Home | History | Annotate | Download | only in gl 
      1 /*
      2  * Copyright 2012 Google Inc.
      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 "GrGLPath.h"
      9 #include "GrGLPathRendering.h"
     10 #include "GrGLGpu.h"
     11 #include "GrStyle.h"
     12 
     13 namespace {
     14 inline GrGLubyte verb_to_gl_path_cmd(SkPath::Verb verb) {
     15     static const GrGLubyte gTable[] = {
     16         GR_GL_MOVE_TO,
     17         GR_GL_LINE_TO,
     18         GR_GL_QUADRATIC_CURVE_TO,
     19         GR_GL_CONIC_CURVE_TO,
     20         GR_GL_CUBIC_CURVE_TO,
     21         GR_GL_CLOSE_PATH,
     22     };
     23     GR_STATIC_ASSERT(0 == SkPath::kMove_Verb);
     24     GR_STATIC_ASSERT(1 == SkPath::kLine_Verb);
     25     GR_STATIC_ASSERT(2 == SkPath::kQuad_Verb);
     26     GR_STATIC_ASSERT(3 == SkPath::kConic_Verb);
     27     GR_STATIC_ASSERT(4 == SkPath::kCubic_Verb);
     28     GR_STATIC_ASSERT(5 == SkPath::kClose_Verb);
     29 
     30     SkASSERT(verb >= 0 && (size_t)verb < SK_ARRAY_COUNT(gTable));
     31     return gTable[verb];
     32 }
     33 
     34 #ifdef SK_DEBUG
     35 inline int num_coords(SkPath::Verb verb) {
     36     static const int gTable[] = {
     37         2, // move
     38         2, // line
     39         4, // quad
     40         5, // conic
     41         6, // cubic
     42         0, // close
     43     };
     44     GR_STATIC_ASSERT(0 == SkPath::kMove_Verb);
     45     GR_STATIC_ASSERT(1 == SkPath::kLine_Verb);
     46     GR_STATIC_ASSERT(2 == SkPath::kQuad_Verb);
     47     GR_STATIC_ASSERT(3 == SkPath::kConic_Verb);
     48     GR_STATIC_ASSERT(4 == SkPath::kCubic_Verb);
     49     GR_STATIC_ASSERT(5 == SkPath::kClose_Verb);
     50 
     51     SkASSERT(verb >= 0 && (size_t)verb < SK_ARRAY_COUNT(gTable));
     52     return gTable[verb];
     53 }
     54 #endif
     55 
     56 inline GrGLenum join_to_gl_join(SkPaint::Join join) {
     57     static GrGLenum gSkJoinsToGrGLJoins[] = {
     58         GR_GL_MITER_REVERT,
     59         GR_GL_ROUND,
     60         GR_GL_BEVEL
     61     };
     62     return gSkJoinsToGrGLJoins[join];
     63     GR_STATIC_ASSERT(0 == SkPaint::kMiter_Join);
     64     GR_STATIC_ASSERT(1 == SkPaint::kRound_Join);
     65     GR_STATIC_ASSERT(2 == SkPaint::kBevel_Join);
     66     GR_STATIC_ASSERT(SK_ARRAY_COUNT(gSkJoinsToGrGLJoins) == SkPaint::kJoinCount);
     67 }
     68 
     69 inline GrGLenum cap_to_gl_cap(SkPaint::Cap cap) {
     70     static GrGLenum gSkCapsToGrGLCaps[] = {
     71         GR_GL_FLAT,
     72         GR_GL_ROUND,
     73         GR_GL_SQUARE
     74     };
     75     return gSkCapsToGrGLCaps[cap];
     76     GR_STATIC_ASSERT(0 == SkPaint::kButt_Cap);
     77     GR_STATIC_ASSERT(1 == SkPaint::kRound_Cap);
     78     GR_STATIC_ASSERT(2 == SkPaint::kSquare_Cap);
     79     GR_STATIC_ASSERT(SK_ARRAY_COUNT(gSkCapsToGrGLCaps) == SkPaint::kCapCount);
     80 }
     81 
     82 #ifdef SK_DEBUG
     83 inline void verify_floats(const float* floats, int count) {
     84     for (int i = 0; i < count; ++i) {
     85         SkASSERT(!SkScalarIsNaN(SkFloatToScalar(floats[i])));
     86     }
     87 }
     88 #endif
     89 
     90 inline void points_to_coords(const SkPoint points[], size_t first_point, size_t amount,
     91                              GrGLfloat coords[]) {
     92     for (size_t i = 0;  i < amount; ++i) {
     93         coords[i * 2] =  SkScalarToFloat(points[first_point + i].fX);
     94         coords[i * 2 + 1] = SkScalarToFloat(points[first_point + i].fY);
     95     }
     96 }
     97 
     98 template<bool checkForDegenerates>
