1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "include/core/SkPaint.h"
9#include "src/core/SkScalerContext.h"
10
11#include "include/core/SkFontMetrics.h"
12#include "include/core/SkMaskFilter.h"
13#include "include/core/SkPathEffect.h"
14#include "include/core/SkStrokeRec.h"
15#include "include/private/SkColorData.h"
16#include "include/private/SkTo.h"
17#include "src/core/SkAutoMalloc.h"
18#include "src/core/SkAutoPixmapStorage.h"
19#include "src/core/SkDescriptor.h"
20#include "src/core/SkDraw.h"
21#include "src/core/SkFontPriv.h"
22#include "src/core/SkGlyph.h"
23#include "src/core/SkMaskGamma.h"
24#include "src/core/SkMatrixProvider.h"
25#include "src/core/SkPaintPriv.h"
26#include "src/core/SkPathPriv.h"
27#include "src/core/SkRasterClip.h"
28#include "src/core/SkReadBuffer.h"
29#include "src/core/SkRectPriv.h"
30#include "src/core/SkStroke.h"
31#include "src/core/SkSurfacePriv.h"
32#include "src/core/SkTextFormatParams.h"
33#include "src/core/SkWriteBuffer.h"
34#include "src/utils/SkMatrix22.h"
35#include <new>
36
37///////////////////////////////////////////////////////////////////////////////
38
39#ifdef SK_DEBUG
40 #define DUMP_RECx
41#endif
42
43SkScalerContextRec SkScalerContext::PreprocessRec(const SkTypeface& typeface,
44 const SkScalerContextEffects& effects,
45 const SkDescriptor& desc) {
46 SkScalerContextRec rec =
47 *static_cast<const SkScalerContextRec*>(desc.findEntry(kRec_SkDescriptorTag, nullptr));
48
49 // Allow the typeface to adjust the rec.
50 typeface.onFilterRec(&rec);
51
52 if (effects.fMaskFilter) {
53 // Pre-blend is not currently applied to filtered text.
54 // The primary filter is blur, for which contrast makes no sense,
55 // and for which the destination guess error is more visible.
56 // Also, all existing users of blur have calibrated for linear.
57 rec.ignorePreBlend();
58 }
59
60 SkColor lumColor = rec.getLuminanceColor();
61
62 if (rec.fMaskFormat == SkMask::kA8_Format) {
63 U8CPU lum = SkComputeLuminance(SkColorGetR(lumColor),
64 SkColorGetG(lumColor),
65 SkColorGetB(lumColor));
66 lumColor = SkColorSetRGB(lum, lum, lum);
67 }
68
69 // TODO: remove CanonicalColor when we to fix up Chrome layout tests.
70 rec.setLuminanceColor(lumColor);
71
72 return rec;
73}
74
75SkScalerContext::SkScalerContext(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
76 const SkDescriptor* desc)
77 : fRec(PreprocessRec(*typeface, effects, *desc))
78 , fTypeface(std::move(typeface))
79 , fPathEffect(sk_ref_sp(effects.fPathEffect))
80 , fMaskFilter(sk_ref_sp(effects.fMaskFilter))
81 // Initialize based on our settings. Subclasses can also force this.
82 , fGenerateImageFromPath(fRec.fFrameWidth > 0 || fPathEffect != nullptr)
83
84 , fPreBlend(fMaskFilter ? SkMaskGamma::PreBlend() : SkScalerContext::GetMaskPreBlend(fRec))
85{
86#ifdef DUMP_REC
87 SkDebugf("SkScalerContext checksum %x count %d length %d\n",
88 desc->getChecksum(), desc->getCount(), desc->getLength());
89 SkDebugf("%s", fRec.dump().c_str());
90 SkDebugf(" effects %x\n", desc->findEntry(kEffects_SkDescriptorTag, nullptr));
91#endif
92}
93
94SkScalerContext::~SkScalerContext() {}
95
96/**
97 * In order to call cachedDeviceLuminance, cachedPaintLuminance, or
98 * cachedMaskGamma the caller must hold the mask_gamma_cache_mutex and continue
99 * to hold it until the returned pointer is refed or forgotten.
100 */
101static SkMutex& mask_gamma_cache_mutex() {
102 static SkMutex& mutex = *(new SkMutex);
103 return mutex;
104}
105
106static SkMaskGamma* gLinearMaskGamma = nullptr;
107static SkMaskGamma* gMaskGamma = nullptr;
108static SkScalar gContrast = SK_ScalarMin;
109static SkScalar gPaintGamma = SK_ScalarMin;
110static SkScalar gDeviceGamma = SK_ScalarMin;
111
112/**
113 * The caller must hold the mask_gamma_cache_mutex() and continue to hold it until
114 * the returned SkMaskGamma pointer is refed or forgotten.
115 */
116static const SkMaskGamma& cached_mask_gamma(SkScalar contrast, SkScalar paintGamma,
117 SkScalar deviceGamma) {
118 mask_gamma_cache_mutex().assertHeld();
119 if (0 == contrast && SK_Scalar1 == paintGamma && SK_Scalar1 == deviceGamma) {
120 if (nullptr == gLinearMaskGamma) {
121 gLinearMaskGamma = new SkMaskGamma;
122 }
123 return *gLinearMaskGamma;
124 }
125 if (gContrast != contrast || gPaintGamma != paintGamma || gDeviceGamma != deviceGamma) {
126 SkSafeUnref(gMaskGamma);
127 gMaskGamma = new SkMaskGamma(contrast, paintGamma, deviceGamma);
128 gContrast = contrast;
129 gPaintGamma = paintGamma;
130 gDeviceGamma = deviceGamma;
131 }
132 return *gMaskGamma;
133}
134
135/**
136 * Expands fDeviceGamma, fPaintGamma, fContrast, and fLumBits into a mask pre-blend.
137 */
138SkMaskGamma::PreBlend SkScalerContext::GetMaskPreBlend(const SkScalerContextRec& rec) {
139 SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
140
141 const SkMaskGamma& maskGamma = cached_mask_gamma(rec.getContrast(),
142 rec.getPaintGamma(),
143 rec.getDeviceGamma());
144
145 // TODO: remove CanonicalColor when we to fix up Chrome layout tests.
