| |
| /* |
| * Copyright 2012 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" |
| |
| typedef SkClipStack::Element Element; |
| //////////////////////////////////////////////////////////////////////////////// |
| |
| namespace GrReducedClip { |
| |
| // helper function |
| void reduced_stack_walker(const SkClipStack& stack, |
| const SkRect& queryBounds, |
| ElementList* result, |
| InitialState* initialState, |
| bool* requiresAA); |
| |
| /* |
| 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. |
| */ |
| void ReduceClipStack(const SkClipStack& stack, |
| const SkIRect& queryBounds, |
| ElementList* result, |
| InitialState* initialState, |
| SkIRect* tighterBounds, |
| bool* requiresAA) { |
| result->reset(); |
| |
| if (stack.isWideOpen()) { |
| *initialState = kAllIn_InitialState; |
| return; |
| } |
| |
| |
| // We initially look at whether the bounds alone is sufficient. We also use the stack bounds to |
| // attempt to compute the tighterBounds. |
| |
| SkClipStack::BoundsType stackBoundsType; |
| SkRect stackBounds; |
| bool iior; |
| stack.getBounds(&stackBounds, &stackBoundsType, &iior); |
| |
| const SkIRect* bounds = &queryBounds; |
| |
| SkRect scalarQueryBounds = SkRect::MakeFromIRect(queryBounds); |
| |
| if (iior) { |
| SkASSERT(SkClipStack::kNormal_BoundsType == stackBoundsType); |
| SkRect isectRect; |
| if (stackBounds.contains(scalarQueryBounds)) { |
| *initialState = kAllIn_InitialState; |
| if (NULL != tighterBounds) { |
| *tighterBounds = queryBounds; |
| } |
| if (NULL != requiresAA) { |
| *requiresAA = false; |
| } |
| } else if (isectRect.intersect(stackBounds, scalarQueryBounds)) { |
| if (NULL != tighterBounds) { |
| isectRect.roundOut(tighterBounds); |
| SkRect scalarTighterBounds = SkRect::MakeFromIRect(*tighterBounds); |
| if (scalarTighterBounds == isectRect) { |
| // the round-out didn't add any area outside the clip rect. |
| *requiresAA = false; |
| *initialState = kAllIn_InitialState; |
| return; |
| } |
| *initialState = kAllOut_InitialState; |
| // iior should only be true if aa/non-aa status matches among all elements. |
| SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart); |
| bool doAA = iter.prev()->isAA(); |
| SkNEW_INSERT_AT_LLIST_HEAD(result, Element, (isectRect, SkRegion::kReplace_Op, doAA)); |
| if (NULL != requiresAA) { |
| *requiresAA = doAA; |
| } |
| } |
| } else { |
| *initialState = kAllOut_InitialState; |
| if (NULL != requiresAA) { |
| *requiresAA = false; |
| } |
| } |
| return; |
| } else { |
| if (SkClipStack::kNormal_BoundsType == stackBoundsType) { |
| if (!SkRect::Intersects(stackBounds, scalarQueryBounds)) { |
| *initialState = kAllOut_InitialState; |
| if (NULL != requiresAA) { |
| *requiresAA = false; |
| } |
| return; |
| } |
| if (NULL != tighterBounds) { |
| SkIRect stackIBounds; |
| stackBounds.roundOut(&stackIBounds); |
| tighterBounds->intersect(queryBounds, stackIBounds); |
| bounds = tighterBounds; |
| } |
| } else { |
| if (stackBounds.contains(scalarQueryBounds)) { |
| *initialState = kAllOut_InitialState; |
| if (NULL != requiresAA) { |
| *requiresAA = false; |
| } |
| return; |
| } |
| if (NULL != tighterBounds) { |
| *tighterBounds = queryBounds; |
| } |
| } |
| } |
| |
| SkRect scalarBounds = SkRect::MakeFromIRect(*bounds); |
| |
| // Now that we have determined the bounds to use and filtered out the trivial cases, call the |
| // helper that actually walks the stack. |
| reduced_stack_walker(stack, scalarBounds, result, initialState, requiresAA); |
| } |
| |
| void reduced_stack_walker(const SkClipStack& stack, |
| const SkRect& queryBounds, |
| ElementList* result, |
| InitialState* initialState, |
| bool* requiresAA) { |
| |
| // 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 |
| |
| static const InitialState kUnknown_InitialState = static_cast<InitialState>(-1); |
| *initialState = kUnknown_InitialState; |
| |
| // 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; |
| |
| SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart); |
