fix edgecase in chopcubic where we computed duplicate tvalues
git-svn-id: http://skia.googlecode.com/svn/trunk@3285 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index 5308d56..de86827 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -834,6 +834,65 @@
}
#endif
+/**
+ * Given an array and count, remove all pair-wise duplicates from the array,
+ * keeping the existing sorting, and return the new count
+ */
+static int collaps_duplicates(float array[], int count) {
+ int n = count;
+ for (int n = count; n > 1; --n) {
+ if (array[0] == array[1]) {
+ for (int i = 1; i < n; ++i) {
+ array[i - 1] = array[i];
+ }
+ count -= 1;
+ } else {
+ array += 1;
+ }
+ }
+ return count;
+}
+
+#ifdef SK_DEBUG
+
+#define TEST_COLLAPS_ENTRY(array) array, SK_ARRAY_COUNT(array)
+
+static void test_collaps_duplicates() {
+ static bool gOnce;
+ if (gOnce) { return; }
+ gOnce = true;
+ const float src0[] = { 0 };
+ const float src1[] = { 0, 0 };
+ const float src2[] = { 0, 1 };
+ const float src3[] = { 0, 0, 0 };
+ const float src4[] = { 0, 0, 1 };
+ const float src5[] = { 0, 1, 1 };
+ const float src6[] = { 0, 1, 2 };
+ const struct {
+ const float* fData;
+ int fCount;
+ int fCollapsedCount;
+ } data[] = {
+ { TEST_COLLAPS_ENTRY(src0), 1 },
+ { TEST_COLLAPS_ENTRY(src1), 1 },
+ { TEST_COLLAPS_ENTRY(src2), 2 },
+ { TEST_COLLAPS_ENTRY(src3), 1 },
+ { TEST_COLLAPS_ENTRY(src4), 2 },
+ { TEST_COLLAPS_ENTRY(src5), 2 },
+ { TEST_COLLAPS_ENTRY(src6), 3 },
+ };
+ for (size_t i = 0; i < SK_ARRAY_COUNT(data); ++i) {
+ float dst[3];
+ memcpy(dst, data[i].fData, data[i].fCount * sizeof(dst[0]));
+ int count = collaps_duplicates(dst, data[i].fCount);
+ SkASSERT(data[i].fCollapsedCount == count);
+ for (int j = 1; j < count; ++j) {
+ SkASSERT(dst[j-1] < dst[j]);
+ }
+ }
+}
+#endif
+
#if defined _WIN32 && _MSC_VER >= 1300 && defined SK_SCALAR_IS_FIXED // disable warning : unreachable code if building fixed point for windows desktop
#pragma warning ( disable : 4702 )
#endif
@@ -841,6 +900,9 @@
/* Solve coeff(t) == 0, returning the number of roots that
lie withing 0 < t < 1.
coeff[0]t^3 + coeff[1]t^2 + coeff[2]t + coeff[3]
+
+ Eliminates repeated roots (so that all tValues are distinct, and are always
+ in increasing order.
*/
static int solve_cubic_polynomial(const SkFP coeff[4], SkScalar tValues[3])
{
@@ -895,8 +957,14 @@
if (is_unit_interval(r))
*roots++ = r;
+ SkDEBUGCODE(test_collaps_duplicates();)
+
// now sort the roots
- bubble_sort(tValues, (int)(roots - tValues));
+ int count = (int)(roots - tValues);
+ SkASSERT((unsigned)count <= 3);
+ bubble_sort(tValues, count);
+ count = collaps_duplicates(tValues, count);
+ roots = tValues + count; // so we compute the proper count below
#endif
}
else // we have 1 real root