| |
| /* |
| * Copyright 2008 The Android Open Source Project |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| |
| #include "SkPathMeasure.h" |
| #include "SkGeometry.h" |
| #include "SkPath.h" |
| #include "SkTSearch.h" |
| |
| // these must be 0,1,2 since they are in our 2-bit field |
| enum { |
| kLine_SegType, |
| kQuad_SegType, |
| kCubic_SegType |
| }; |
| |
| #define kMaxTValue 32767 |
| |
| static inline SkScalar tValue2Scalar(int t) { |
| SkASSERT((unsigned)t <= kMaxTValue); |
| return t * 3.05185e-5f; // t / 32767 |
| } |
| |
| SkScalar SkPathMeasure::Segment::getScalarT() const { |
| return tValue2Scalar(fTValue); |
| } |
| |
| const SkPathMeasure::Segment* SkPathMeasure::NextSegment(const Segment* seg) { |
| unsigned ptIndex = seg->fPtIndex; |
| |
| do { |
| ++seg; |
| } while (seg->fPtIndex == ptIndex); |
| return seg; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| static inline int tspan_big_enough(int tspan) { |
| SkASSERT((unsigned)tspan <= kMaxTValue); |
| return tspan >> 10; |
| } |
| |
| // can't use tangents, since we need [0..1..................2] to be seen |
| // as definitely not a line (it is when drawn, but not parametrically) |
| // so we compare midpoints |
| #define CHEAP_DIST_LIMIT (SK_Scalar1/2) // just made this value up |
| |
| static bool quad_too_curvy(const SkPoint pts[3]) { |
| // diff = (a/4 + b/2 + c/4) - (a/2 + c/2) |
| // diff = -a/4 + b/2 - c/4 |
| SkScalar dx = SkScalarHalf(pts[1].fX) - |
| SkScalarHalf(SkScalarHalf(pts[0].fX + pts[2].fX)); |
| SkScalar dy = SkScalarHalf(pts[1].fY) - |
| SkScalarHalf(SkScalarHalf(pts[0].fY + pts[2].fY)); |
| |
| SkScalar dist = SkMaxScalar(SkScalarAbs(dx), SkScalarAbs(dy)); |
| return dist > CHEAP_DIST_LIMIT; |
| } |
| |
| static bool cheap_dist_exceeds_limit(const SkPoint& pt, |
| SkScalar x, SkScalar y) { |
| SkScalar dist = SkMaxScalar(SkScalarAbs(x - pt.fX), SkScalarAbs(y - pt.fY)); |
| // just made up the 1/2 |
| return dist > CHEAP_DIST_LIMIT; |
| } |
| |
| static bool cubic_too_curvy(const SkPoint pts[4]) { |
| return cheap_dist_exceeds_limit(pts[1], |
| SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1/3), |
| SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1/3)) |
| || |
| cheap_dist_exceeds_limit(pts[2], |
| SkScalarInterp(pts[0].fX, pts[3].fX, SK_Scalar1*2/3), |
| SkScalarInterp(pts[0].fY, pts[3].fY, SK_Scalar1*2/3)); |
| } |
| |
| SkScalar SkPathMeasure::compute_quad_segs(const SkPoint pts[3], |
| SkScalar distance, int mint, int maxt, int ptIndex) { |
| if (tspan_big_enough(maxt - mint) && quad_too_curvy(pts)) { |
| SkPoint tmp[5]; |
| int halft = (mint + maxt) >> 1; |
| |
| SkChopQuadAtHalf(pts, tmp); |
| distance = this->compute_quad_segs(tmp, distance, mint, halft, ptIndex); |
| distance = this->compute_quad_segs(&tmp[2], distance, halft, maxt, ptIndex); |
| } else { |
| SkScalar d = SkPoint::Distance(pts[0], pts[2]); |
| SkScalar prevD = distance; |
| distance += d; |
| if (distance > prevD) { |
| Segment* seg = fSegments.append(); |
| seg->fDistance = distance; |
| seg->fPtIndex = ptIndex; |
| seg->fType = kQuad_SegType; |
| seg->fTValue = maxt; |
| } |
| } |
| return distance; |
| } |
| |
| SkScalar SkPathMeasure::compute_cubic_segs(const SkPoint pts[4], |
| SkScalar distance, int mint, int maxt, int ptIndex) { |
| if (tspan_big_enough(maxt - mint) && cubic_too_curvy(pts)) { |
| SkPoint tmp[7]; |
| int halft = (mint + maxt) >> 1; |
| |
| SkChopCubicAtHalf(pts, tmp); |
| distance = this->compute_cubic_segs(tmp, distance, mint, halft, ptIndex); |
| distance = this->compute_cubic_segs(&tmp[3], distance, halft, maxt, ptIndex); |
