text: /*
   * Copyright 2014 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  
  #include "GrDashOp.h"
  #include "GrAppliedClip.h"
  #include "GrCaps.h"
  #include "GrContext.h"
  #include "GrCoordTransform.h"
  #include "GrDefaultGeoProcFactory.h"
  #include "GrDrawOpTest.h"
  #include "GrGeometryProcessor.h"
  #include "GrOpFlushState.h"
  #include "GrProcessor.h"
  #include "GrStyle.h"
  #include "SkGr.h"
  #include "glsl/GrGLSLFragmentShaderBuilder.h"
  #include "glsl/GrGLSLGeometryProcessor.h"
  #include "glsl/GrGLSLProgramDataManager.h"
  #include "glsl/GrGLSLUniformHandler.h"
  #include "glsl/GrGLSLVarying.h"
  #include "glsl/GrGLSLVertexGeoBuilder.h"
  #include "ops/GrMeshDrawOp.h"
  
  using AAMode = GrDashOp::AAMode;
  
  ///////////////////////////////////////////////////////////////////////////////
  
  // Returns whether or not the gpu can fast path the dash line effect.
  bool GrDashOp::CanDrawDashLine(const SkPoint pts[2], const GrStyle& style,
                                 const SkMatrix& viewMatrix) {
      // Pts must be either horizontal or vertical in src space
      if (pts[0].fX != pts[1].fX && pts[0].fY != pts[1].fY) {
          return false;
      }
  
      // May be able to relax this to include skew. As of now cannot do perspective
      // because of the non uniform scaling of bloating a rect
      if (!viewMatrix.preservesRightAngles()) {
          return false;
      }
  
      if (!style.isDashed() || 2 != style.dashIntervalCnt()) {
          return false;
      }
  
      const SkScalar* intervals = style.dashIntervals();
      if (0 == intervals[0] && 0 == intervals[1]) {
          return false;
      }
  
      SkPaint::Cap cap = style.strokeRec().getCap();
      if (SkPaint::kRound_Cap == cap) {
          // Current we don't support round caps unless the on interval is zero
          if (intervals[0] != 0.f) {
              return false;
          }
          // If the width of the circle caps in greater than the off interval we will pick up unwanted
          // segments of circles at the start and end of the dash line.
          if (style.strokeRec().getWidth() > intervals[1]) {
              return false;
          }
      }
  
      return true;
  }
  
  namespace {
  struct DashLineVertex {
      SkPoint fPos;
      SkPoint fDashPos;
      SkScalar fIntervalLength;
      SkRect fRect;
  };
  struct DashCircleVertex {
      SkPoint fPos;
      SkPoint fDashPos;
      SkScalar fIntervalLength;
      SkScalar fRadius;
      SkScalar fCenterX;
  };
  };
  
  static void calc_dash_scaling(SkScalar* parallelScale, SkScalar* perpScale,
                              const SkMatrix& viewMatrix, const SkPoint pts[2]) {
      SkVector vecSrc = pts[1] - pts[0];
      SkScalar magSrc = vecSrc.length();
      SkScalar invSrc = magSrc ? SkScalarInvert(magSrc) : 0;
      vecSrc.scale(invSrc);
  
      SkVector vecSrcPerp;
      vecSrc.rotateCW(&vecSrcPerp);
      viewMatrix.mapVectors(&vecSrc, 1);
      viewMatrix.mapVectors(&vecSrcPerp, 1);
  
      // parallelScale tells how much to scale along the line parallel to the dash line
      // perpScale tells how much to scale in the direction perpendicular to the dash line
      *parallelScale = vecSrc.length();
      *perpScale = vecSrcPerp.length();
  }
  
  // calculates the rotation needed to aligned pts to the x axis with pts[0] < pts[1]
  // Stores the rotation matrix in rotMatrix, and the mapped points in ptsRot
  static void align_to_x_axis(const SkPoint pts[2], SkMatrix* rotMatrix, SkPoint ptsRot[2] = nullptr) {
      SkVector vec = pts[1] - pts[0];
      SkScalar mag = vec.length();
      SkScalar inv = mag ? SkScalarInvert(mag) : 0;
  
      vec.scale(inv);
      rotMatrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
      if (ptsRot) {
          rotMatrix->mapPoints(ptsRot, pts, 2);
          // correction for numerical issues if map doesn't make ptsRot exactly horizontal
          ptsRot[1].fY = pts[0].fY;
      }
  }
  
  // Assumes phase < sum of all intervals
  static SkScalar calc_start_adjustment(const SkScalar intervals[2], SkScalar phase) {
      SkASSERT(phase < intervals[0] + intervals[1]);
      if (phase >= intervals[0] && phase != 0) {
          SkScalar srcIntervalLen = intervals[0] + intervals[1];
          return srcIntervalLen - phase;
      }
      return 0;
  }
  
  static SkScalar calc_end_adjustment(const SkScalar intervals[2], const SkPoint pts[2],
                                      SkScalar phase, SkScalar* endingInt) {
      if (pts[1].fX <= pts[0].fX) {
          return 0;
      }
      SkScalar srcIntervalLen = intervals[0] + intervals[1];
      SkScalar totalLen = pts[1].fX - pts[0].fX;
      SkScalar temp = totalLen / srcIntervalLen;
      SkScalar numFullIntervals = SkScalarFloorToScalar(temp);
      *endingInt = totalLen - numFullIntervals * srcIntervalLen + phase;
      temp = *endingInt / srcIntervalLen;
      *endingInt = *endingInt - SkScalarFloorToScalar(temp) * srcIntervalLen;
      if (0 == *endingInt) {
          *endingInt = srcIntervalLen;
      }
      if (*endingInt > intervals[0]) {
          return *endingInt - intervals[0];
      }
      return 0;
  }
  
  enum DashCap {
      kRound_DashCap,
      kNonRound_DashCap,
  };
  
  static int kDashVertices = 4;
  
  template <typename T>
  void setup_dashed_rect_common(const SkRect& rect, const SkMatrix& matrix, T* vertices, int idx,
                                SkScalar offset, SkScalar bloatX, SkScalar bloatY, SkScalar len,
                                SkScalar stroke) {
      SkScalar startDashX = offset - bloatX;
      SkScalar endDashX = offset + len + bloatX;
      SkScalar startDashY = -stroke - bloatY;
      SkScalar endDashY = stroke + bloatY;
      vertices[idx].fDashPos = SkPoint::Make(startDashX , startDashY);
      vertices[idx + 1].fDashPos = SkPoint::Make(startDashX, endDashY);
      vertices[idx + 2].fDashPos = SkPoint::Make(endDashX, startDashY);
      vertices[idx + 3].fDashPos = SkPoint::Make(endDashX, endDashY);
  
      vertices[idx].fPos = SkPoint::Make(rect.fLeft, rect.fTop);
      vertices[idx + 1].fPos = SkPoint::Make(rect.fLeft, rect.fBottom);
      vertices[idx + 2].fPos = SkPoint::Make(rect.fRight, rect.fTop);
      vertices[idx + 3].fPos = SkPoint::Make(rect.fRight, rect.fBottom);
  
      matrix.mapPointsWithStride(&vertices[idx].fPos, sizeof(T), 4);
  }
  
  static void setup_dashed_rect(const SkRect& rect, void* vertices, int idx,
                                const SkMatrix& matrix, SkScalar offset, SkScalar bloatX,
                                SkScalar bloatY, SkScalar len, SkScalar stroke,
                                SkScalar startInterval, SkScalar endInterval, SkScalar strokeWidth,
                                DashCap cap, const size_t vertexStride) {
      SkScalar intervalLength = startInterval + endInterval;
  
      if (kRound_DashCap == cap) {
          SkASSERT(vertexStride == sizeof(DashCircleVertex));
          DashCircleVertex* verts = reinterpret_cast<DashCircleVertex*>(vertices);
  
          setup_dashed_rect_common<DashCircleVertex>(rect, matrix, verts, idx, offset, bloatX,
                                                     bloatY, len, stroke);
  
