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1 /*
2  * Copyright 2019 Google LLC
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 #include "include/core/SkColor.h"
8 #include "include/core/SkFontStyle.h"
9 #include "include/core/SkPictureRecorder.h"
10 #include "include/core/SkString.h"
11 
12 #include "modules/skparagraph/include/DartTypes.h"
13 #include "modules/skparagraph/include/Paragraph.h"
14 #include "modules/skparagraph/include/TextStyle.h"
15 #include "modules/skparagraph/include/TypefaceFontProvider.h"
16 #include "modules/skparagraph/src/ParagraphBuilderImpl.h"
17 #include "modules/skparagraph/src/ParagraphImpl.h"
18 #include "modules/skunicode/include/SkUnicode.h"
19 
20 #if defined(SK_UNICODE_ICU_IMPLEMENTATION)
21 #include "modules/skunicode/include/SkUnicode_icu.h"
22 #endif
23 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
24 #include "modules/skunicode/include/SkUnicode_client.h"
25 #endif
26 
27 #include <string>
28 #include <vector>
29 
30 #include <emscripten.h>
31 #include <emscripten/bind.h>
32 #include "modules/canvaskit/WasmCommon.h"
33 
34 using namespace emscripten;
35 using namespace skia_private;
36 
37 namespace para = skia::textlayout;
38 
39 // switch to ptrToSkColor4f (canvaskit_bindings.cpp)
toSkColor4f(WASMPointerF32 cPtr)40 SkColor4f toSkColor4f(WASMPointerF32 cPtr) {
41     float* fourFloats = reinterpret_cast<float*>(cPtr);
42     SkColor4f color = {fourFloats[0], fourFloats[1], fourFloats[2], fourFloats[3]};
43     return color;
44 }
45 
46 struct SimpleFontStyle {
47     SkFontStyle::Slant slant;
48     SkFontStyle::Weight weight;
49     SkFontStyle::Width width;
50 };
51 
52 // TODO(jlavrova, kjlubick) This should probably be created explicitly by the client
53 // (either one based on ICU data or a client explicitly made) and passed in to build().
get_unicode()54 static sk_sp<SkUnicode> get_unicode() {
55     // For code size reasons, we prefer to use the unicode implementation first
56     // over the full ICU version.
57 #if defined(SK_UNICODE_ICU_IMPLEMENTATION)
58     return SkUnicodes::ICU::Make();
59 #else
60     return nullptr;
61 #endif
62 }
63 
64 struct SimpleTextStyle {
65     WASMPointerF32 colorPtr;
66     WASMPointerF32 foregroundColorPtr;
67     WASMPointerF32 backgroundColorPtr;
68     uint8_t decoration;
69     SkScalar decorationThickness;
70     WASMPointerF32 decorationColorPtr;
71     para::TextDecorationStyle decorationStyle;
72     para::TextBaseline textBaseline;
73     SkScalar fontSize;
74     SkScalar letterSpacing;
75     SkScalar wordSpacing;
76     SkScalar heightMultiplier;
77     bool halfLeading;
78     WASMPointerU8 localePtr;
79     int localeLen;
80     SimpleFontStyle fontStyle;
81 
82     WASMPointerU8 fontFamiliesPtr;
83     int fontFamiliesLen;
84 
85     int shadowLen;
86     WASMPointerF32 shadowColorsPtr;
87     WASMPointerF32 shadowOffsetsPtr;
88     WASMPointerF32 shadowBlurRadiiPtr;
89 
90     int fontFeatureLen;
91     WASMPointerF32 fontFeatureNamesPtr;
92     WASMPointerF32 fontFeatureValuesPtr;
93 
94     int fontVariationLen;
95     WASMPointerF32 fontVariationAxesPtr;
96     WASMPointerF32 fontVariationValuesPtr;
97 };
98 
99 struct SimpleStrutStyle {
100     WASMPointerU32 fontFamiliesPtr;
101     int fontFamiliesLen;
102     SimpleFontStyle fontStyle;
103     SkScalar fontSize;
104     SkScalar heightMultiplier;
105     bool halfLeading;
106     SkScalar leading;
107     bool strutEnabled;
108     bool forceStrutHeight;
109 };
110 
toStrutStyle(const SimpleStrutStyle & s)111 para::StrutStyle toStrutStyle(const SimpleStrutStyle& s) {
112     para::StrutStyle ss;
113 
114     const char** fontFamilies = reinterpret_cast<const char**>(s.fontFamiliesPtr);
115     if (fontFamilies != nullptr) {
116         std::vector<SkString> ff;
117         for (int i = 0; i < s.fontFamiliesLen; i++) {
118             ff.emplace_back(fontFamilies[i]);
119         }
120         ss.setFontFamilies(ff);
121     }
122 
123     SkFontStyle fs(s.fontStyle.weight, s.fontStyle.width, s.fontStyle.slant);
124     ss.setFontStyle(fs);
125 
126     if (s.fontSize != -1) {
127         ss.setFontSize(s.fontSize);
128     }
129     if (s.heightMultiplier != -1) {
130         ss.setHeight(s.heightMultiplier);
131         ss.setHeightOverride(true);
132     }
133     ss.setHalfLeading(s.halfLeading);
134 
135     if (s.leading != 0) {
136         ss.setLeading(s.leading);
137     }
138 
139     ss.setStrutEnabled(s.strutEnabled);
140     ss.setForceStrutHeight(s.forceStrutHeight);
141 
142     return ss;
143 }
144 
toTextStyle(const SimpleTextStyle & s)145 para::TextStyle toTextStyle(const SimpleTextStyle& s) {
146     para::TextStyle ts;
147 
148     // textstyle.color doesn't support a 4f color, however the foreground and background fields
149     // below do.
