/* * Copyright 2018 Google LLC * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #include "SkCubicMap.h" #include "SkDashPathEffect.h" #include "SkFloatBits.h" #include "SkFloatingPoint.h" #include "SkMatrix.h" #include "SkPaint.h" #include "SkPaintDefaults.h" #include "SkParsePath.h" #include "SkPath.h" #include "SkPathOps.h" #include "SkRect.h" #include "SkString.h" #include "SkStrokeRec.h" #include "SkTrimPathEffect.h" #include <emscripten/emscripten.h> #include <emscripten/bind.h> using namespace emscripten; static const int MOVE = 0; static const int LINE = 1; static const int QUAD = 2; static const int CONIC = 3; static const int CUBIC = 4; static const int CLOSE = 5; // Just for self-documenting purposes where the main thing being returned is an // SkPath, but in an error case, something of type null (which is val) could also be // returned; using SkPathOrNull = emscripten::val; // Self-documenting for when we return a string using JSString = emscripten::val; using JSArray = emscripten::val; // ================================================================================= // Creating/Exporting Paths with cmd arrays // ================================================================================= template <typename VisitFunc> void VisitPath(const SkPath& p, VisitFunc&& f) { SkPath::RawIter iter(p); SkPoint pts[4]; SkPath::Verb verb; while ((verb = iter.next(pts)) != SkPath::kDone_Verb) { f(verb, pts, iter); } } JSArray EMSCRIPTEN_KEEPALIVE ToCmds(const SkPath& path) { JSArray cmds = emscripten::val::array(); VisitPath(path, [&cmds](SkPath::Verb verb, const SkPoint pts[4], SkPath::RawIter iter) { JSArray cmd = emscripten::val::array(); switch (verb) { case SkPath::kMove_Verb: cmd.call<void>("push", MOVE, pts[0].x(), pts[0].y()); break; case SkPath::kLine_Verb: cmd.call<void>("push", LINE, pts[1].x(), pts[1].y()); break; case SkPath::kQuad_Verb: cmd.call<void>("push", QUAD, pts[1].x(), pts[1].y(), pts[2].x(), pts[2].y()); break; case SkPath::kConic_Verb: cmd.call<void>("push", CONIC, pts[1].x(), pts[1].y(), pts[2].x(), pts[2].y(), iter.conicWeight()); break; case SkPath::kCubic_Verb: cmd.call<void>("push", CUBIC, pts[1].x(), pts[1].y(), pts[2].x(), pts[2].y(), pts[3].x(), pts[3].y()); break; case SkPath::kClose_Verb: cmd.call<void>("push", CLOSE); break; case SkPath::kDone_Verb: SkASSERT(false); break; } cmds.call<void>("push", cmd); }); return cmds; } // This type signature is a mess, but it's necessary. See, we can't use "bind" (EMSCRIPTEN_BINDINGS) // and pointers to primitive types (Only bound types like SkPoint). We could if we used // cwrap (see https://becominghuman.ai/passing-and-returning-webassembly-array-parameters-a0f572c65d97) // but that requires us to stick to C code and, AFAIK, doesn't allow us to return nice things like // SkPath or SkOpBuilder. // // So, basically, if we are using C++ and EMSCRIPTEN_BINDINGS, we can't have primative pointers // in our function type signatures. (this gives an error message like "Cannot call foo due to unbound // types Pi, Pf"). But, we can just pretend they are numbers and cast them to be pointers and // the compiler is happy. SkPathOrNull EMSCRIPTEN_KEEPALIVE FromCmds(uintptr_t /* float* */ cptr, int numCmds) { const auto* cmds = reinterpret_cast<const float*>(cptr); SkPath path; float x1, y1, x2, y2, x3, y3; // if there are not enough arguments, bail with the path we've constructed so far. #define