The Tor Browser: gfx/skia/trunk/src/effects/SkDashPathEffect.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/effects/SkDashPathEffect.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/effects/SkDashPathEffect.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*
  * Copyright 2006 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 "SkDashPathEffect.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkPathMeasure.h"
 static inline int is_even(int x) {
     return (~x) << 31;
 }
 static SkScalar FindFirstInterval(const SkScalar intervals[], SkScalar phase,
                                   int32_t* index, int count) {
     for (int i = 0; i < count; ++i) {
         if (phase > intervals[i]) {
             phase -= intervals[i];
         } else {
             *index = i;
             return intervals[i] - phase;
         }
     }
     // If we get here, phase "appears" to be larger than our length. This
     // shouldn't happen with perfect precision, but we can accumulate errors
     // during the initial length computation (rounding can make our sum be too
     // big or too small. In that event, we just have to eat the error here.
     *index = 0;
     return intervals[0];
 }
 SkDashPathEffect::SkDashPathEffect(const SkScalar intervals[], int count,
                                    SkScalar phase, bool scaleToFit)
         : fScaleToFit(scaleToFit) {
     SkASSERT(intervals);
     SkASSERT(count > 1 && SkAlign2(count) == count);
     fIntervals = (SkScalar*)sk_malloc_throw(sizeof(SkScalar) * count);
     fCount = count;
     SkScalar len = 0;
     for (int i = 0; i < count; i++) {
         SkASSERT(intervals[i] >= 0);
         fIntervals[i] = intervals[i];
         len += intervals[i];
     }
     fIntervalLength = len;
     // watch out for values that might make us go out of bounds
     if ((len > 0) && SkScalarIsFinite(phase) && SkScalarIsFinite(len)) {
         // Adjust phase to be between 0 and len, "flipping" phase if negative.
         // e.g., if len is 100, then phase of -20 (or -120) is equivalent to 80
         if (phase < 0) {
             phase = -phase;
             if (phase > len) {
                 phase = SkScalarMod(phase, len);
             }
             phase = len - phase;
             // Due to finite precision, it's possible that phase == len,
             // even after the subtract (if len >>> phase), so fix that here.
             // This fixes http://crbug.com/124652 .
             SkASSERT(phase <= len);
             if (phase == len) {
                 phase = 0;
             }
         } else if (phase >= len) {
             phase = SkScalarMod(phase, len);
         }
         SkASSERT(phase >= 0 && phase < len);
         fInitialDashLength = FindFirstInterval(intervals, phase,
                                                &fInitialDashIndex, count);
         SkASSERT(fInitialDashLength >= 0);
         SkASSERT(fInitialDashIndex >= 0 && fInitialDashIndex < fCount);
     } else {
         fInitialDashLength = -1;    // signal bad dash intervals
     }
 }
 SkDashPathEffect::~SkDashPathEffect() {
     sk_free(fIntervals);
 }
 static void outset_for_stroke(SkRect* rect, const SkStrokeRec& rec) {
     SkScalar radius = SkScalarHalf(rec.getWidth());
     if (0 == radius) {
         radius = SK_Scalar1;    // hairlines
     }
     if (SkPaint::kMiter_Join == rec.getJoin()) {
         radius = SkScalarMul(radius, rec.getMiter());
     }
     rect->outset(radius, radius);
 }
 // Only handles lines for now. If returns true, dstPath is the new (smaller)
 // path. If returns false, then dstPath parameter is ignored.
 static bool cull_path(const SkPath& srcPath, const SkStrokeRec& rec,
                       const SkRect* cullRect, SkScalar intervalLength,
                       SkPath* dstPath) {
     if (NULL == cullRect) {
         return false;
     }
     SkPoint pts[2];
     if (!srcPath.isLine(pts)) {
         return false;
     }
     SkRect bounds = *cullRect;
     outset_for_stroke(&bounds, rec);
     SkScalar dx = pts[1].x() - pts[0].x();
     SkScalar dy = pts[1].y() - pts[0].y();
     // just do horizontal lines for now (lazy)
     if (dy) {
         return false;
     }
     SkScalar minX = pts[0].fX;
     SkScalar maxX = pts[1].fX;
     if (maxX < bounds.fLeft || minX > bounds.fRight) {
         return false;
     }
     if (dx < 0) {
         SkTSwap(minX, maxX);
     }
     // Now we actually perform the chop, removing the excess to the left and
     // right of the bounds (keeping our new line "in phase" with the dash,
     // hence the (mod intervalLength).
