From 6d2f73c364d0d823f14d1ddebc88e0bcbc8f0634 Mon Sep 17 00:00:00 2001 From: "joel.liang" Date: Tue, 20 Dec 2016 18:58:53 -0800 Subject: [PATCH] Generate Signed Distance Field directly from vector path Add SkGenerateDistanceFieldFromPath API to generate signed distance field directly from SkPath. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1643143002 Committed: https://skia.googlesource.com/skia/+/4de97a64e8829323a7070b623411d9f9ddb0cd0f Committed: https://skia.googlesource.com/skia/+/e8f0a7b986f1e5583c9bc162efcdd92fd6430549 Committed: https://skia.googlesource.com/skia/+/67c7c81a82b6351e9fbbf235084d7120162d9268 Review-Url: https://codereview.chromium.org/1643143002 Committed: https://skia.googlesource.com/skia/+/64b70b096ac20833d9737758a4bd5f2a51078bc4 Review-Url: https://codereview.chromium.org/1643143002 --- gn/gpu.gni | 2 + src/gpu/GrDistanceFieldGenFromVector.cpp | 849 ++++++++++++++++++++++++++ src/gpu/GrDistanceFieldGenFromVector.h | 35 ++ src/gpu/ops/GrAADistanceFieldPathRenderer.cpp | 76 ++- src/gpu/text/GrAtlasGlyphCache.cpp | 59 +- 5 files changed, 972 insertions(+), 49 deletions(-) create mode 100644 src/gpu/GrDistanceFieldGenFromVector.cpp create mode 100644 src/gpu/GrDistanceFieldGenFromVector.h diff --git a/gn/gpu.gni b/gn/gpu.gni index eee9003..33ed316 100644 --- a/gn/gpu.gni +++ b/gn/gpu.gni @@ -90,6 +90,8 @@ skia_gpu_sources = [ "$_src/gpu/GrCoordTransform.cpp", "$_src/gpu/GrDefaultGeoProcFactory.cpp", "$_src/gpu/GrDefaultGeoProcFactory.h", + "$_src/gpu/GrDistanceFieldGenFromVector.cpp", + "$_src/gpu/GrDistanceFieldGenFromVector.h", "$_src/gpu/GrDrawingManager.cpp", "$_src/gpu/GrDrawingManager.h", "$_src/gpu/GrDrawOpAtlas.cpp", diff --git a/src/gpu/GrDistanceFieldGenFromVector.cpp b/src/gpu/GrDistanceFieldGenFromVector.cpp new file mode 100644 index 0000000..0874616 --- /dev/null +++ b/src/gpu/GrDistanceFieldGenFromVector.cpp @@ -0,0 +1,849 @@ +/* + * Copyright 2016 ARM Ltd. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#include "GrDistanceFieldGenFromVector.h" +#include "SkPoint.h" +#include "SkGeometry.h" +#include "SkPathOps.h" +#include "GrPathUtils.h" +#include "GrConfig.h" + +/** + * If a scanline (a row of texel) cross from the kRight_SegSide + * of a segment to the kLeft_SegSide, the winding score should + * add 1. + * And winding score should subtract 1 if the scanline cross + * from kLeft_SegSide to kRight_SegSide. + * Always return kNA_SegSide if the scanline does not cross over + * the segment. Winding score should be zero in this case. + * You can get the winding number for each texel of the scanline + * by adding the winding score from left to right. + * Assuming we always start from outside, so the winding number + * should always start from zero. + * ________ ________ + * | | | | + * ...R|L......L|R.....L|R......R|L..... <= Scanline & side of segment + * |+1 |-1 |-1 |+1 <= Winding score + * 0 | 1 ^ 0 ^ -1 |0 <= Winding number + * |________| |________| + * + * .......NA................NA.......... + * 0 0 + */ +enum SegSide { + kLeft_SegSide = -1, + kOn_SegSide = 0, + kRight_SegSide = 1, + kNA_SegSide = 2, +}; + +struct DFData { + float fDistSq; // distance squared to nearest (so far) edge + int fDeltaWindingScore; // +1 or -1 whenever a scanline cross over a segment +}; + +/////////////////////////////////////////////////////////////////////////////// + +/* + * Type definition for double precision DPoint and DAffineMatrix + */ + +// Point with double precision +struct DPoint { + double fX, fY; + + static DPoint Make(double x, double y) { + DPoint pt; + pt.set(x, y); + return pt; + } + + double x() const { return fX; } + double y() const { return fY; } + + void set(double x, double y) { fX = x; fY = y; } + + /** Returns the euclidian distance from (0,0) to (x,y) + */ + static double Length(double x, double y) { + return sqrt(x * x + y * y); + } + + /** Returns the euclidian distance between a and b + */ + static double Distance(const DPoint& a, const DPoint& b) { + return Length(a.fX - b.fX, a.fY - b.fY); + } + + double distanceToSqd(const DPoint& pt) const { + double dx = fX - pt.fX; + double dy = fY - pt.fY; + return dx * dx + dy * dy; + } +}; + +// Matrix with double precision for affine transformation. +// We don't store row 3 because its always (0, 0, 1). +class DAffineMatrix { +public: + double operator[](int index) const { + SkASSERT((unsigned)index < 6); + return fMat[index]; + } + + double& operator[](int index) { + SkASSERT((unsigned)index < 6); + return fMat[index]; + } + + void setAffine(double m11, double m12, double m13, + double m21, double m22, double m23) { + fMat[0] = m11; + fMat[1] = m12; + fMat[2] = m13; + fMat[3] = m21; + fMat[4] = m22; + fMat[5] = m23; + } + + /** Set the matrix to identity + */ + void reset() { + fMat[0] = fMat[4] = 1.0; + fMat[1] = fMat[3] = + fMat[2] = fMat[5] = 0.0; + } + + // alias for reset() + void setIdentity() { this->reset(); } + + DPoint mapPoint(const SkPoint& src) const { + DPoint pt = DPoint::Make(src.x(), src.y()); + return this->mapPoint(pt); + } + + DPoint mapPoint(const DPoint& src) const { + return DPoint::Make(fMat[0] * src.x() + fMat[1] * src.y() + fMat[2], + fMat[3] * src.x() + fMat[4] * src.y() + fMat[5]); + } +private: + double fMat[6]; +}; + +/////////////////////////////////////////////////////////////////////////////// + +static const double kClose = (SK_Scalar1 / 16.0); +static const double kCloseSqd = SkScalarMul(kClose, kClose); +static const double kNearlyZero = (SK_Scalar1 / (1 << 18)); +static const double kTangentTolerance = (SK_Scalar1 / (1 << 11)); +static const float kConicTolerance = 0.25f; + +static inline bool between_closed_open(double a, double b, double c, + double tolerance = 0.0, + bool xformToleranceToX = false) { + SkASSERT(tolerance >= 0.0); + double tolB = tolerance; + double tolC = tolerance; + + if (xformToleranceToX) { + // Canonical space is y = x^2 and the derivative of x^2 is 2x. + // So the slope of the tangent line at point (x, x^2) is 2x. + // + // /| + // sqrt(2x * 2x + 1 * 1) / | 2x + // /__| + // 1 + tolB = tolerance / sqrt(4.0 * b * b + 1.0); + tolC = tolerance / sqrt(4.0 * c * c + 1.0); + } + return b < c ? (a >= b - tolB && a < c - tolC) : + (a >= c - tolC && a < b - tolB); +} + +static inline bool between_closed(double a, double b, double c, + double tolerance = 0.0, + bool xformToleranceToX = false) { + SkASSERT(tolerance >= 0.0); + double tolB = tolerance; + double tolC = tolerance; + + if (xformToleranceToX) { + tolB = tolerance / sqrt(4.0 * b * b + 1.0); + tolC = tolerance / sqrt(4.0 * c * c + 1.0); + } + return b < c ? (a >= b - tolB && a <= c + tolC) : + (a >= c - tolC && a <= b + tolB); +} + +static inline bool nearly_zero(double x, double tolerance = kNearlyZero) { + SkASSERT(tolerance >= 0.0); + return fabs(x) <= tolerance; +} + +static inline bool nearly_equal(double x, double y, + double tolerance = kNearlyZero, + bool xformToleranceToX = false) { + SkASSERT(tolerance >= 0.0); + if (xformToleranceToX) { + tolerance = tolerance / sqrt(4.0 * y * y + 1.0); + } + return fabs(x - y) <= tolerance; +} + +static inline double sign_of(const double &val) { + return (val < 0.0) ? -1.0 : 1.0; +} + +static bool is_colinear(const SkPoint pts[3]) { + return nearly_zero((pts[1].y() - pts[0].y()) * (pts[1].x() - pts[2].x()) - + (pts[1].y() - pts[2].y()) * (pts[1].x() - pts[0].x()), kCloseSqd); +} + +class PathSegment { +public: + enum { + // These enum values are assumed in member functions below. + kLine = 0, + kQuad = 1, + } fType; + + // line uses 2 pts, quad uses 3 pts + SkPoint fPts[3]; + + DPoint fP0T, fP2T; + DAffineMatrix fXformMatrix; + double fScalingFactor; + double fScalingFactorSqd; + double fNearlyZeroScaled; + double fTangentTolScaledSqd; + SkRect fBoundingBox; + + void init(); + + int countPoints() { + GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); + return fType + 2; + } + + const SkPoint& endPt() const { + GR_STATIC_ASSERT(0 == kLine && 1 == kQuad); + return fPts[fType + 1]; + } +}; + +typedef SkTArray PathSegmentArray; + +void PathSegment::init() { + const DPoint p0 = DPoint::Make(fPts[0].x(), fPts[0].y()); + const DPoint p2 = DPoint::Make(this->endPt().x(), this->endPt().y()); + const double p0x = p0.x(); + const double p0y = p0.y(); + const double p2x = p2.x(); + const double p2y = p2.y(); + + fBoundingBox.set(fPts[0], this->endPt()); + + if (fType == PathSegment::kLine) { + fScalingFactorSqd = fScalingFactor = 1.0; + double hypotenuse = DPoint::Distance(p0, p2); + + const double cosTheta = (p2x - p0x) / hypotenuse; + const double sinTheta = (p2y - p0y) / hypotenuse; + + fXformMatrix.setAffine( + cosTheta, sinTheta, -(cosTheta * p0x) - (sinTheta * p0y), + -sinTheta, cosTheta, (sinTheta * p0x) - (cosTheta * p0y) + ); + } else { + SkASSERT(fType == PathSegment::kQuad); + + // Calculate bounding box + const SkPoint _P1mP0 = fPts[1] - fPts[0]; + SkPoint t = _P1mP0 - fPts[2] + fPts[1]; + t.fX = _P1mP0.x() / t.x(); + t.fY = _P1mP0.y() / t.y(); + t.fX = SkScalarClampMax(t.x(), 1.0); + t.fY = SkScalarClampMax(t.y(), 1.0); + t.fX = _P1mP0.x() * t.x(); + t.fY = _P1mP0.y() * t.y(); + const SkPoint m = fPts[0] + t; + fBoundingBox.growToInclude(&m, 1); + + const double p1x = fPts[1].x(); + const double p1y = fPts[1].y(); + + const double p0xSqd = p0x * p0x; + const double p0ySqd = p0y * p0y; + const double p2xSqd = p2x * p2x; + const double p2ySqd = p2y * p2y; + const double p1xSqd = p1x * p1x; + const double p1ySqd = p1y * p1y; + + const double p01xProd = p0x * p1x; + const double p02xProd = p0x * p2x; + const double b12xProd = p1x * p2x; + const double p01yProd = p0y * p1y; + const double p02yProd = p0y * p2y; + const double b12yProd = p1y * p2y; + + const double sqrtA = p0y - (2.0 * p1y) + p2y; + const double a = sqrtA * sqrtA; + const double h = -1.0 * (p0y - (2.0 * p1y) + p2y) * (p0x - (2.0 * p1x) + p2x); + const double sqrtB = p0x - (2.0 * p1x) + p2x; + const double b = sqrtB * sqrtB; + const double c = (p0xSqd * p2ySqd) - (4.0 * p01xProd * b12yProd) + - (2.0 * p02xProd * p02yProd) + (4.0 * p02xProd * p1ySqd) + + (4.0 * p1xSqd * p02yProd) - (4.0 * b12xProd * p01yProd) + + (p2xSqd * p0ySqd); + const double g = (p0x * p02yProd) - (2.0 * p0x * p1ySqd) + + (2.0 * p0x * b12yProd) - (p0x * p2ySqd) + + (2.0 * p1x * p01yProd) - (4.0 * p1x * p02yProd) + + (2.0 * p1x * b12yProd) - (p2x * p0ySqd) + + (2.0 * p2x * p01yProd) + (p2x * p02yProd) + - (2.0 * p2x * p1ySqd); + const double f = -((p0xSqd * p2y) - (2.0 * p01xProd * p1y) + - (2.0 * p01xProd * p2y) - (p02xProd * p0y) + + (4.0 * p02xProd * p1y) - (p02xProd * p2y) + + (2.0 * p1xSqd * p0y) + (2.0 * p1xSqd * p2y) + - (2.0 * b12xProd * p0y) - (2.0 * b12xProd * p1y) + + (p2xSqd * p0y)); + + const double cosTheta = sqrt(a / (a + b)); + const double sinTheta = -1.0 * sign_of((a + b) * h) * sqrt(b / (a + b)); + + const double gDef = cosTheta * g - sinTheta * f; + const double fDef = sinTheta * g + cosTheta * f; + + + const double x0 = gDef / (a + b); + const double y0 = (1.0 / (2.0 * fDef)) * (c - (gDef * gDef / (a + b))); + + + const double lambda = -1.0 * ((a + b) / (2.0 * fDef)); + fScalingFactor = fabs(1.0 / lambda); + fScalingFactorSqd = fScalingFactor * fScalingFactor; + + const double lambda_cosTheta = lambda * cosTheta; + const double lambda_sinTheta = lambda * sinTheta; + + fXformMatrix.setAffine( + lambda_cosTheta, -lambda_sinTheta, lambda * x0, + lambda_sinTheta, lambda_cosTheta, lambda * y0 + ); + } + + fNearlyZeroScaled = kNearlyZero / fScalingFactor; + fTangentTolScaledSqd = kTangentTolerance * kTangentTolerance / fScalingFactorSqd; + + fP0T = fXformMatrix.mapPoint(p0); + fP2T = fXformMatrix.mapPoint(p2); +} + +static void init_distances(DFData* data, int size) { + DFData* currData = data; + + for (int i = 0; i < size; ++i) { + // init distance to "far away" + currData->fDistSq = SK_DistanceFieldMagnitude * SK_DistanceFieldMagnitude; + currData->fDeltaWindingScore = 0; + ++currData; + } +} + +static inline void add_line_to_segment(const SkPoint pts[2], + PathSegmentArray* segments) { + segments->push_back(); + segments->back().fType = PathSegment::kLine; + segments->back().fPts[0] = pts[0]; + segments->back().fPts[1] = pts[1]; + + segments->back().init(); +} + +static inline void add_quad_segment(const SkPoint pts[3], + PathSegmentArray* segments) { + if (pts[0].distanceToSqd(pts[1]) < kCloseSqd || + pts[1].distanceToSqd(pts[2]) < kCloseSqd || + is_colinear(pts)) { + if (pts[0] != pts[2]) { + SkPoint line_pts[2]; + line_pts[0] = pts[0]; + line_pts[1] = pts[2]; + add_line_to_segment(line_pts, segments); + } + } else { + segments->push_back(); + segments->back().fType = PathSegment::kQuad; + segments->back().fPts[0] = pts[0]; + segments->back().fPts[1] = pts[1]; + segments->back().fPts[2] = pts[2]; + + segments->back().init(); + } +} + +static inline void add_cubic_segments(const SkPoint pts[4], + PathSegmentArray* segments) { + SkSTArray<15, SkPoint, true> quads; + GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, &quads); + int count = quads.count(); + for (int q = 0; q < count; q += 3) { + add_quad_segment(&quads[q], segments); + } +} + +static float