| /* |
| * Copyright 2016 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "GrReducedClip.h" |
| |
| #include "GrClip.h" |
| |
| typedef SkClipStack::Element Element; |
| |
| /** |
| * There are plenty of optimizations that could be added here. Maybe flips could be folded into |
| * earlier operations. Or would inserting flips and reversing earlier ops ever be a win? Perhaps |
| * for the case where the bounds are kInsideOut_BoundsType. We could restrict earlier operations |
| * based on later intersect operations, and perhaps remove intersect-rects. We could optionally |
| * take a rect in case the caller knows a bound on what is to be drawn through this clip. |
| */ |
| GrReducedClip::GrReducedClip(const SkClipStack& stack, const SkRect& queryBounds) { |
| SkASSERT(!queryBounds.isEmpty()); |
| fHasIBounds = false; |
| |
| if (stack.isWideOpen()) { |
| fInitialState = InitialState::kAllIn; |
| return; |
| } |
| |
| SkClipStack::BoundsType stackBoundsType; |
| SkRect stackBounds; |
| bool iior; |
| stack.getBounds(&stackBounds, &stackBoundsType, &iior); |
| |
| if (stackBounds.isEmpty() || GrClip::IsOutsideClip(stackBounds, queryBounds)) { |
| bool insideOut = SkClipStack::kInsideOut_BoundsType == stackBoundsType; |
| fInitialState = insideOut ? InitialState::kAllIn : InitialState::kAllOut; |
| return; |
| } |
| |
| if (iior) { |
| // "Is intersection of rects" means the clip is a single rect indicated by the stack bounds. |
| // This should only be true if aa/non-aa status matches among all elements. |
| SkASSERT(SkClipStack::kNormal_BoundsType == stackBoundsType); |
| SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart); |
| if (!iter.prev()->isAA() || GrClip::IsPixelAligned(stackBounds)) { |
| // The clip is a non-aa rect. This is the one spot where we can actually implement the |
| // clip (using fIBounds) rather than just telling the caller what it should be. |
| stackBounds.round(&fIBounds); |
| fHasIBounds = true; |
| fInitialState = fIBounds.isEmpty() ? InitialState::kAllOut : InitialState::kAllIn; |
| return; |
| } |
| if (GrClip::IsInsideClip(stackBounds, queryBounds)) { |
| fInitialState = InitialState::kAllIn; |
| return; |
| } |
| |
| SkRect tightBounds; |
| SkAssertResult(tightBounds.intersect(stackBounds, queryBounds)); |
| fIBounds = GrClip::GetPixelIBounds(tightBounds); |
| SkASSERT(!fIBounds.isEmpty()); // Empty should have been blocked by IsOutsideClip above. |
| fHasIBounds = true; |
| |
| // Implement the clip with an AA rect element. |
| fElements.addToHead(stackBounds, SkRegion::kReplace_Op, true/*doAA*/); |
| fElementsGenID = stack.getTopmostGenID(); |
| fRequiresAA = true; |
| |
| fInitialState = InitialState::kAllOut; |
| return; |
| } |
| |
| SkRect tighterQuery = queryBounds; |
| if (SkClipStack::kNormal_BoundsType == stackBoundsType) { |
| // Tighten the query by introducing a new clip at the stack's pixel boundaries. (This new |
| // clip will be enforced by the scissor through fIBounds.) |
| SkAssertResult(tighterQuery.intersect(GrClip::GetPixelBounds(stackBounds))); |
| } |
| |
| fIBounds = GrClip::GetPixelIBounds(tighterQuery); |
| SkASSERT(!fIBounds.isEmpty()); // Empty should have been blocked by IsOutsideClip above. |
| fHasIBounds = true; |
| |
| // Now that we have determined the bounds to use and filtered out the trivial cases, call the |
| // helper that actually walks the stack. |
| this->walkStack(stack, tighterQuery); |
| } |
| |
| void GrReducedClip::walkStack(const SkClipStack& stack, const SkRect& queryBounds) { |
| // walk backwards until we get to: |
| // a) the beginning |
| // b) an operation that is known to make the bounds all inside/outside |
| // c) a replace operation |
| |
| enum class InitialTriState { |
| kUnknown = -1, |
| kAllIn = (int)GrReducedClip::InitialState::kAllIn, |
| kAllOut = (int)GrReducedClip::InitialState::kAllOut |
| } initialTriState = InitialTriState::kUnknown; |
| |
| // During our backwards walk, track whether we've seen ops that either grow or shrink the clip. |
| // TODO: track these per saved clip so that we can consider them on the forward pass. |