     99 inline bool init_path_object_for_general_path(GrGLGpu* gpu, GrGLuint pathID,
    100                                               const SkPath& skPath) {
    101     SkDEBUGCODE(int numCoords = 0);
    102     int verbCnt = skPath.countVerbs();
    103     int pointCnt = skPath.countPoints();
    104     int minCoordCnt = pointCnt * 2;
    105 
    106     SkSTArray<16, GrGLubyte, true> pathCommands(verbCnt);
    107     SkSTArray<16, GrGLfloat, true> pathCoords(minCoordCnt);
    108     bool lastVerbWasMove = true; // A path with just "close;" means "moveto(0,0); close;"
    109     SkPoint points[4];
    110     SkPath::RawIter iter(skPath);
    111     SkPath::Verb verb;
    112     while ((verb = iter.next(points)) != SkPath::kDone_Verb) {
    113         pathCommands.push_back(verb_to_gl_path_cmd(verb));
    114         GrGLfloat coords[6];
    115         int coordsForVerb;
    116         switch (verb) {
    117             case SkPath::kMove_Verb:
    118                 if (checkForDegenerates) {
    119                     lastVerbWasMove = true;
    120                 }
    121                 points_to_coords(points, 0, 1, coords);
    122                 coordsForVerb = 2;
    123                 break;
    124             case SkPath::kLine_Verb:
    125                 if (checkForDegenerates) {
    126                     if (SkPath::IsLineDegenerate(points[0], points[1], true)) {
    127                         return false;
    128                     }
    129                     lastVerbWasMove = false;
    130                 }
    131 
    132                 points_to_coords(points, 1, 1, coords);
    133                 coordsForVerb = 2;
    134                 break;
    135             case SkPath::kConic_Verb:
    136                 if (checkForDegenerates) {
    137                     if (SkPath::IsQuadDegenerate(points[0], points[1], points[2], true)) {
    138                         return false;
    139                     }
    140                     lastVerbWasMove = false;
    141                 }
    142                 points_to_coords(points, 1, 2, coords);
    143                 coords[4] = SkScalarToFloat(iter.conicWeight());
    144                 coordsForVerb = 5;
    145                 break;
    146             case SkPath::kQuad_Verb:
    147                 if (checkForDegenerates) {
    148                     if (SkPath::IsQuadDegenerate(points[0], points[1], points[2], true)) {
    149                         return false;
    150                     }
    151                     lastVerbWasMove = false;
    152                 }
    153                 points_to_coords(points, 1, 2, coords);
    154                 coordsForVerb = 4;
    155                 break;
    156             case SkPath::kCubic_Verb:
    157                 if (checkForDegenerates) {
    158                     if (SkPath::IsCubicDegenerate(points[0], points[1], points[2], points[3],
    159                                                   true)) {
    160                         return false;
    161                     }
    162                     lastVerbWasMove = false;
    163                 }
    164                 points_to_coords(points, 1, 3, coords);
    165                 coordsForVerb = 6;
    166                 break;
    167             case SkPath::kClose_Verb:
    168                 if (checkForDegenerates) {
    169                     if (lastVerbWasMove) {
    170                         // Interpret "move(x,y);close;" as "move(x,y);lineto(x,y);close;".
    171                         // which produces a degenerate segment.