| } else { |
| SkScalar d = SkPoint::Distance(pts[0], pts[3]); |
| SkScalar prevD = distance; |
| distance += d; |
| if (distance > prevD) { |
| Segment* seg = fSegments.append(); |
| seg->fDistance = distance; |
| seg->fPtIndex = ptIndex; |
| seg->fType = kCubic_SegType; |
| seg->fTValue = maxt; |
| } |
| } |
| return distance; |
| } |
| |
| void SkPathMeasure::buildSegments() { |
| SkPoint pts[4]; |
| int ptIndex = fFirstPtIndex; |
| SkScalar distance = 0; |
| bool isClosed = fForceClosed; |
| bool firstMoveTo = ptIndex < 0; |
| Segment* seg; |
| |
| /* Note: |
| * as we accumulate distance, we have to check that the result of += |
| * actually made it larger, since a very small delta might be > 0, but |
| * still have no effect on distance (if distance >>> delta). |
| * |
| * We do this check below, and in compute_quad_segs and compute_cubic_segs |
| */ |
| fSegments.reset(); |
| bool done = false; |
| do { |
| switch (fIter.next(pts)) { |
| case SkPath::kConic_Verb: |
| SkASSERT(0); |
| break; |
| case SkPath::kMove_Verb: |
| ptIndex += 1; |
| fPts.append(1, pts); |
| if (!firstMoveTo) { |
| done = true; |
| break; |
| } |
| firstMoveTo = false; |
| break; |
| |
| case SkPath::kLine_Verb: { |
| SkScalar d = SkPoint::Distance(pts[0], pts[1]); |
| SkASSERT(d >= 0); |
| SkScalar prevD = distance; |
| distance += d; |
| if (distance > prevD) { |
| seg = fSegments.append(); |
| seg->fDistance = distance; |
| seg->fPtIndex = ptIndex; |
| seg->fType = kLine_SegType; |
| seg->fTValue = kMaxTValue; |
| fPts.append(1, pts + 1); |
| ptIndex++; |
| } |
| } break; |
| |
| case SkPath::kQuad_Verb: { |
| SkScalar prevD = distance; |
| distance = this->compute_quad_segs(pts, distance, 0, |
| kMaxTValue, ptIndex); |
| if (distance > prevD) { |
| fPts.append(2, pts + 1); |
| ptIndex += 2; |
| } |
| } break; |
| |
| case SkPath::kCubic_Verb: { |
| SkScalar prevD = distance; |
| distance = this->compute_cubic_segs(pts, distance, 0, |
| kMaxTValue, ptIndex); |
| if (distance > prevD) { |
| fPts.append(3, pts + 1); |
| ptIndex += 3; |
| } |
| } break; |
| |
| case SkPath::kClose_Verb: |
| isClosed = true; |
| break; |
| |
| case SkPath::kDone_Verb: |
| done = true; |
| break; |
| } |
| } while (!done); |
| |
| fLength = distance; |
| fIsClosed = isClosed; |
| fFirstPtIndex = ptIndex; |
| |
| #ifdef SK_DEBUG |
| { |
| const Segment* seg = fSegments.begin(); |
| const Segment* stop = fSegments.end(); |
| unsigned ptIndex = 0; |
| SkScalar distance = 0; |
| |
| while (seg < stop) { |
| SkASSERT(seg->fDistance > distance); |
| SkASSERT(seg->fPtIndex >= ptIndex); |
| SkASSERT(seg->fTValue > 0); |
| |
| const Segment* s = seg; |
| while (s < stop - 1 && s[0].fPtIndex == s[1].fPtIndex) { |
| SkASSERT(s[0].fType == s[1].fType); |
| SkASSERT(s[0].fTValue < s[1].fTValue); |
| s += 1; |
| } |
| |
| distance = seg->fDistance; |
| ptIndex = seg->fPtIndex; |
| seg += 1; |
| } |
| // SkDebugf("\n"); |
| } |
| #endif |
| } |
| |
| static void compute_pos_tan(const SkPoint pts[], int segType, |
| SkScalar t, SkPoint* pos, SkVector* tangent) { |
| switch (segType) { |
| case kLine_SegType: |
| if (pos) { |
| pos->set(SkScalarInterp(pts[0].fX, pts[1].fX, t), |
| SkScalarInterp(pts[0].fY, pts[1].fY, t)); |
| } |
| if (tangent) { |
| tangent->setNormalize(pts[1].fX - pts[0].fX, pts[1].fY - pts[0].fY); |
| } |
| break; |
| case kQuad_SegType: |
| SkEvalQuadAt(pts, t, pos, tangent); |
| if (tangent) { |
| tangent->normalize(); |
| } |
| break; |
| case kCubic_SegType: |
| SkEvalCubicAt(pts, t, pos, tangent, NULL); |
| if (tangent) { |
| tangent->normalize(); |
| } |