          SkScalar radius = SkScalarHalf(strokeWidth) - 0.5f;
          SkScalar centerX = SkScalarHalf(endInterval);
  
          for (int i = 0; i < kDashVertices; i++) {
              verts[idx + i].fIntervalLength = intervalLength;
              verts[idx + i].fRadius = radius;
              verts[idx + i].fCenterX = centerX;
          }
      } else {
          SkASSERT(kNonRound_DashCap == cap && vertexStride == sizeof(DashLineVertex));
          DashLineVertex* verts = reinterpret_cast<DashLineVertex*>(vertices);
  
          setup_dashed_rect_common<DashLineVertex>(rect, matrix, verts, idx, offset, bloatX,
                                                   bloatY, len, stroke);
  
          SkScalar halfOffLen = SkScalarHalf(endInterval);
          SkScalar halfStroke = SkScalarHalf(strokeWidth);
          SkRect rectParam;
          rectParam.set(halfOffLen + 0.5f, -halfStroke + 0.5f,
                        halfOffLen + startInterval - 0.5f, halfStroke - 0.5f);
          for (int i = 0; i < kDashVertices; i++) {
              verts[idx + i].fIntervalLength = intervalLength;
              verts[idx + i].fRect = rectParam;
          }
      }
  }
  
  static void setup_dashed_rect_pos(const SkRect& rect, int idx, const SkMatrix& matrix,
                                    SkPoint* verts) {
      verts[idx] = SkPoint::Make(rect.fLeft, rect.fTop);
      verts[idx + 1] = SkPoint::Make(rect.fLeft, rect.fBottom);
      verts[idx + 2] = SkPoint::Make(rect.fRight, rect.fTop);
      verts[idx + 3] = SkPoint::Make(rect.fRight, rect.fBottom);
      matrix.mapPoints(&verts[idx], 4);
  }
  
  
  /**
   * An GrGeometryProcessor that renders a dashed line.
   * This GrGeometryProcessor is meant for dashed lines that only have a single on/off interval pair.
   * Bounding geometry is rendered and the effect computes coverage based on the fragment's
   * position relative to the dashed line.
   */
  static sk_sp<GrGeometryProcessor> make_dash_gp(GrColor,
                                                 AAMode aaMode,
                                                 DashCap cap,
                                                 const SkMatrix& localMatrix,
                                                 bool usesLocalCoords);
  
  class DashOp final : public GrMeshDrawOp {
  public:
      DEFINE_OP_CLASS_ID
  
      struct LineData {
          SkMatrix fViewMatrix;
          SkMatrix fSrcRotInv;
          SkPoint fPtsRot[2];
          SkScalar fSrcStrokeWidth;
          SkScalar fPhase;
          SkScalar fIntervals[2];
          SkScalar fParallelScale;
          SkScalar fPerpendicularScale;
      };
  
      static std::unique_ptr<GrDrawOp> Make(GrPaint&& paint, const LineData& geometry,
                                            SkPaint::Cap cap, AAMode aaMode, bool fullDash,
                                            const GrUserStencilSettings* stencilSettings) {
          return std::unique_ptr<GrDrawOp>(
                  new DashOp(std::move(paint), geometry, cap, aaMode, fullDash, stencilSettings));
      }
  
      const char* name() const override { return "DashOp"; }
  
      void visitProxies(const VisitProxyFunc& func) const override {
          fProcessorSet.visitProxies(func);
      }
  
      SkString dumpInfo() const override {
          SkString string;
          for (const auto& geo : fLines) {
              string.appendf("Pt0: [%.2f, %.2f], Pt1: [%.2f, %.2f], Width: %.2f, Ival0: %.2f, "
                             "Ival1 : %.2f, Phase: %.2f\n",
                             geo.fPtsRot[0].fX, geo.fPtsRot[0].fY,
                             geo.fPtsRot[1].fX, geo.fPtsRot[1].fY,
                             geo.fSrcStrokeWidth,
                             geo.fIntervals[0],
                             geo.fIntervals[1],
                             geo.fPhase);
          }
          string += fProcessorSet.dumpProcessors();
          string += INHERITED::dumpInfo();
          return string;
      }
  
      FixedFunctionFlags fixedFunctionFlags() const override {
          FixedFunctionFlags flags = FixedFunctionFlags::kNone;
          if (AAMode::kCoverageWithMSAA == fAAMode) {
              flags |= FixedFunctionFlags::kUsesHWAA;
          }
          if (fStencilSettings != &GrUserStencilSettings::kUnused) {
              flags |= FixedFunctionFlags::kUsesStencil;
          }
          return flags;
      }
  
      RequiresDstTexture finalize(const GrCaps& caps, const GrAppliedClip* clip,
                                  GrPixelConfigIsClamped dstIsClamped) override {
          GrProcessorAnalysisCoverage coverage;
          if (AAMode::kNone == fAAMode && !clip->numClipCoverageFragmentProcessors()) {
              coverage = GrProcessorAnalysisCoverage::kNone;
          } else {
              coverage = GrProcessorAnalysisCoverage::kSingleChannel;
          }
          auto analysis = fProcessorSet.finalize(fColor, coverage, clip, false, caps, dstIsClamped,
                                                 &fColor);
          fDisallowCombineOnTouchOrOverlap = analysis.requiresDstTexture() ||
                                             (fProcessorSet.xferProcessor() &&
                                              fProcessorSet.xferProcessor()->xferBarrierType(caps));
          fUsesLocalCoords = analysis.usesLocalCoords();
          return analysis.requiresDstTexture() ? RequiresDstTexture::kYes : RequiresDstTexture::kNo;
      }
  
  private:
      DashOp(GrPaint&& paint, const LineData& geometry, SkPaint::Cap cap, AAMode aaMode,
             bool fullDash, const GrUserStencilSettings* stencilSettings)
              : INHERITED(ClassID())
              , fColor(paint.getColor())
              , fAllowsSRGBInputs(paint.getAllowSRGBInputs())
              , fDisableSRGBOutputConversion(paint.getDisableOutputConversionToSRGB())
              , fFullDash(fullDash)
              , fCap(cap)
              , fAAMode(aaMode)
              , fProcessorSet(std::move(paint))
              , fStencilSettings(stencilSettings) {
          fLines.push_back(geometry);
  
          // compute bounds
          SkScalar halfStrokeWidth = 0.5f * geometry.fSrcStrokeWidth;
          SkScalar xBloat = SkPaint::kButt_Cap == cap ? 0 : halfStrokeWidth;
          SkRect bounds;
          bounds.set(geometry.fPtsRot[0], geometry.fPtsRot[1]);
          bounds.outset(xBloat, halfStrokeWidth);
  
