Add base types for path ops
Paths contain lines, quads, and cubics, which are
collectively curves.
To work with path intersections, intermediary curves
are constructed. For now, those intermediates use
doubles to guarantee sufficient precision.
The DVector, DPoint, DLine, DQuad, and DCubic
structs encapsulate these intermediate curves.
The DRect and DTriangle structs are created to
describe intersectable areas of interest.
The Bounds struct inherits from SkRect to create
a SkScalar-based rectangle that intersects shared
edges.
This also includes common math equalities and
debugging that the remainder of path ops builds on,
as well as a temporary top-level interface in
include/pathops/SkPathOps.h.
Review URL: https://codereview.chromium.org/12827020
git-svn-id: http://skia.googlecode.com/svn/trunk@8551 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pathops/SkPathOpsOp.cpp b/src/pathops/SkPathOpsOp.cpp
new file mode 100644
index 0000000..5a3576f
--- /dev/null
+++ b/src/pathops/SkPathOpsOp.cpp
@@ -0,0 +1,272 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "SkAddIntersections.h"
+#include "SkOpEdgeBuilder.h"
+#include "SkPathOpsCommon.h"
+#include "SkPathWriter.h"
+
+// FIXME: this and find chase should be merge together, along with
+// other code that walks winding in angles
+// OPTIMIZATION: Probably, the walked winding should be rolled into the angle structure
+// so it isn't duplicated by walkers like this one
+static SkOpSegment* findChaseOp(SkTDArray<SkOpSpan*>& chase, int& nextStart, int& nextEnd) {
+ while (chase.count()) {
+ SkOpSpan* span;
+ chase.pop(&span);
+ const SkOpSpan& backPtr = span->fOther->span(span->fOtherIndex);
+ SkOpSegment* segment = backPtr.fOther;
+ nextStart = backPtr.fOtherIndex;
+ SkTDArray<SkOpAngle> angles;
+ int done = 0;
+ if (segment->activeAngle(nextStart, &done, &angles)) {
+ SkOpAngle* last = angles.end() - 1;
+ nextStart = last->start();
+ nextEnd = last->end();
+ #if TRY_ROTATE
+ *chase.insert(0) = span;
+ #else
+ *chase.append() = span;
+ #endif
+ return last->segment();
+ }
+ if (done == angles.count()) {
+ continue;
+ }
+ SkTDArray<SkOpAngle*> sorted;
+ bool sortable = SkOpSegment::SortAngles(angles, &sorted);
+ int angleCount = sorted.count();
+#if DEBUG_SORT
+ sorted[0]->segment()->debugShowSort(__FUNCTION__, sorted, 0);
+#endif
+ if (!sortable) {
+ continue;
+ }
+ // find first angle, initialize winding to computed fWindSum
+ int firstIndex = -1;
+ const SkOpAngle* angle;
+ do {
+ angle = sorted[++firstIndex];
+ segment = angle->segment();
+ } while (segment->windSum(angle) == SK_MinS32);
+ #if DEBUG_SORT
+ segment->debugShowSort(__FUNCTION__, sorted, firstIndex);
+ #endif
+ int sumMiWinding = segment->updateWindingReverse(angle);
+ int sumSuWinding = segment->updateOppWindingReverse(angle);
+ if (segment->operand()) {
+ SkTSwap<int>(sumMiWinding, sumSuWinding);
+ }
+ int nextIndex = firstIndex + 1;
+ int lastIndex = firstIndex != 0 ? firstIndex : angleCount;
+ SkOpSegment* first = NULL;
+ do {
+ SkASSERT(nextIndex != firstIndex);
+ if (nextIndex == angleCount) {
+ nextIndex = 0;
+ }
+ angle = sorted[nextIndex];
+ segment = angle->segment();
+ int start = angle->start();
+ int end = angle->end();
+ int maxWinding, sumWinding, oppMaxWinding, oppSumWinding;
+ segment->setUpWindings(start, end, &sumMiWinding, &sumSuWinding,
+ &maxWinding, &sumWinding, &oppMaxWinding, &oppSumWinding);
+ if (!segment->done(angle)) {
+ if (!first) {
+ first = segment;
+ nextStart = start;
+ nextEnd = end;
+ }
+ (void) segment->markAngle(maxWinding, sumWinding, oppMaxWinding,
+ oppSumWinding, true, angle);
+ }
+ } while (++nextIndex != lastIndex);
+ if (first) {
+ #if TRY_ROTATE
+ *chase.insert(0) = span;
+ #else
+ *chase.append() = span;
+ #endif
+ return first;
+ }
+ }
+ return NULL;
+}
+
+/*
+static bool windingIsActive(int winding, int oppWinding, int spanWinding, int oppSpanWinding,
+ bool windingIsOp, PathOp op) {
+ bool active = windingIsActive(winding, spanWinding);
+ if (!active) {
+ return false;
+ }
+ if (oppSpanWinding && windingIsActive(oppWinding, oppSpanWinding)) {
+ switch (op) {
+ case kIntersect_Op:
+ case kUnion_Op:
+ return true;
+ case kDifference_Op: {
+ int absSpan = abs(spanWinding);
+ int absOpp = abs(oppSpanWinding);
+ return windingIsOp ? absSpan < absOpp : absSpan > absOpp;
+ }
+ case kXor_Op:
+ return spanWinding != oppSpanWinding;
+ default:
+ SkASSERT(0);
+ }
+ }
+ bool opActive = oppWinding != 0;
+ return gOpLookup[op][opActive][windingIsOp];
+}
+*/
+