146 return maskGamma.preBlend(rec.getLuminanceColor());
147}
148
149size_t SkScalerContext::GetGammaLUTSize(SkScalar contrast, SkScalar paintGamma,
150 SkScalar deviceGamma, int* width, int* height) {
151 SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
152 const SkMaskGamma& maskGamma = cached_mask_gamma(contrast,
153 paintGamma,
154 deviceGamma);
155
156 maskGamma.getGammaTableDimensions(width, height);
157 size_t size = (*width)*(*height)*sizeof(uint8_t);
158
159 return size;
160}
161
162bool SkScalerContext::GetGammaLUTData(SkScalar contrast, SkScalar paintGamma, SkScalar deviceGamma,
163 uint8_t* data) {
164 SkAutoMutexExclusive ama(mask_gamma_cache_mutex());
165 const SkMaskGamma& maskGamma = cached_mask_gamma(contrast,
166 paintGamma,
167 deviceGamma);
168 const uint8_t* gammaTables = maskGamma.getGammaTables();
169 if (!gammaTables) {
170 return false;
171 }
172
173 int width, height;
174 maskGamma.getGammaTableDimensions(&width, &height);
175 size_t size = width*height * sizeof(uint8_t);
176 memcpy(data, gammaTables, size);
177 return true;
178}
179
180void SkScalerContext::getAdvance(SkGlyph* glyph) {
181 if (generateAdvance(glyph)) {
182 glyph->fMaskFormat = MASK_FORMAT_JUST_ADVANCE;
183 } else {
184 this->getMetrics(glyph);
185 SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
186 }
187}
188
189void SkScalerContext::getMetrics(SkGlyph* glyph) {
190 bool generatingImageFromPath = fGenerateImageFromPath;
191 if (!generatingImageFromPath) {
192 generateMetrics(glyph);
193 SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
194 } else {
195 SkPath devPath;
196 generatingImageFromPath = this->internalGetPath(glyph->getPackedID(), &devPath);
197 if (!generatingImageFromPath) {
198 generateMetrics(glyph);
199 SkASSERT(glyph->fMaskFormat != MASK_FORMAT_UNKNOWN);
200 } else {
201 uint8_t originMaskFormat = glyph->fMaskFormat;
202 if (!generateAdvance(glyph)) {
203 generateMetrics(glyph);
204 }
205
206 if (originMaskFormat != MASK_FORMAT_UNKNOWN) {
207 glyph->fMaskFormat = originMaskFormat;
208 } else {
209 glyph->fMaskFormat = fRec.fMaskFormat;
210 }
211
212 // If we are going to create the mask, then we cannot keep the color
213 if (SkMask::kARGB32_Format == glyph->fMaskFormat) {
214 glyph->fMaskFormat = SkMask::kA8_Format;
215 }
216
217 const SkIRect ir = devPath.getBounds().roundOut();
218 if (ir.isEmpty() || !SkRectPriv::Is16Bit(ir)) {
219 goto SK_ERROR;
220 }
221 glyph->fLeft = ir.fLeft;
222 glyph->fTop = ir.fTop;
223 glyph->fWidth = SkToU16(ir.width());
224 glyph->fHeight = SkToU16(ir.height());
225
226 if (glyph->fWidth > 0) {
227 switch (glyph->fMaskFormat) {
228 case SkMask::kLCD16_Format:
229 if (fRec.fFlags & SkScalerContext::kLCD_Vertical_Flag) {
230 glyph->fHeight += 2;
231 glyph->fTop -= 1;
232 } else {
233 glyph->fWidth += 2;
234 glyph->fLeft -= 1;
235 }
236 break;
237 default:
238 break;
239 }
240 }
241 }
242 }
243
244 // if either dimension is empty, zap the image bounds of the glyph
245 if (0 == glyph->fWidth || 0 == glyph->fHeight) {
246 glyph->fWidth = 0;
247 glyph->fHeight = 0;
248 glyph->fTop = 0;
249 glyph->fLeft = 0;
250 glyph->fMaskFormat = 0;
251 return;
252 }
253
254 if (fMaskFilter) {
255 SkMask src = glyph->mask(),
256 dst;
257 SkMatrix matrix;
258
259 fRec.getMatrixFrom2x2(&matrix);
260
261 src.fImage = nullptr; // only want the bounds from the filter
262 if (as_MFB(fMaskFilter)->filterMask(&dst, src, matrix, nullptr)) {
263 if (dst.fBounds.isEmpty() || !SkRectPriv::Is16Bit(dst.fBounds)) {
264 goto SK_ERROR;
265 }
266 SkASSERT(dst.fImage == nullptr);
267 glyph->fLeft = dst.fBounds.fLeft;
268 glyph->fTop = dst.fBounds.fTop;
269 glyph->fWidth = SkToU16(dst.fBounds.width());
270 glyph->fHeight = SkToU16(dst.fBounds.height());
271 glyph->fMaskFormat = dst.fFormat;
272 }
273 }
274 return;
275
276SK_ERROR:
277 // draw nothing 'cause we failed
278 glyph->fLeft = 0;
279 glyph->fTop = 0;
280 glyph->fWidth = 0;
281 glyph->fHeight = 0;
282 // put a valid value here, in case it was earlier set to
283 // MASK_FORMAT_JUST_ADVANCE
284 glyph->fMaskFormat = fRec.fMaskFormat;
285}
286
287#define SK_SHOW_TEXT_BLIT_COVERAGE 0
288
289static void applyLUTToA8Mask(const SkMask& mask, const uint8_t* lut) {
290 uint8_t* SK_RESTRICT dst = (uint8_t*)mask.fImage;
291 unsigned rowBytes = mask.fRowBytes;
292
293 for (int y = mask.fBounds.height() - 1; y >= 0; --y) {
294 for (int x = mask.fBounds.width() - 1; x >= 0; --x) {
295 dst[x] = lut[dst[x]];
296 }
297 dst += rowBytes;
298 }
299}
300
301static void pack4xHToLCD16(const SkPixmap& src, const SkMask& dst,
302 const SkMaskGamma::PreBlend& maskPreBlend,
303 const bool doBGR, const bool doVert) {
304#define SAMPLES_PER_PIXEL 4
305#define LCD_PER_PIXEL 3
306 SkASSERT(kAlpha_8_SkColorType == src.colorType());
307 SkASSERT(SkMask::kLCD16_Format == dst.fFormat);
308
309 // doVert in this function means swap x and y when writing to dst.