    172                         return false;
    173                     }
    174                 }
    175                 continue;
    176             default:
    177                 SkASSERT(false);  // Not reached.
    178                 continue;
    179         }
    180         SkDEBUGCODE(numCoords += num_coords(verb));
    181         SkDEBUGCODE(verify_floats(coords, coordsForVerb));
    182         pathCoords.push_back_n(coordsForVerb, coords);
    183     }
    184     SkASSERT(verbCnt == pathCommands.count());
    185     SkASSERT(numCoords == pathCoords.count());
    186 
    187     GR_GL_CALL(gpu->glInterface(),
    188                PathCommands(pathID, pathCommands.count(), pathCommands.begin(),
    189                             pathCoords.count(), GR_GL_FLOAT, pathCoords.begin()));
    190     return true;
    191 }
    192 
    193 /*
    194  * For now paths only natively support winding and even odd fill types
    195  */
    196 static GrPathRendering::FillType convert_skpath_filltype(SkPath::FillType fill) {
    197     switch (fill) {
    198         default:
    199             SK_ABORT("Incomplete Switch\n");
    200         case SkPath::kWinding_FillType:
    201         case SkPath::kInverseWinding_FillType:
    202             return GrPathRendering::kWinding_FillType;
    203         case SkPath::kEvenOdd_FillType:
    204         case SkPath::kInverseEvenOdd_FillType:
    205             return GrPathRendering::kEvenOdd_FillType;
    206     }
    207 }
    208 
    209 } // namespace
    210 
    211 bool GrGLPath::InitPathObjectPathDataCheckingDegenerates(GrGLGpu* gpu, GrGLuint pathID,
    212                                                          const SkPath& skPath) {
    213     return init_path_object_for_general_path<true>(gpu, pathID, skPath);
    214 }
    215 
    216 void GrGLPath::InitPathObjectPathData(GrGLGpu* gpu,
    217                                       GrGLuint pathID,
    218                                       const SkPath& skPath) {
    219     SkASSERT(!skPath.isEmpty());
    220 
    221 #if 1  //  SK_SCALAR_IS_FLOAT
    222     // This branch does type punning, converting SkPoint* to GrGLfloat*.
    223     if ((skPath.getSegmentMasks() & SkPath::kConic_SegmentMask) == 0) {
    224         int verbCnt = skPath.countVerbs();
    225         int pointCnt = skPath.countPoints();
    226         int coordCnt = pointCnt * 2;
    227         SkSTArray<16, GrGLubyte, true> pathCommands(verbCnt);
    228         SkSTArray<16, GrGLfloat, true> pathCoords(coordCnt);
    229 
    230         static_assert(sizeof(SkPoint) == sizeof(GrGLfloat) * 2, "sk_point_not_two_floats");
    231 
    232         pathCommands.resize_back(verbCnt);
    233         pathCoords.resize_back(coordCnt);
    234         skPath.getPoints(reinterpret_cast<SkPoint*>(&pathCoords[0]), pointCnt);
    235         skPath.getVerbs(&pathCommands[0], verbCnt);
    236 
    237         SkDEBUGCODE(int verbCoordCnt = 0);
    238         for (int i = 0; i < verbCnt; ++i) {
    239             SkPath::Verb v = static_cast<SkPath::Verb>(pathCommands[i]);
    240             pathCommands[i] = verb_to_gl_path_cmd(v);
    241             SkDEBUGCODE(verbCoordCnt += num_coords(v));
    242         }
    243         SkASSERT(verbCnt == pathCommands.count());
    244         SkASSERT(verbCoordCnt == pathCoords.count());
    245         SkDEBUGCODE(verify_floats(&pathCoords[0], pathCoords.count()));
    246         GR_GL_CALL(gpu->glInterface(), PathCommands(pathID, pathCommands.count(), &pathCommands[0],
    247                                                     pathCoords.count(), GR_GL_FLOAT,
    248                                                     &pathCoords[0]));
    249         return;
    250     }
    251 #endif
    252     SkAssertResult(init_path_object_for_general_path<false>(gpu, pathID, skPath));
    253 }
    254 
    255 void GrGLPath::InitPathObjectStroke(GrGLGpu* gpu, GrGLuint pathID, const SkStrokeRec& stroke) {
    256     SkASSERT(!stroke.isHairlineStyle());