CHECK_NUM_ARGS(n) \ if ((i + n) > numCmds) { \ SkDebugf("Not enough args to match the verbs. Saw %d commands\n", numCmds); \ return emscripten::val::null(); \ } for(int i = 0; i < numCmds;){ switch (sk_float_floor2int(cmds[i++])) { case MOVE: CHECK_NUM_ARGS(2); x1 = cmds[i++], y1 = cmds[i++]; path.moveTo(x1, y1); break; case LINE: CHECK_NUM_ARGS(2); x1 = cmds[i++], y1 = cmds[i++]; path.lineTo(x1, y1); break; case QUAD: CHECK_NUM_ARGS(4); x1 = cmds[i++], y1 = cmds[i++]; x2 = cmds[i++], y2 = cmds[i++]; path.quadTo(x1, y1, x2, y2); break; case CONIC: CHECK_NUM_ARGS(5); x1 = cmds[i++], y1 = cmds[i++]; x2 = cmds[i++], y2 = cmds[i++]; x3 = cmds[i++]; // weight path.conicTo(x1, y1, x2, y2, x3); break; case CUBIC: CHECK_NUM_ARGS(6); x1 = cmds[i++], y1 = cmds[i++]; x2 = cmds[i++], y2 = cmds[i++]; x3 = cmds[i++], y3 = cmds[i++]; path.cubicTo(x1, y1, x2, y2, x3, y3); break; case CLOSE: path.close(); break; default: SkDebugf(" path: UNKNOWN command %f, aborting dump...\n", cmds[i-1]); return emscripten::val::null(); } } #undef CHECK_NUM_ARGS return emscripten::val(path); } SkPath EMSCRIPTEN_KEEPALIVE NewPath() { return SkPath(); } SkPath EMSCRIPTEN_KEEPALIVE CopyPath(const SkPath& a) { SkPath copy(a); return copy; } bool EMSCRIPTEN_KEEPALIVE Equals(const SkPath& a, const SkPath& b) { return a == b; } //======================================================================================== // Path things //======================================================================================== // All these Apply* methods are simple wrappers to avoid returning an object. // The default WASM bindings produce code that will leak if a return value // isn't assigned to a JS variable and has delete() called on it. // These Apply methods, combined with the smarter binding code allow for chainable // commands that don't leak if the return value is ignored (i.e. when used intuitively). void ApplyArcTo(SkPath& p, SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar radius) { p.arcTo(x1, y1, x2, y2, radius); } void ApplyClose(SkPath& p) { p.close(); } void ApplyConicTo(SkPath& p, SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar w) { p.conicTo(x1, y1, x2, y2, w); } void ApplyCubicTo(SkPath& p, SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2, SkScalar x3, SkScalar y3) { p.cubicTo(x1, y1, x2, y2, x3, y3); } void ApplyLineTo(SkPath& p, SkScalar x, SkScalar y) { p.lineTo(x, y); } void ApplyMoveTo(SkPath& p, SkScalar x, SkScalar y) { p.moveTo(x, y); } void ApplyQuadTo(SkPath& p, SkScalar x1, SkScalar y1, SkScalar x2, SkScalar y2) { p.quadTo(x1, y1, x2, y2); } //======================================================================================== // SVG things //======================================================================================== JSString EMSCRIPTEN_KEEPALIVE ToSVGString(const SkPath& path) { SkString s; SkParsePath::ToSVGString(path, &s); // Wrapping it in val automatically turns it into a JS string. // Not too sure on performance implications, but is is simpler than // returning a raw pointer to const char * and then using // Pointer_stringify() on the calling side. return emscripten::val(s.c_str()); } SkPathOrNull EMSCRIPTEN_KEEPALIVE FromSVGString(std::string str) { SkPath path; if (SkParsePath::FromSVGString(str.c_str(), &path)) { return emscripten::val(path); } return emscripten::val::null(); } //======================================================================================== // PATHOP