150     ts.setColor(toSkColor4f(s.colorPtr).toSkColor());
151 
152     // It is functionally important that these paints be unset when no value was provided.
153     if (s.foregroundColorPtr) {
154         SkPaint p1;
155         p1.setColor4f(toSkColor4f(s.foregroundColorPtr));
156         ts.setForegroundColor(p1);
157     }
158 
159     if (s.backgroundColorPtr) {
160         SkPaint p2;
161         p2.setColor4f(toSkColor4f(s.backgroundColorPtr));
162         ts.setBackgroundColor(p2);
163     }
164 
165     if (s.fontSize != -1) {
166         ts.setFontSize(s.fontSize);
167     }
168     if (s.letterSpacing != 0) {
169         ts.setLetterSpacing(s.letterSpacing);
170     }
171     if (s.wordSpacing != 0) {
172         ts.setWordSpacing(s.wordSpacing);
173     }
174 
175     if (s.heightMultiplier != -1) {
176         ts.setHeight(s.heightMultiplier);
177         ts.setHeightOverride(true);
178     }
179 
180     ts.setHalfLeading(s.halfLeading);
181 
182     ts.setDecoration(para::TextDecoration(s.decoration));
183     ts.setDecorationStyle(s.decorationStyle);
184     if (s.decorationThickness != 0) {
185         ts.setDecorationThicknessMultiplier(s.decorationThickness);
186     }
187     if (s.decorationColorPtr) {
188         ts.setDecorationColor(toSkColor4f(s.decorationColorPtr).toSkColor());
189     }
190 
191     if (s.localeLen > 0) {
192         const char* localePtr = reinterpret_cast<const char*>(s.localePtr);
193         SkString lStr(localePtr, s.localeLen);
194         ts.setLocale(lStr);
195     }
196 
197     const char** fontFamilies = reinterpret_cast<const char**>(s.fontFamiliesPtr);
198     if (fontFamilies != nullptr) {
199         std::vector<SkString> ff;
200         for (int i = 0; i < s.fontFamiliesLen; i++) {
201             ff.emplace_back(fontFamilies[i]);
202         }
203         ts.setFontFamilies(ff);
204     }
205 
206     ts.setTextBaseline(s.textBaseline);
207 
208     SkFontStyle fs(s.fontStyle.weight, s.fontStyle.width, s.fontStyle.slant);
209     ts.setFontStyle(fs);
210 
211     if (s.shadowLen > 0) {
212         const SkColor4f* colors = reinterpret_cast<const SkColor4f*>(s.shadowColorsPtr);
213         const SkPoint* offsets = reinterpret_cast<const SkPoint*>(s.shadowOffsetsPtr);
214         const float* blurRadii = reinterpret_cast<const float*>(s.shadowBlurRadiiPtr);
215         for (int i = 0; i < s.shadowLen; i++) {
216             para::TextShadow shadow(colors[i].toSkColor(), offsets[i], blurRadii[i]);
217             ts.addShadow(shadow);
218         }
219     }
220 
221 
222     if (s.fontFeatureLen > 0) {
223         const char** fontFeatureNames = reinterpret_cast<const char**>(s.fontFeatureNamesPtr);
224         const int* fontFeatureValues = reinterpret_cast<const int*>(s.fontFeatureValuesPtr);
225         for (int i = 0; i < s.fontFeatureLen; i++) {
226             // Font features names are 4-character simple strings.
227             SkString name(fontFeatureNames[i], 4);
228             ts.addFontFeature(name, fontFeatureValues[i]);
229         }
230     }
231 
232     if (s.fontVariationLen > 0) {
233         const char** fontVariationAxes = reinterpret_cast<const char**>(s.fontVariationAxesPtr);
234         const float* fontVariationValues = reinterpret_cast<const float*>(s.fontVariationValuesPtr);
235         std::vector<SkFontArguments::VariationPosition::Coordinate> coordinates;
236         for (int i = 0; i < s.fontVariationLen; i++) {
237             // Font variation axis tags are 4-character simple strings.