310 if (doVert) {
311 SkASSERT(src.width() == (dst.fBounds.height() - 2) * 4);
312 SkASSERT(src.height() == dst.fBounds.width());
313 } else {
314 SkASSERT(src.width() == (dst.fBounds.width() - 2) * 4);
315 SkASSERT(src.height() == dst.fBounds.height());
316 }
317
318 const int sample_width = src.width();
319 const int height = src.height();
320
321 uint16_t* dstImage = (uint16_t*)dst.fImage;
322 size_t dstRB = dst.fRowBytes;
323 // An N tap FIR is defined by
324 // out[n] = coeff[0]*x[n] + coeff[1]*x[n-1] + ... + coeff[N]*x[n-N]
325 // or
326 // out[n] = sum(i, 0, N, coeff[i]*x[n-i])
327
328 // The strategy is to use one FIR (different coefficients) for each of r, g, and b.
329 // This means using every 4th FIR output value of each FIR and discarding the rest.
330 // The FIRs are aligned, and the coefficients reach 5 samples to each side of their 'center'.
331 // (For r and b this is technically incorrect, but the coeffs outside round to zero anyway.)
332
333 // These are in some fixed point repesentation.
334 // Adding up to more than one simulates ink spread.
335 // For implementation reasons, these should never add up to more than two.
336
337 // Coefficients determined by a gausian where 5 samples = 3 std deviations (0x110 'contrast').
338 // Calculated using tools/generate_fir_coeff.py
339 // With this one almost no fringing is ever seen, but it is imperceptibly blurry.
340 // The lcd smoothed text is almost imperceptibly different from gray,
341 // but is still sharper on small stems and small rounded corners than gray.
342 // This also seems to be about as wide as one can get and only have a three pixel kernel.
343 // TODO: calculate these at runtime so parameters can be adjusted (esp contrast).
344 static const unsigned int coefficients[LCD_PER_PIXEL][SAMPLES_PER_PIXEL*3] = {
345 //The red subpixel is centered inside the first sample (at 1/6 pixel), and is shifted.
346 { 0x03, 0x0b, 0x1c, 0x33, 0x40, 0x39, 0x24, 0x10, 0x05, 0x01, 0x00, 0x00, },
347 //The green subpixel is centered between two samples (at 1/2 pixel), so is symetric
348 { 0x00, 0x02, 0x08, 0x16, 0x2b, 0x3d, 0x3d, 0x2b, 0x16, 0x08, 0x02, 0x00, },
349 //The blue subpixel is centered inside the last sample (at 5/6 pixel), and is shifted.
350 { 0x00, 0x00, 0x01, 0x05, 0x10, 0x24, 0x39, 0x40, 0x33, 0x1c, 0x0b, 0x03, },
351 };
352
353 for (int y = 0; y < height; ++y) {
354 uint16_t* dstP;
355 size_t dstPDelta;
356 if (doVert) {
357 dstP = dstImage + y;
358 dstPDelta = dstRB;
359 } else {
360 dstP = SkTAddOffset<uint16_t>(dstImage, dstRB * y);
361 dstPDelta = sizeof(uint16_t);
362 }
363
364 const uint8_t* srcP = src.addr8(0, y);
365
366 // TODO: this fir filter implementation is straight forward, but slow.
367 // It should be possible to make it much faster.
368 for (int sample_x = -4; sample_x < sample_width + 4; sample_x += 4) {
369 int fir[LCD_PER_PIXEL] = { 0 };
370 for (int sample_index = std::max(0, sample_x - 4), coeff_index = sample_index - (sample_x - 4)
371 ; sample_index < std::min(sample_x + 8, sample_width)
372 ; ++sample_index, ++coeff_index)
373 {
374 int sample_value = srcP[sample_index];
375 for (int subpxl_index = 0; subpxl_index < LCD_PER_PIXEL; ++subpxl_index) {
376 fir[subpxl_index] += coefficients[subpxl_index][coeff_index] * sample_value;
377 }
378 }
379 for (int subpxl_index = 0; subpxl_index < LCD_PER_PIXEL; ++subpxl_index) {
380 fir[subpxl_index] /= 0x100;
381 fir[subpxl_index] = std::min(fir[subpxl_index], 255);
382 }
383
384 U8CPU r, g, b;
385 if (doBGR) {
386 r = fir[2];
387 g = fir[1];
388 b = fir[0];
389 } else {
390 r = fir[0];
391 g = fir[1];
392 b = fir[2];
393 }
394 if (maskPreBlend.isApplicable()) {
395 r = maskPreBlend.fR[r];
396 g = maskPreBlend.fG[g];
397 b = maskPreBlend.fB[b];
398 }
399#if SK_SHOW_TEXT_BLIT_COVERAGE
400 r = std::max(r, 10); g = std::max(g, 10); b = std::max(b, 10);
401#endif
402 *dstP = SkPack888ToRGB16(r, g, b);
403 dstP = SkTAddOffset<uint16_t>(dstP, dstPDelta);
404 }
405 }
406}
407
408static inline int convert_8_to_1(unsigned byte) {
409 SkASSERT(byte <= 0xFF);
410 return byte >> 7;
411}
412
413static uint8_t pack_8_to_1(const uint8_t alpha[8]) {
414 unsigned bits = 0;
415 for (int i = 0; i < 8; ++i) {
416 bits <<= 1;
417 bits |= convert_8_to_1(alpha[i]);
418 }
419 return SkToU8(bits);
420}
421
422static void packA8ToA1(const SkMask& mask, const uint8_t* src, size_t srcRB) {
423 const int height = mask.fBounds.height();
424 const int width = mask.fBounds.width();
425 const int octs = width >> 3;
426 const int leftOverBits = width & 7;
427
428 uint8_t* dst = mask.fImage;
429 const int dstPad = mask.fRowBytes - SkAlign8(width)/8;
430 SkASSERT(dstPad >= 0);
431
432 SkASSERT(width >= 0);
433 SkASSERT(srcRB >= (size_t)width);
434 const size_t srcPad = srcRB - width;
435
436 for (int y = 0; y < height; ++y) {
437 for (int i = 0; i < octs; ++i) {
438 *dst++ = pack_8_to_1(src);
439 src += 8;
440 }
441 if (leftOverBits > 0) {
442 unsigned bits = 0;
443 int shift = 7;
444 for (int i = 0; i < leftOverBits; ++i, --shift) {
445 bits |= convert_8_to_1(*src++) << shift;
446 }
447 *dst++ = bits;
448 }
449 src += srcPad;
450 dst += dstPad;
451 }
452}
453
454static void generateMask(const SkMask& mask, const SkPath& path,
455 const SkMaskGamma::PreBlend& maskPreBlend,
456 bool doBGR, bool doVert) {
457 SkPaint paint;
458
459 int srcW = mask.fBounds.width();
460 int srcH = mask.fBounds.height();
461 int dstW = srcW;
462 int dstH = srcH;
463 int dstRB = mask.fRowBytes;
464
465 SkMatrix matrix;
466 matrix.setTranslate(-SkIntToScalar(mask.fBounds.fLeft),
467 -SkIntToScalar(mask.fBounds.fTop));
468