          // Note, we actually create the combined matrix here, and save the work
          SkMatrix& combinedMatrix = fLines[0].fSrcRotInv;
          combinedMatrix.postConcat(geometry.fViewMatrix);
  
          IsZeroArea zeroArea = geometry.fSrcStrokeWidth ? IsZeroArea::kNo : IsZeroArea::kYes;
          HasAABloat aaBloat = (aaMode == AAMode::kNone) ? HasAABloat ::kNo : HasAABloat::kYes;
          this->setTransformedBounds(bounds, combinedMatrix, aaBloat, zeroArea);
      }
  
      struct DashDraw {
          DashDraw(const LineData& geo) {
              memcpy(fPtsRot, geo.fPtsRot, sizeof(geo.fPtsRot));
              memcpy(fIntervals, geo.fIntervals, sizeof(geo.fIntervals));
              fPhase = geo.fPhase;
          }
          SkPoint fPtsRot[2];
          SkScalar fIntervals[2];
          SkScalar fPhase;
          SkScalar fStartOffset;
          SkScalar fStrokeWidth;
          SkScalar fLineLength;
          SkScalar fHalfDevStroke;
          SkScalar fDevBloatX;
          SkScalar fDevBloatY;
          bool fLineDone;
          bool fHasStartRect;
          bool fHasEndRect;
      };
  
      void onPrepareDraws(Target* target) override {
          int instanceCount = fLines.count();
          SkPaint::Cap cap = this->cap();
          bool isRoundCap = SkPaint::kRound_Cap == cap;
          DashCap capType = isRoundCap ? kRound_DashCap : kNonRound_DashCap;
  
          sk_sp<GrGeometryProcessor> gp;
          if (this->fullDash()) {
              gp = make_dash_gp(this->color(), this->aaMode(), capType, this->viewMatrix(),
                                fUsesLocalCoords);
          } else {
              // Set up the vertex data for the line and start/end dashes
              using namespace GrDefaultGeoProcFactory;
              Color color(this->color());
              LocalCoords::Type localCoordsType =
                      fUsesLocalCoords ? LocalCoords::kUsePosition_Type : LocalCoords::kUnused_Type;
              gp = MakeForDeviceSpace(color, Coverage::kSolid_Type, localCoordsType,
                                      this->viewMatrix());
          }
  
          if (!gp) {
              SkDebugf("Could not create GrGeometryProcessor\n");
              return;
          }
  
          // useAA here means Edge AA or MSAA
          bool useAA = this->aaMode() != AAMode::kNone;
          bool fullDash = this->fullDash();
  
          // We do two passes over all of the dashes.  First we setup the start, end, and bounds,
          // rectangles.  We preserve all of this work in the rects / draws arrays below.  Then we
          // iterate again over these decomposed dashes to generate vertices
          static const int kNumStackDashes = 128;
          SkSTArray<kNumStackDashes, SkRect, true> rects;
          SkSTArray<kNumStackDashes, DashDraw, true> draws;
  
          int totalRectCount = 0;
          int rectOffset = 0;
          rects.push_back_n(3 * instanceCount);
          for (int i = 0; i < instanceCount; i++) {
              const LineData& args = fLines[i];
  
              DashDraw& draw = draws.push_back(args);
  
              bool hasCap = SkPaint::kButt_Cap != cap;
  
              // We always want to at least stroke out half a pixel on each side in device space
              // so 0.5f / perpScale gives us this min in src space
              SkScalar halfSrcStroke =
                      SkMaxScalar(args.fSrcStrokeWidth * 0.5f, 0.5f / args.fPerpendicularScale);
  
              SkScalar strokeAdj;
              if (!hasCap) {
                  strokeAdj = 0.f;
              } else {
                  strokeAdj = halfSrcStroke;
              }
  
              SkScalar startAdj = 0;
  
              bool lineDone = false;
  
              // Too simplify the algorithm, we always push back rects for start and end rect.
              // Otherwise we'd have to track start / end rects for each individual geometry
              SkRect& bounds = rects[rectOffset++];
              SkRect& startRect = rects[rectOffset++];
              SkRect& endRect = rects[rectOffset++];
  
              bool hasStartRect = false;
              // If we are using AA, check to see if we are drawing a partial dash at the start. If so
              // draw it separately here and adjust our start point accordingly
              if (useAA) {
                  if (draw.fPhase > 0 && draw.fPhase < draw.fIntervals[0]) {
                      SkPoint startPts[2];
                      startPts[0] = draw.fPtsRot[0];
                      startPts[1].fY = startPts[0].fY;
                      startPts[1].fX = SkMinScalar(startPts[0].fX + draw.fIntervals[0] - draw.fPhase,
                                                   draw.fPtsRot[1].fX);
                      startRect.set(startPts, 2);
                      startRect.outset(strokeAdj, halfSrcStroke);
  
                      hasStartRect = true;
                      startAdj = draw.fIntervals[0] + draw.fIntervals[1] - draw.fPhase;
                  }
              }
  
              // adjustments for start and end of bounding rect so we only draw dash intervals
              // contained in the original line segment.
              startAdj += calc_start_adjustment(draw.fIntervals, draw.fPhase);
              if (startAdj != 0) {
                  draw.fPtsRot[0].fX += startAdj;
                  draw.fPhase = 0;
              }
              SkScalar endingInterval = 0;
              SkScalar endAdj = calc_end_adjustment(draw.fIntervals, draw.fPtsRot, draw.fPhase,
                                                    &endingInterval);
              draw.fPtsRot[1].fX -= endAdj;
              if (draw.fPtsRot[0].fX >= draw.fPtsRot[1].fX) {
                  lineDone = true;
              }
  
              bool hasEndRect = false;
              // If we are using AA, check to see if we are drawing a partial dash at then end. If so
              // draw it separately here and adjust our end point accordingly
              if (useAA && !lineDone) {
                  // If we adjusted the end then we will not be drawing a partial dash at the end.
                  // If we didn't adjust the end point then we just need to make sure the ending
                  // dash isn't a full dash
                  if (0 == endAdj && endingInterval != draw.fIntervals[0]) {
                      SkPoint endPts[2];
                      endPts[1] = draw.fPtsRot[1];
                      endPts[0].fY = endPts[1].fY;
                      endPts[0].fX = endPts[1].fX - endingInterval;
  
                      endRect.set(endPts, 2);
                      endRect.outset(strokeAdj, halfSrcStroke);
  
                      hasEndRect = true;
                      endAdj = endingInterval + draw.fIntervals[1];
  
                      draw.fPtsRot[1].fX -= endAdj;
                      if (draw.fPtsRot[0].fX >= draw.fPtsRot[1].fX) {
                          lineDone = true;
                      }
                  }
              }
  
              if (startAdj != 0) {
                  draw.fPhase = 0;
              }
  
              // Change the dashing info from src space into device space
              SkScalar* devIntervals = draw.fIntervals;
              devIntervals[0] = draw.fIntervals[0] * args.fParallelScale;
              devIntervals[1] = draw.fIntervals[1] * args.fParallelScale;
              SkScalar devPhase = draw.fPhase * args.fParallelScale;
              SkScalar strokeWidth = args.fSrcStrokeWidth * args.fPerpendicularScale;
  
              if ((strokeWidth < 1.f && useAA) || 0.f == strokeWidth) {
                  strokeWidth = 1.f;
              }
  
