Make the clip stack reduction test generate inverse filled paths.
Also adds some comments to GrReduceClipStack.
R=robertphillips@google.com
Review URL: https://codereview.appspot.com/6847109
git-svn-id: http://skia.googlecode.com/svn/trunk@6561 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/core/SkRandom.h b/include/core/SkRandom.h
index c8d7199..73dc491 100644
--- a/include/core/SkRandom.h
+++ b/include/core/SkRandom.h
@@ -111,6 +111,13 @@
*/
bool nextBool() { return this->nextU() >= 0x80000000; }
+ /** A biased version of nextBool().
+ */
+ bool nextBiasedBool(SkScalar fractionTrue) {
+ SkASSERT(fractionTrue >= 0 && fractionTrue <= SK_Scalar1);
+ return this->nextUScalar1() <= fractionTrue;
+ }
+
/** Return the next pseudo random number as a signed 64bit value.
*/
void next64(Sk64* a) {
diff --git a/src/gpu/GrClipMaskManager.cpp b/src/gpu/GrClipMaskManager.cpp
index cf1d2b3..2f24b22 100644
--- a/src/gpu/GrClipMaskManager.cpp
+++ b/src/gpu/GrClipMaskManager.cpp
@@ -130,7 +130,7 @@
case SkRegion::kIntersect_Op:
if (*resultsAreBounded) {
// check if the shape intersected contains the entire bounds and therefore can
- // be skipped or it is outside the entire bounds and therfore makes the clip
+ // be skipped or it is outside the entire bounds and therefore makes the clip
// empty.
if (clip->isInverseFilled()) {
if (clip->contains(*resultBounds)) {
@@ -154,8 +154,8 @@
break;
case SkRegion::kUnion_Op:
if (*resultsAreBounded) {
- // If the unioned shape contains the entire bounds then after this element
- // the bounds is entirely inside the clip. If the unioned shape is outside the
+ // If the union-ed shape contains the entire bounds then after this element
+ // the bounds is entirely inside the clip. If the union-ed shape is outside the
// bounds then this op can be skipped.
if (clip->isInverseFilled()) {
if (clip->contains(*resultBounds)) {
@@ -179,6 +179,10 @@
break;
case SkRegion::kXOR_Op:
if (*resultsAreBounded) {
+ // If the bounds is entirely inside the shape being xor-ed then the effect is
+ // to flip the inside/outside state of every point in the bounds. We may be
+ // able to take advantage of this in the forward pass. If the xor-ed shape
+ // doesn't intersect the bounds then it can be skipped.
if (clip->isInverseFilled()) {
if (clip->contains(*resultBounds)) {
skippable = true;
@@ -198,6 +202,10 @@
}
break;
case SkRegion::kReverseDifference_Op:
+ // When the bounds is entirely within the rev-diff shape then this behaves like xor
+ // and reverses every point inside the bounds. If the shape is completely outside
+ // the bounds then we know after this element is applied that the bounds will be
+ // all outside the current clip.B
if (*resultsAreBounded) {
if (clip->isInverseFilled()) {
if (clip->contains(*resultBounds)) {
@@ -220,7 +228,11 @@
}
break;
case SkRegion::kReplace_Op:
- if (*resultsAreBounded) {
+ // Replace will always terminate our walk. We will either begin the forward walk
+ // at the replace op or detect here than the shape is either completely inside
+ // or completely outside the bounds. In this latter case it can be skipped by
+ // setting the correct value for initialState.
+ if (*resultsAreBounded) {
if (clip->isInverseFilled()) {
if (clip->contains(*resultBounds)) {
*initialState = kAllOut_InitialState;
@@ -276,9 +288,11 @@
bool skippable = false;
switch (clip->fOp) {
case SkRegion::kDifference_Op:
+ // subtracting from the empty set yields the empty set.
skippable = kAllOut_InitialState == *initialState;
break;
case SkRegion::kIntersect_Op:
+ // intersecting with the empty set yields the empty set
skippable = kAllOut_InitialState == *initialState;
break;
case SkRegion::kUnion_Op:
diff --git a/tests/ClipStackTest.cpp b/tests/ClipStackTest.cpp
index 8e4d301..8eb1102 100644
--- a/tests/ClipStackTest.cpp
+++ b/tests/ClipStackTest.cpp
@@ -647,25 +647,44 @@
///////////////////////////////////////////////////////////////////////////////////////////////////
#if SK_SUPPORT_GPU
+// Functions that add a shape to the clip stack. The shape is computed from a rectangle.