| break; |
| default: |
| SkDEBUGFAIL("unknown segType"); |
| } |
| } |
| |
| static void seg_to(const SkPoint pts[], int segType, |
| SkScalar startT, SkScalar stopT, SkPath* dst) { |
| SkASSERT(startT >= 0 && startT <= SK_Scalar1); |
| SkASSERT(stopT >= 0 && stopT <= SK_Scalar1); |
| SkASSERT(startT <= stopT); |
| |
| if (startT == stopT) { |
| return; // should we report this, to undo a moveTo? |
| } |
| |
| SkPoint tmp0[7], tmp1[7]; |
| |
| switch (segType) { |
| case kLine_SegType: |
| if (SK_Scalar1 == stopT) { |
| dst->lineTo(pts[1]); |
| } else { |
| dst->lineTo(SkScalarInterp(pts[0].fX, pts[1].fX, stopT), |
| SkScalarInterp(pts[0].fY, pts[1].fY, stopT)); |
| } |
| break; |
| case kQuad_SegType: |
| if (0 == startT) { |
| if (SK_Scalar1 == stopT) { |
| dst->quadTo(pts[1], pts[2]); |
| } else { |
| SkChopQuadAt(pts, tmp0, stopT); |
| dst->quadTo(tmp0[1], tmp0[2]); |
| } |
| } else { |
| SkChopQuadAt(pts, tmp0, startT); |
| if (SK_Scalar1 == stopT) { |
| dst->quadTo(tmp0[3], tmp0[4]); |
| } else { |
| SkChopQuadAt(&tmp0[2], tmp1, SkScalarDiv(stopT - startT, |
| SK_Scalar1 - startT)); |
| dst->quadTo(tmp1[1], tmp1[2]); |
| } |
| } |
| break; |
| case kCubic_SegType: |
| if (0 == startT) { |
| if (SK_Scalar1 == stopT) { |
| dst->cubicTo(pts[1], pts[2], pts[3]); |
| } else { |
| SkChopCubicAt(pts, tmp0, stopT); |
| dst->cubicTo(tmp0[1], tmp0[2], tmp0[3]); |
| } |
| } else { |
| SkChopCubicAt(pts, tmp0, startT); |
| if (SK_Scalar1 == stopT) { |
| dst->cubicTo(tmp0[4], tmp0[5], tmp0[6]); |
| } else { |
| SkChopCubicAt(&tmp0[3], tmp1, SkScalarDiv(stopT - startT, |
| SK_Scalar1 - startT)); |
| dst->cubicTo(tmp1[1], tmp1[2], tmp1[3]); |
| } |
| } |
| break; |
| default: |
| SkDEBUGFAIL("unknown segType"); |
| sk_throw(); |
| } |
| } |
| |
| //////////////////////////////////////////////////////////////////////////////// |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| SkPathMeasure::SkPathMeasure() { |
| fPath = NULL; |
| fLength = -1; // signal we need to compute it |
| fForceClosed = false; |
| fFirstPtIndex = -1; |
| } |
| |
| SkPathMeasure::SkPathMeasure(const SkPath& path, bool forceClosed) { |
| fPath = &path; |
| fLength = -1; // signal we need to compute it |
| fForceClosed = forceClosed; |
| fFirstPtIndex = -1; |
| |
| fIter.setPath(path, forceClosed); |
| } |
| |
| SkPathMeasure::~SkPathMeasure() {} |
| |
| /** Assign a new path, or null to have none. |
| */ |
| void SkPathMeasure::setPath(const SkPath* path, bool forceClosed) { |
| fPath = path; |
| fLength = -1; // signal we need to compute it |
| fForceClosed = forceClosed; |
| fFirstPtIndex = -1; |
| |
| if (path) { |
| fIter.setPath(*path, forceClosed); |
| } |
| fSegments.reset(); |
| fPts.reset(); |
| } |
| |
| SkScalar SkPathMeasure::getLength() { |
| if (fPath == NULL) { |
| return 0; |
| } |
| if (fLength < 0) { |
| this->buildSegments(); |
| } |
| SkASSERT(fLength >= 0); |
| return fLength; |
| } |
| |
| const SkPathMeasure::Segment* SkPathMeasure::distanceToSegment( |
| SkScalar distance, SkScalar* t) { |
| SkDEBUGCODE(SkScalar length = ) this->getLength(); |
| SkASSERT(distance >= 0 && distance <= length); |
| |
| const Segment* seg = fSegments.begin(); |
| int count = fSegments.count(); |
| |
| int index = SkTSearch<SkScalar>(&seg->fDistance, count, distance, sizeof(Segment)); |
| // don't care if we hit an exact match or not, so we xor index if it is negative |
| index ^= (index >> 31); |
| seg = &seg[index]; |
| |
| // now interpolate t-values with the prev segment (if possible) |
| SkScalar startT = 0, startD = 0; |