+static bool bridgeOp(SkTDArray<SkOpContour*>& contourList, const SkPathOp op,
+ const int xorMask, const int xorOpMask, SkPathWriter* simple) {
+ bool firstContour = true;
+ bool unsortable = false;
+ bool topUnsortable = false;
+ SkPoint topLeft = {SK_ScalarMin, SK_ScalarMin};
+ do {
+ int index, endIndex;
+ bool done;
+ SkOpSegment* current = FindSortableTop(contourList, &firstContour, &index, &endIndex,
+ &topLeft, &topUnsortable, &done, true);
+ if (!current) {
+ if (topUnsortable || !done) {
+ topUnsortable = false;
+ SkASSERT(topLeft.fX != SK_ScalarMin && topLeft.fY != SK_ScalarMin);
+ topLeft.fX = topLeft.fY = SK_ScalarMin;
+ continue;
+ }
+ break;
+ }
+ SkTDArray<SkOpSpan*> chaseArray;
+ do {
+ if (current->activeOp(index, endIndex, xorMask, xorOpMask, op)) {
+ do {
+ #if DEBUG_ACTIVE_SPANS
+ if (!unsortable && current->done()) {
+ DebugShowActiveSpans(contourList);
+ }
+ #endif
+ SkASSERT(unsortable || !current->done());
+ int nextStart = index;
+ int nextEnd = endIndex;
+ SkOpSegment* next = current->findNextOp(&chaseArray, &nextStart, &nextEnd,
+ &unsortable, op, xorMask, xorOpMask);
+ if (!next) {
+ if (!unsortable && simple->hasMove()
+ && current->verb() != SkPath::kLine_Verb
+ && !simple->isClosed()) {
+ current->addCurveTo(index, endIndex, simple, true);
+ SkASSERT(simple->isClosed());
+ }
+ break;
+ }
+ #if DEBUG_FLOW
+ SkDebugf("%s current id=%d from=(%1.9g,%1.9g) to=(%1.9g,%1.9g)\n", __FUNCTION__,
+ current->debugID(), current->xyAtT(index).fX, current->xyAtT(index).fY,
+ current->xyAtT(endIndex).fX, current->xyAtT(endIndex).fY);
+ #endif
+ current->addCurveTo(index, endIndex, simple, true);
+ current = next;
+ index = nextStart;
+ endIndex = nextEnd;
+ } while (!simple->isClosed() && ((!unsortable)
+ || !current->done(SkMin32(index, endIndex))));
+ if (current->activeWinding(index, endIndex) && !simple->isClosed()) {
+ SkASSERT(unsortable);
+ int min = SkMin32(index, endIndex);
+ if (!current->done(min)) {
+ current->addCurveTo(index, endIndex, simple, true);
+ current->markDoneBinary(min);
+ }
+ }
+ simple->close();
+ } else {
+ SkOpSpan* last = current->markAndChaseDoneBinary(index, endIndex);
+ if (last && !last->fLoop) {
+ *chaseArray.append() = last;
+ }
+ }
+ current = findChaseOp(chaseArray, index, endIndex);
+ #if DEBUG_ACTIVE_SPANS
+ DebugShowActiveSpans(contourList);
+ #endif
+ if (!current) {
+ break;
+ }
+ } while (true);
+ } while (true);
+ return simple->someAssemblyRequired();
+}
+
+void Op(const SkPath& one, const SkPath& two, SkPathOp op, SkPath* result) {
+#if DEBUG_SORT || DEBUG_SWAP_TOP
+ gDebugSortCount = gDebugSortCountDefault;
+#endif
+ result->reset();
+ result->setFillType(SkPath::kEvenOdd_FillType);
+ // turn path into list of segments
+ SkTArray<SkOpContour> contours;
+ // FIXME: add self-intersecting cubics' T values to segment
+ SkOpEdgeBuilder builder(one, contours);
+ const int xorMask = builder.xorMask();
+ builder.addOperand(two);
+ builder.finish();
+ const int xorOpMask = builder.xorMask();
+ SkTDArray<SkOpContour*> contourList;
+ MakeContourList(contours, contourList, xorMask == kEvenOdd_PathOpsMask,
+ xorOpMask == kEvenOdd_PathOpsMask);
+ SkOpContour** currentPtr = contourList.begin();
+ if (!currentPtr) {
+ return;
+ }
+ SkOpContour** listEnd = contourList.end();
+ // find all intersections between segments
+ do {
+ SkOpContour** nextPtr = currentPtr;
+ SkOpContour* current = *currentPtr++;
+ if (current->containsCubics()) {
+ AddSelfIntersectTs(current);
+ }
+ SkOpContour* next;
+ do {
+ next = *nextPtr++;
+ } while (AddIntersectTs(current, next) && nextPtr != listEnd);
+ } while (currentPtr != listEnd);
+ // eat through coincident edges
+
+ int total = 0;
+ int index;
+ for (index = 0; index < contourList.count(); ++index) {
+ total += contourList[index]->segments().count();
+ }
+#if DEBUG_SHOW_WINDING
+ SkOpContour::debugShowWindingValues(contourList);
+#endif
+ CoincidenceCheck(&contourList, total);
+#if DEBUG_SHOW_WINDING
+ SkOpContour::debugShowWindingValues(contourList);
+#endif
+ FixOtherTIndex(&contourList);
+ SortSegments(&contourList);
+#if DEBUG_ACTIVE_SPANS
+ DebugShowActiveSpans(contourList);
+#endif
+ // construct closed contours
+ SkPathWriter wrapper(*result);
+ bridgeOp(contourList, op, xorMask, xorOpMask, &wrapper);
+ { // if some edges could not be resolved, assemble remaining fragments
+ SkPath temp;
+ temp.setFillType(SkPath::kEvenOdd_FillType);
+ SkPathWriter assembled(temp);
+ Assemble(wrapper, &assembled);
+ *result = *assembled.nativePath();
+ }
+}