              SkScalar halfDevStroke = strokeWidth * 0.5f;
  
              if (SkPaint::kSquare_Cap == cap) {
                  // add cap to on interval and remove from off interval
                  devIntervals[0] += strokeWidth;
                  devIntervals[1] -= strokeWidth;
              }
              SkScalar startOffset = devIntervals[1] * 0.5f + devPhase;
  
              // For EdgeAA, we bloat in X & Y for both square and round caps.
              // For MSAA, we don't bloat at all for square caps, and bloat in Y only for round caps.
              SkScalar devBloatX = this->aaMode() == AAMode::kCoverage ? 0.5f : 0.0f;
              SkScalar devBloatY;
              if (SkPaint::kRound_Cap == cap && this->aaMode() == AAMode::kCoverageWithMSAA) {
                  devBloatY = 0.5f;
              } else {
                  devBloatY = devBloatX;
              }
  
              SkScalar bloatX = devBloatX / args.fParallelScale;
              SkScalar bloatY = devBloatY / args.fPerpendicularScale;
  
              if (devIntervals[1] <= 0.f && useAA) {
                  // Case when we end up drawing a solid AA rect
                  // Reset the start rect to draw this single solid rect
                  // but it requires to upload a new intervals uniform so we can mimic
                  // one giant dash
                  draw.fPtsRot[0].fX -= hasStartRect ? startAdj : 0;
                  draw.fPtsRot[1].fX += hasEndRect ? endAdj : 0;
                  startRect.set(draw.fPtsRot, 2);
                  startRect.outset(strokeAdj, halfSrcStroke);
                  hasStartRect = true;
                  hasEndRect = false;
                  lineDone = true;
  
                  SkPoint devicePts[2];
                  args.fViewMatrix.mapPoints(devicePts, draw.fPtsRot, 2);
                  SkScalar lineLength = SkPoint::Distance(devicePts[0], devicePts[1]);
                  if (hasCap) {
                      lineLength += 2.f * halfDevStroke;
                  }
                  devIntervals[0] = lineLength;
              }
  
              totalRectCount += !lineDone ? 1 : 0;
              totalRectCount += hasStartRect ? 1 : 0;
              totalRectCount += hasEndRect ? 1 : 0;
  
              if (SkPaint::kRound_Cap == cap && 0 != args.fSrcStrokeWidth) {
                  // need to adjust this for round caps to correctly set the dashPos attrib on
                  // vertices
                  startOffset -= halfDevStroke;
              }
  
              if (!lineDone) {
                  SkPoint devicePts[2];
                  args.fViewMatrix.mapPoints(devicePts, draw.fPtsRot, 2);
                  draw.fLineLength = SkPoint::Distance(devicePts[0], devicePts[1]);
                  if (hasCap) {
                      draw.fLineLength += 2.f * halfDevStroke;
                  }
  
                  bounds.set(draw.fPtsRot[0].fX, draw.fPtsRot[0].fY,
                             draw.fPtsRot[1].fX, draw.fPtsRot[1].fY);
                  bounds.outset(bloatX + strokeAdj, bloatY + halfSrcStroke);
              }
  
              if (hasStartRect) {
                  SkASSERT(useAA);  // so that we know bloatX and bloatY have been set
                  startRect.outset(bloatX, bloatY);
              }
  
              if (hasEndRect) {
                  SkASSERT(useAA);  // so that we know bloatX and bloatY have been set
                  endRect.outset(bloatX, bloatY);
              }
  
              draw.fStartOffset = startOffset;
              draw.fDevBloatX = devBloatX;
              draw.fDevBloatY = devBloatY;
              draw.fHalfDevStroke = halfDevStroke;
              draw.fStrokeWidth = strokeWidth;
              draw.fHasStartRect = hasStartRect;
              draw.fLineDone = lineDone;
              draw.fHasEndRect = hasEndRect;
          }
  
          if (!totalRectCount) {
              return;
          }
  
          QuadHelper helper;
          void* vertices = helper.init(target, gp->getVertexStride(), totalRectCount);
          if (!vertices) {
              return;
          }
  
          int curVIdx = 0;
          int rectIndex = 0;
          for (int i = 0; i < instanceCount; i++) {
              const LineData& geom = fLines[i];
  
              if (!draws[i].fLineDone) {
                  if (fullDash) {
                      setup_dashed_rect(rects[rectIndex], vertices, curVIdx, geom.fSrcRotInv,
                                        draws[i].fStartOffset, draws[i].fDevBloatX,
                                        draws[i].fDevBloatY, draws[i].fLineLength,
                                        draws[i].fHalfDevStroke, draws[i].fIntervals[0],
                                        draws[i].fIntervals[1], draws[i].fStrokeWidth,
                                        capType, gp->getVertexStride());
                  } else {
                      SkPoint* verts = reinterpret_cast<SkPoint*>(vertices);
                      SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
                      setup_dashed_rect_pos(rects[rectIndex], curVIdx, geom.fSrcRotInv, verts);
                  }
                  curVIdx += 4;
              }
              rectIndex++;
  
              if (draws[i].fHasStartRect) {
                  if (fullDash) {
                      setup_dashed_rect(rects[rectIndex], vertices, curVIdx, geom.fSrcRotInv,
                                        draws[i].fStartOffset, draws[i].fDevBloatX,
                                        draws[i].fDevBloatY, draws[i].fIntervals[0],
                                        draws[i].fHalfDevStroke, draws[i].fIntervals[0],
                                        draws[i].fIntervals[1], draws[i].fStrokeWidth, capType,
                                        gp->getVertexStride());
                  } else {
                      SkPoint* verts = reinterpret_cast<SkPoint*>(vertices);
                      SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
                      setup_dashed_rect_pos(rects[rectIndex], curVIdx, geom.fSrcRotInv, verts);
                  }
                  curVIdx += 4;
              }
              rectIndex++;
  
              if (draws[i].fHasEndRect) {
                  if (fullDash) {
                      setup_dashed_rect(rects[rectIndex], vertices, curVIdx, geom.fSrcRotInv,
                                        draws[i].fStartOffset, draws[i].fDevBloatX,
                                        draws[i].fDevBloatY, draws[i].fIntervals[0],
                                        draws[i].fHalfDevStroke, draws[i].fIntervals[0],
                                        draws[i].fIntervals[1], draws[i].fStrokeWidth, capType,
                                        gp->getVertexStride());
                  } else {
                      SkPoint* verts = reinterpret_cast<SkPoint*>(vertices);
                      SkASSERT(gp->getVertexStride() == sizeof(SkPoint));
                      setup_dashed_rect_pos(rects[rectIndex], curVIdx, geom.fSrcRotInv, verts);
                  }
                  curVIdx += 4;
              }
              rectIndex++;
          }
          SkASSERT(0 == (curVIdx % 4) && (curVIdx / 4) == totalRectCount);
          uint32_t pipelineFlags = 0;
          if (AAMode::kCoverageWithMSAA == fAAMode) {
              pipelineFlags |= GrPipeline::kHWAntialias_Flag;
          }
          if (fDisableSRGBOutputConversion) {
              pipelineFlags |= GrPipeline::kDisableOutputConversionToSRGB_Flag;
          }
          if (fAllowsSRGBInputs) {
              pipelineFlags |= GrPipeline::kAllowSRGBInputs_Flag;
          }
          const GrPipeline* pipeline = target->makePipeline(pipelineFlags, std::move(fProcessorSet),
                                                            target->detachAppliedClip());
          helper.recordDraw(target, gp.get(), pipeline);
      }
  
