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-rw-r--r--chromium/third_party/skia/src/utils/SkDashPath.cpp328
1 files changed, 328 insertions, 0 deletions
diff --git a/chromium/third_party/skia/src/utils/SkDashPath.cpp b/chromium/third_party/skia/src/utils/SkDashPath.cpp
new file mode 100644
index 00000000000..3c4aef343d3
--- /dev/null
+++ b/chromium/third_party/skia/src/utils/SkDashPath.cpp
@@ -0,0 +1,328 @@
+/*
+ * 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 "SkDashPathPriv.h"
+#include "SkPathMeasure.h"
+
+static inline int is_even(int x) {
+ return (~x) << 31;
+}
+
+static SkScalar find_first_interval(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];
+}
+
+void SkDashPath::CalcDashParameters(SkScalar phase, const SkScalar intervals[], int32_t count,
+ SkScalar* initialDashLength, int32_t* initialDashIndex,
+ SkScalar* intervalLength, SkScalar* adjustedPhase) {
+ SkScalar len = 0;
+ for (int i = 0; i < count; i++) {
+ len += intervals[i];
+ }
+ *intervalLength = 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 (adjustedPhase) {
+ 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);
+ }
+ *adjustedPhase = phase;
+ }
+ SkASSERT(phase >= 0 && phase < len);
+
+ *initialDashLength = find_first_interval(intervals, phase,
+ initialDashIndex, count);
+
+ SkASSERT(*initialDashLength >= 0);
+ SkASSERT(*initialDashIndex >= 0 && *initialDashIndex < count);
+ } else {
+ *initialDashLength = -1; // signal bad dash intervals
+ }
+}
+
+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 SkDashPath::FilterDashPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
+ const SkRect* cullRect, const SkScalar aIntervals[],
+ int32_t count, SkScalar initialDashLength, int32_t initialDashIndex,
+ SkScalar intervalLength) {
+
+ // we do nothing if the src wants to be filled, or if our dashlength is 0
+ if (rec->isFillStyle() || initialDashLength < 0) {
+ return false;
+ }
+
+ const SkScalar* intervals = aIntervals;
+ SkScalar dashCount = 0;
+ int segCount = 0;
+
+ SkPath cullPathStorage;
+ const SkPath* srcPtr = &src;
+ if (cull_path(src, *rec, cullRect, intervalLength, &cullPathStorage)) {
+ srcPtr = &cullPathStorage;
+ }
+
+ SpecialLineRec lineRec;
+ bool specialLine = lineRec.init(*srcPtr, dst, rec, count >> 1, intervalLength);
+
+ SkPathMeasure meas(*srcPtr, false);
+
+ do {
+ bool skipFirstSegment = meas.isClosed();
+ bool addedSegment = false;
+ SkScalar length = meas.getLength();
+ int index = initialDashIndex;
+
+ // 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 * (count >> 1) / intervalLength;
+ if (dashCount > kMaxDashCount) {
+ dst->reset();
+ return false;
+ }
+
+ // 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 = initialDashLength;
+
+ 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 <= count);
+ if (index == count) {
+ index = 0;
+ }
+
+ // fetch our next dlen
+ dlen = intervals[index];
+ }
+
+ // extend if we ended on a segment and we need to join up with the (skipped) initial segment
+ if (meas.isClosed() && is_even(initialDashIndex) &&
+ initialDashLength > 0) {
+ meas.getSegment(0, initialDashLength, dst, !addedSegment);
+ ++segCount;
+ }
+ } while (meas.nextContour());
+
+ if (segCount > 1) {
+ dst->setConvexity(SkPath::kConcave_Convexity);
+ }
+
+ return true;
+}
+
+bool SkDashPath::FilterDashPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
+ const SkRect* cullRect, const SkPathEffect::DashInfo& info) {
+ SkScalar initialDashLength = 0;
+ int32_t initialDashIndex = 0;
+ SkScalar intervalLength = 0;
+ CalcDashParameters(info.fPhase, info.fIntervals, info.fCount,
+ &initialDashLength, &initialDashIndex, &intervalLength);
+ return FilterDashPath(dst, src, rec, cullRect, info.fIntervals, info.fCount, initialDashLength,
+ initialDashIndex, intervalLength);
+}
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