| bool embiggens = false; |
| bool emsmallens = false; |
| |
| // We use a slightly relaxed set of query bounds for element containment tests. This is to |
| // account for floating point rounding error that may have occurred during coord transforms. |
| SkRect relaxedQueryBounds = queryBounds.makeInset(GrClip::kBoundsTolerance, |
| GrClip::kBoundsTolerance); |
| |
| SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart); |
| int numAAElements = 0; |
| while (InitialTriState::kUnknown == initialTriState) { |
| const Element* element = iter.prev(); |
| if (nullptr == element) { |
| initialTriState = InitialTriState::kAllIn; |
| break; |
| } |
| if (SkClipStack::kEmptyGenID == element->getGenID()) { |
| initialTriState = InitialTriState::kAllOut; |
| break; |
| } |
| if (SkClipStack::kWideOpenGenID == element->getGenID()) { |
| initialTriState = InitialTriState::kAllIn; |
| break; |
| } |
| |
| bool skippable = false; |
| bool isFlip = false; // does this op just flip the in/out state of every point in the bounds |
| |
| switch (element->getOp()) { |
| case SkRegion::kDifference_Op: |
| // check if the shape subtracted either contains the entire bounds (and makes |
| // the clip empty) or is outside the bounds and therefore can be skipped. |
| if (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| emsmallens = true; |
| } |
| break; |
| case SkRegion::kIntersect_Op: |
| // check if the shape intersected contains the entire bounds and therefore can |
| // be skipped or it is outside the entire bounds and therefore makes the clip |
| // empty. |
| if (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| skippable = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (!embiggens && !element->isAA() && |
| Element::kRect_Type == element->getType()) { |
| // fIBounds and queryBounds have already acccounted for this element via |
| // clip stack bounds; here we just apply the non-aa rounding effect. |
| SkIRect nonaaRect; |
| element->getRect().round(&nonaaRect); |
| if (!this->intersectIBounds(nonaaRect)) { |
| return; |
| } |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| emsmallens = true; |
| } |
| break; |
| case SkRegion::kUnion_Op: |
| // 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 (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllIn; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllIn; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| embiggens = true; |
| } |
| break; |
| case SkRegion::kXOR_Op: |
| // 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 (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| isFlip = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| isFlip = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| emsmallens = embiggens = true; |
| } |
| 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 (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| isFlip = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| isFlip = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| emsmallens = embiggens = true; |
| } |
| break; |
| |
| case SkRegion::kReplace_Op: |
| // 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 initialTriState. |
| if (element->isInverseFilled()) { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllIn; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(relaxedQueryBounds)) { |
| initialTriState = InitialTriState::kAllIn; |
| skippable = true; |
| } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) { |
| initialTriState = InitialTriState::kAllOut; |
| skippable = true; |
| } else if (!embiggens && !element->isAA() && |
| Element::kRect_Type == element->getType()) { |
| // fIBounds and queryBounds have already acccounted for this element via |
| // clip stack bounds; here we just apply the non-aa rounding effect. |
| SkIRect nonaaRect; |
| element->getRect().round(&nonaaRect); |
| if (!this->intersectIBounds(nonaaRect)) { |
| return; |
| } |
| initialTriState = InitialTriState::kAllIn; |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| initialTriState = InitialTriState::kAllOut; |
| embiggens = emsmallens = true; |
| } |
| break; |
| default: |