calculate_nearest_point_for_quad( + const PathSegment& segment, + const DPoint &xFormPt) { + static const float kThird = 0.33333333333f; + static const float kTwentySeventh = 0.037037037f; + + const float a = 0.5f - (float)xFormPt.y(); + const float b = -0.5f * (float)xFormPt.x(); + + const float a3 = a * a * a; + const float b2 = b * b; + + const float c = (b2 * 0.25f) + (a3 * kTwentySeventh); + + if (c >= 0.f) { + const float sqrtC = sqrt(c); + const float result = (float)cbrt((-b * 0.5f) + sqrtC) + (float)cbrt((-b * 0.5f) - sqrtC); + return result; + } else { + const float cosPhi = (float)sqrt((b2 * 0.25f) * (-27.f / a3)) * ((b > 0) ? -1.f : 1.f); + const float phi = (float)acos(cosPhi); + float result; + if (xFormPt.x() > 0.f) { + result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThird); + if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) { + result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThird) + (SK_ScalarPI * 2.f * kThird)); + } + } else { + result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThird) + (SK_ScalarPI * 2.f * kThird)); + if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) { + result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThird); + } + } + return result; + } +} + +// This structure contains some intermediate values shared by the same row. +// It is used to calculate segment side of a quadratic bezier. +struct RowData { + // The intersection type of a scanline and y = x * x parabola in canonical space. + enum IntersectionType { + kNoIntersection, + kVerticalLine, + kTangentLine, + kTwoPointsIntersect + } fIntersectionType; + + // The direction of the quadratic segment/scanline in the canonical space. + // 1: The quadratic segment/scanline going from negative x-axis to positive x-axis. + // 0: The scanline is a vertical line in the canonical space. + // -1: The quadratic segment/scanline going from positive x-axis to negative x-axis. + int fQuadXDirection; + int fScanlineXDirection; + + // The y-value(equal to x*x) of intersection point for the kVerticalLine intersection type. + double fYAtIntersection; + + // The x-value for two intersection points. + double fXAtIntersection1; + double fXAtIntersection2; +}; + +void precomputation_for_row( + RowData *rowData, + const PathSegment& segment, + const SkPoint& pointLeft, + const SkPoint& pointRight + ) { + if (segment.fType != PathSegment::kQuad) { + return; + } + + const DPoint& xFormPtLeft = segment.fXformMatrix.mapPoint(pointLeft); + const DPoint& xFormPtRight = segment.fXformMatrix.mapPoint(pointRight);; + + rowData->fQuadXDirection = (int)sign_of(segment.fP2T.x() - segment.fP0T.x()); + rowData->fScanlineXDirection = (int)sign_of(xFormPtRight.x() - xFormPtLeft.x()); + + const double x1 = xFormPtLeft.x(); + const double y1 = xFormPtLeft.y(); + const double x2 = xFormPtRight.x(); + const double y2 = xFormPtRight.y(); + + if (nearly_equal(x1, x2, segment.fNearlyZeroScaled, true)) { + rowData->fIntersectionType = RowData::kVerticalLine; + rowData->fYAtIntersection = x1 * x1; + rowData->fScanlineXDirection = 0; + return; + } + + // Line y = mx + b + const double m = (y2 - y1) / (x2 - x1); + const double b = -m * x1 + y1; + + const double m2 = m * m; + const double c = m2 + 4.0 * b; + + const double tol = 4.0 * segment.fTangentTolScaledSqd / (m2 + 1.0); + + // Check if the scanline is the tangent line of the curve, + // and the curve start or end at the same y-coordinate of the scanline + if ((rowData->fScanlineXDirection == 1 && + (segment.fPts[0].y() == pointLeft.y() || + segment.fPts[2].y() == pointLeft.y())) && + nearly_zero(c, tol)) { + rowData->fIntersectionType = RowData::kTangentLine; + rowData->fXAtIntersection1 = m / 2.0; + rowData->fXAtIntersection2 = m / 2.0; + } else if (c <= 0.0) { + rowData->fIntersectionType = RowData::kNoIntersection; + return; + } else { + rowData->fIntersectionType = RowData::kTwoPointsIntersect; + const double d = sqrt(c); + rowData->fXAtIntersection1 = (m + d) / 2.0; + rowData->fXAtIntersection2 = (m - d) / 2.0; + } +} + +SegSide calculate_side_of_quad( + const PathSegment& segment, + const SkPoint& point, + const DPoint& xFormPt, + const RowData& rowData) { + SegSide side = kNA_SegSide; + + if (RowData::kVerticalLine == rowData.fIntersectionType) { + side = (SegSide)(int)(sign_of(xFormPt.y() - rowData.fYAtIntersection) * rowData.fQuadXDirection); + } + else