      bool onCombineIfPossible(GrOp* t, const GrCaps& caps) override {
          DashOp* that = t->cast<DashOp>();
          if (fProcessorSet != that->fProcessorSet) {
              return false;
          }
          if (fDisallowCombineOnTouchOrOverlap &&
              GrRectsTouchOrOverlap(this->bounds(), that->bounds())) {
              return false;
          }
  
          if (this->aaMode() != that->aaMode()) {
              return false;
          }
  
          if (this->fullDash() != that->fullDash()) {
              return false;
          }
  
          if (this->cap() != that->cap()) {
              return false;
          }
  
          // TODO vertex color
          if (this->color() != that->color()) {
              return false;
          }
  
          if (fUsesLocalCoords && !this->viewMatrix().cheapEqualTo(that->viewMatrix())) {
              return false;
          }
  
          fLines.push_back_n(that->fLines.count(), that->fLines.begin());
          this->joinBounds(*that);
          return true;
      }
  
      GrColor color() const { return fColor; }
      const SkMatrix& viewMatrix() const { return fLines[0].fViewMatrix; }
      AAMode aaMode() const { return fAAMode; }
      bool fullDash() const { return fFullDash; }
      SkPaint::Cap cap() const { return fCap; }
  
      static const int kVertsPerDash = 4;
      static const int kIndicesPerDash = 6;
  
      SkSTArray<1, LineData, true> fLines;
      GrColor fColor;
      bool fAllowsSRGBInputs : 1;
      bool fDisableSRGBOutputConversion : 1;
      bool fDisallowCombineOnTouchOrOverlap : 1;
      bool fUsesLocalCoords : 1;
      bool fFullDash : 1;
      // We use 3 bits for this 3-value enum because MSVS makes the underlying types signed.
      SkPaint::Cap fCap : 3;
      AAMode fAAMode;
      GrProcessorSet fProcessorSet;
      const GrUserStencilSettings* fStencilSettings;
  
      typedef GrMeshDrawOp INHERITED;
  };
  
  std::unique_ptr<GrDrawOp> GrDashOp::MakeDashLineOp(GrPaint&& paint,
                                                     const SkMatrix& viewMatrix,
                                                     const SkPoint pts[2],
                                                     AAMode aaMode,
                                                     const GrStyle& style,
                                                     const GrUserStencilSettings* stencilSettings) {
      SkASSERT(GrDashOp::CanDrawDashLine(pts, style, viewMatrix));
      const SkScalar* intervals = style.dashIntervals();
      SkScalar phase = style.dashPhase();
  
      SkPaint::Cap cap = style.strokeRec().getCap();
  
      DashOp::LineData lineData;
      lineData.fSrcStrokeWidth = style.strokeRec().getWidth();
  
      // the phase should be normalized to be [0, sum of all intervals)
      SkASSERT(phase >= 0 && phase < intervals[0] + intervals[1]);
  
      // Rotate the src pts so they are aligned horizontally with pts[0].fX < pts[1].fX
      if (pts[0].fY != pts[1].fY || pts[0].fX > pts[1].fX) {
          SkMatrix rotMatrix;
          align_to_x_axis(pts, &rotMatrix, lineData.fPtsRot);
          if (!rotMatrix.invert(&lineData.fSrcRotInv)) {
              SkDebugf("Failed to create invertible rotation matrix!\n");
              return nullptr;
          }
      } else {
          lineData.fSrcRotInv.reset();
          memcpy(lineData.fPtsRot, pts, 2 * sizeof(SkPoint));
      }
  
      // Scale corrections of intervals and stroke from view matrix
      calc_dash_scaling(&lineData.fParallelScale, &lineData.fPerpendicularScale, viewMatrix,
                        lineData.fPtsRot);
  
      SkScalar offInterval = intervals[1] * lineData.fParallelScale;
      SkScalar strokeWidth = lineData.fSrcStrokeWidth * lineData.fPerpendicularScale;
  
      if (SkPaint::kSquare_Cap == cap && 0 != lineData.fSrcStrokeWidth) {
          // add cap to on interveal and remove from off interval
          offInterval -= strokeWidth;
      }
  
      // TODO we can do a real rect call if not using fulldash(ie no off interval, not using AA)
      bool fullDash = offInterval > 0.f || aaMode != AAMode::kNone;
  
      lineData.fViewMatrix = viewMatrix;
      lineData.fPhase = phase;
      lineData.fIntervals[0] = intervals[0];
      lineData.fIntervals[1] = intervals[1];
  
      return DashOp::Make(std::move(paint), lineData, cap, aaMode, fullDash, stencilSettings);
  }
  
  //////////////////////////////////////////////////////////////////////////////
  
  class GLDashingCircleEffect;
  
  /*
   * This effect will draw a dotted line (defined as a dashed lined with round caps and no on
   * interval). The radius of the dots is given by the strokeWidth and the spacing by the DashInfo.
   * Both of the previous two parameters are in device space. This effect also requires the setting of
   * a float2 vertex attribute for the the four corners of the bounding rect. This attribute is the
   * "dash position" of each vertex. In other words it is the vertex coords (in device space) if we
   * transform the line to be horizontal, with the start of line at the origin then shifted to the
   * right by half the off interval. The line then goes in the positive x direction.
   */
  class DashingCircleEffect : public GrGeometryProcessor {
  public:
      typedef SkPathEffect::DashInfo DashInfo;
  
      static sk_sp<GrGeometryProcessor> Make(GrColor,
                                             AAMode aaMode,
                                             const SkMatrix& localMatrix,
                                             bool usesLocalCoords);
  
      const char* name() const override { return "DashingCircleEffect"; }
  
      const Attribute* inPosition() const { return fInPosition; }
  
      const Attribute* inDashParams() const { return fInDashParams; }
  
      const Attribute* inCircleParams() const { return fInCircleParams; }
  
      AAMode aaMode() const { return fAAMode; }
  
      GrColor color() const { return fColor; }
  
      const SkMatrix& localMatrix() const { return fLocalMatrix; }
  
      bool usesLocalCoords() const { return fUsesLocalCoords; }
  
      void getGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder* b) const override;
  
      GrGLSLPrimitiveProcessor* createGLSLInstance(const GrShaderCaps&) const override;
  
  private:
      DashingCircleEffect(GrColor, AAMode aaMode, const SkMatrix& localMatrix,
                          bool usesLocalCoords);
  
      GrColor             fColor;
      SkMatrix            fLocalMatrix;
      bool                fUsesLocalCoords;
      AAMode              fAAMode;
      const Attribute*    fInPosition;
      const Attribute*    fInDashParams;
      const Attribute*    fInCircleParams;
  
      GR_DECLARE_GEOMETRY_PROCESSOR_TEST
  
      typedef GrGeometryProcessor INHERITED;
  };
  