469 paint.setAntiAlias(SkMask::kBW_Format != mask.fFormat);
470 switch (mask.fFormat) {
471 case SkMask::kBW_Format:
472 dstRB = 0; // signals we need a copy
473 break;
474 case SkMask::kA8_Format:
475 break;
476 case SkMask::kLCD16_Format:
477 if (doVert) {
478 dstW = 4*dstH - 8;
479 dstH = srcW;
480 matrix.setAll(0, 4, -SkIntToScalar(mask.fBounds.fTop + 1) * 4,
481 1, 0, -SkIntToScalar(mask.fBounds.fLeft),
482 0, 0, 1);
483 } else {
484 dstW = 4*dstW - 8;
485 matrix.setAll(4, 0, -SkIntToScalar(mask.fBounds.fLeft + 1) * 4,
486 0, 1, -SkIntToScalar(mask.fBounds.fTop),
487 0, 0, 1);
488 }
489 dstRB = 0; // signals we need a copy
490 break;
491 default:
492 SkDEBUGFAIL("unexpected mask format");
493 }
494
495 SkRasterClip clip;
496 clip.setRect(SkIRect::MakeWH(dstW, dstH));
497
498 const SkImageInfo info = SkImageInfo::MakeA8(dstW, dstH);
499 SkAutoPixmapStorage dst;
500
501 if (0 == dstRB) {
502 if (!dst.tryAlloc(info)) {
503 // can't allocate offscreen, so empty the mask and return
504 sk_bzero(mask.fImage, mask.computeImageSize());
505 return;
506 }
507 } else {
508 dst.reset(info, mask.fImage, dstRB);
509 }
510 sk_bzero(dst.writable_addr(), dst.computeByteSize());
511
512 SkDraw draw;
513 SkSimpleMatrixProvider matrixProvider(matrix);
514 draw.fDst = dst;
515 draw.fRC = &clip;
516 draw.fMatrixProvider = &matrixProvider;
517 draw.drawPath(path, paint);
518
519 switch (mask.fFormat) {
520 case SkMask::kBW_Format:
521 packA8ToA1(mask, dst.addr8(0, 0), dst.rowBytes());
522 break;
523 case SkMask::kA8_Format:
524 if (maskPreBlend.isApplicable()) {
525 applyLUTToA8Mask(mask, maskPreBlend.fG);
526 }
527 break;
528 case SkMask::kLCD16_Format:
529 pack4xHToLCD16(dst, mask, maskPreBlend, doBGR, doVert);
530 break;
531 default:
532 break;
533 }
534}
535
536void SkScalerContext::getImage(const SkGlyph& origGlyph) {
537 const SkGlyph* glyph = &origGlyph;
538 SkGlyph tmpGlyph{origGlyph.getPackedID()};
539
540 // in case we need to call generateImage on a mask-format that is different
541 // (i.e. larger) than what our caller allocated by looking at origGlyph.
542 SkAutoMalloc tmpGlyphImageStorage;
543
544 if (fMaskFilter) { // restore the prefilter bounds
545
546 // need the original bounds, sans our maskfilter
547 sk_sp<SkMaskFilter> mf = std::move(fMaskFilter);
548 this->getMetrics(&tmpGlyph);
549 fMaskFilter = std::move(mf);
550
551 // we need the prefilter bounds to be <= filter bounds
552 SkASSERT(tmpGlyph.fWidth <= origGlyph.fWidth);
553 SkASSERT(tmpGlyph.fHeight <= origGlyph.fHeight);
554
555 if (tmpGlyph.fMaskFormat == origGlyph.fMaskFormat) {
556 tmpGlyph.fImage = origGlyph.fImage;
557 } else {
558 tmpGlyphImageStorage.reset(tmpGlyph.imageSize());
559 tmpGlyph.fImage = tmpGlyphImageStorage.get();
560 }
561 glyph = &tmpGlyph;
562 }
563
564 if (!fGenerateImageFromPath) {
565 generateImage(*glyph);
566 } else {
567 SkPath devPath;
568 SkMask mask = glyph->mask();
569
570 if (!this->internalGetPath(glyph->getPackedID(), &devPath)) {
571 generateImage(*glyph);
572 } else {
573 SkASSERT(SkMask::kARGB32_Format != origGlyph.fMaskFormat);
574 SkASSERT(SkMask::kARGB32_Format != mask.fFormat);
575 const bool doBGR = SkToBool(fRec.fFlags & SkScalerContext::kLCD_BGROrder_Flag);
576 const bool doVert = SkToBool(fRec.fFlags & SkScalerContext::kLCD_Vertical_Flag);
577 generateMask(mask, devPath, fPreBlend, doBGR, doVert);
578 }
579 }
580
581 if (fMaskFilter) {
582 // the src glyph image shouldn't be 3D
583 SkASSERT(SkMask::k3D_Format != glyph->fMaskFormat);
584
585 SkMask srcM = glyph->mask(),
586 dstM;
587 SkMatrix matrix;
588
589 fRec.getMatrixFrom2x2(&matrix);
590
591 if (as_MFB(fMaskFilter)->filterMask(&dstM, srcM, matrix, nullptr)) {
592 int width = std::min<int>(origGlyph.fWidth, dstM.fBounds.width());
593 int height = std::min<int>(origGlyph.fHeight, dstM.fBounds.height());
594 int dstRB = origGlyph.rowBytes();
595 int srcRB = dstM.fRowBytes;
596
597 const uint8_t* src = (const uint8_t*)dstM.fImage;
598 uint8_t* dst = (uint8_t*)origGlyph.fImage;
599
600 if (SkMask::k3D_Format == dstM.fFormat) {
601 // we have to copy 3 times as much
602 height *= 3;
603 }
604
605 // clean out our glyph, since it may be larger than dstM
606 //sk_bzero(dst, height * dstRB);
607
608 while (--height >= 0) {
609 memcpy(dst, src, width);
610 src += srcRB;
611 dst += dstRB;
612 }
613 SkMask::FreeImage(dstM.fImage);
614 }
615 }
616}
617
618bool SkScalerContext::getPath(SkPackedGlyphID glyphID, SkPath* path) {
619 return this->internalGetPath(glyphID, path);
620}
621
622void SkScalerContext::getFontMetrics(SkFontMetrics* fm) {
623 SkASSERT(fm);
624 this->generateFontMetrics(fm);
625}
626
627///////////////////////////////////////////////////////////////////////////////
628
629bool SkScalerContext::internalGetPath(SkPackedGlyphID glyphID, SkPath* devPath) {
630 SkPath path;
631 if (!generatePath(glyphID.glyphID(), &path)) {
632 return false;
633 }
634
635 if (fRec.fFlags & SkScalerContext::kSubpixelPositioning_Flag) {
636 SkFixed dx = glyphID.getSubXFixed();
637 SkFixed dy = glyphID.getSubYFixed();
638 if (dx | dy) {
639 path.offset(SkFixedToScalar(dx), SkFixedToScalar(dy));
640 }
641 }
642
643 if (fRec.fFrameWidth > 0 || fPathEffect != nullptr) {
644 // need the path in user-space, with only the point-size applied
645 // so that our stroking and effects will operate the same way they
646 // would if the user had extracted the path themself, and then
647 // called drawPath
648 SkPath localPath;
649 SkMatrix matrix, inverse;
650
651 fRec.getMatrixFrom2x2(&matrix);
652 if (!matrix.invert(&inverse)) {
653 // assume devPath is already empty.