238             SkString axis(fontVariationAxes[i]);
239             if (axis.size() != 4) {
240                 continue;
241             }
242             coordinates.push_back({
243                 SkSetFourByteTag(axis[0], axis[1], axis[2], axis[3]),
244                 fontVariationValues[i]
245             });
246         }
247         SkFontArguments::VariationPosition position = {
248             coordinates.data(),
249             static_cast<int>(coordinates.size())
250         };
251         ts.setFontArguments(SkFontArguments().setVariationDesignPosition(position));
252     }
253 
254     return ts;
255 }
256 
257 struct SimpleParagraphStyle {
258     bool disableHinting;
259     WASMPointerU8 ellipsisPtr;
260     size_t ellipsisLen;
261     SkScalar heightMultiplier;
262     size_t maxLines;
263     bool replaceTabCharacters;
264     para::TextAlign textAlign;
265     para::TextDirection textDirection;
266     para::TextHeightBehavior textHeightBehavior;
267     SimpleTextStyle textStyle;
268     SimpleStrutStyle strutStyle;
269     bool applyRoundingHack;
270 };
271 
toParagraphStyle(const SimpleParagraphStyle & s)272 para::ParagraphStyle toParagraphStyle(const SimpleParagraphStyle& s) {
273     para::ParagraphStyle ps;
274     if (s.disableHinting) {
275         ps.turnHintingOff();
276     }
277 
278     if (s.ellipsisLen > 0) {
279         const char* ellipsisPtr = reinterpret_cast<const char*>(s.ellipsisPtr);
280         SkString eStr(ellipsisPtr, s.ellipsisLen);
281         ps.setEllipsis(eStr);
282     }
283     ps.setTextAlign(s.textAlign);
284     ps.setTextDirection(s.textDirection);
285     auto ts = toTextStyle(s.textStyle);
286     ps.setTextStyle(ts);
287     auto ss = toStrutStyle(s.strutStyle);
288     ps.setStrutStyle(ss);
289     if (s.heightMultiplier != -1) {
290         ps.setHeight(s.heightMultiplier);
291     }
292     if (s.maxLines != 0) {
293         ps.setMaxLines(s.maxLines);
294     }
295     ps.setApplyRoundingHack(s.applyRoundingHack);
296     ps.setTextHeightBehavior(s.textHeightBehavior);
297     ps.setReplaceTabCharacters(s.replaceTabCharacters);
298     return ps;
299 }
300 
301 struct SimpleTextBox {
302     SkRect rect;
303     // This isn't the most efficient way to represent this, but it is much easier to keep
304     // everything as floats when unpacking on the JS side.
305     // 0.0 = RTL, 1.0 = LTr
306     SkScalar direction;
307 };
308 
TextBoxesToFloat32Array(std::vector<para::TextBox> boxes)309 Float32Array TextBoxesToFloat32Array(std::vector<para::TextBox> boxes) {
310     // Pack these text boxes into an array of n groups of 5 SkScalar (floats)
311     if (!boxes.size()) {
312         return emscripten::val::null();
313     }
314     SimpleTextBox* rects = new SimpleTextBox[boxes.size()];
315     for (size_t i = 0; i < boxes.size(); i++) {
316         rects[i].rect = boxes[i].rect;
317         if (boxes[i].direction == para::TextDirection::kRtl) {
318             rects[i].direction = 0;
319         } else {
320             rects[i].direction = 1;
321         }
322     }
323     float* fPtr = reinterpret_cast<float*>(rects);
324     // Of note: now that we have cast rects to float*, emscripten is smart enough to wrap this
325     // into a Float32Array for us.
326     return Float32Array(typed_memory_view(boxes.size() * 5, fPtr));
327 }
328 
GetRectsForRange(para::Paragraph & self,unsigned start,unsigned end,para::RectHeightStyle heightStyle,para::RectWidthStyle widthStyle)329 Float32Array GetRectsForRange(para::Paragraph& self,
330                               unsigned start,
331                               unsigned end,
332                               para::RectHeightStyle heightStyle,
333                               para::RectWidthStyle widthStyle) {
334     std::vector<para::TextBox> boxes = self.getRectsForRange(start, end, heightStyle, widthStyle);
335     return TextBoxesToFloat32Array(boxes);
336 }
337 
GetRectsForPlaceholders(para::Paragraph & self)338 Float32Array GetRectsForPlaceholders(para::Paragraph& self) {
339     std::vector<para::TextBox> boxes = self.getRectsForPlaceholders();
340     return TextBoxesToFloat32Array(boxes);
341 }
342 
JSObjectFromLineMetrics(skia::textlayout::LineMetrics & metrics)343 JSObject JSObjectFromLineMetrics(skia::textlayout::LineMetrics& metrics) {
344     JSObject m = emscripten::val::object();
345     m.set("startIndex", metrics.fStartIndex);
346     m.set("endIndex", metrics.fEndIndex);
347     m.set("endExcludingWhitespaces", metrics.fEndExcludingWhitespaces);
348     m.set("endIncludingNewline", metrics.fEndIncludingNewline);
349     m.set("isHardBreak", metrics.fHardBreak);
350     m.set("ascent", metrics.fAscent);
351     m.set("descent", metrics.fDescent);
352     m.set("height", metrics.fHeight);
353     m.set("width", metrics.fWidth);
354     m.set("left", metrics.fLeft);
355     m.set("baseline", metrics.fBaseline);
356     m.set("lineNumber", metrics.fLineNumber);
357     return m;
358 }
359 
JSObjectFromGlyphInfo(skia::textlayout::Paragraph::GlyphInfo & glyphInfo)360 JSObject JSObjectFromGlyphInfo(skia::textlayout::Paragraph::GlyphInfo& glyphInfo) {
361     JSObject object = emscripten::val::object();
362 
363     JSObject range = emscripten::val::object();
364     range.set("start", glyphInfo.fGraphemeClusterTextRange.start);
365     range.set("end",  glyphInfo.fGraphemeClusterTextRange.end);
366     object.set("graphemeClusterTextRange", range);
367 
368     JSArray rect = emscripten::val::array();
369     rect.call<void>("push", glyphInfo.fGraphemeLayoutBounds.left());
370     rect.call<void>("push", glyphInfo.fGraphemeLayoutBounds.top());