things //======================================================================================== bool EMSCRIPTEN_KEEPALIVE ApplySimplify(SkPath& path) { return Simplify(path, &path); } bool EMSCRIPTEN_KEEPALIVE ApplyPathOp(SkPath& pathOne, const SkPath& pathTwo, SkPathOp op) { return Op(pathOne, pathTwo, op, &pathOne); } SkPathOrNull EMSCRIPTEN_KEEPALIVE MakeFromOp(const SkPath& pathOne, const SkPath& pathTwo, SkPathOp op) { SkPath out; if (Op(pathOne, pathTwo, op, &out)) { return emscripten::val(out); } return emscripten::val::null(); } SkPathOrNull EMSCRIPTEN_KEEPALIVE ResolveBuilder(SkOpBuilder& builder) { SkPath path; if (builder.resolve(&path)) { return emscripten::val(path); } return emscripten::val::null(); } //======================================================================================== // Canvas things //======================================================================================== void EMSCRIPTEN_KEEPALIVE ToCanvas(const SkPath& path, emscripten::val /* Path2D or Canvas*/ ctx) { SkPath::Iter iter(path, false); SkPoint pts[4]; SkPath::Verb verb; while ((verb = iter.next(pts, false)) != SkPath::kDone_Verb) { switch (verb) { case SkPath::kMove_Verb: ctx.call<void>("moveTo", pts[0].x(), pts[0].y()); break; case SkPath::kLine_Verb: ctx.call<void>("lineTo", pts[1].x(), pts[1].y()); break; case SkPath::kQuad_Verb: ctx.call<void>("quadraticCurveTo", pts[1].x(), pts[1].y(), pts[2].x(), pts[2].y()); break; case SkPath::kConic_Verb: SkPoint quads[5]; // approximate with 2^1=2 quads. SkPath::ConvertConicToQuads(pts[0], pts[1], pts[2], iter.conicWeight(), quads, 1); ctx.call<void>("quadraticCurveTo", quads[1].x(), quads[1].y(), quads[2].x(), quads[2].y()); ctx.call<void>("quadraticCurveTo", quads[3].x(), quads[3].y(), quads[4].x(), quads[4].y()); break; case SkPath::kCubic_Verb: ctx.call<void>("bezierCurveTo", pts[1].x(), pts[1].y(), pts[2].x(), pts[2].y(), pts[3].x(), pts[3].y()); break; case SkPath::kClose_Verb: ctx.call<void>("closePath"); break; case SkPath::kDone_Verb: break; } } } emscripten::val JSPath2D = emscripten::val::global("Path2D"); emscripten::val EMSCRIPTEN_KEEPALIVE ToPath2D(const SkPath& path) { emscripten::val retVal = JSPath2D.new_(); ToCanvas(path, retVal); return retVal; } // ====================================================================================== // Path2D API things // ====================================================================================== void ApplyAddRect(SkPath& path, SkScalar x, SkScalar y, SkScalar width, SkScalar height) { path.addRect(x, y, x+width, y+height); } void ApplyAddArc(SkPath& path, SkScalar x, SkScalar y, SkScalar radius, SkScalar startAngle, SkScalar endAngle, bool ccw) { SkPath temp; SkRect bounds = SkRect::MakeLTRB(x-radius, y-radius, x+radius, y+radius); const auto sweep = SkRadiansToDegrees(endAngle - startAngle) - 360 * ccw; temp.addArc(bounds, SkRadiansToDegrees(startAngle), sweep); path.addPath(temp, SkPath::kExtend_AddPathMode); } void ApplyEllipse(SkPath& path, SkScalar x, SkScalar y, SkScalar radiusX, SkScalar radiusY, SkScalar rotation, SkScalar startAngle, SkScalar endAngle, bool ccw) { // This is easiest to do by making a new path and then extending the current path // (this properly catches the cases of if there's a moveTo before this call or not). SkRect bounds = SkRect::MakeLTRB(x-radiusX, y-radiusY, x+radiusX, y+radiusY); SkPath