654 return true;
655 }
656 path.transform(inverse, &localPath);
657 // now localPath is only affected by the paint settings, and not the canvas matrix
658
659 SkStrokeRec rec(SkStrokeRec::kFill_InitStyle);
660
661 if (fRec.fFrameWidth > 0) {
662 rec.setStrokeStyle(fRec.fFrameWidth,
663 SkToBool(fRec.fFlags & kFrameAndFill_Flag));
664 // glyphs are always closed contours, so cap type is ignored,
665 // so we just pass something.
666 rec.setStrokeParams((SkPaint::Cap)fRec.fStrokeCap,
667 (SkPaint::Join)fRec.fStrokeJoin,
668 fRec.fMiterLimit);
669 }
670
671 if (fPathEffect) {
672 SkPath effectPath;
673 if (fPathEffect->filterPath(&effectPath, localPath, &rec, nullptr)) {
674 localPath.swap(effectPath);
675 }
676 }
677
678 if (rec.needToApply()) {
679 SkPath strokePath;
680 if (rec.applyToPath(&strokePath, localPath)) {
681 localPath.swap(strokePath);
682 }
683 }
684
685 // now return stuff to the caller
686 if (devPath) {
687 localPath.transform(matrix, devPath);
688 }
689 } else { // nothing tricky to do
690 if (devPath) {
691 devPath->swap(path);
692 }
693 }
694
695 if (devPath) {
696 devPath->updateBoundsCache();
697 }
698 return true;
699}
700
701
702void SkScalerContextRec::getMatrixFrom2x2(SkMatrix* dst) const {
703 dst->setAll(fPost2x2[0][0], fPost2x2[0][1], 0,
704 fPost2x2[1][0], fPost2x2[1][1], 0,
705 0, 0, 1);
706}
707
708void SkScalerContextRec::getLocalMatrix(SkMatrix* m) const {
709 *m = SkFontPriv::MakeTextMatrix(fTextSize, fPreScaleX, fPreSkewX);
710}
711
712void SkScalerContextRec::getSingleMatrix(SkMatrix* m) const {
713 this->getLocalMatrix(m);
714
715 // now concat the device matrix
716 SkMatrix deviceMatrix;
717 this->getMatrixFrom2x2(&deviceMatrix);
718 m->postConcat(deviceMatrix);
719}
720
721bool SkScalerContextRec::computeMatrices(PreMatrixScale preMatrixScale, SkVector* s, SkMatrix* sA,
722 SkMatrix* GsA, SkMatrix* G_inv, SkMatrix* A_out)
723{
724 // A is the 'total' matrix.
725 SkMatrix A;
726 this->getSingleMatrix(&A);
727
728 // The caller may find the 'total' matrix useful when dealing directly with EM sizes.
729 if (A_out) {
730 *A_out = A;
731 }
732
733 // GA is the matrix A with rotation removed.
734 SkMatrix GA;
735 bool skewedOrFlipped = A.getSkewX() || A.getSkewY() || A.getScaleX() < 0 || A.getScaleY() < 0;
736 if (skewedOrFlipped) {
737 // QR by Givens rotations. G is Q^T and GA is R. G is rotational (no reflections).
738 // h is where A maps the horizontal baseline.
739 SkPoint h = SkPoint::Make(SK_Scalar1, 0);
740 A.mapPoints(&h, 1);
741
742 // G is the Givens Matrix for A (rotational matrix where GA[0][1] == 0).
743 SkMatrix G;
744 SkComputeGivensRotation(h, &G);
745
746 GA = G;
747 GA.preConcat(A);
748
749 // The 'remainingRotation' is G inverse, which is fairly simple since G is 2x2 rotational.
750 if (G_inv) {
751 G_inv->setAll(
752 G.get(SkMatrix::kMScaleX), -G.get(SkMatrix::kMSkewX), G.get(SkMatrix::kMTransX),
753 -G.get(SkMatrix::kMSkewY), G.get(SkMatrix::kMScaleY), G.get(SkMatrix::kMTransY),
754 G.get(SkMatrix::kMPersp0), G.get(SkMatrix::kMPersp1), G.get(SkMatrix::kMPersp2));
755 }
756 } else {
757 GA = A;
758 if (G_inv) {
759 G_inv->reset();
760 }
761 }
762
763 // If the 'total' matrix is singular, set the 'scale' to something finite and zero the matrices.
764 // All underlying ports have issues with zero text size, so use the matricies to zero.
765 // If one of the scale factors is less than 1/256 then an EM filling square will
766 // never affect any pixels.
767 // If there are any nonfinite numbers in the matrix, bail out and set the matrices to zero.