     if (minX < bounds.fLeft) {
         minX = bounds.fLeft - SkScalarMod(bounds.fLeft - minX,
                                           intervalLength);
     }
     if (maxX > bounds.fRight) {
         maxX = bounds.fRight + SkScalarMod(maxX - bounds.fRight,
                                            intervalLength);
     }
     SkASSERT(maxX >= minX);
     if (dx < 0) {
         SkTSwap(minX, maxX);
     }
     pts[0].fX = minX;
     pts[1].fX = maxX;
     dstPath->moveTo(pts[0]);
     dstPath->lineTo(pts[1]);
     return true;
 }
 class SpecialLineRec {
 public:
     bool init(const SkPath& src, SkPath* dst, SkStrokeRec* rec,
               int intervalCount, SkScalar intervalLength) {
         if (rec->isHairlineStyle() || !src.isLine(fPts)) {
             return false;
         }
         // can relax this in the future, if we handle square and round caps
         if (SkPaint::kButt_Cap != rec->getCap()) {
             return false;
         }
         SkScalar pathLength = SkPoint::Distance(fPts[0], fPts[1]);
         fTangent = fPts[1] - fPts[0];
         if (fTangent.isZero()) {
             return false;
         }
         fPathLength = pathLength;
         fTangent.scale(SkScalarInvert(pathLength));
         fTangent.rotateCCW(&fNormal);
         fNormal.scale(SkScalarHalf(rec->getWidth()));
         // now estimate how many quads will be added to the path
         //     resulting segments = pathLen * intervalCount / intervalLen
         //     resulting points = 4 * segments
         SkScalar ptCount = SkScalarMulDiv(pathLength,
                                           SkIntToScalar(intervalCount),
                                           intervalLength);
         int n = SkScalarCeilToInt(ptCount) << 2;
         dst->incReserve(n);
         // we will take care of the stroking
         rec->setFillStyle();
         return true;
     }
     void addSegment(SkScalar d0, SkScalar d1, SkPath* path) const {
         SkASSERT(d0 < fPathLength);
         // clamp the segment to our length
         if (d1 > fPathLength) {
             d1 = fPathLength;
         }
         SkScalar x0 = fPts[0].fX + SkScalarMul(fTangent.fX, d0);
         SkScalar x1 = fPts[0].fX + SkScalarMul(fTangent.fX, d1);
         SkScalar y0 = fPts[0].fY + SkScalarMul(fTangent.fY, d0);
         SkScalar y1 = fPts[0].fY + SkScalarMul(fTangent.fY, d1);
         SkPoint pts[4];
         pts[0].set(x0 + fNormal.fX, y0 + fNormal.fY);   // moveTo
         pts[1].set(x1 + fNormal.fX, y1 + fNormal.fY);   // lineTo
         pts[2].set(x1 - fNormal.fX, y1 - fNormal.fY);   // lineTo
         pts[3].set(x0 - fNormal.fX, y0 - fNormal.fY);   // lineTo
         path->addPoly(pts, SK_ARRAY_COUNT(pts), false);
     }
 private:
     SkPoint fPts[2];
     SkVector fTangent;
     SkVector fNormal;
     SkScalar fPathLength;
 };
 bool SkDashPathEffect::filterPath(SkPath* dst, const SkPath& src,
                               SkStrokeRec* rec, const SkRect* cullRect) const {
     // we do nothing if the src wants to be filled, or if our dashlength is 0
     if (rec->isFillStyle() || fInitialDashLength < 0) {
         return false;
     }
     const SkScalar* intervals = fIntervals;
     SkScalar        dashCount = 0;
     int             segCount = 0;
     SkPath cullPathStorage;
     const SkPath* srcPtr = &src;
     if (cull_path(src, *rec, cullRect, fIntervalLength, &cullPathStorage)) {
         srcPtr = &cullPathStorage;
     }
     SpecialLineRec lineRec;
     bool specialLine = lineRec.init(*srcPtr, dst, rec, fCount >> 1, fIntervalLength);
     SkPathMeasure   meas(*srcPtr, false);
     do {
         bool        skipFirstSegment = meas.isClosed();
         bool        addedSegment = false;
         SkScalar    length = meas.getLength();
         int         index = fInitialDashIndex;
         SkScalar    scale = SK_Scalar1;
         // Since the path length / dash length ratio may be arbitrarily large, we can exert
         // significant memory pressure while attempting to build the filtered path. To avoid this,
         // we simply give up dashing beyond a certain threshold.
