Add SkOffsetSimplePolygon.
Performs inset and outset operations on simple polygons and returns
a simple polygon, if possible.
Bug: skia:
Change-Id: I6d468174ad70b5279b736c532e19cbb84ff9f955
Reviewed-on: https://skia-review.googlesource.com/116483
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/tests/OffsetSimplePolyTest.cpp b/tests/OffsetSimplePolyTest.cpp
new file mode 100644
index 0000000..50f680e
--- /dev/null
+++ b/tests/OffsetSimplePolyTest.cpp
@@ -0,0 +1,210 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "Test.h"
+#include "SkOffsetPolygon.h"
+
+static bool is_convex(const SkTDArray<SkPoint>& poly) {
+ if (poly.count() < 3) {
+ return false;
+ }
+
+ SkVector v0 = poly[0] - poly[poly.count() - 1];
+ SkVector v1 = poly[1] - poly[poly.count() - 1];
+ SkScalar winding = v0.cross(v1);
+
+ for (int i = 0; i < poly.count()-1; ++i) {
+ int j = i + 1;
+ int k = (i + 2) % poly.count();
+
+ SkVector v0 = poly[j] - poly[i];
+ SkVector v1 = poly[k] - poly[i];
+ SkScalar perpDot = v0.cross(v1);
+ if (winding*perpDot < 0) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+DEF_TEST(OffsetSimplePoly, reporter) {
+ SkTDArray<SkPoint> rrectPoly;
+
+ ///////////////////////////////////////////////////////////////////////
+ // Try convex tests first
+
+ // round rect
+ *rrectPoly.push() = SkPoint::Make(-100, 55);
+ *rrectPoly.push() = SkPoint::Make(100, 55);
+ *rrectPoly.push() = SkPoint::Make(100 + 2.5f, 50 + 4.330127f);
+ *rrectPoly.push() = SkPoint::Make(100 + 3.535534f, 50 + 3.535534f);
+ *rrectPoly.push() = SkPoint::Make(100 + 4.330127f, 50 + 2.5f);
+ *rrectPoly.push() = SkPoint::Make(105, 50);
+ *rrectPoly.push() = SkPoint::Make(105, -50);
+ *rrectPoly.push() = SkPoint::Make(100 + 4.330127f, -50 - 2.5f);
+ *rrectPoly.push() = SkPoint::Make(100 + 3.535534f, -50 - 3.535534f);
+ *rrectPoly.push() = SkPoint::Make(100 + 2.5f, -50 - 4.330127f);
+ *rrectPoly.push() = SkPoint::Make(100, -55);
+ *rrectPoly.push() = SkPoint::Make(-100, -55);
+ *rrectPoly.push() = SkPoint::Make(-100 - 2.5f, -50 - 4.330127f);
+ *rrectPoly.push() = SkPoint::Make(-100 - 3.535534f, -50 - 3.535534f);
+ *rrectPoly.push() = SkPoint::Make(-100 - 4.330127f, -50 - 2.5f);
+ *rrectPoly.push() = SkPoint::Make(-105, -50);
+ *rrectPoly.push() = SkPoint::Make(-105, 50);
+ *rrectPoly.push() = SkPoint::Make(-100 - 4.330127f, 50 + 2.5f);
+ *rrectPoly.push() = SkPoint::Make(-100 - 3.535534f, 50 + 3.535534f);
+ *rrectPoly.push() = SkPoint::Make(-100 - 2.5f, 50 + 4.330127f);
+ REPORTER_ASSERT(reporter, is_convex(rrectPoly));
+
+ // inset a little
+ SkTDArray<SkPoint> offsetPoly;
+ bool result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 3, &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+ REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+
+ // inset to rect
+ result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 10, &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+ REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+ REPORTER_ASSERT(reporter, offsetPoly.count() == 4);
+ if (offsetPoly.count() == 4) {
+ REPORTER_ASSERT(reporter, offsetPoly[0].equals(-95, 45));
+ REPORTER_ASSERT(reporter, offsetPoly[1].equals(95, 45));
+ REPORTER_ASSERT(reporter, offsetPoly[2].equals(95, -45));
+ REPORTER_ASSERT(reporter, offsetPoly[3].equals(-95, -45));
+ }
+
+ // just to full inset
+ // fails, but outputs a line segment
+ result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 55, &offsetPoly);
+ REPORTER_ASSERT(reporter, !result);
+ REPORTER_ASSERT(reporter, !is_convex(offsetPoly));
+ REPORTER_ASSERT(reporter, offsetPoly.count() == 2);
+ if (offsetPoly.count() == 2) {
+ REPORTER_ASSERT(reporter, offsetPoly[0].equals(-50, 0));
+ REPORTER_ASSERT(reporter, offsetPoly[1].equals(50, 0));
+ }
+
+ // past full inset
+ result = SkOffsetSimplePolygon(&rrectPoly[0], rrectPoly.count(), 75, &offsetPoly);
+ REPORTER_ASSERT(reporter, !result);
+ REPORTER_ASSERT(reporter, offsetPoly.count() == 0);
+
+ // troublesome case
+ SkTDArray<SkPoint> clippedRRectPoly;
+ *clippedRRectPoly.push() = SkPoint::Make(335.928101f, 428.219055f);
+ *clippedRRectPoly.push() = SkPoint::Make(330.414459f, 423.034912f);
+ *clippedRRectPoly.push() = SkPoint::Make(325.749084f, 417.395508f);
+ *clippedRRectPoly.push() = SkPoint::Make(321.931946f, 411.300842f);
+ *clippedRRectPoly.push() = SkPoint::Make(318.963074f, 404.750977f);