  //////////////////////////////////////////////////////////////////////////////
  
  class GLDashingCircleEffect : public GrGLSLGeometryProcessor {
  public:
      GLDashingCircleEffect();
  
      void onEmitCode(EmitArgs&, GrGPArgs*) override;
  
      static inline void GenKey(const GrGeometryProcessor&,
                                const GrShaderCaps&,
                                GrProcessorKeyBuilder*);
  
      void setData(const GrGLSLProgramDataManager&, const GrPrimitiveProcessor&,
                   FPCoordTransformIter&& transformIter) override;
  private:
      UniformHandle fParamUniform;
      UniformHandle fColorUniform;
      GrColor       fColor;
      SkScalar      fPrevRadius;
      SkScalar      fPrevCenterX;
      SkScalar      fPrevIntervalLength;
      typedef GrGLSLGeometryProcessor INHERITED;
  };
  
  GLDashingCircleEffect::GLDashingCircleEffect() {
      fColor = GrColor_ILLEGAL;
      fPrevRadius = SK_ScalarMin;
      fPrevCenterX = SK_ScalarMin;
      fPrevIntervalLength = SK_ScalarMax;
  }
  
  void GLDashingCircleEffect::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
      const DashingCircleEffect& dce = args.fGP.cast<DashingCircleEffect>();
      GrGLSLVertexBuilder* vertBuilder = args.fVertBuilder;
      GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
      GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
  
      // emit attributes
      varyingHandler->emitAttributes(dce);
  
      // XY are dashPos, Z is dashInterval
      GrGLSLVertToFrag dashParams(kHalf3_GrSLType);
      varyingHandler->addVarying("DashParam", &dashParams);
      vertBuilder->codeAppendf("%s = %s;", dashParams.vsOut(), dce.inDashParams()->fName);
  
      // x refers to circle radius - 0.5, y refers to cicle's center x coord
      GrGLSLVertToFrag circleParams(kHalf2_GrSLType);
      varyingHandler->addVarying("CircleParams", &circleParams);
      vertBuilder->codeAppendf("%s = %s;", circleParams.vsOut(), dce.inCircleParams()->fName);
  
      GrGLSLPPFragmentBuilder* fragBuilder = args.fFragBuilder;
      // Setup pass through color
      this->setupUniformColor(fragBuilder, uniformHandler, args.fOutputColor, &fColorUniform);
  
      // Setup position
      this->writeOutputPosition(vertBuilder, gpArgs, dce.inPosition()->fName);
  
      // emit transforms
      this->emitTransforms(vertBuilder,
                           varyingHandler,
                           uniformHandler,
                           gpArgs->fPositionVar,
                           dce.inPosition()->fName,
                           dce.localMatrix(),
                           args.fFPCoordTransformHandler);
  
      // transforms all points so that we can compare them to our test circle
      fragBuilder->codeAppendf("half xShifted = %s.x - floor(%s.x / %s.z) * %s.z;",
                               dashParams.fsIn(), dashParams.fsIn(), dashParams.fsIn(),
                               dashParams.fsIn());
      fragBuilder->codeAppendf("half2 fragPosShifted = half2(xShifted, %s.y);", dashParams.fsIn());
      fragBuilder->codeAppendf("half2 center = half2(%s.y, 0.0);", circleParams.fsIn());
      fragBuilder->codeAppend("half dist = length(center - fragPosShifted);");
      if (dce.aaMode() != AAMode::kNone) {
          fragBuilder->codeAppendf("half diff = dist - %s.x;", circleParams.fsIn());
          fragBuilder->codeAppend("diff = 1.0 - diff;");
          fragBuilder->codeAppend("half alpha = clamp(diff, 0.0, 1.0);");
      } else {
          fragBuilder->codeAppendf("half alpha = 1.0;");
          fragBuilder->codeAppendf("alpha *=  dist < %s.x + 0.5 ? 1.0 : 0.0;", circleParams.fsIn());
      }
      fragBuilder->codeAppendf("%s = half4(alpha);", args.fOutputCoverage);
  }
  
  void GLDashingCircleEffect::setData(const GrGLSLProgramDataManager& pdman,
                                      const GrPrimitiveProcessor& processor,
                                      FPCoordTransformIter&& transformIter)  {
      const DashingCircleEffect& dce = processor.cast<DashingCircleEffect>();
      if (dce.color() != fColor) {
          float c[4];
          GrColorToRGBAFloat(dce.color(), c);
          pdman.set4fv(fColorUniform, 1, c);
          fColor = dce.color();
      }
      this->setTransformDataHelper(dce.localMatrix(), pdman, &transformIter);
  }
  
  void GLDashingCircleEffect::GenKey(const GrGeometryProcessor& gp,
                                     const GrShaderCaps&,
                                     GrProcessorKeyBuilder* b) {
      const DashingCircleEffect& dce = gp.cast<DashingCircleEffect>();
      uint32_t key = 0;
      key |= dce.usesLocalCoords() && dce.localMatrix().hasPerspective() ? 0x1 : 0x0;
      key |= static_cast<uint32_t>(dce.aaMode()) << 1;
      b->add32(key);
  }
  
  //////////////////////////////////////////////////////////////////////////////
  
  sk_sp<GrGeometryProcessor> DashingCircleEffect::Make(GrColor color,
                                                       AAMode aaMode,
                                                       const SkMatrix& localMatrix,
                                                       bool usesLocalCoords) {
      return sk_sp<GrGeometryProcessor>(
          new DashingCircleEffect(color, aaMode, localMatrix, usesLocalCoords));
  }
  
  void DashingCircleEffect::getGLSLProcessorKey(const GrShaderCaps& caps,
                                                GrProcessorKeyBuilder* b) const {
      GLDashingCircleEffect::GenKey(*this, caps, b);
  }
  
  GrGLSLPrimitiveProcessor* DashingCircleEffect::createGLSLInstance(const GrShaderCaps&) const {
      return new GLDashingCircleEffect();
  }
  
  DashingCircleEffect::DashingCircleEffect(GrColor color,
                                           AAMode aaMode,
                                           const SkMatrix& localMatrix,
                                           bool usesLocalCoords)
      : INHERITED(kDashingCircleEffect_ClassID)
      , fColor(color)
      , fLocalMatrix(localMatrix)
      , fUsesLocalCoords(usesLocalCoords)
      , fAAMode(aaMode) {
      fInPosition = &this->addVertexAttrib("inPosition", kFloat2_GrVertexAttribType);
      fInDashParams = &this->addVertexAttrib("inDashParams", kHalf3_GrVertexAttribType);
      fInCircleParams = &this->addVertexAttrib("inCircleParams", kHalf2_GrVertexAttribType);
  }
  
  GR_DEFINE_GEOMETRY_PROCESSOR_TEST(DashingCircleEffect);
  
  #if GR_TEST_UTILS
  sk_sp<GrGeometryProcessor> DashingCircleEffect::TestCreate(GrProcessorTestData* d) {
      AAMode aaMode = static_cast<AAMode>(d->fRandom->nextULessThan(GrDashOp::kAAModeCnt));
      return DashingCircleEffect::Make(GrRandomColor(d->fRandom),
                                      aaMode, GrTest::TestMatrix(d->fRandom),
                                      d->fRandom->nextBool());
  }
  #endif
  