371     rect.call<void>("push", glyphInfo.fGraphemeLayoutBounds.right());
372     rect.call<void>("push", glyphInfo.fGraphemeLayoutBounds.bottom());
373     object.set("graphemeLayoutBounds", rect);
374 
375     object.set("dir", glyphInfo.fDirection == skia::textlayout::TextDirection::kRtl ? 0 : 1);
376     object.set("isEllipsis", glyphInfo.fIsEllipsis);
377     return object;
378 }
379 
GetLineMetrics(para::Paragraph & self)380 JSArray GetLineMetrics(para::Paragraph& self) {
381     std::vector<skia::textlayout::LineMetrics> metrics;
382     self.getLineMetrics(metrics);
383     JSArray result = emscripten::val::array();
384     for (auto metric : metrics) {
385         result.call<void>("push", JSObjectFromLineMetrics(metric));
386     }
387     return result;
388 }
389 
GetLineMetricsAt(para::Paragraph & self,size_t lineNumber)390 JSObject GetLineMetricsAt(para::Paragraph& self, size_t lineNumber) {
391     skia::textlayout::LineMetrics metrics;
392     return self.getLineMetricsAt(lineNumber, &metrics)
393         ? JSObjectFromLineMetrics(metrics)
394         : emscripten::val::null();
395 }
396 
GetGlyphInfoAt(para::Paragraph & self,size_t index)397 JSObject GetGlyphInfoAt(para::Paragraph& self, size_t index) {
398     skia::textlayout::Paragraph::GlyphInfo glyphInfo;
399     return self.getGlyphInfoAtUTF16Offset(index, &glyphInfo)
400         ? JSObjectFromGlyphInfo(glyphInfo)
401         : emscripten::val::null();
402 }
403 
GetClosestGlyphInfoAtCoordinate(para::Paragraph & self,SkScalar dx,SkScalar dy)404 JSObject GetClosestGlyphInfoAtCoordinate(para::Paragraph& self, SkScalar dx, SkScalar dy) {
405     skia::textlayout::Paragraph::GlyphInfo glyphInfo;
406     return self.getClosestUTF16GlyphInfoAt(dx, dy, &glyphInfo)
407         ? JSObjectFromGlyphInfo(glyphInfo)
408         : emscripten::val::null();
409 }
410 
411 /*
412  *  Returns Lines[]
413  */
GetShapedLines(para::Paragraph & self)414 JSArray GetShapedLines(para::Paragraph& self) {
415     struct LineAccumulate {
416         int         lineNumber  = -1;   // deliberately -1 from starting value
417         uint32_t    minOffset   = 0xFFFFFFFF;
418         uint32_t    maxOffset   = 0;
419         float       minAscent   = 0;
420         float       maxDescent  = 0;
421         // not really accumulated, but definitely set
422         float       baseline    = 0;
423 
424         void reset(int newLineNum) {
425             new (this) LineAccumulate;
426             this->lineNumber = newLineNum;
427         }
428     };
429 
430     // where we accumulate our js output
431     JSArray  jlines = emscripten::val::array();
432     JSObject jline = emscripten::val::null();
433     JSArray  jruns = emscripten::val::null();
434     LineAccumulate accum;
435 
436     self.visit([&](int lineNumber, const para::Paragraph::VisitorInfo* info) {
437         if (!info) {
438             if (!jline) return; // how???
439             // end of current line
440             JSObject range = emscripten::val::object();
441             range.set("first", accum.minOffset);
442             range.set("last",  accum.maxOffset);
443             jline.set("textRange", range);
444 
445             jline.set("top", accum.baseline + accum.minAscent);
446             jline.set("bottom", accum.baseline + accum.maxDescent);
447             jline.set("baseline", accum.baseline);
448             return;
449         }
450 
451         if (lineNumber != accum.lineNumber) {
452             SkASSERT(lineNumber == accum.lineNumber + 1);   // assume monotonic
453 
454             accum.reset(lineNumber);
455             jruns = emscripten::val::array();
456 
457             jline = emscripten::val::object();
458             jline.set("runs", jruns);
459             // will assign textRange and metrics on end-of-line signal
460 
461             jlines.call<void>("push", jline);
462         }
463 
464         // append the run
465         const int N = info->count;   // glyphs
466         const int N1 = N + 1;       // positions, offsets have 1 extra (trailing) slot
467 
468         JSObject jrun = emscripten::val::object();
469 
470         jrun.set("flags",    info->flags);
471 
472         jrun.set("typeface", info->font.refTypeface());
473         jrun.set("size",        info->font.getSize());
474         if (info->font.getScaleX()) {
475             jrun.set("scaleX",  info->font.getScaleX());
476         }
477 
478         jrun.set("glyphs",   MakeTypedArray(N,  info->glyphs));
479         jrun.set("offsets",  MakeTypedArray(N1, info->utf8Starts));
480 
481         // we need to modify the positions, so make a temp copy
482         AutoSTMalloc<32, SkPoint> positions(N1);
483         for (int i = 0; i < N; ++i) {
484             positions.get()[i] = info->positions[i] + info->origin;
485         }
486         positions.get()[N] = { info->advanceX, positions.get()[N - 1].fY };
487         jrun.set("positions", MakeTypedArray(N1*2, (const float*)positions.get()));
488 
489         jruns.call<void>("push", jrun);
490 
491         // update accum
492         {   SkFontMetrics fm;
493             info->font.getMetrics(&fm);
494 
495             accum.minAscent  = std::min(accum.minAscent,  fm.fAscent);
496             accum.maxDescent = std::max(accum.maxDescent, fm.fDescent);
497             accum.baseline   = info->origin.fY;
498 
499             accum.minOffset  = std::min(accum.minOffset,  info->utf8Starts[0]);
500             accum.maxOffset  = std::max(accum.maxOffset,  info->utf8Starts[N]);
501         }
502 
503     });
504     return jlines;
505 }
506 
convertArrayU32(WASMPointerU32 array,size_t count)507 std::vector<SkUnicode::Position> convertArrayU32(WASMPointerU32 array, size_t count) {