temp; const auto sweep = SkRadiansToDegrees(endAngle - startAngle) - (360 * ccw); temp.addArc(bounds, SkRadiansToDegrees(startAngle), sweep); SkMatrix m; m.setRotate(SkRadiansToDegrees(rotation), x, y); path.addPath(temp, m, SkPath::kExtend_AddPathMode); } // Allows for full matix control. void ApplyAddPath(SkPath& orig, const SkPath& newPath, SkScalar scaleX, SkScalar skewX, SkScalar transX, SkScalar skewY, SkScalar scaleY, SkScalar transY, SkScalar pers0, SkScalar pers1, SkScalar pers2) { SkMatrix m = SkMatrix::MakeAll(scaleX, skewX , transX, skewY , scaleY, transY, pers0 , pers1 , pers2); orig.addPath(newPath, m); } JSString GetFillTypeString(const SkPath& path) { if (path.getFillType() == SkPath::FillType::kWinding_FillType) { return emscripten::val("nonzero"); } else if (path.getFillType() == SkPath::FillType::kEvenOdd_FillType) { return emscripten::val("evenodd"); } else { SkDebugf("warning: can't translate inverted filltype to HTML Canvas\n"); return emscripten::val("nonzero"); //Use default } } //======================================================================================== // Path Effects //======================================================================================== bool ApplyDash(SkPath& path, SkScalar on, SkScalar off, SkScalar phase) { SkScalar intervals[] = { on, off }; auto pe = SkDashPathEffect::Make(intervals, 2, phase); if (!pe) { SkDebugf("Invalid args to dash()\n"); return false; } SkStrokeRec rec(SkStrokeRec::InitStyle::kHairline_InitStyle); if (pe->filterPath(&path, path, &rec, nullptr)) { return true; } SkDebugf("Could not make dashed path\n"); return false; } bool ApplyTrim(SkPath& path, SkScalar startT, SkScalar stopT, bool isComplement) { auto mode = isComplement ? SkTrimPathEffect::Mode::kInverted : SkTrimPathEffect::Mode::kNormal; auto pe = SkTrimPathEffect::Make(startT, stopT, mode); if (!pe) { SkDebugf("Invalid args to trim(): startT and stopT must be in [0,1]\n"); return false; } SkStrokeRec rec(SkStrokeRec::InitStyle::kHairline_InitStyle); if (pe->filterPath(&path, path, &rec, nullptr)) { return true; } SkDebugf("Could not trim path\n"); return false; } struct StrokeOpts { // Default values are set in chaining.js which allows clients // to set any number of them. Otherwise, the binding code complains if // any are omitted. SkScalar width; SkScalar miter_limit; SkPaint::Join join; SkPaint::Cap cap; }; bool ApplyStroke(SkPath& path, StrokeOpts opts) { SkPaint p; p.setStyle(SkPaint::kStroke_Style); p.setStrokeCap(opts.cap); p.setStrokeJoin(opts.join); p.setStrokeWidth(opts.width); p.setStrokeMiter(opts.miter_limit); return p.getFillPath(path, &path); } //======================================================================================== // Matrix things //======================================================================================== struct SimpleMatrix { SkScalar scaleX, skewX, transX; SkScalar skewY, scaleY, transY; SkScalar pers0, pers1, pers2; }; SkMatrix toSkMatrix(const SimpleMatrix& sm) { return SkMatrix::MakeAll(sm.scaleX, sm.skewX , sm.transX, sm.skewY , sm.scaleY, sm.transY, sm.pers0 , sm.pers1 , sm.pers2); } void ApplyTransform(SkPath& orig, const SimpleMatrix& sm) { orig.transform(toSkMatrix(sm)); } void ApplyTransform(SkPath& orig, SkScalar scaleX, SkScalar skewX, SkScalar transX, SkScalar skewY, SkScalar scaleY, SkScalar transY, SkScalar pers0, SkScalar pers1, SkScalar pers2) { SkMatrix m = SkMatrix::MakeAll(scaleX, skewX , transX, skewY , scaleY, transY, pers0 , pers1 , pers2); orig.transform(m); } //======================================================================================== // Testing things //======================================================================================== // The use case for this is on the JS side is something like: // PathKit.SkBits2FloatUnsigned(parseInt("0xc0a00000")) // to have precise float values for tests. In the C++ tests, we can use SkBits2Float because // it takes int32_t, but the JS parseInt basically returns an unsigned int. So, we add in // this helper which casts for us on the way to SkBits2Float. float SkBits2FloatUnsigned(uint32_t floatAsBits) { return SkBits2Float((int32_t) floatAsBits); } // Binds the classes to the JS // // See https://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/embind.html#non-member-functions-on-the-javascript-prototype // for more on binding non-member functions to the JS object, allowing us to rewire // various functions. That is, we can make the SkPath we expose appear to have methods // that the original SkPath does not, like rect(x, y, width, height) and toPath2D(). // // An important detail for binding non-member functions is that the first argument // must be SkPath& (the reference part is very important). // // Note that we can't expose default or optional arguments, but we can have multiple // declarations of the same function that take different amounts of arguments. // For example, see _transform // Additionally, we are perfectly happy to handle default arguments and function // overloads in the JS glue code (see chaining.js::addPath() for an example). EMSCRIPTEN_BINDINGS(skia) { class_<SkPath>("SkPath") .constructor<>() .constructor<const SkPath&>() // Path2D API .function("_addPath", &ApplyAddPath) // 3 additional overloads of addPath are handled in JS bindings .function("_arc", &ApplyAddArc) .function("_arcTo", &ApplyArcTo) //"bezierCurveTo" alias handled in JS bindings .function("_close", &ApplyClose) //"closePath" alias handled in JS bindings .function("_conicTo", &ApplyConicTo) .function("_cubicTo", &ApplyCubicTo) .function("_ellipse", &ApplyEllipse) .function("_lineTo", &ApplyLineTo) .function("_moveTo", &ApplyMoveTo) // "quadraticCurveTo" alias handled in JS bindings .function("_quadTo", &ApplyQuadTo) .function("_rect", &ApplyAddRect) // Extra features .function("setFillType", &SkPath::setFillType) .function("getFillType", &SkPath::getFillType) .function("getFillTypeString", &GetFillTypeString) .function("getBounds", &SkPath::getBounds) .function("computeTightBounds", &SkPath::computeTightBounds) .function("equals", &Equals) .function("copy", &CopyPath) // PathEffects .function("_dash", &ApplyDash) .function("_trim", &ApplyTrim) .function("_stroke", &ApplyStroke) // Matrix .function("_transform", select_overload<void(SkPath& orig, const SimpleMatrix& sm)>(&ApplyTransform)) .function("_transform", select_overload<void(SkPath& orig, SkScalar, SkScalar, SkScalar, SkScalar, SkScalar, SkScalar, SkScalar, SkScalar, SkScalar)>(&ApplyTransform)) // PathOps .function("_simplify", &ApplySimplify) .function("_op", &ApplyPathOp) // Exporting .function("toCmds", &ToCmds) .function("toPath2D", &ToPath2D) .function("toCanvas", &ToCanvas) .function("toSVGString", &ToSVGString) #ifdef PATHKIT_TESTING .function("dump", select_overload<void() const>(&SkPath::dump)) .function("dumpHex", select_overload<void() const>(&SkPath::dumpHex)) #endif ; class_<SkOpBuilder>("SkOpBuilder") .constructor<>() .function("add", &SkOpBuilder::add) .function("make", &ResolveBuilder) .function("resolve", &ResolveBuilder); // Without these function() bindings, the function would be exposed but oblivious to // our types (e.g. SkPath) // Import function("FromSVGString", &FromSVGString); function("NewPath", &NewPath); function("NewPath", &CopyPath); // FromCmds is defined in helper.js to make use of TypedArrays transparent. function("_FromCmds", &FromCmds); // Path2D is opaque, so we can't read in from it. // PathOps function("MakeFromOp", &MakeFromOp); enum_<SkPathOp>("PathOp") .value("DIFFERENCE", SkPathOp::kDifference_SkPathOp) .value("INTERSECT", SkPathOp::kIntersect_SkPathOp) .value("UNION", SkPathOp::kUnion_SkPathOp) .value("XOR", SkPathOp::kXOR_SkPathOp) .value("REVERSE_DIFFERENCE", SkPathOp::kReverseDifference_SkPathOp); enum_<SkPath::FillType>("FillType") .value("WINDING", SkPath::FillType::kWinding_FillType) .value("EVENODD", SkPath::FillType::kEvenOdd_FillType) .value("INVERSE_WINDING", SkPath::FillType::kInverseWinding_FillType) .value("INVERSE_EVENODD", SkPath::FillType::kInverseEvenOdd_FillType); constant("MOVE_VERB", MOVE); constant("LINE_VERB", LINE); constant("QUAD_VERB", QUAD); constant("CONIC_VERB", CONIC); constant("CUBIC_VERB", CUBIC); constant("CLOSE_VERB", CLOSE); // A value object is much simpler than a class - it is returned as a JS // object and does not require delete(). // https://kripken.github.io/emscripten-site/docs/porting/connecting_cpp_and_javascript/embind.html#value-types value_object<SkRect>("SkRect") .field("fLeft", &SkRect::fLeft) .field("fTop", &SkRect::fTop) .field("fRight", &SkRect::fRight) .field("fBottom", &SkRect::fBottom); function("LTRBRect", &SkRect::MakeLTRB); // Stroke enum_<SkPaint::Join>("StrokeJoin") .value("MITER", SkPaint::Join::kMiter_Join) .value("ROUND", SkPaint::Join::kRound_Join) .value("BEVEL", SkPaint::Join::kBevel_Join); enum_<SkPaint::Cap>("StrokeCap") .value("BUTT", SkPaint::Cap::kButt_Cap) .value("ROUND", SkPaint::Cap::kRound_Cap) .value("SQUARE", SkPaint::Cap::kSquare_Cap); value_object<StrokeOpts>("StrokeOpts") .field("width", &StrokeOpts::width) .field("miter_limit", &StrokeOpts::miter_limit) .field("join", &StrokeOpts::join) .field("cap", &StrokeOpts::cap); // Matrix // Allows clients to supply a 1D array of 9 elements and the bindings // will automatically turn it into a 3x3 2D matrix. // e.g. path.transform([0,1,2,3,4,5,6,7,8]) // This is likely simpler for the client than exposing SkMatrix // directly and requiring them to do a lot of .delete(). value_array<SimpleMatrix>("SkMatrix") .element(&SimpleMatrix::scaleX) .element(&SimpleMatrix::skewX) .element(&SimpleMatrix::transX) .element(&SimpleMatrix::skewY) .element(&SimpleMatrix::scaleY) .element(&SimpleMatrix::transY) .element(&SimpleMatrix::pers0) .element(&SimpleMatrix::pers1) .element(&SimpleMatrix::pers2); value_array<SkPoint>("SkPoint") .element(&SkPoint::fX) .element(&SkPoint::fY); // Not intended for external clients to call directly. // See helper.js for the client-facing implementation. class_<SkCubicMap>("_SkCubicMap") .constructor<SkPoint, SkPoint>() .function("computeYFromX", &SkCubicMap::computeYFromX) .function("computePtFromT", &SkCubicMap::computeFromT); // Test Utils function("SkBits2FloatUnsigned", &SkBits2FloatUnsigned); }