a more involved path is rect bug
This is bug number ten in the series, and is the
most interesting. It exploits that the code tracks
corners 0, 2, and 3 but not corner 1.
Changing the code to track all corners is the biggest
so far, and while it (hopefully) simplifies things,
the presence of new code may signify more bugs to come.
R=robertphillips@google.com
Bug: 824145,skia::7792
Change-Id: Ia18e4d80fbed06ae6d9c89dcb4c462c5610213cc
Reviewed-on: https://skia-review.googlesource.com/121487
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 2fd5201..d5538f7 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -435,7 +435,7 @@
FIXME: If the API passes fill-only, return true if the filled stroke
is a rectangle, though the caller failed to close the path.
- first,last,next direction state-machine:
+ directions values:
0x1 is set if the segment is horizontal
0x2 is set if the segment is moving to the right or down
thus:
@@ -456,9 +456,7 @@
const SkPoint* pts = *ptsPtr;
const SkPoint* savePts = nullptr; // used to allow caller to iterate through a pair of rects
lineStart.set(0, 0);
- int firstDirection = 0;
- int lastDirection = 0;
- int nextDirection = 0;
+ signed char directions[] = {-1, -1, -1, -1}; // -1 to 3; -1 is uninitialized
bool closedOrMoved = false;
bool addedLine = false;
bool autoClose = false;
@@ -486,9 +484,9 @@
break; // single point on side OK
}
addedLine = true;
- nextDirection = rect_make_dir(lineDelta.fX, lineDelta.fY);
+ int nextDirection = rect_make_dir(lineDelta.fX, lineDelta.fY); // 0 to 3
if (0 == corners) {
- firstDirection = nextDirection;
+ directions[0] = nextDirection;
lineStart = lineEnd;
corners = 1;
closedOrMoved = false;
@@ -497,26 +495,27 @@
if (closedOrMoved) {
return false; // closed followed by a line
}
- if (autoClose && nextDirection == firstDirection) {
+ if (autoClose && nextDirection == directions[0]) {
break; // colinear with first
}
closedOrMoved = autoClose;
- if (lastDirection != nextDirection) {
- if (++corners > 4) {
- return false; // too many direction changes
- }
- }
lineStart = lineEnd;
- if (lastDirection == nextDirection) {
+ if (directions[corners - 1] == nextDirection) {
break; // colinear segment
}
- // Possible values for corners are 2, 3, and 4.
- // When corners == 3, nextDirection opposes firstDirection.
- // Otherwise, nextDirection at corner 2 opposes corner 4.
- int turn = firstDirection ^ (corners - 1);
- int directionCycle = 3 == corners ? 0 : nextDirection ^ turn;
- if ((directionCycle ^ turn) != nextDirection) {
- return false; // direction didn't follow cycle
+ if (corners >= 4) {
+ return false; // too many direction changes
+ }
+ directions[corners++] = nextDirection;
+ // opposite lines must point in opposite directions; xoring them should equal 2
+ if (corners == 3) {
+ if ((directions[0] ^ directions[2]) != 2) {
+ return false;
+ }
+ } else if (corners == 4) {
+ if ((directions[1] ^ directions[3]) != 2) {
+ return false;
+ }
}
break;
}
@@ -525,7 +524,7 @@
case kCubic_Verb:
return false; // quadratic, cubic not allowed
case kMove_Verb:
- if (allowPartial && !autoClose && firstDirection) {
+ if (allowPartial && !autoClose && directions[0] >= 0) {
insertClose = true;
*currVerb -= 1; // try move again afterwards
goto addMissingClose;
@@ -544,7 +543,6 @@
break;
}
*currVerb += 1;
- lastDirection = nextDirection;
addMissingClose:
;
}
@@ -567,7 +565,7 @@
}
int closeDirection = rect_make_dir(closeXY.fX, closeXY.fY);
// make sure the close-segment doesn't double-back on itself
- if (3 == corners || closeDirection == lastDirection) {
+ if (3 == corners || (closeDirection ^ directions[1]) == 2) {
result = true;
autoClose = false; // we are not closed
}
@@ -583,7 +581,7 @@
*isClosed = autoClose;
}
if (result && direction) {
- *direction = firstDirection == ((lastDirection + 1) & 3) ? kCCW_Direction : kCW_Direction;
+ *direction = directions[0] == ((directions[1] + 1) & 3) ? kCW_Direction : kCCW_Direction;
}
return result;
}