508     std::vector<size_t> vec;
509     vec.resize(count);
510     SkUnicode::Position* data = reinterpret_cast<SkUnicode::Position*>(array);
511     std::memcpy(vec.data(), data, count * sizeof(size_t));
512     return vec;
513 }
514 
UnresolvedCodepoints(para::Paragraph & self)515 JSArray UnresolvedCodepoints(para::Paragraph& self) {
516     JSArray result = emscripten::val::array();
517     for (auto cp : self.unresolvedCodepoints()) {
518         result.call<void>("push", cp);
519     }
520     return result;
521 }
522 
EMSCRIPTEN_BINDINGS(Paragraph)523 EMSCRIPTEN_BINDINGS(Paragraph) {
524 
525     class_<para::Paragraph>("Paragraph")
526         .function("didExceedMaxLines", &para::Paragraph::didExceedMaxLines)
527         .function("getAlphabeticBaseline", &para::Paragraph::getAlphabeticBaseline)
528         .function("getGlyphPositionAtCoordinate", &para::Paragraph::getGlyphPositionAtCoordinate)
529         .function("getHeight", &para::Paragraph::getHeight)
530         .function("getIdeographicBaseline", &para::Paragraph::getIdeographicBaseline)
531         .function("getLineMetrics", &GetLineMetrics)
532         .function("getLineMetricsAt", &GetLineMetricsAt)
533         .function("getLineNumberAt", &para::Paragraph::getLineNumberAt)
534         .function("getLongestLine", &para::Paragraph::getLongestLine)
535         .function("getMaxIntrinsicWidth", &para::Paragraph::getMaxIntrinsicWidth)
536         .function("getMaxWidth", &para::Paragraph::getMaxWidth)
537         .function("getMinIntrinsicWidth", &para::Paragraph::getMinIntrinsicWidth)
538         .function("getNumberOfLines", &para::Paragraph::lineNumber)
539         .function("_getClosestGlyphInfoAtCoordinate", &GetClosestGlyphInfoAtCoordinate)
540         .function("_getGlyphInfoAt", &GetGlyphInfoAt)
541         .function("_getRectsForPlaceholders", &GetRectsForPlaceholders)
542         .function("_getRectsForRange", &GetRectsForRange)
543         .function("getShapedLines", &GetShapedLines)
544         .function("getWordBoundary", &para::Paragraph::getWordBoundary)
545         .function("layout", &para::Paragraph::layout)
546         .function("unresolvedCodepoints", &UnresolvedCodepoints);
547 
548     class_<para::ParagraphBuilderImpl>("ParagraphBuilder")
549             .class_function(
550                     "_Make",
551                     optional_override([](SimpleParagraphStyle style, sk_sp<SkFontMgr> fontMgr)
552                                               -> std::unique_ptr<para::ParagraphBuilderImpl> {
553                         auto fc = sk_make_sp<para::FontCollection>();
554                         fc->setDefaultFontManager(fontMgr);
555                         fc->enableFontFallback();
556                         auto ps = toParagraphStyle(style);
557                         auto pb = para::ParagraphBuilderImpl::make(ps, fc, get_unicode());
558                         return std::unique_ptr<para::ParagraphBuilderImpl>(
559                                 static_cast<para::ParagraphBuilderImpl*>(pb.release()));
560                     }),
561                     allow_raw_pointers())
562             .class_function(
563                     "_MakeFromFontProvider",
564                     optional_override([](SimpleParagraphStyle style,
565                                          sk_sp<para::TypefaceFontProvider> fontProvider)
566                                               -> std::unique_ptr<para::ParagraphBuilderImpl> {
567                         auto fc = sk_make_sp<para::FontCollection>();
568                         fc->setDefaultFontManager(fontProvider);
569                         fc->enableFontFallback();
570                         auto ps = toParagraphStyle(style);
571                         auto pb = para::ParagraphBuilderImpl::make(ps, fc, get_unicode());
572                         return std::unique_ptr<para::ParagraphBuilderImpl>(
573                                 static_cast<para::ParagraphBuilderImpl*>(pb.release()));
574                     }),
575                     allow_raw_pointers())
576             .class_function(
577                     "_MakeFromFontCollection",
578                     optional_override([](SimpleParagraphStyle style,
579                                          sk_sp<para::FontCollection> fontCollection)
580                                               -> std::unique_ptr<para::ParagraphBuilderImpl> {
581                         auto ps = toParagraphStyle(style);
582                         auto pb = para::ParagraphBuilderImpl::make(ps, fontCollection, get_unicode());
583                         return std::unique_ptr<para::ParagraphBuilderImpl>(
584                                 static_cast<para::ParagraphBuilderImpl*>(pb.release()));
585                     }),
586                     allow_raw_pointers())
587             .class_function(
588                     "_ShapeText",
589                     optional_override([](JSString jtext, JSArray jruns, float width) -> JSArray {
590                 std::string textStorage = jtext.as<std::string>();
591                 const char* text = textStorage.data();
592                 size_t      textCount = textStorage.size();
593 
594                 auto fc = sk_make_sp<para::FontCollection>();
595                 fc->setDefaultFontManager(SkFontMgr::RefEmpty());
596                 fc->enableFontFallback();
597 
598                 para::ParagraphStyle pstyle;
599                 {
600                     // For the most part this is ignored, since we set an explicit TextStyle
601                     // for all of our text runs, but it is required by SkParagraph.