  //////////////////////////////////////////////////////////////////////////////
  
  class GLDashingLineEffect;
  
  /*
   * This effect will draw a dashed line. The width of the dash is given by the strokeWidth and the
   * length and spacing by the DashInfo. Both of the previous two parameters are in device space.
   * This effect also requires the setting of a float2 vertex attribute for the the four corners of the
   * bounding rect. This attribute is the "dash position" of each vertex. In other words it is the
   * vertex coords (in device space) if we transform the line to be horizontal, with the start of
   * line at the origin then shifted to the right by half the off interval. The line then goes in the
   * positive x direction.
   */
  class DashingLineEffect : public GrGeometryProcessor {
  public:
      typedef SkPathEffect::DashInfo DashInfo;
  
      static sk_sp<GrGeometryProcessor> Make(GrColor,
                                             AAMode aaMode,
                                             const SkMatrix& localMatrix,
                                             bool usesLocalCoords);
  
      const char* name() const override { return "DashingEffect"; }
  
      const Attribute* inPosition() const { return fInPosition; }
  
      const Attribute* inDashParams() const { return fInDashParams; }
  
      const Attribute* inRectParams() const { return fInRectParams; }
  
      AAMode aaMode() const { return fAAMode; }
  
      GrColor color() const { return fColor; }
  
       const SkMatrix& localMatrix() const { return fLocalMatrix; }
  
      bool usesLocalCoords() const { return fUsesLocalCoords; }
  
      void getGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override;
  
      GrGLSLPrimitiveProcessor* createGLSLInstance(const GrShaderCaps&) const override;
  
  private:
      DashingLineEffect(GrColor, AAMode aaMode, const SkMatrix& localMatrix,
                        bool usesLocalCoords);
  
      GrColor             fColor;
      SkMatrix            fLocalMatrix;
      bool                fUsesLocalCoords;
      AAMode              fAAMode;
      const Attribute*    fInPosition;
      const Attribute*    fInDashParams;
      const Attribute*    fInRectParams;
  
      GR_DECLARE_GEOMETRY_PROCESSOR_TEST
  
      typedef GrGeometryProcessor INHERITED;
  };
  
  //////////////////////////////////////////////////////////////////////////////
  
  class GLDashingLineEffect : public GrGLSLGeometryProcessor {
  public:
      GLDashingLineEffect();
  
      void onEmitCode(EmitArgs&, GrGPArgs*) override;
  
      static inline void GenKey(const GrGeometryProcessor&,
                                const GrShaderCaps&,
                                GrProcessorKeyBuilder*);
  
      void setData(const GrGLSLProgramDataManager&, const GrPrimitiveProcessor&,
                   FPCoordTransformIter&& iter) override;
  
  private:
      GrColor       fColor;
      UniformHandle fColorUniform;
      typedef GrGLSLGeometryProcessor INHERITED;
  };
  
  GLDashingLineEffect::GLDashingLineEffect() : fColor(GrColor_ILLEGAL) {}
  
  void GLDashingLineEffect::onEmitCode(EmitArgs& args, GrGPArgs* gpArgs) {
      const DashingLineEffect& de = args.fGP.cast<DashingLineEffect>();
  
      GrGLSLVertexBuilder* vertBuilder = args.fVertBuilder;
      GrGLSLVaryingHandler* varyingHandler = args.fVaryingHandler;
      GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
  
      // emit attributes
      varyingHandler->emitAttributes(de);
  
      // XY refers to dashPos, Z is the dash interval length
      GrGLSLVertToFrag inDashParams(kFloat3_GrSLType);
      varyingHandler->addVarying("DashParams", &inDashParams);
      vertBuilder->codeAppendf("%s = %s;", inDashParams.vsOut(), de.inDashParams()->fName);
  
      // The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
      // respectively.
      GrGLSLVertToFrag inRectParams(kFloat4_GrSLType);
      varyingHandler->addVarying("RectParams", &inRectParams);
      vertBuilder->codeAppendf("%s = %s;", inRectParams.vsOut(), de.inRectParams()->fName);
  
      GrGLSLPPFragmentBuilder* fragBuilder = args.fFragBuilder;
      // Setup pass through color
      this->setupUniformColor(fragBuilder, uniformHandler, args.fOutputColor, &fColorUniform);
  
      // Setup position
      this->writeOutputPosition(vertBuilder, gpArgs, de.inPosition()->fName);
  
      // emit transforms
      this->emitTransforms(vertBuilder,
                           varyingHandler,
                           uniformHandler,
                           gpArgs->fPositionVar,
                           de.inPosition()->fName,
                           de.localMatrix(),
                           args.fFPCoordTransformHandler);
  
      // transforms all points so that we can compare them to our test rect
      fragBuilder->codeAppendf("half xShifted = %s.x - floor(%s.x / %s.z) * %s.z;",
                               inDashParams.fsIn(), inDashParams.fsIn(), inDashParams.fsIn(),
                               inDashParams.fsIn());
      fragBuilder->codeAppendf("half2 fragPosShifted = half2(xShifted, %s.y);", inDashParams.fsIn());
      if (de.aaMode() == AAMode::kCoverage) {
          // The amount of coverage removed in x and y by the edges is computed as a pair of negative
          // numbers, xSub and ySub.
          fragBuilder->codeAppend("half xSub, ySub;");
          fragBuilder->codeAppendf("xSub = min(fragPosShifted.x - %s.x, 0.0);", inRectParams.fsIn());
          fragBuilder->codeAppendf("xSub += min(%s.z - fragPosShifted.x, 0.0);", inRectParams.fsIn());
          fragBuilder->codeAppendf("ySub = min(fragPosShifted.y - %s.y, 0.0);", inRectParams.fsIn());
          fragBuilder->codeAppendf("ySub += min(%s.w - fragPosShifted.y, 0.0);", inRectParams.fsIn());
          // Now compute coverage in x and y and multiply them to get the fraction of the pixel
          // covered.
          fragBuilder->codeAppendf(
              "half alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));");
      } else if (de.aaMode() == AAMode::kCoverageWithMSAA) {
          // For MSAA, we don't modulate the alpha by the Y distance, since MSAA coverage will handle
          // AA on the the top and bottom edges. The shader is only responsible for intra-dash alpha.
          fragBuilder->codeAppend("half xSub;");
          fragBuilder->codeAppendf("xSub = min(fragPosShifted.x - %s.x, 0.0);", inRectParams.fsIn());
          fragBuilder->codeAppendf("xSub += min(%s.z - fragPosShifted.x, 0.0);", inRectParams.fsIn());
          // Now compute coverage in x to get the fraction of the pixel covered.
          fragBuilder->codeAppendf("half alpha = (1.0 + max(xSub, -1.0));");
      } else {
          // Assuming the bounding geometry is tight so no need to check y values
          fragBuilder->codeAppendf("half alpha = 1.0;");
          fragBuilder->codeAppendf("alpha *= (fragPosShifted.x - %s.x) > -0.5 ? 1.0 : 0.0;",
                                   inRectParams.fsIn());
          fragBuilder->codeAppendf("alpha *= (%s.z - fragPosShifted.x) >= -0.5 ? 1.0 : 0.0;",
                                   inRectParams.fsIn());
      }
      fragBuilder->codeAppendf("%s = half4(alpha);", args.fOutputCoverage);
  }
  
