkGlyph& glyph, SkPath* path) {
this->internalGetPath(glyph, nullptr, path, nullptr);
}
void SkScalerContext::getFontMetrics(SkPaint::FontMetrics* fm) {
this->generateFontMetrics(fm);
}
SkUnichar SkScalerContext::generateGlyphToChar(uint16_t glyph) {
return 0;
}
///////////////////////////////////////////////////////////////////////////////
void SkScalerContext::internalGetPath(const SkGlyph& glyph, SkPath* fillPath,
SkPath* devPath, SkMatrix* fillToDevMatrix) {
SkPath path;
generatePath(glyph, &path);
if (fRec.fFlags & SkScalerContext::kSubpixelPositioning_Flag) {
SkFixed dx = glyph.getSubXFixed();
SkFixed dy = glyph.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 fillPath and devPath are already empty.
return;
}
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 (fillToDevMatrix) {
*fillToDevMatrix = matrix;
}
if (devPath) {
localPath.transform(matrix, devPath);
}
if (fillPath) {
fillPath->swap(localPath);
}
} else { // nothing tricky to do
if (fillToDevMatrix) {
fillToDevMatrix->reset();
}
if (devPath) {
if (fillPath == nullptr) {
devPath->swap(path);
} else {
*devPath = path;
}
}
if (fillPath) {
fillPath->swap(path);
}
}
if (devPath) {
devPath->updateBoundsCache();
}
if (fillPath) {
fillPath->updateBoundsCache();
}
}
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 {
SkPaint::SetTextMatrix(m, 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);
}
void 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;
}
// 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.
// Map the vectors [0,1], [1,0], [1,1] and [1,-1] (the EM) through the 'total' matrix.
// If the length of one of these vectors is less than 1/256 then an EM filling square will
// never affect any pixels.
SkVector diag[4] = { { A.getScaleX() , A.getSkewY() },
{ A.getSkewX(), A.getScaleY() },
{ A.getScaleX() + A.getSkewX(), A.getScaleY() + A.getSkewY() },
{ A.getScaleX() - A.getSkewX(), A.getScaleY() - A.getSkewY() }, };
if (diag[0].lengthSqd() <= SK_ScalarNearlyZero * SK_ScalarNearlyZero ||
diag[1].lengthSqd() <= SK_ScalarNearlyZero * SK_ScalarNearlyZero ||
diag[2].lengthSqd() <= SK_ScalarNearlyZero * SK_ScalarNearlyZero ||
diag[3].lengthSqd() <= SK_ScalarNearlyZero * SK_ScalarNearlyZero)
{
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;
}
// GA is the matrix A with rotation removed.
SkMatrix GA;
bool skewedOrFlipped = A.getSkewX() || A.getSkewY() || A.getScaleX() < 0 || A.getScaleY() < 0;
if (skewedOrFlipped) {
// 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();
}
}
// 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));
}
}
SkAxisAlignment SkScalerContext::computeAxisAlignmentForHText() {
// 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 (0 == fRec.fPost2x2[1][0]) {
// The x axis is mapped onto the x axis.
return kX_SkAxisAlignment;
}
if (0 == fRec.fPost2x2[0][0]) {
// The x axis is mapped onto the y axis.
return kY_SkAxisAlignment;
}
return kNone_SkAxisAlignment;
}
///////////////////////////////////////////////////////////////////////////////
class SkScalerContext_Empty : public SkScalerContext {
public:
SkScalerContext_Empty(SkTypeface* typeface, const SkScalerContextEffects& effects,
const SkDescriptor* desc)
: SkScalerContext(typeface, effects, desc) {}
protected:
unsigned generateGlyphCount() override {
return 0;
}
uint16_t generateCharToGlyph(SkUnichar uni) override {
return 0;
}
void generateAdvance(SkGlyph* glyph) override {
glyph->zeroMetrics();
}
void generateMetrics(SkGlyph* glyph) override {
glyph->zeroMetrics();
}
void generateImage(const SkGlyph& glyph) override {}
void generatePath(const SkGlyph& glyph, SkPath* path) override {}
void generateFontMetrics(SkPaint::FontMetrics* metrics) override {
if (metrics) {
sk_bzero(metrics, sizeof(*metrics));
}
}
};
extern SkScalerContext* SkCreateColorScalerContext(const SkDescriptor* desc);
SkScalerContext* SkTypeface::createScalerContext(const SkScalerContextEffects& effects,
const SkDescriptor* desc,
bool allowFailure) const {
SkScalerContext* c = this->onCreateScalerContext(effects, desc);
if (!c && !allowFailure) {
c = new SkScalerContext_Empty(const_cast<SkTypeface*>(this), effects, desc);
}
return c;
}
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