602                     para::TextStyle style;
603                     style.setFontFamilies({SkString("sans-serif")});
604                     style.setFontSize(32);
605                     pstyle.setTextStyle(style);
606                 }
607 
608                 auto pb = para::ParagraphBuilder::make(pstyle, fc, get_unicode());
609 
610                 // tease apart the FontBlock runs
611                 size_t runCount = jruns["length"].as<size_t>();
612                 for (size_t i = 0; i < runCount; ++i) {
613                     emscripten::val r = jruns[i];
614 
615                     para::TextStyle style;
616                     style.setTypeface(r["typeface"].as< sk_sp<SkTypeface> >());
617                     style.setFontSize(r["size"].as<float>());
618 
619                     const size_t subTextCount = r["length"].as<size_t>();
620                     if (subTextCount > textCount) {
621                         return emscripten::val("block runs exceed text length!");
622                     }
623 
624                     pb->pushStyle(style);
625                     pb->addText(text, subTextCount);
626                     pb->pop();
627 
628                     text += subTextCount;
629                     textCount -= subTextCount;
630                 }
631                 if (textCount != 0) {
632                     return emscripten::val("Didn't have enough block runs to cover text");
633                 }
634 
635                 auto pa = pb->Build();
636                 pa->layout(width);
637 
638                 // workaround until this is fixed in SkParagraph
639                 {
640                     SkPictureRecorder rec;
641                     pa->paint(rec.beginRecording({0,0,9999,9999}), 0, 0);
642                 }
643                 return GetShapedLines(*pa);
644             }),
645             allow_raw_pointers())
646             .class_function("RequiresClientICU", &para::ParagraphBuilderImpl::RequiresClientICU)
647             .function("addText",
648                       optional_override([](para::ParagraphBuilderImpl& self, std::string text) {
649                           return self.addText(text.c_str(), text.length());
650                       }))
651             .function("build", &para::ParagraphBuilderImpl::Build, allow_raw_pointers())
652             .function("build", optional_override([](para::ParagraphBuilderImpl& self) {
653 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
654                           auto [words, graphemeBreaks, lineBreaks] = self.getClientICUData();
655                           auto text = self.getText();
656                           sk_sp<SkUnicode> clientICU = SkUnicodes::Client::Make(text, words, graphemeBreaks, lineBreaks);
657                           self.SetUnicode(clientICU);
658 #endif
659                           return self.Build();
660                       }), allow_raw_pointers())
661             .function("pop", &para::ParagraphBuilderImpl::pop)
662             .function("reset", &para::ParagraphBuilderImpl::Reset, allow_raw_pointers())
663             .function("_pushStyle", optional_override([](para::ParagraphBuilderImpl& self,
664                                                          SimpleTextStyle textStyle) {
665                           auto ts = toTextStyle(textStyle);
666                           self.pushStyle(ts);
667                       }))
668             // A method of pushing a textStyle with paints instead of colors for foreground and
669             // background. Since SimpleTextStyle is a value object, it cannot contain paints, which
670             // are not primitives. This binding is here to accept them. Any color that is specified
671             // in the textStyle is overridden.