         //
         // The original bug report (http://crbug.com/165432) is based on a path yielding more than
         // 90 million dash segments and crashing the memory allocator. A limit of 1 million
         // segments seems reasonable: at 2 verbs per segment * 9 bytes per verb, this caps the
         // maximum dash memory overhead at roughly 17MB per path.
         static const SkScalar kMaxDashCount = 1000000;
         dashCount += length * (fCount >> 1) / fIntervalLength;
         if (dashCount > kMaxDashCount) {
             dst->reset();
             return false;
         }
         if (fScaleToFit) {
             if (fIntervalLength >= length) {
                 scale = SkScalarDiv(length, fIntervalLength);
             } else {
                 SkScalar div = SkScalarDiv(length, fIntervalLength);
                 int n = SkScalarFloorToInt(div);
                 scale = SkScalarDiv(length, n * fIntervalLength);
             }
         }
         // Using double precision to avoid looping indefinitely due to single precision rounding
         // (for extreme path_length/dash_length ratios). See test_infinite_dash() unittest.
         double  distance = 0;
         double  dlen = SkScalarMul(fInitialDashLength, scale);
         while (distance < length) {
             SkASSERT(dlen >= 0);
             addedSegment = false;
             if (is_even(index) && dlen > 0 && !skipFirstSegment) {
                 addedSegment = true;
                 ++segCount;
                 if (specialLine) {
                     lineRec.addSegment(SkDoubleToScalar(distance),
                                        SkDoubleToScalar(distance + dlen),
                                        dst);
                 } else {
                     meas.getSegment(SkDoubleToScalar(distance),
                                     SkDoubleToScalar(distance + dlen),
                                     dst, true);
                 }
             }
             distance += dlen;
             // clear this so we only respect it the first time around
             skipFirstSegment = false;
             // wrap around our intervals array if necessary
             index += 1;
             SkASSERT(index <= fCount);
             if (index == fCount) {
                 index = 0;
             }
             // fetch our next dlen
             dlen = SkScalarMul(intervals[index], scale);
         }
         // extend if we ended on a segment and we need to join up with the (skipped) initial segment
         if (meas.isClosed() && is_even(fInitialDashIndex) &&
                 fInitialDashLength > 0) {
             meas.getSegment(0, SkScalarMul(fInitialDashLength, scale), dst, !addedSegment);
             ++segCount;
         }
     } while (meas.nextContour());
     if (segCount > 1) {
         dst->setConvexity(SkPath::kConcave_Convexity);
     }
     return true;
 }
 // Currently asPoints is more restrictive then it needs to be. In the future
 // we need to:
 //      allow kRound_Cap capping (could allow rotations in the matrix with this)
 //      allow paths to be returned
 bool SkDashPathEffect::asPoints(PointData* results,
                                 const SkPath& src,
                                 const SkStrokeRec& rec,
                                 const SkMatrix& matrix,
                                 const SkRect* cullRect) const {
     // width < 0 -> fill && width == 0 -> hairline so requiring width > 0 rules both out
     if (fInitialDashLength < 0 || 0 >= rec.getWidth()) {
         return false;
     }
     // TODO: this next test could be eased up. We could allow any number of
     // intervals as long as all the ons match and all the offs match.