+ *clippedRRectPoly.push() = SkPoint::Make(316.842468f, 397.745850f);
+ *clippedRRectPoly.push() = SkPoint::Make(315.570068f, 390.285522f);
+ *clippedRRectPoly.push() = SkPoint::Make(315.145966f, 382.369965f);
+ *clippedRRectPoly.push() = SkPoint::Make(315.570068f, 374.454346f);
+ *clippedRRectPoly.push() = SkPoint::Make(316.842468f, 366.994019f);
+ *clippedRRectPoly.push() = SkPoint::Make(318.963074f, 359.988892f);
+ *clippedRRectPoly.push() = SkPoint::Make(321.931946f, 353.439056f);
+ *clippedRRectPoly.push() = SkPoint::Make(325.749084f, 347.344421f);
+ *clippedRRectPoly.push() = SkPoint::Make(330.414459f, 341.705017f);
+ *clippedRRectPoly.push() = SkPoint::Make(335.928101f, 336.520813f);
+ *clippedRRectPoly.push() = SkPoint::Make(342.289948f, 331.791901f);
+ *clippedRRectPoly.push() = SkPoint::Make(377.312134f, 331.791901f);
+ *clippedRRectPoly.push() = SkPoint::Make(381.195313f, 332.532593f);
+ *clippedRRectPoly.push() = SkPoint::Make(384.464935f, 334.754700f);
+ *clippedRRectPoly.push() = SkPoint::Make(386.687042f, 338.024292f);
+ *clippedRRectPoly.push() = SkPoint::Make(387.427765f, 341.907532f);
+ *clippedRRectPoly.push() = SkPoint::Make(387.427765f, 422.832367f);
+ *clippedRRectPoly.push() = SkPoint::Make(386.687042f, 426.715576f);
+ *clippedRRectPoly.push() = SkPoint::Make(384.464935f, 429.985168f);
+ *clippedRRectPoly.push() = SkPoint::Make(381.195313f, 432.207275f);
+ *clippedRRectPoly.push() = SkPoint::Make(377.312134f, 432.947998f);
+ *clippedRRectPoly.push() = SkPoint::Make(342.289948f, 432.947998f);
+ REPORTER_ASSERT(reporter, is_convex(clippedRRectPoly));
+
+ result = SkOffsetSimplePolygon(&clippedRRectPoly[0], clippedRRectPoly.count(), 32.3699417f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+ REPORTER_ASSERT(reporter, is_convex(offsetPoly));
+
+ ////////////////////////////////////////////////////////////////////////////////
+ // Concave tests
+
+ SkTDArray<SkPoint> starPoly;
+ *starPoly.push() = SkPoint::Make(0.0f, -50.0f);
+ *starPoly.push() = SkPoint::Make(14.43f, -25.0f);
+ *starPoly.push() = SkPoint::Make(43.30f, -25.0f);
+ *starPoly.push() = SkPoint::Make(28.86f, 0.0f);
+ *starPoly.push() = SkPoint::Make(43.30f, 25.0f);
+ *starPoly.push() = SkPoint::Make(14.43f, 25.0f);
+ *starPoly.push() = SkPoint::Make(0.0f, 50.0f);
+ *starPoly.push() = SkPoint::Make(-14.43f, 25.0f);
+ *starPoly.push() = SkPoint::Make(-43.30f, 25.0f);
+ *starPoly.push() = SkPoint::Make(-28.86f, 0.0f);
+ *starPoly.push() = SkPoint::Make(-43.30f, -25.0f);
+ *starPoly.push() = SkPoint::Make(-14.43f, -25.0f);
+
+ // try a variety of distances
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 0.1f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 5.665f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 28,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ // down to a point
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 28.866f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, !result);
+
+ // and past
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), 50.5f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, !result);
+
+ // and now out
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -0.1f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -5.6665f,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -50,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ result = SkOffsetSimplePolygon(&starPoly[0], starPoly.count(), -100,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, result);
+
+ SkTDArray<SkPoint> intersectingPoly;
+ *intersectingPoly.push() = SkPoint::Make(0.0f, -50.0f);
+ *intersectingPoly.push() = SkPoint::Make(14.43f, -25.0f);
+ *intersectingPoly.push() = SkPoint::Make(43.30f, -25.0f);
+ *intersectingPoly.push() = SkPoint::Make(-28.86f, 0.0f);
+ *intersectingPoly.push() = SkPoint::Make(43.30f, 25.0f);
+ *intersectingPoly.push() = SkPoint::Make(14.43f, 25.0f);
+ *intersectingPoly.push() = SkPoint::Make(0.0f, 50.0f);
+ *intersectingPoly.push() = SkPoint::Make(-14.43f, 25.0f);
+ *intersectingPoly.push() = SkPoint::Make(-43.30f, 25.0f);
+ *intersectingPoly.push() = SkPoint::Make(28.86f, 0.0f);
+ *intersectingPoly.push() = SkPoint::Make(-43.30f, -25.0f);
+ *intersectingPoly.push() = SkPoint::Make(-14.43f, -25.0f);
+
+ result = SkOffsetSimplePolygon(&intersectingPoly[0], intersectingPoly.count(), -100,
+ &offsetPoly);
+ REPORTER_ASSERT(reporter, !result);
+
+
+
+}