672             .function("_pushPaintStyle",
673                       optional_override([](para::ParagraphBuilderImpl& self,
674                                            SimpleTextStyle textStyle, SkPaint foreground,
675                                            SkPaint background) {
676                           auto ts = toTextStyle(textStyle);
677                           ts.setForegroundColor(foreground);
678                           ts.setBackgroundColor(background);
679                           self.pushStyle(ts);
680                       }))
681             .function("_addPlaceholder", optional_override([](para::ParagraphBuilderImpl& self,
682                                                               SkScalar width,
683                                                               SkScalar height,
684                                                               para::PlaceholderAlignment alignment,
685                                                               para::TextBaseline baseline,
686                                                               SkScalar offset) {
687                           para::PlaceholderStyle ps(width, height, alignment, baseline, offset);
688                           self.addPlaceholder(ps);
689                       }))
690             .function("getText",
691                       optional_override([](para::ParagraphBuilderImpl& self) -> JSString {
692                           auto text = self.getText();
693                           return emscripten::val(std::string(text.data(), text.size()).c_str());
694                       }))
695             .function("_setWordsUtf8",
696                       optional_override([](para::ParagraphBuilderImpl& self,
697                                            WASMPointerU32 clientWords, size_t wordsNum) {
698 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
699                       self.setWordsUtf8(convertArrayU32(clientWords, wordsNum));
700 #endif
701                   }))
702             .function("_setWordsUtf16",
703                       optional_override([](para::ParagraphBuilderImpl& self,
704                                            WASMPointerU32 clientWords, size_t wordsNum) {
705 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
706                       self.setWordsUtf16(convertArrayU32(clientWords, wordsNum));
707 #endif
708                   }))
709             .function("_setGraphemeBreaksUtf8",
710                       optional_override([](para::ParagraphBuilderImpl& self,
711                                            WASMPointerU32 clientGraphemes, size_t graphemesNum) {
712 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
713                       self.setGraphemeBreaksUtf8(convertArrayU32(clientGraphemes, graphemesNum));
714 #endif
715                   }))
716             .function("_setGraphemeBreaksUtf16",
717                       optional_override([](para::ParagraphBuilderImpl& self,
718                                            WASMPointerU32 clientGraphemes, size_t graphemesNum) {
719 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
720                       self.setGraphemeBreaksUtf16(convertArrayU32(clientGraphemes, graphemesNum));
721 #endif
722                   }))
723             .function("_setLineBreaksUtf8",
724                       optional_override([](para::ParagraphBuilderImpl& self,
725                                            WASMPointerU32 clientLineBreaks, size_t lineBreaksNum) {
726 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
727                       SkUnicode::Position* lineBreakData = reinterpret_cast<SkUnicode::Position*>(clientLineBreaks);
728                       std::vector<SkUnicode::LineBreakBefore> lineBreaks;
729                       for (size_t i = 0; i < lineBreaksNum; i += 2) {
730                           auto pos = lineBreakData[i];
731                           auto breakType = lineBreakData[i+1];
732                           if (breakType == 0) {
733                               lineBreaks.emplace_back(pos, SkUnicode::LineBreakType::kSoftLineBreak);
734                           } else {
735                               lineBreaks.emplace_back(pos, SkUnicode::LineBreakType::kHardLineBreak);
736                           }
737                       }
738                       self.setLineBreaksUtf8(std::move(lineBreaks));
739 #endif
740                   }))
741             .function("_setLineBreaksUtf16",
742                       optional_override([](para::ParagraphBuilderImpl& self,
743                                            WASMPointerU32 clientLineBreaks, size_t lineBreaksNum) {
744 #if defined(SK_UNICODE_CLIENT_IMPLEMENTATION)
745                       SkUnicode::Position* lineBreakData = reinterpret_cast<SkUnicode::Position*>(clientLineBreaks);
746                       std::vector<SkUnicode::LineBreakBefore> lineBreaks;
747                       for (size_t i = 0; i < lineBreaksNum; i += 2) {
748                           auto pos = lineBreakData[i];
749                           auto breakType = lineBreakData[i+1];
750                           if (breakType == 0) {
751                               lineBreaks.emplace_back(pos, SkUnicode::LineBreakType::kSoftLineBreak);
752                           } else {
753                               lineBreaks.emplace_back(pos, SkUnicode::LineBreakType::kHardLineBreak);
754                           }
755                       }
756                       self.setLineBreaksUtf16(std::move(lineBreaks));
757 #endif
758                   }));
759 
760     class_<para::TypefaceFontProvider, base<SkFontMgr>>("TypefaceFontProvider")
761       .smart_ptr<sk_sp<para::TypefaceFontProvider>>("sk_sp<TypefaceFontProvider>")
762       .class_function("Make", optional_override([]()-> sk_sp<para::TypefaceFontProvider> {
763           return sk_make_sp<para::TypefaceFontProvider>();
764       }))
765       .function("_registerFont", optional_override([](para::TypefaceFontProvider& self,
766                                                       sk_sp<SkTypeface> typeface,
767                                                       WASMPointerU8 familyPtr) {
768           const char* fPtr = reinterpret_cast<const char*>(familyPtr);
769           SkString fStr(fPtr);
770           self.registerTypeface(typeface, fStr);
771       }), allow_raw_pointers());
772 
773     class_<para::FontCollection>("FontCollection")
774       .smart_ptr<sk_sp<para::FontCollection>>("sk_sp<FontCollection>")
775       .class_function("Make", optional_override([]()-> sk_sp<para::FontCollection> {
776           return sk_make_sp<para::FontCollection>();
777       }))
778       .function("setDefaultFontManager", optional_override([](para::FontCollection& self,
779                                                               const sk_sp<para::TypefaceFontProvider>& fontManager) {
780         self.setDefaultFontManager(fontManager);
781       }), allow_raw_pointers())
782       .function("enableFontFallback", &para::FontCollection::enableFontFallback);
783 
784     // These value objects make it easier to send data across the wire.