if (RowData::kTwoPointsIntersect == rowData.fIntersectionType) { + const double p1 = rowData.fXAtIntersection1; + const double p2 = rowData.fXAtIntersection2; + + int signP1 = (int)sign_of(p1 - xFormPt.x()); + bool includeP1 = true; + bool includeP2 = true; + + if (rowData.fScanlineXDirection == 1) { + if ((rowData.fQuadXDirection == -1 && segment.fPts[0].y() <= point.y() && + nearly_equal(segment.fP0T.x(), p1, segment.fNearlyZeroScaled, true)) || + (rowData.fQuadXDirection == 1 && segment.fPts[2].y() <= point.y() && + nearly_equal(segment.fP2T.x(), p1, segment.fNearlyZeroScaled, true))) { + includeP1 = false; + } + if ((rowData.fQuadXDirection == -1 && segment.fPts[2].y() <= point.y() && + nearly_equal(segment.fP2T.x(), p2, segment.fNearlyZeroScaled, true)) || + (rowData.fQuadXDirection == 1 && segment.fPts[0].y() <= point.y() && + nearly_equal(segment.fP0T.x(), p2, segment.fNearlyZeroScaled, true))) { + includeP2 = false; + } + } + + if (includeP1 && between_closed(p1, segment.fP0T.x(), segment.fP2T.x(), + segment.fNearlyZeroScaled, true)) { + side = (SegSide)(signP1 * rowData.fQuadXDirection); + } + if (includeP2 && between_closed(p2, segment.fP0T.x(), segment.fP2T.x(), + segment.fNearlyZeroScaled, true)) { + int signP2 = (int)sign_of(p2 - xFormPt.x()); + if (side == kNA_SegSide || signP2 == 1) { + side = (SegSide)(-signP2 * rowData.fQuadXDirection); + } + } + } else if (RowData::kTangentLine == rowData.fIntersectionType) { + // The scanline is the tangent line of current quadratic segment. + + const double p = rowData.fXAtIntersection1; + int signP = (int)sign_of(p - xFormPt.x()); + if (rowData.fScanlineXDirection == 1) { + // The path start or end at the tangent point. + if (segment.fPts[0].y() == point.y()) { + side = (SegSide)(signP); + } else if (segment.fPts[2].y() == point.y()) { + side = (SegSide)(-signP); + } + } + } + + return side; +} + +static float distance_to_segment(const SkPoint& point, + const PathSegment& segment, + const RowData& rowData, + SegSide* side) { + SkASSERT(side); + + const DPoint xformPt = segment.fXformMatrix.mapPoint(point); + + if (segment.fType == PathSegment::kLine) { + float result = SK_DistanceFieldPad * SK_DistanceFieldPad; + + if (between_closed(xformPt.x(), segment.fP0T.x(), segment.fP2T.x())) { + result = (float)(xformPt.y() * xformPt.y()); + } else if (xformPt.x() < segment.fP0T.x()) { + result = (float)(xformPt.x() * xformPt.x() + xformPt.y() * xformPt.y()); + } else { + result = (float)((xformPt.x() - segment.fP2T.x()) * (xformPt.x() - segment.fP2T.x()) + + xformPt.y() * xformPt.y()); + } + + if (between_closed_open(point.y(), segment.fBoundingBox.top(), + segment.fBoundingBox.bottom())) { + *side = (SegSide)(int)sign_of(xformPt.y()); + } else { + *side = kNA_SegSide; + } + return result; + } else { + SkASSERT(segment.fType == PathSegment::kQuad); + + const float nearestPoint = calculate_nearest_point_for_quad(segment, xformPt); + + float dist; + + if (between_closed(nearestPoint, segment.fP0T.x(), segment.fP2T.x())) { + DPoint x = DPoint::Make(nearestPoint, nearestPoint * nearestPoint); + dist = (float)xformPt.distanceToSqd(x); + } else { + const float distToB0T = (float)xformPt.distanceToSqd(segment.fP0T); + const float distToB2T = (float)xformPt.distanceToSqd(segment.fP2T); + + if (distToB0T < distToB2T) { + dist = distToB0T; + } else { + dist = distToB2T; + } + } + + if (between_closed_open(point.y(), segment.fBoundingBox.top(), + segment.fBoundingBox.bottom())) { + *side = calculate_side_of_quad(segment, point, xformPt, rowData); + } else { + *side = kNA_SegSide; + } + + return (float)(dist * segment.fScalingFactorSqd); + } +} + +static void calculate_distance_field_data(PathSegmentArray* segments, + DFData* dataPtr, + int width, int height) { + int count = segments->count(); + for (int a = 0; a < count; ++a) { + PathSegment& segment = (*segments)[a]; + const SkRect& segBB = segment.fBoundingBox.makeOutset( + SK_DistanceFieldPad, SK_DistanceFieldPad); + int startColumn = (int)segBB.left(); + int endColumn = SkScalarCeilToInt(segBB.right()); + + int startRow = (int)segBB.top(); + int endRow = SkScalarCeilToInt(segBB.bottom()); + + SkASSERT((startColumn >= 0) && "StartColumn < 0!"); + SkASSERT((endColumn <= width) && "endColumn > width!"); + SkASSERT((startRow >= 0) && "StartRow < 0!"); + SkASSERT((endRow <= height) && "EndRow > height!"); + + for (int row = startRow; row < endRow; ++row) { + SegSide prevSide = kNA_SegSide; + const float pY = row + 0.5f; + RowData rowData; + + const SkPoint pointLeft = SkPoint::Make((SkScalar)startColumn, pY); + const SkPoint pointRight = SkPoint::Make((SkScalar)endColumn, pY); + + if (between_closed_open(pY, segment.fBoundingBox.top(), + segment.fBoundingBox.bottom())) { + precomputation_for_row(&rowData, segment, pointLeft, pointRight); + } + + for (int col = startColumn; col < endColumn; ++col) { + int idx = (row * width) + col; + + const float pX = col + 0.5f; + const SkPoint point = SkPoint::Make(pX, pY); + + const float distSq = dataPtr[idx].fDistSq; + int dilation = distSq < 1.5 * 1.5 ? 1 : + distSq < 2.5 * 2.5 ? 2 : + distSq < 3.5 * 3.5 ? 3 : SK_DistanceFieldPad; + if (dilation > SK_DistanceFieldPad) { + dilation = SK_DistanceFieldPad; + } + + // Optimisation for not calculating some points. + if (dilation != SK_DistanceFieldPad && !segment.fBoundingBox.roundOut() + .makeOutset(dilation, dilation).contains(col, row)) { + continue; + } + + SegSide side = kNA_SegSide; + int deltaWindingScore = 0; + float currDistSq = distance_to_segment(point, segment, rowData, &side); + if (prevSide == kLeft_SegSide && side == kRight_SegSide) { + deltaWindingScore = -1; + } else if (prevSide == kRight_SegSide && side == kLeft_SegSide) { + deltaWindingScore = 1; + } + + prevSide = side; + + if (currDistSq < distSq) { + dataPtr[idx].fDistSq = currDistSq; + } + + dataPtr[idx].fDeltaWindingScore += deltaWindingScore; + } + } + } +} + +template +static unsigned char pack_distance_field_val(float dist) { + // The distance field is constructed as unsigned char values, so that the zero value is at 128, + // Beside 128, we have 128 values in range [0, 128), but only 127 values in range (128, 255]. + // So we multiply distanceMagnitude by 127/128 at the latter range to avoid overflow. + dist = SkScalarPin(-dist, -distanceMagnitude, distanceMagnitude * 127.0f / 128.0f); + + // Scale into the positive range for unsigned distance. + dist += distanceMagnitude; + + // Scale into unsigned char range. + // Round to place negative and positive values as equally as possible around 128 + // (which represents zero). + return (unsigned char)SkScalarRoundToInt(dist / (2 * distanceMagnitude) * 256.0f); +} + +bool GrGenerateDistanceFieldFromPath(unsigned char* distanceField, + const SkPath& path, const SkMatrix& drawMatrix, + int width, int height, size_t rowBytes) { + SkASSERT(distanceField); + + SkPath simplifiedPath; + SkPath workingPath; + if (Simplify(path, &simplifiedPath)) { + workingPath = simplifiedPath; + } else { + workingPath = path; + } + + if (!IsDistanceFieldSupportedFillType(workingPath.getFillType())) { + return false; + } + + workingPath.transform(drawMatrix); + + // translate path to offset (SK_DistanceFieldPad, SK_DistanceFieldPad) + SkMatrix dfMatrix; + dfMatrix.setTranslate(SK_DistanceFieldPad, SK_DistanceFieldPad); + workingPath.transform(dfMatrix); + + // create temp data + size_t dataSize = width * height * sizeof(DFData); + SkAutoSMalloc<1024> dfStorage(dataSize); + DFData* dataPtr = (DFData*) dfStorage.get(); + + // create initial distance data + init_distances(dataPtr, width * height); + + SkPath::Iter iter(workingPath, true); + SkSTArray<15, PathSegment, true> segments; + + for (;;) { + SkPoint pts[4]; + SkPath::Verb verb = iter.next(pts); + switch (verb) { + case SkPath::kMove_Verb: + break; + case SkPath::kLine_Verb: { + add_line_to_segment(pts, &segments); + break; + } + case SkPath::kQuad_Verb: + add_quad_segment(pts, &segments); + break; + case SkPath::kConic_Verb: { + SkScalar weight = iter.conicWeight(); + SkAutoConicToQuads converter; + const SkPoint* quadPts = converter.computeQuads(pts, weight, kConicTolerance); + for (int i = 0; i < converter.countQuads(); ++i) { + add_quad_segment(quadPts + 2*i, &segments); + } + break; + } + case SkPath::kCubic_Verb: { + add_cubic_segments(pts, &segments); + break; + }; + default: + break; + } + if (verb == SkPath::kDone_Verb) { + break; + } + } + + calculate_distance_field_data(&segments, dataPtr, width, height); + + for (int row = 0; row < height; ++row) { + int windingNumber = 0; // Winding number start from zero for each scanline + for (int col = 0; col < width; ++col) { + int idx = (row * width) + col; + windingNumber += dataPtr[idx].fDeltaWindingScore; + + enum