| // check if the prev segment is legal, and references the same set of points |
| if (index > 0) { |
| startD = seg[-1].fDistance; |
| if (seg[-1].fPtIndex == seg->fPtIndex) { |
| SkASSERT(seg[-1].fType == seg->fType); |
| startT = seg[-1].getScalarT(); |
| } |
| } |
| |
| SkASSERT(seg->getScalarT() > startT); |
| SkASSERT(distance >= startD); |
| SkASSERT(seg->fDistance > startD); |
| |
| *t = startT + SkScalarMulDiv(seg->getScalarT() - startT, |
| distance - startD, |
| seg->fDistance - startD); |
| return seg; |
| } |
| |
| bool SkPathMeasure::getPosTan(SkScalar distance, SkPoint* pos, |
| SkVector* tangent) { |
| if (NULL == fPath) { |
| return false; |
| } |
| |
| SkScalar length = this->getLength(); // call this to force computing it |
| int count = fSegments.count(); |
| |
| if (count == 0 || length == 0) { |
| return false; |
| } |
| |
| // pin the distance to a legal range |
| if (distance < 0) { |
| distance = 0; |
| } else if (distance > length) { |
| distance = length; |
| } |
| |
| SkScalar t; |
| const Segment* seg = this->distanceToSegment(distance, &t); |
| |
| compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, t, pos, tangent); |
| return true; |
| } |
| |
| bool SkPathMeasure::getMatrix(SkScalar distance, SkMatrix* matrix, |
| MatrixFlags flags) { |
| if (NULL == fPath) { |
| return false; |
| } |
| |
| SkPoint position; |
| SkVector tangent; |
| |
| if (this->getPosTan(distance, &position, &tangent)) { |
| if (matrix) { |
| if (flags & kGetTangent_MatrixFlag) { |
| matrix->setSinCos(tangent.fY, tangent.fX, 0, 0); |
| } else { |
| matrix->reset(); |
| } |
| if (flags & kGetPosition_MatrixFlag) { |
| matrix->postTranslate(position.fX, position.fY); |
| } |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| bool SkPathMeasure::getSegment(SkScalar startD, SkScalar stopD, SkPath* dst, |
| bool startWithMoveTo) { |
| SkASSERT(dst); |
| |
| SkScalar length = this->getLength(); // ensure we have built our segments |
| |
| if (startD < 0) { |
| startD = 0; |
| } |
| if (stopD > length) { |
| stopD = length; |
| } |
| if (startD >= stopD) { |
| return false; |
| } |
| |
| SkPoint p; |
| SkScalar startT, stopT; |
| const Segment* seg = this->distanceToSegment(startD, &startT); |
| const Segment* stopSeg = this->distanceToSegment(stopD, &stopT); |
| SkASSERT(seg <= stopSeg); |
| |
| if (startWithMoveTo) { |
| compute_pos_tan(&fPts[seg->fPtIndex], seg->fType, startT, &p, NULL); |
| dst->moveTo(p); |
| } |
| |
| if (seg->fPtIndex == stopSeg->fPtIndex) { |
| seg_to(&fPts[seg->fPtIndex], seg->fType, startT, stopT, dst); |
| } else { |
| do { |
| seg_to(&fPts[seg->fPtIndex], seg->fType, startT, SK_Scalar1, dst); |
| seg = SkPathMeasure::NextSegment(seg); |
| startT = 0; |
| } while (seg->fPtIndex < stopSeg->fPtIndex); |
| seg_to(&fPts[seg->fPtIndex], seg->fType, 0, stopT, dst); |
| } |
| return true; |
| } |
| |
| bool SkPathMeasure::isClosed() { |
| (void)this->getLength(); |
| return fIsClosed; |
| } |
| |
| /** Move to the next contour in the path. Return true if one exists, or false if |
| we're done with the path. |
| */ |
| bool SkPathMeasure::nextContour() { |
| fLength = -1; |
| return this->getLength() > 0; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #ifdef SK_DEBUG |
| |
| void SkPathMeasure::dump() { |
| SkDebugf("pathmeas: length=%g, segs=%d\n", fLength, fSegments.count()); |
| |
| for (int i = 0; i < fSegments.count(); i++) { |
| const Segment* seg = &fSegments[i]; |
| SkDebugf("pathmeas: seg[%d] distance=%g, point=%d, t=%g, type=%d\n", |
| i, seg->fDistance, seg->fPtIndex, seg->getScalarT(), |
| seg->fType); |
| } |
| } |
| |
| #endif |