785     value_object<para::PositionWithAffinity>("PositionWithAffinity")
786         .field("pos",      &para::PositionWithAffinity::position)
787         .field("affinity", &para::PositionWithAffinity::affinity);
788 
789     value_object<SimpleFontStyle>("FontStyle")
790         .field("slant",     &SimpleFontStyle::slant)
791         .field("weight",    &SimpleFontStyle::weight)
792         .field("width",     &SimpleFontStyle::width);
793 
794     value_object<SimpleParagraphStyle>("ParagraphStyle")
795         .field("disableHinting",       &SimpleParagraphStyle::disableHinting)
796         .field("_ellipsisPtr",         &SimpleParagraphStyle::ellipsisPtr)
797         .field("_ellipsisLen",         &SimpleParagraphStyle::ellipsisLen)
798         .field("heightMultiplier",     &SimpleParagraphStyle::heightMultiplier)
799         .field("maxLines",             &SimpleParagraphStyle::maxLines)
800         .field("replaceTabCharacters", &SimpleParagraphStyle::replaceTabCharacters)
801         .field("textAlign",            &SimpleParagraphStyle::textAlign)
802         .field("textDirection",        &SimpleParagraphStyle::textDirection)
803         .field("textHeightBehavior",   &SimpleParagraphStyle::textHeightBehavior)
804         .field("textStyle",            &SimpleParagraphStyle::textStyle)
805         .field("strutStyle",           &SimpleParagraphStyle::strutStyle)
806         .field("applyRoundingHack",    &SimpleParagraphStyle::applyRoundingHack);
807 
808     value_object<SimpleStrutStyle>("StrutStyle")
809         .field("_fontFamiliesPtr", &SimpleStrutStyle::fontFamiliesPtr)
810         .field("_fontFamiliesLen", &SimpleStrutStyle::fontFamiliesLen)
811         .field("strutEnabled",     &SimpleStrutStyle::strutEnabled)
812         .field("fontSize",         &SimpleStrutStyle::fontSize)
813         .field("fontStyle",        &SimpleStrutStyle::fontStyle)
814         .field("heightMultiplier", &SimpleStrutStyle::heightMultiplier)
815         .field("halfLeading",      &SimpleStrutStyle::halfLeading)
816         .field("leading",          &SimpleStrutStyle::leading)
817         .field("forceStrutHeight", &SimpleStrutStyle::forceStrutHeight);
818 
819     value_object<SimpleTextStyle>("TextStyle")
820         .field("_colorPtr",             &SimpleTextStyle::colorPtr)
821         .field("_foregroundColorPtr",   &SimpleTextStyle::foregroundColorPtr)
822         .field("_backgroundColorPtr",   &SimpleTextStyle::backgroundColorPtr)
823         .field("decoration",            &SimpleTextStyle::decoration)
824         .field("decorationThickness",   &SimpleTextStyle::decorationThickness)
825         .field("_decorationColorPtr",   &SimpleTextStyle::decorationColorPtr)
826         .field("decorationStyle",       &SimpleTextStyle::decorationStyle)
827         .field("_fontFamiliesPtr",      &SimpleTextStyle::fontFamiliesPtr)
828         .field("_fontFamiliesLen",      &SimpleTextStyle::fontFamiliesLen)
829         .field("fontSize",              &SimpleTextStyle::fontSize)
830         .field("letterSpacing",         &SimpleTextStyle::letterSpacing)
831         .field("wordSpacing",           &SimpleTextStyle::wordSpacing)
832         .field("heightMultiplier",      &SimpleTextStyle::heightMultiplier)
833         .field("halfLeading",           &SimpleTextStyle::halfLeading)
834         .field("_localePtr",            &SimpleTextStyle::localePtr)
835         .field("_localeLen",            &SimpleTextStyle::localeLen)
836         .field("fontStyle",             &SimpleTextStyle::fontStyle)
837         .field("_shadowLen",            &SimpleTextStyle::shadowLen)
838         .field("_shadowColorsPtr",      &SimpleTextStyle::shadowColorsPtr)
839         .field("_shadowOffsetsPtr",     &SimpleTextStyle::shadowOffsetsPtr)
840         .field("_shadowBlurRadiiPtr",   &SimpleTextStyle::shadowBlurRadiiPtr)
841         .field("_fontFeatureLen",       &SimpleTextStyle::fontFeatureLen)
842         .field("_fontFeatureNamesPtr",  &SimpleTextStyle::fontFeatureNamesPtr)
843         .field("_fontFeatureValuesPtr", &SimpleTextStyle::fontFeatureValuesPtr)
844         .field("_fontVariationLen",     &SimpleTextStyle::fontVariationLen)
845         .field("_fontVariationAxesPtr", &SimpleTextStyle::fontVariationAxesPtr)
846         .field("_fontVariationValuesPtr", &SimpleTextStyle::fontVariationValuesPtr);
847 
848     // The U stands for unsigned - we can't bind a generic/template object, so we have to specify it
849     // with the type we are using.
850     // TODO(kjlubick) make this a typedarray.
851     value_object<para::SkRange<size_t>>("URange")
852         .field("start",    &para::SkRange<size_t>::start)
853         .field("end",      &para::SkRange<size_t>::end);
854 
855     // TextDecoration should be a const because they can be combined
856     constant("NoDecoration", int(para::TextDecoration::kNoDecoration));
857     constant("UnderlineDecoration", int(para::TextDecoration::kUnderline));
858     constant("OverlineDecoration", int(para::TextDecoration::kOverline));
859     constant("LineThroughDecoration", int(para::TextDecoration::kLineThrough));
860 }
861