     // Additionally, they do not necessarily need to be integers.
     // We cannot allow arbitrary intervals since we want the returned points
     // to be uniformly sized.
     if (fCount != 2 ||
         !SkScalarNearlyEqual(fIntervals[0], fIntervals[1]) ||
         !SkScalarIsInt(fIntervals[0]) ||
         !SkScalarIsInt(fIntervals[1])) {
         return false;
     }
     // TODO: this next test could be eased up. The rescaling should not impact
     // the equality of the ons & offs. However, we would need to remove the
     // integer intervals restriction first
     if (fScaleToFit) {
         return false;
     }
     SkPoint pts[2];
     if (!src.isLine(pts)) {
         return false;
     }
     // TODO: this test could be eased up to allow circles
     if (SkPaint::kButt_Cap != rec.getCap()) {
         return false;
     }
     // TODO: this test could be eased up for circles. Rotations could be allowed.
     if (!matrix.rectStaysRect()) {
         return false;
     }
     SkScalar        length = SkPoint::Distance(pts[1], pts[0]);
     SkVector tangent = pts[1] - pts[0];
     if (tangent.isZero()) {
         return false;
     }
     tangent.scale(SkScalarInvert(length));
     // TODO: make this test for horizontal & vertical lines more robust
     bool isXAxis = true;
     if (SK_Scalar1 == tangent.fX || -SK_Scalar1 == tangent.fX) {
         results->fSize.set(SkScalarHalf(fIntervals[0]), SkScalarHalf(rec.getWidth()));
     } else if (SK_Scalar1 == tangent.fY || -SK_Scalar1 == tangent.fY) {
         results->fSize.set(SkScalarHalf(rec.getWidth()), SkScalarHalf(fIntervals[0]));
         isXAxis = false;
     } else if (SkPaint::kRound_Cap != rec.getCap()) {
         // Angled lines don't have axis-aligned boxes.
         return false;
     }
     if (NULL != results) {
         results->fFlags = 0;
         SkScalar clampedInitialDashLength = SkMinScalar(length, fInitialDashLength);
         if (SkPaint::kRound_Cap == rec.getCap()) {
             results->fFlags |= PointData::kCircles_PointFlag;
         }
         results->fNumPoints = 0;
         SkScalar len2 = length;
         if (clampedInitialDashLength > 0 || 0 == fInitialDashIndex) {
             SkASSERT(len2 >= clampedInitialDashLength);
             if (0 == fInitialDashIndex) {
                 if (clampedInitialDashLength > 0) {
                     if (clampedInitialDashLength >= fIntervals[0]) {
                         ++results->fNumPoints;  // partial first dash
                     }
                     len2 -= clampedInitialDashLength;
                 }
                 len2 -= fIntervals[1];  // also skip first space
                 if (len2 < 0) {
                     len2 = 0;
                 }
             } else {
                 len2 -= clampedInitialDashLength; // skip initial partial empty
             }
         }
         int numMidPoints = SkScalarFloorToInt(SkScalarDiv(len2, fIntervalLength));
         results->fNumPoints += numMidPoints;
         len2 -= numMidPoints * fIntervalLength;
         bool partialLast = false;
         if (len2 > 0) {
             if (len2 < fIntervals[0]) {
                 partialLast = true;
             } else {
                 ++numMidPoints;
                 ++results->fNumPoints;
             }
         }
         results->fPoints = new SkPoint[results->fNumPoints];
         SkScalar    distance = 0;
         int         curPt = 0;
         if (clampedInitialDashLength > 0 || 0 == fInitialDashIndex) {
             SkASSERT(clampedInitialDashLength <= length);
             if (0 == fInitialDashIndex) {
                 if (clampedInitialDashLength > 0) {
                     // partial first block
                     SkASSERT(SkPaint::kRound_Cap != rec.getCap()); // can't handle partial circles
                     SkScalar x = pts[0].fX + SkScalarMul(tangent.fX, SkScalarHalf(clampedInitialDashLength));
                     SkScalar y = pts[0].fY + SkScalarMul(tangent.fY, SkScalarHalf(clampedInitialDashLength));