  void GLDashingLineEffect::setData(const GrGLSLProgramDataManager& pdman,
                                    const GrPrimitiveProcessor& processor,
                                    FPCoordTransformIter&& transformIter) {
      const DashingLineEffect& de = processor.cast<DashingLineEffect>();
      if (de.color() != fColor) {
          float c[4];
          GrColorToRGBAFloat(de.color(), c);
          pdman.set4fv(fColorUniform, 1, c);
          fColor = de.color();
      }
      this->setTransformDataHelper(de.localMatrix(), pdman, &transformIter);
  }
  
  void GLDashingLineEffect::GenKey(const GrGeometryProcessor& gp,
                                   const GrShaderCaps&,
                                   GrProcessorKeyBuilder* b) {
      const DashingLineEffect& de = gp.cast<DashingLineEffect>();
      uint32_t key = 0;
      key |= de.usesLocalCoords() && de.localMatrix().hasPerspective() ? 0x1 : 0x0;
      key |= static_cast<int>(de.aaMode()) << 8;
      b->add32(key);
  }
  
  //////////////////////////////////////////////////////////////////////////////
  
  sk_sp<GrGeometryProcessor> DashingLineEffect::Make(GrColor color,
                                                     AAMode aaMode,
                                                     const SkMatrix& localMatrix,
                                                     bool usesLocalCoords) {
      return sk_sp<GrGeometryProcessor>(
          new DashingLineEffect(color, aaMode, localMatrix, usesLocalCoords));
  }
  
  void DashingLineEffect::getGLSLProcessorKey(const GrShaderCaps& caps,
                                              GrProcessorKeyBuilder* b) const {
      GLDashingLineEffect::GenKey(*this, caps, b);
  }
  
  GrGLSLPrimitiveProcessor* DashingLineEffect::createGLSLInstance(const GrShaderCaps&) const {
      return new GLDashingLineEffect();
  }
  
  DashingLineEffect::DashingLineEffect(GrColor color,
                                       AAMode aaMode,
                                       const SkMatrix& localMatrix,
                                       bool usesLocalCoords)
      : INHERITED(kDashingLineEffect_ClassID)
      , fColor(color)
      , fLocalMatrix(localMatrix)
      , fUsesLocalCoords(usesLocalCoords)
      , fAAMode(aaMode) {
      fInPosition = &this->addVertexAttrib("inPosition", kFloat2_GrVertexAttribType);
      fInDashParams = &this->addVertexAttrib("inDashParams", kHalf3_GrVertexAttribType);
      fInRectParams = &this->addVertexAttrib("inRect", kHalf4_GrVertexAttribType);
  }
  
  GR_DEFINE_GEOMETRY_PROCESSOR_TEST(DashingLineEffect);
  
  #if GR_TEST_UTILS
  sk_sp<GrGeometryProcessor> DashingLineEffect::TestCreate(GrProcessorTestData* d) {
      AAMode aaMode = static_cast<AAMode>(d->fRandom->nextULessThan(GrDashOp::kAAModeCnt));
      return DashingLineEffect::Make(GrRandomColor(d->fRandom),
                                     aaMode, GrTest::TestMatrix(d->fRandom),
                                     d->fRandom->nextBool());
  }
  #endif
  
  //////////////////////////////////////////////////////////////////////////////
  
  static sk_sp<GrGeometryProcessor> make_dash_gp(GrColor color,
                                                 AAMode aaMode,
                                                 DashCap cap,
                                                 const SkMatrix& viewMatrix,
                                                 bool usesLocalCoords) {
      SkMatrix invert;
      if (usesLocalCoords && !viewMatrix.invert(&invert)) {
          SkDebugf("Failed to invert\n");
          return nullptr;
      }
  
      switch (cap) {
          case kRound_DashCap:
              return DashingCircleEffect::Make(color, aaMode, invert, usesLocalCoords);
          case kNonRound_DashCap:
              return DashingLineEffect::Make(color, aaMode, invert, usesLocalCoords);
      }
      return nullptr;
  }
  
  /////////////////////////////////////////////////////////////////////////////////////////////////
  
  #if GR_TEST_UTILS
  
  GR_DRAW_OP_TEST_DEFINE(DashOp) {
      SkMatrix viewMatrix = GrTest::TestMatrixPreservesRightAngles(random);
      AAMode aaMode;
      do {
          aaMode = static_cast<AAMode>(random->nextULessThan(GrDashOp::kAAModeCnt));
      } while (AAMode::kCoverageWithMSAA == aaMode && GrFSAAType::kUnifiedMSAA != fsaaType);
  
      // We can only dash either horizontal or vertical lines
      SkPoint pts[2];
      if (random->nextBool()) {
          // vertical
          pts[0].fX = 1.f;
          pts[0].fY = random->nextF() * 10.f;
          pts[1].fX = 1.f;
          pts[1].fY = random->nextF() * 10.f;
      } else {
          // horizontal
          pts[0].fX = random->nextF() * 10.f;
          pts[0].fY = 1.f;
          pts[1].fX = random->nextF() * 10.f;
          pts[1].fY = 1.f;
      }
  
      // pick random cap
      SkPaint::Cap cap = SkPaint::Cap(random->nextULessThan(SkPaint::kCapCount));
  
      SkScalar intervals[2];
  
      // We can only dash with the following intervals
      enum Intervals {
          kOpenOpen_Intervals ,
          kOpenClose_Intervals,
          kCloseOpen_Intervals,
      };
  
      Intervals intervalType = SkPaint::kRound_Cap == cap ?
                               kOpenClose_Intervals :
                               Intervals(random->nextULessThan(kCloseOpen_Intervals + 1));
      static const SkScalar kIntervalMin = 0.1f;
      static const SkScalar kIntervalMinCircles = 1.f; // Must be >= to stroke width
      static const SkScalar kIntervalMax = 10.f;
      switch (intervalType) {
          case kOpenOpen_Intervals:
              intervals[0] = random->nextRangeScalar(kIntervalMin, kIntervalMax);
              intervals[1] = random->nextRangeScalar(kIntervalMin, kIntervalMax);
              break;
          case kOpenClose_Intervals: {
              intervals[0] = 0.f;
              SkScalar min = SkPaint::kRound_Cap == cap ? kIntervalMinCircles : kIntervalMin;
              intervals[1] = random->nextRangeScalar(min, kIntervalMax);
              break;
          }
          case kCloseOpen_Intervals:
              intervals[0] = random->nextRangeScalar(kIntervalMin, kIntervalMax);
              intervals[1] = 0.f;
              break;
  
      }
  
      // phase is 0 < sum (i0, i1)
      SkScalar phase = random->nextRangeScalar(0, intervals[0] + intervals[1]);
  
      SkPaint p;
      p.setStyle(SkPaint::kStroke_Style);
      p.setStrokeWidth(SkIntToScalar(1));
      p.setStrokeCap(cap);
      p.setPathEffect(GrTest::TestDashPathEffect::Make(intervals, 2, phase));
  
      GrStyle style(p);
  
      return GrDashOp::MakeDashLineOp(std::move(paint), viewMatrix, pts, aaMode, style,
                                      GrGetRandomStencil(random, context));
  }
  
  #endif
  