768 if (SkScalarAbs(GA.get(SkMatrix::kMScaleX)) <= SK_ScalarNearlyZero ||
769 SkScalarAbs(GA.get(SkMatrix::kMScaleY)) <= SK_ScalarNearlyZero ||
770 !GA.isFinite())
771 {
772 s->fX = SK_Scalar1;
773 s->fY = SK_Scalar1;
774 sA->setScale(0, 0);
775 if (GsA) {
776 GsA->setScale(0, 0);
777 }
778 if (G_inv) {
779 G_inv->reset();
780 }
781 return false;
782 }
783
784 // At this point, given GA, create s.
785 switch (preMatrixScale) {
786 case kFull_PreMatrixScale:
787 s->fX = SkScalarAbs(GA.get(SkMatrix::kMScaleX));
788 s->fY = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
789 break;
790 case kVertical_PreMatrixScale: {
791 SkScalar yScale = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
792 s->fX = yScale;
793 s->fY = yScale;
794 break;
795 }
796 case kVerticalInteger_PreMatrixScale: {
797 SkScalar realYScale = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
798 SkScalar intYScale = SkScalarRoundToScalar(realYScale);
799 if (intYScale == 0) {
800 intYScale = SK_Scalar1;
801 }
802 s->fX = intYScale;
803 s->fY = intYScale;
804 break;
805 }
806 }
807
808 // The 'remaining' matrix sA is the total matrix A without the scale.
809 if (!skewedOrFlipped && (
810 (kFull_PreMatrixScale == preMatrixScale) ||
811 (kVertical_PreMatrixScale == preMatrixScale && A.getScaleX() == A.getScaleY())))
812 {
813 // If GA == A and kFull_PreMatrixScale, sA is identity.
814 // If GA == A and kVertical_PreMatrixScale and A.scaleX == A.scaleY, sA is identity.
815 sA->reset();
816 } else if (!skewedOrFlipped && kVertical_PreMatrixScale == preMatrixScale) {
817 // If GA == A and kVertical_PreMatrixScale, sA.scaleY is SK_Scalar1.
818 sA->reset();
819 sA->setScaleX(A.getScaleX() / s->fY);
820 } else {
821 // TODO: like kVertical_PreMatrixScale, kVerticalInteger_PreMatrixScale with int scales.
822 *sA = A;
823 sA->preScale(SkScalarInvert(s->fX), SkScalarInvert(s->fY));
824 }
825
826 // The 'remainingWithoutRotation' matrix GsA is the non-rotational part of A without the scale.
827 if (GsA) {
828 *GsA = GA;
829 // G is rotational so reorders with the scale.
830 GsA->preScale(SkScalarInvert(s->fX), SkScalarInvert(s->fY));
831 }
832
833 return true;
834}
835
836SkAxisAlignment SkScalerContext::computeAxisAlignmentForHText() const {
837 return fRec.computeAxisAlignmentForHText();
838}
839
840SkAxisAlignment SkScalerContextRec::computeAxisAlignmentForHText() const {
841 // Why fPost2x2 can be used here.
842 // getSingleMatrix multiplies in getLocalMatrix, which consists of
843 // * fTextSize (a scale, which has no effect)
844 // * fPreScaleX (a scale in x, which has no effect)
845 // * fPreSkewX (has no effect, but would on vertical text alignment).
846 // In other words, making the text bigger, stretching it along the
847 // horizontal axis, or fake italicizing it does not move the baseline.
848 if (!SkToBool(fFlags & SkScalerContext::kBaselineSnap_Flag)) {
849 return kNone_SkAxisAlignment;
850 }
851
852 if (0 == fPost2x2[1][0]) {
853 // The x axis is mapped onto the x axis.
854 return kX_SkAxisAlignment;
855 }
856 if (0 == fPost2x2[0][0]) {
857 // The x axis is mapped onto the y axis.
858 return kY_SkAxisAlignment;
859 }
860 return kNone_SkAxisAlignment;
861}
862
863void SkScalerContextRec::setLuminanceColor(SkColor c) {
864 fLumBits = SkMaskGamma::CanonicalColor(
865 SkColorSetRGB(SkColorGetR(c), SkColorGetG(c), SkColorGetB(c)));
866}
867
868extern SkScalerContext* SkCreateColorScalerContext(const SkDescriptor* desc);
869
870std::unique_ptr<SkScalerContext> SkTypeface::createScalerContext(
871 const SkScalerContextEffects& effects, const SkDescriptor* desc) const {
872 auto answer = std::unique_ptr<SkScalerContext>{this->onCreateScalerContext(effects, desc)};
873 SkASSERT(answer != nullptr);
874 return answer;
875}
876
877/*
878 * Return the scalar with only limited fractional precision. Used to consolidate matrices
879 * that vary only slightly when we create our key into the font cache, since the font scaler
880 * typically returns the same looking resuts for tiny changes in the matrix.
881 */
882static SkScalar sk_relax(SkScalar x) {
883 SkScalar n = SkScalarRoundToScalar(x * 1024);
884 return n / 1024.0f;
885}
886
887static SkMask::Format compute_mask_format(const SkFont& font) {
888 switch (font.getEdging()) {
889 case SkFont::Edging::kAlias:
890 return SkMask::kBW_Format;
891 case SkFont::Edging::kAntiAlias:
892 return SkMask::kA8_Format;
893 case SkFont::Edging::kSubpixelAntiAlias:
894 return SkMask::kLCD16_Format;
895 }
896 SkASSERT(false);
897 return SkMask::kA8_Format;
898}
899
900// Beyond this size, LCD doesn't appreciably improve quality, but it always
901// cost more RAM and draws slower, so we set a cap.
902#ifndef SK_MAX_SIZE_FOR_LCDTEXT
903 #define SK_MAX_SIZE_FOR_LCDTEXT 48
904#endif
905
906const SkScalar gMaxSize2ForLCDText = SK_MAX_SIZE_FOR_LCDTEXT * SK_MAX_SIZE_FOR_LCDTEXT;
907
908static bool too_big_for_lcd(const SkScalerContextRec& rec, bool checkPost2x2) {
909 if (checkPost2x2) {
910 SkScalar area = rec.fPost2x2[0][0] * rec.fPost2x2[1][1] -
911 rec.fPost2x2[1][0] * rec.fPost2x2[0][1];
912 area *= rec.fTextSize * rec.fTextSize;
913 return area > gMaxSize2ForLCDText;
914 } else {
915 return rec.fTextSize > SK_MAX_SIZE_FOR_LCDTEXT;
916 }
917}
918
919// The only reason this is not file static is because it needs the context of SkScalerContext to
920// access SkPaint::computeLuminanceColor.