DFSign { + kInside = -1, + kOutside = 1 + } dfSign; + + if (workingPath.getFillType() == SkPath::kWinding_FillType) { + dfSign = windingNumber ? kInside : kOutside; + } else if (workingPath.getFillType() == SkPath::kInverseWinding_FillType) { + dfSign = windingNumber ? kOutside : kInside; + } else if (workingPath.getFillType() == SkPath::kEvenOdd_FillType) { + dfSign = (windingNumber % 2) ? kInside : kOutside; + } else { + SkASSERT(workingPath.getFillType() == SkPath::kInverseEvenOdd_FillType); + dfSign = (windingNumber % 2) ? kOutside : kInside; + } + + // The winding number at the end of a scanline should be zero. + // SkASSERT(((col != width - 1) || (windingNumber == 0)) && + // "Winding number should be zero at the end of a scan line."); + // Fallback to use SkPath::contains to determine the sign of pixel instead of assertion. + if (col == width - 1 && windingNumber != 0) { + for (int col = 0; col < width; ++col) { + int idx = (row * width) + col; + dfSign = workingPath.contains(col + 0.5, row + 0.5) ? kInside : kOutside; + const float miniDist = sqrt(dataPtr[idx].fDistSq); + const float dist = dfSign * miniDist; + + unsigned char pixelVal = pack_distance_field_val(dist); + + distanceField[(row * rowBytes) + col] = pixelVal; + } + continue; + } + + const float miniDist = sqrt(dataPtr[idx].fDistSq); + const float dist = dfSign * miniDist; + + unsigned char pixelVal = pack_distance_field_val(dist); + + distanceField[(row * rowBytes) + col] = pixelVal; + } + } + return true; +} diff --git a/src/gpu/GrDistanceFieldGenFromVector.h b/src/gpu/GrDistanceFieldGenFromVector.h new file mode 100644 index 0000000..1d83ee2 --- /dev/null +++ b/src/gpu/GrDistanceFieldGenFromVector.h @@ -0,0 +1,35 @@ +/* + * Copyright 2016 ARM Ltd. + * + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +#ifndef GrDistanceFieldGenFromVector_DEFINED +#define GrDistanceFieldGenFromVector_DEFINED + +#include "SkDistanceFieldGen.h" +#include "SkPath.h" +#include "SkMatrix.h" + +/** Given a vector path, generate the associated distance field. + + * @param distanceField The distance field to be generated. Should already be allocated + * by the client with the padding defined in "SkDistanceFieldGen.h". + * @param path The path we're using to generate the distance field. + * @param matrix Transformation matrix for path. + * @param width Width of the distance field. + * @param height Height of the distance field. + * @param rowBytes Size of each row in the distance field, in bytes. + */ +bool GrGenerateDistanceFieldFromPath(unsigned char* distanceField, + const SkPath& path, const SkMatrix& viewMatrix, + int width, int height, size_t rowBytes); + +inline bool IsDistanceFieldSupportedFillType(SkPath::FillType fFillType) +{ + return (SkPath::kEvenOdd_FillType == fFillType || + SkPath::kInverseEvenOdd_FillType == fFillType); +} + +#endif diff --git a/src/gpu/ops/GrAADistanceFieldPathRenderer.cpp b/src/gpu/ops/GrAADistanceFieldPathRenderer.cpp index 00d3ed7..4ee9d3d 100644 --- a/src/gpu/ops/GrAADistanceFieldPathRenderer.cpp +++ b/src/gpu/ops/GrAADistanceFieldPathRenderer.cpp @@ -1,5 +1,6 @@ /* * Copyright 2014 Google Inc. + * Copyright 2016 ARM Ltd. * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. @@ -19,7 +20,9 @@ #include "effects/GrDistanceFieldGeoProc.h" #include "ops/GrMeshDrawOp.h" +#include "SkPathOps.h" #include "SkDistanceFieldGen.h" +#include "GrDistanceFieldGenFromVector.h" #define ATLAS_TEXTURE_WIDTH 2048 #define ATLAS_TEXTURE_HEIGHT 2048 @@ -335,45 +338,56 @@ private: drawMatrix.setScale(scale, scale); drawMatrix.postTranslate(intPad - dx, intPad - dy); - // setup bitmap backing SkASSERT(devPathBounds.fLeft == 0); SkASSERT(devPathBounds.fTop == 0); - SkAutoPixmapStorage dst; - if (!dst.tryAlloc(SkImageInfo::MakeA8(devPathBounds.width(), - devPathBounds.height()))) { - return false; - } - sk_bzero(dst.writable_addr(), dst.getSafeSize()); - - // rasterize path - SkPaint paint; - paint.setStyle(SkPaint::kFill_Style); - paint.setAntiAlias(true); - - SkDraw draw; - sk_bzero(&draw, sizeof(draw)); - SkRasterClip rasterClip; - rasterClip.setRect(devPathBounds); - draw.fRC = &rasterClip; - draw.fMatrix = &drawMatrix; - draw.fDst = dst; + // setup signed distance field storage + SkIRect dfBounds = devPathBounds.makeOutset(SK_DistanceFieldPad, SK_DistanceFieldPad); + width = dfBounds.width(); + height = dfBounds.height(); + // TODO