| SkDEBUGFAIL("Unexpected op."); |
| break; |
| } |
| if (!skippable) { |
| if (0 == fElements.count()) { |
| // This will be the last element. Record the stricter genID. |
| fElementsGenID = element->getGenID(); |
| } |
| |
| // if it is a flip, change it to a bounds-filling rect |
| if (isFlip) { |
| SkASSERT(SkRegion::kXOR_Op == element->getOp() || |
| SkRegion::kReverseDifference_Op == element->getOp()); |
| fElements.addToHead(SkRect::Make(fIBounds), SkRegion::kReverseDifference_Op, false); |
| } else { |
| Element* newElement = fElements.addToHead(*element); |
| if (newElement->isAA()) { |
| ++numAAElements; |
| } |
| // Intersecting an inverse shape is the same as differencing the non-inverse shape. |
| // Replacing with an inverse shape is the same as setting initialState=kAllIn and |
| // differencing the non-inverse shape. |
| bool isReplace = SkRegion::kReplace_Op == newElement->getOp(); |
| if (newElement->isInverseFilled() && |
| (SkRegion::kIntersect_Op == newElement->getOp() || isReplace)) { |
| newElement->invertShapeFillType(); |
| newElement->setOp(SkRegion::kDifference_Op); |
| if (isReplace) { |
| SkASSERT(InitialTriState::kAllOut == initialTriState); |
| initialTriState = InitialTriState::kAllIn; |
| } |
| } |
| } |
| } |
| } |
| |
| if ((InitialTriState::kAllOut == initialTriState && !embiggens) || |
| (InitialTriState::kAllIn == initialTriState && !emsmallens)) { |
| fElements.reset(); |
| numAAElements = 0; |
| } else { |
| Element* element = fElements.headIter().get(); |
| while (element) { |
| bool skippable = false; |
| switch (element->getOp()) { |
| case SkRegion::kDifference_Op: |
| // subtracting from the empty set yields the empty set. |
| skippable = InitialTriState::kAllOut == initialTriState; |
| break; |
| case SkRegion::kIntersect_Op: |
| // intersecting with the empty set yields the empty set |
| if (InitialTriState::kAllOut == initialTriState) { |
| skippable = true; |
| } else { |
| // We can clear to zero and then simply draw the clip element. |
| initialTriState = InitialTriState::kAllOut; |
| element->setOp(SkRegion::kReplace_Op); |
| } |
| break; |
| case SkRegion::kUnion_Op: |
| if (InitialTriState::kAllIn == initialTriState) { |
| // unioning the infinite plane with anything is a no-op. |
| skippable = true; |
| } else { |
| // unioning the empty set with a shape is the shape. |
| element->setOp(SkRegion::kReplace_Op); |
| } |
| break; |
| case SkRegion::kXOR_Op: |
| if (InitialTriState::kAllOut == initialTriState) { |
| // xor could be changed to diff in the kAllIn case, not sure it's a win. |
| element->setOp(SkRegion::kReplace_Op); |
| } |
| break; |
| case SkRegion::kReverseDifference_Op: |
| if (InitialTriState::kAllIn == initialTriState) { |
| // subtracting the whole plane will yield the empty set. |
| skippable = true; |
| initialTriState = InitialTriState::kAllOut; |
| } else { |
| // this picks up flips inserted in the backwards pass. |
| skippable = element->isInverseFilled() ? |
| GrClip::IsOutsideClip(element->getBounds(), queryBounds) : |
| element->contains(relaxedQueryBounds); |
| if (skippable) { |
| initialTriState = InitialTriState::kAllIn; |
| } else { |
| element->setOp(SkRegion::kReplace_Op); |
| } |
| } |
| break; |
| case SkRegion::kReplace_Op: |
| skippable = false; // we would have skipped it in the backwards walk if we |
| // could've. |
| break; |
| default: |
| SkDEBUGFAIL("Unexpected op."); |
| break; |
| } |
| if (!skippable) { |
| break; |
| } else { |
| if (element->isAA()) { |
| --numAAElements; |
| } |
| fElements.popHead(); |
| element = fElements.headIter().get(); |
| } |
| } |
| } |
| fRequiresAA = numAAElements > 0; |
| |
| SkASSERT(InitialTriState::kUnknown != initialTriState); |
| fInitialState = static_cast<GrReducedClip::InitialState>(initialTriState); |
| } |
| |
| inline bool GrReducedClip::intersectIBounds(const SkIRect& irect) { |
| SkASSERT(fHasIBounds); |
| if (!fIBounds.intersect(irect)) { |
| fHasIBounds = false; |
| fElements.reset(); |
| fRequiresAA = false; |
| fInitialState = InitialState::kAllOut; |
| return false; |
| } |
| return true; |
| } |