921void SkScalerContext::MakeRecAndEffects(const SkFont& font, const SkPaint& paint,
922 const SkSurfaceProps& surfaceProps,
923 SkScalerContextFlags scalerContextFlags,
924 const SkMatrix& deviceMatrix,
925 SkScalerContextRec* rec,
926 SkScalerContextEffects* effects) {
927 SkASSERT(!deviceMatrix.hasPerspective());
928
929 sk_bzero(rec, sizeof(SkScalerContextRec));
930
931 SkTypeface* typeface = font.getTypefaceOrDefault();
932
933 rec->fFontID = typeface->uniqueID();
934 rec->fTextSize = font.getSize();
935 rec->fPreScaleX = font.getScaleX();
936 rec->fPreSkewX = font.getSkewX();
937
938 bool checkPost2x2 = false;
939
940 const SkMatrix::TypeMask mask = deviceMatrix.getType();
941 if (mask & SkMatrix::kScale_Mask) {
942 rec->fPost2x2[0][0] = sk_relax(deviceMatrix.getScaleX());
943 rec->fPost2x2[1][1] = sk_relax(deviceMatrix.getScaleY());
944 checkPost2x2 = true;
945 } else {
946 rec->fPost2x2[0][0] = rec->fPost2x2[1][1] = SK_Scalar1;
947 }
948 if (mask & SkMatrix::kAffine_Mask) {
949 rec->fPost2x2[0][1] = sk_relax(deviceMatrix.getSkewX());
950 rec->fPost2x2[1][0] = sk_relax(deviceMatrix.getSkewY());
951 checkPost2x2 = true;
952 } else {
953 rec->fPost2x2[0][1] = rec->fPost2x2[1][0] = 0;
954 }
955
956 SkPaint::Style style = paint.getStyle();
957 SkScalar strokeWidth = paint.getStrokeWidth();
958
959 unsigned flags = 0;
960
961 if (font.isEmbolden()) {
962#ifdef SK_USE_FREETYPE_EMBOLDEN
963 flags |= SkScalerContext::kEmbolden_Flag;
964#else
965 SkScalar fakeBoldScale = SkScalarInterpFunc(font.getSize(),
966 kStdFakeBoldInterpKeys,
967 kStdFakeBoldInterpValues,
968 kStdFakeBoldInterpLength);
969 SkScalar extra = font.getSize() * fakeBoldScale;
970
971 if (style == SkPaint::kFill_Style) {
972 style = SkPaint::kStrokeAndFill_Style;
973 strokeWidth = extra; // ignore paint's strokeWidth if it was "fill"
974 } else {
975 strokeWidth += extra;
976 }
977#endif
978 }
979
980 if (style != SkPaint::kFill_Style && strokeWidth > 0) {
981 rec->fFrameWidth = strokeWidth;
982 rec->fMiterLimit = paint.getStrokeMiter();
983 rec->fStrokeJoin = SkToU8(paint.getStrokeJoin());
984 rec->fStrokeCap = SkToU8(paint.getStrokeCap());
985
986 if (style == SkPaint::kStrokeAndFill_Style) {
987 flags |= SkScalerContext::kFrameAndFill_Flag;
988 }
989 } else {
990 rec->fFrameWidth = 0;
991 rec->fMiterLimit = 0;
992 rec->fStrokeJoin = 0;
993 rec->fStrokeCap = 0;
994 }
995
996 rec->fMaskFormat = SkToU8(compute_mask_format(font));
997
998 if (SkMask::kLCD16_Format == rec->fMaskFormat) {
999 if (too_big_for_lcd(*rec, checkPost2x2)) {
1000 rec->fMaskFormat = SkMask::kA8_Format;
1001 flags |= SkScalerContext::kGenA8FromLCD_Flag;
1002 } else {
1003 SkPixelGeometry geometry = surfaceProps.pixelGeometry();
1004
1005 switch (geometry) {
1006 case kUnknown_SkPixelGeometry:
1007 // eeek, can't support LCD
1008 rec->fMaskFormat = SkMask::kA8_Format;
1009 flags |= SkScalerContext::kGenA8FromLCD_Flag;
1010 break;
1011 case kRGB_H_SkPixelGeometry:
1012 // our default, do nothing.
1013 break;
1014 case kBGR_H_SkPixelGeometry:
1015 flags |= SkScalerContext::kLCD_BGROrder_Flag;
1016 break;
1017 case kRGB_V_SkPixelGeometry:
1018 flags |= SkScalerContext::kLCD_Vertical_Flag;
1019 break;
1020 case kBGR_V_SkPixelGeometry:
1021 flags |= SkScalerContext::kLCD_Vertical_Flag;
1022 flags |= SkScalerContext::kLCD_BGROrder_Flag;
1023 break;
1024 }
1025 }
1026 }
1027
1028 if (font.isEmbeddedBitmaps()) {
1029 flags |= SkScalerContext::kEmbeddedBitmapText_Flag;
1030 }
1031 if (font.isSubpixel()) {
1032 flags |= SkScalerContext::kSubpixelPositioning_Flag;
1033 }
1034 if (font.isForceAutoHinting()) {
1035 flags |= SkScalerContext::kForceAutohinting_Flag;
1036 }
1037 if (font.isLinearMetrics()) {
1038 flags |= SkScalerContext::kLinearMetrics_Flag;
1039 }
1040 if (font.isBaselineSnap()) {
1041 flags |= SkScalerContext::kBaselineSnap_Flag;
1042 }
1043 rec->fFlags = SkToU16(flags);
1044
1045 // these modify fFlags, so do them after assigning fFlags
1046 rec->setHinting(font.getHinting());
1047 rec->setLuminanceColor(SkPaintPriv::ComputeLuminanceColor(paint));
1048
1049 // For now always set the paint gamma equal to the device gamma.
1050 // The math in SkMaskGamma can handle them being different,
1051 // but it requires superluminous masks when
1052 // Ex : deviceGamma(x) < paintGamma(x) and x is sufficiently large.
1053 rec->setDeviceGamma(SK_GAMMA_EXPONENT);
1054 rec->setPaintGamma(SK_GAMMA_EXPONENT);
1055
1056#ifdef SK_GAMMA_CONTRAST
1057 rec->setContrast(SK_GAMMA_CONTRAST);
1058#else
1059 // A value of 0.5 for SK_GAMMA_CONTRAST appears to be a good compromise.