                     SkScalar halfWidth, halfHeight;
                     if (isXAxis) {
                         halfWidth = SkScalarHalf(clampedInitialDashLength);
                         halfHeight = SkScalarHalf(rec.getWidth());
                     } else {
                         halfWidth = SkScalarHalf(rec.getWidth());
                         halfHeight = SkScalarHalf(clampedInitialDashLength);
                     }
                     if (clampedInitialDashLength < fIntervals[0]) {
                         // This one will not be like the others
                         results->fFirst.addRect(x - halfWidth, y - halfHeight,
                                                 x + halfWidth, y + halfHeight);
                     } else {
                         SkASSERT(curPt < results->fNumPoints);
                         results->fPoints[curPt].set(x, y);
                         ++curPt;
                     }
                     distance += clampedInitialDashLength;
                 }
                 distance += fIntervals[1];  // skip over the next blank block too
             } else {
                 distance += clampedInitialDashLength;
             }
         }
         if (0 != numMidPoints) {
             distance += SkScalarHalf(fIntervals[0]);
             for (int i = 0; i < numMidPoints; ++i) {
                 SkScalar x = pts[0].fX + SkScalarMul(tangent.fX, distance);
                 SkScalar y = pts[0].fY + SkScalarMul(tangent.fY, distance);
                 SkASSERT(curPt < results->fNumPoints);
                 results->fPoints[curPt].set(x, y);
                 ++curPt;
                 distance += fIntervalLength;
             }
             distance -= SkScalarHalf(fIntervals[0]);
         }
         if (partialLast) {
             // partial final block
             SkASSERT(SkPaint::kRound_Cap != rec.getCap()); // can't handle partial circles
             SkScalar temp = length - distance;
             SkASSERT(temp < fIntervals[0]);
             SkScalar x = pts[0].fX + SkScalarMul(tangent.fX, distance + SkScalarHalf(temp));
             SkScalar y = pts[0].fY + SkScalarMul(tangent.fY, distance + SkScalarHalf(temp));
             SkScalar halfWidth, halfHeight;
             if (isXAxis) {
                 halfWidth = SkScalarHalf(temp);
                 halfHeight = SkScalarHalf(rec.getWidth());
             } else {
                 halfWidth = SkScalarHalf(rec.getWidth());
                 halfHeight = SkScalarHalf(temp);
             }
             results->fLast.addRect(x - halfWidth, y - halfHeight,
                                    x + halfWidth, y + halfHeight);
         }
         SkASSERT(curPt == results->fNumPoints);
     }
     return true;
 }
 SkFlattenable::Factory SkDashPathEffect::getFactory() const {
     return CreateProc;
 }
 void SkDashPathEffect::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeInt(fInitialDashIndex);
     buffer.writeScalar(fInitialDashLength);
     buffer.writeScalar(fIntervalLength);
     buffer.writeBool(fScaleToFit);
     buffer.writeScalarArray(fIntervals, fCount);
 }
 SkFlattenable* SkDashPathEffect::CreateProc(SkReadBuffer& buffer) {
     return SkNEW_ARGS(SkDashPathEffect, (buffer));
 }
 SkDashPathEffect::SkDashPathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {
     fInitialDashIndex = buffer.readInt();
     fInitialDashLength = buffer.readScalar();
     fIntervalLength = buffer.readScalar();
     fScaleToFit = buffer.readBool();
     fCount = buffer.getArrayCount();
     size_t allocSize = sizeof(SkScalar) * fCount;
     if (buffer.validateAvailable(allocSize)) {
         fIntervals = (SkScalar*)sk_malloc_throw(allocSize);
         buffer.readScalarArray(fIntervals, fCount);
     } else {
         fIntervals = NULL;
     }
 }

The Tor Browser / annotate

gfx/skia/trunk/src/effects/SkDashPathEffect.cpp@6474c204b198 (annotated)

gfx/skia/trunk/src/effects/SkDashPathEffect.cpp