    257     GR_GL_CALL(gpu->glInterface(),
    258                PathParameterf(pathID, GR_GL_PATH_STROKE_WIDTH, SkScalarToFloat(stroke.getWidth())));
    259     GR_GL_CALL(gpu->glInterface(),
    260                PathParameterf(pathID, GR_GL_PATH_MITER_LIMIT, SkScalarToFloat(stroke.getMiter())));
    261     GrGLenum join = join_to_gl_join(stroke.getJoin());
    262     GR_GL_CALL(gpu->glInterface(), PathParameteri(pathID, GR_GL_PATH_JOIN_STYLE, join));
    263     GrGLenum cap = cap_to_gl_cap(stroke.getCap());
    264     GR_GL_CALL(gpu->glInterface(), PathParameteri(pathID, GR_GL_PATH_END_CAPS, cap));
    265     GR_GL_CALL(gpu->glInterface(), PathParameterf(pathID, GR_GL_PATH_STROKE_BOUND, 0.02f));
    266 }
    267 
    268 void GrGLPath::InitPathObjectEmptyPath(GrGLGpu* gpu, GrGLuint pathID) {
    269     GR_GL_CALL(gpu->glInterface(), PathCommands(pathID, 0, nullptr, 0, GR_GL_FLOAT, nullptr));
    270 }
    271 
    272 GrGLPath::GrGLPath(GrGLGpu* gpu, const SkPath& origSkPath, const GrStyle& style)
    273     : INHERITED(gpu, origSkPath, style),
    274       fPathID(gpu->glPathRendering()->genPaths(1)) {
    275 
    276     if (origSkPath.isEmpty()) {
    277         InitPathObjectEmptyPath(gpu, fPathID);
    278         fShouldStroke = false;
    279         fShouldFill = false;
    280     } else {
    281         const SkPath* skPath = &origSkPath;
    282         SkTLazy<SkPath> tmpPath;
    283         SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
    284 
    285         if (style.pathEffect()) {
    286             // Skia stroking and NVPR stroking differ with respect to dashing
    287             // pattern.
    288             // Convert a dashing (or other path effect) to either a stroke or a fill.
    289             if (style.applyPathEffectToPath(tmpPath.init(), &stroke, *skPath, SK_Scalar1)) {
    290                 skPath = tmpPath.get();
    291             }
    292         } else {
    293             stroke = style.strokeRec();
    294         }
    295 
    296         bool didInit = false;
    297         if (stroke.needToApply() && stroke.getCap() != SkPaint::kButt_Cap) {
    298             // Skia stroking and NVPR stroking differ with respect to stroking
    299             // end caps of empty subpaths.
    300             // Convert stroke to fill if path contains empty subpaths.
    301             didInit = InitPathObjectPathDataCheckingDegenerates(gpu, fPathID, *skPath);
    302             if (!didInit) {
    303                 if (!tmpPath.isValid()) {
    304                     tmpPath.init();
    305                 }
    306                 SkAssertResult(stroke.applyToPath(tmpPath.get(), *skPath));
    307                 skPath = tmpPath.get();
    308                 stroke.setFillStyle();
    309             }
    310         }
    311 
    312         if (!didInit) {
    313             InitPathObjectPathData(gpu, fPathID, *skPath);
    314         }
    315 
    316         fShouldStroke = stroke.needToApply();
    317         fShouldFill = stroke.isFillStyle() ||
    318                 stroke.getStyle() == SkStrokeRec::kStrokeAndFill_Style;
    319 
    320         fFillType = convert_skpath_filltype(skPath->getFillType());
    321         fBounds = skPath->getBounds();
    322         SkScalar radius = stroke.getInflationRadius();
    323         fBounds.outset(radius, radius);
    324         if (fShouldStroke) {
    325             InitPathObjectStroke(gpu, fPathID, stroke);
    326         }
    327     }
    328 
    329     this->registerWithCache(SkBudgeted::kYes);
    330 }
    331 
    332 void GrGLPath::onRelease() {
    333     if (0 != fPathID) {
    334         static_cast<GrGLGpu*>(this->getGpu())->glPathRendering()->deletePaths(fPathID, 1);
    335         fPathID = 0;
    336     }
    337 
    338     INHERITED::onRelease();
    339 }
    340 
    341 void GrGLPath::onAbandon() {
    342     fPathID = 0;
    343 
    344     INHERITED::onAbandon();
    345 }
    346