1060 // With lower values small text appears washed out (though correctly so).
1061 // With higher values lcd fringing is worse and the smoothing effect of
1062 // partial coverage is diminished.
1063 rec->setContrast(0.5f);
1064#endif
1065
1066 if (!SkToBool(scalerContextFlags & SkScalerContextFlags::kFakeGamma)) {
1067 rec->ignoreGamma();
1068 }
1069 if (!SkToBool(scalerContextFlags & SkScalerContextFlags::kBoostContrast)) {
1070 rec->setContrast(0);
1071 }
1072
1073 new (effects) SkScalerContextEffects{paint};
1074}
1075
1076SkDescriptor* SkScalerContext::MakeDescriptorForPaths(SkFontID typefaceID,
1077 SkAutoDescriptor* ad) {
1078 SkScalerContextRec rec;
1079 memset((void*)&rec, 0, sizeof(rec));
1080 rec.fFontID = typefaceID;
1081 rec.fTextSize = SkFontPriv::kCanonicalTextSizeForPaths;
1082 rec.fPreScaleX = rec.fPost2x2[0][0] = rec.fPost2x2[1][1] = SK_Scalar1;
1083 return AutoDescriptorGivenRecAndEffects(rec, SkScalerContextEffects(), ad);
1084}
1085
1086SkDescriptor* SkScalerContext::CreateDescriptorAndEffectsUsingPaint(
1087 const SkFont& font, const SkPaint& paint, const SkSurfaceProps& surfaceProps,
1088 SkScalerContextFlags scalerContextFlags, const SkMatrix& deviceMatrix, SkAutoDescriptor* ad,
1089 SkScalerContextEffects* effects)
1090{
1091 SkScalerContextRec rec;
1092 MakeRecAndEffects(font, paint, surfaceProps, scalerContextFlags, deviceMatrix, &rec, effects);
1093 return AutoDescriptorGivenRecAndEffects(rec, *effects, ad);
1094}
1095
1096static size_t calculate_size_and_flatten(const SkScalerContextRec& rec,
1097 const SkScalerContextEffects& effects,
1098 SkBinaryWriteBuffer* effectBuffer) {
1099 size_t descSize = sizeof(rec);
1100 int entryCount = 1;
1101
1102 if (effects.fPathEffect || effects.fMaskFilter) {
1103 if (effects.fPathEffect) { effectBuffer->writeFlattenable(effects.fPathEffect); }
1104 if (effects.fMaskFilter) { effectBuffer->writeFlattenable(effects.fMaskFilter); }
1105 entryCount += 1;
1106 descSize += effectBuffer->bytesWritten();
1107 }
1108
1109 descSize += SkDescriptor::ComputeOverhead(entryCount);
1110 return descSize;
1111}
1112
1113static void generate_descriptor(const SkScalerContextRec& rec,
1114 const SkBinaryWriteBuffer& effectBuffer,
1115 SkDescriptor* desc) {
1116 desc->addEntry(kRec_SkDescriptorTag, sizeof(rec), &rec);
1117
1118 if (effectBuffer.bytesWritten() > 0) {
1119 effectBuffer.writeToMemory(desc->addEntry(kEffects_SkDescriptorTag,
1120 effectBuffer.bytesWritten(),
1121 nullptr));
1122 }
1123
1124 desc->computeChecksum();
1125}
1126
1127SkDescriptor* SkScalerContext::AutoDescriptorGivenRecAndEffects(
1128 const SkScalerContextRec& rec,
1129 const SkScalerContextEffects& effects,
1130 SkAutoDescriptor* ad)
1131{
1132 SkBinaryWriteBuffer buf;
1133
1134 ad->reset(calculate_size_and_flatten(rec, effects, &buf));
1135 generate_descriptor(rec, buf, ad->getDesc());
1136
1137 return ad->getDesc();
1138}
1139
1140std::unique_ptr<SkDescriptor> SkScalerContext::DescriptorGivenRecAndEffects(
1141 const SkScalerContextRec& rec,
1142 const SkScalerContextEffects& effects)
1143{
1144 SkBinaryWriteBuffer buf;
1145
1146 auto desc = SkDescriptor::Alloc(calculate_size_and_flatten(rec, effects, &buf));
1147 generate_descriptor(rec, buf, desc.get());
1148
1149 return desc;
1150}
1151
1152void SkScalerContext::DescriptorBufferGiveRec(const SkScalerContextRec& rec, void* buffer) {
1153 generate_descriptor(rec, SkBinaryWriteBuffer{}, (SkDescriptor*)buffer);
1154}
1155
1156bool SkScalerContext::CheckBufferSizeForRec(const SkScalerContextRec& rec,
1157 const SkScalerContextEffects& effects,
1158 size_t size) {
1159 SkBinaryWriteBuffer buf;
1160 return size >= calculate_size_and_flatten(rec, effects, &buf);
1161}
1162
1163SkScalerContext* SkScalerContext::MakeEmptyContext(
1164 sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
1165 const SkDescriptor* desc) {
1166 class SkScalerContext_Empty : public SkScalerContext {
1167 public:
1168 SkScalerContext_Empty(sk_sp<SkTypeface> typeface, const SkScalerContextEffects& effects,
1169 const SkDescriptor* desc)
1170 : SkScalerContext(std::move(typeface), effects, desc) {}
1171
1172 protected:
1173 unsigned generateGlyphCount() override {
1174 return 0;
1175 }
1176 bool generateAdvance(SkGlyph* glyph) override {
1177 glyph->zeroMetrics();
1178 return true;
1179 }
1180 void generateMetrics(SkGlyph* glyph) override {
1181 glyph->fMaskFormat = fRec.fMaskFormat;
1182 glyph->zeroMetrics();
1183 }
1184 void generateImage(const SkGlyph& glyph) override {}
1185 bool generatePath(SkGlyphID glyph, SkPath* path) override {
1186 path->reset();
1187 return false;
1188 }
1189 void generateFontMetrics(SkFontMetrics* metrics) override {
1190 if (metrics) {
1191 sk_bzero(metrics, sizeof(*metrics));
1192 }
1193 }
1194 };
1195
1196 return new SkScalerContext_Empty{std::move(typeface), effects, desc};
1197}
1198
1199
1200
1201
1202