+// AA is always disabled since the clip stack reducer can cause changes in aa rasterization of the
+// stack. A fractional edge repeated in different elements may be rasterized fewer times using the
+// reduced stack.
+typedef void (*AddElementFunc) (const SkRect& rect,
+ bool invert,
+ SkRegion::Op op,
+ SkClipStack* stack);
-typedef void (*AddElementFunc) (const SkRect& rect, bool aa, SkRegion::Op op, SkClipStack* stack);
-
-static void add_round_rect(const SkRect& rect, bool aa, SkRegion::Op op, SkClipStack* stack) {
+static void add_round_rect(const SkRect& rect, bool invert, SkRegion::Op op, SkClipStack* stack) {
SkPath path;
SkScalar rx = rect.width() / 10;
- SkScalar ry = rect.width() / 20;
+ SkScalar ry = rect.height() / 20;
path.addRoundRect(rect, rx, ry);
- stack->clipDevPath(path, op, aa);
+ if (invert) {
+ path.setFillType(SkPath::kInverseWinding_FillType);
+ }
+ stack->clipDevPath(path, op, false);
};
-static void add_rect(const SkRect& rect, bool aa, SkRegion::Op op, SkClipStack* stack) {
- stack->clipDevRect(rect, op, aa);
+static void add_rect(const SkRect& rect, bool invert, SkRegion::Op op, SkClipStack* stack) {
+ if (invert) {
+ SkPath path;
+ path.addRect(rect);
+ path.setFillType(SkPath::kInverseWinding_FillType);
+ stack->clipDevPath(path, op, false);
+ } else {
+ stack->clipDevRect(rect, op, false);
+ }
};
-static void add_oval(const SkRect& rect, bool aa, SkRegion::Op op, SkClipStack* stack) {
+static void add_oval(const SkRect& rect, bool invert, SkRegion::Op op, SkClipStack* stack) {
SkPath path;
path.addOval(rect);
- stack->clipDevPath(path, op, aa);
+ if (invert) {
+ path.setFillType(SkPath::kInverseWinding_FillType);
+ }
+ stack->clipDevPath(path, op, false);
};
static void add_elem_to_stack(const SkClipStack::Iter::Clip& clip, SkClipStack* stack) {
@@ -706,11 +725,12 @@
"RD",
"RP",
};
- if (clip.fRect || clip.fPath) {
+ if (NULL != clip.fRect || NULL != clip.fPath) {
const SkRect& bounds = clip.getBounds();
- SkDebugf("%s %s [%f %f] x [%f %f]\n",
+ SkDebugf("%s %s %s [%f %f] x [%f %f]\n",
kOpStrs[clip.fOp],
- (clip.fRect ? "R" : "P"),
+ (NULL != clip.fRect ? "R" : "P"),
+ ((NULL != clip.fPath && clip.fPath->isInverseFillType() ? "I" : " ")),
bounds.fLeft, bounds.fRight, bounds.fTop, bounds.fBottom);
} else {
SkDebugf("EM\n");
@@ -748,6 +768,9 @@
// the optimizer.
static const int kReplaceDiv = 4 * kMaxElemsPerTest;
+ // We want to test inverse fills. However, they are quite rare in practice so don't over do it.
+ static const SkScalar kFractionInverted = SK_Scalar1 / kMaxElemsPerTest;
+
static const AddElementFunc kElementFuncs[] = {
add_rect,
add_round_rect,
@@ -781,10 +804,8 @@
SkRect rect = SkRect::MakeXYWH(xy.fX, xy.fY, size.fWidth, size.fHeight);
- // AA is always disabled. The optimizer can cause changes in aa rasterization of the
- // clip stack. A fractional edge repeated in different elements may be rasterized fewer
- // times using the reduced stack.
- kElementFuncs[r.nextULessThan(SK_ARRAY_COUNT(kElementFuncs))](rect, false, op, &stack);
+ bool invert = r.nextBiasedBool(kFractionInverted);
+ kElementFuncs[r.nextULessThan(SK_ARRAY_COUNT(kElementFuncs))](rect, invert, op, &stack);
if (doSave) {
stack.save();
}