We should really generate this directly into the plot somehow + SkAutoSMalloc<1024> dfStorage(width * height * sizeof(unsigned char)); SkPath path; shape.asPath(&path); - draw.drawPathCoverage(path, paint); +#ifndef SK_USE_LEGACY_DISTANCE_FIELDS + // Generate signed distance field directly from SkPath + bool succeed = GrGenerateDistanceFieldFromPath((unsigned char*)dfStorage.get(), + path, drawMatrix, + width, height, width * sizeof(unsigned char)); + if (!succeed) { +#endif + // setup bitmap backing + SkAutoPixmapStorage dst; + if (!dst.tryAlloc(SkImageInfo::MakeA8(devPathBounds.width(), + devPathBounds.height()))) { + return false; + } + sk_bzero(dst.writable_addr(), dst.getSafeSize()); - // generate signed distance field - devPathBounds.outset(SK_DistanceFieldPad, SK_DistanceFieldPad); - width = devPathBounds.width(); - height = devPathBounds.height(); - // TODO We should really generate this directly into the plot somehow - SkAutoSMalloc<1024> dfStorage(width * height * sizeof(unsigned char)); + // rasterize path + SkPaint paint; + paint.setStyle(SkPaint::kFill_Style); + paint.setAntiAlias(true); + + SkDraw draw; + sk_bzero(&draw, sizeof(draw)); - // Generate signed distance field - SkGenerateDistanceFieldFromA8Image((unsigned char*)dfStorage.get(), - (const unsigned char*)dst.addr(), - dst.width(), dst.height(), dst.rowBytes()); + SkRasterClip rasterClip; + rasterClip.setRect(devPathBounds); + draw.fRC = &rasterClip; + draw.fMatrix = &drawMatrix; + draw.fDst = dst; + + draw.drawPathCoverage(path, paint); + + // Generate signed distance field + SkGenerateDistanceFieldFromA8Image((unsigned char*)dfStorage.get(), + (const unsigned char*)dst.addr(), + dst.width(), dst.height(), dst.rowBytes()); +#ifndef SK_USE_LEGACY_DISTANCE_FIELDS + } +#endif // add to atlas SkIPoint16 atlasLocation; diff --git a/src/gpu/text/GrAtlasGlyphCache.cpp b/src/gpu/text/GrAtlasGlyphCache.cpp index 803dbb4..b466ca8 100644 --- a/src/gpu/text/GrAtlasGlyphCache.cpp +++ b/src/gpu/text/GrAtlasGlyphCache.cpp @@ -14,6 +14,7 @@ #include "SkString.h" #include "SkDistanceFieldGen.h" +#include "GrDistanceFieldGenFromVector.h" bool GrAtlasGlyphCache::initAtlas(GrMaskFormat format) { int index = MaskFormatToAtlasIndex(format); @@ -320,29 +321,51 @@ static bool get_packed_glyph_df_image(SkGlyphCache* cache, const SkGlyph& glyph, int width, int height, void* dst) { SkASSERT(glyph.fWidth + 2*SK_DistanceFieldPad == width); SkASSERT(glyph.fHeight + 2*SK_DistanceFieldPad == height); - const void* image = cache->findImage(glyph); - if (nullptr == image) { + +#ifndef SK_USE_LEGACY_DISTANCE_FIELDS + const SkPath* path = cache->findPath(glyph); + if (nullptr == path) { return false; } + // now generate the distance field SkASSERT(dst); - SkMask::Format maskFormat = static_cast(glyph.fMaskFormat); - if (SkMask::kA8_Format == maskFormat) { - // make the distance field from the image - SkGenerateDistanceFieldFromA8Image((unsigned char*)dst, - (unsigned char*)image, - glyph.fWidth, glyph.fHeight, - glyph.rowBytes()); - } else if (SkMask::kBW_Format == maskFormat) { - // make the distance field from the image - SkGenerateDistanceFieldFromBWImage((unsigned char*)dst, - (unsigned char*)image, - glyph.fWidth, glyph.fHeight, - glyph.rowBytes()); - } else { - return false; - } + SkMatrix drawMatrix; + drawMatrix.setTranslate((SkScalar)-glyph.fLeft, (SkScalar)-glyph.fTop); + + // Generate signed distance field directly from SkPath + bool succeed = GrGenerateDistanceFieldFromPath((unsigned char*)dst, + *path, drawMatrix, + width, height, width * sizeof(unsigned char)); + + if (!succeed) { +#endif + const void* image = cache->findImage(glyph); + if (nullptr == image) { + return false; + } + // now generate the distance field + SkASSERT(dst); + SkMask::Format maskFormat = static_cast(glyph.fMaskFormat); + if (SkMask::kA8_Format == maskFormat) { + // make the distance field from the image + SkGenerateDistanceFieldFromA8Image((unsigned char*)dst, + (unsigned char*)image, + glyph.fWidth, glyph.fHeight, + glyph.rowBytes()); + } else if (SkMask::kBW_Format == maskFormat) { + // make the distance field from the image + SkGenerateDistanceFieldFromBWImage((unsigned char*)dst, + (unsigned char*)image, + glyph.fWidth, glyph.fHeight, + glyph.rowBytes()); + } else { + return false; + } +#ifndef SK_USE_LEGACY_DISTANCE_FIELDS + } +#endif return true; } -- 2.7.4