| int numAAElements = 0; |
| while ((kUnknown_InitialState == *initialState)) { |
| const Element* element = iter.prev(); |
| if (NULL == element) { |
| *initialState = kAllIn_InitialState; |
| break; |
| } |
| if (SkClipStack::kEmptyGenID == element->getGenID()) { |
| *initialState = kAllOut_InitialState; |
| break; |
| } |
| if (SkClipStack::kWideOpenGenID == element->getGenID()) { |
| *initialState = kAllIn_InitialState; |
| 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(queryBounds)) { |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(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(queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| skippable = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| 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(queryBounds)) { |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllIn_InitialState; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| *initialState = kAllIn_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(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(queryBounds)) { |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| isFlip = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| isFlip = true; |
| } else if (!SkRect::Intersects(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(queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| isFlip = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| isFlip = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| 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 initialState. |
| if (element->isInverseFilled()) { |
| if (element->contains(queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllIn_InitialState; |
| skippable = true; |
| } |
| } else { |
| if (element->contains(queryBounds)) { |
| *initialState = kAllIn_InitialState; |
| skippable = true; |
| } else if (!SkRect::Intersects(element->getBounds(), queryBounds)) { |
| *initialState = kAllOut_InitialState; |
| skippable = true; |
| } |
| } |
| if (!skippable) { |
| *initialState = kAllOut_InitialState; |
| embiggens = emsmallens = true; |
| } |
| break; |
| default: |
| SkDEBUGFAIL("Unexpected op."); |
| break; |
| } |
| if (!skippable) { |
| // 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()); |
| SkNEW_INSERT_AT_LLIST_HEAD(result, |
| Element, |
| (queryBounds, SkRegion::kReverseDifference_Op, false)); |
| } else { |
| Element* newElement = result->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(kAllOut_InitialState == *initialState); |
| *initialState = kAllIn_InitialState; |
| } |
| } |
| } |
| } |
| } |
| |
| if ((kAllOut_InitialState == *initialState && !embiggens) || |
| (kAllIn_InitialState == *initialState && !emsmallens)) { |
| result->reset(); |
| } else { |
| Element* element = result->headIter().get(); |
| while (NULL != element) { |
| bool skippable = false; |
| switch (element->getOp()) { |
| 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 |
| if (kAllOut_InitialState == *initialState) { |
| skippable = true; |
| } else { |
| // We can clear to zero and then simply draw the clip element. |
| *initialState = kAllOut_InitialState; |
| element->setOp(SkRegion::kReplace_Op); |
| } |
| break; |
| case SkRegion::kUnion_Op: |
| if (kAllIn_InitialState == *initialState) { |
| // 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 (kAllOut_InitialState == *initialState) { |
| // 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 (kAllIn_InitialState == *initialState) { |
| // subtracting the whole plane will yield the empty set. |
| skippable = true; |
| *initialState = kAllOut_InitialState; |
| } else { |
| // this picks up flips inserted in the backwards pass. |
| skippable = element->isInverseFilled() ? |
| !SkRect::Intersects(element->getBounds(), queryBounds) : |
| element->contains(queryBounds); |
| if (skippable) { |
| *initialState = kAllIn_InitialState; |
| } 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; |
| } |
| result->popHead(); |
| element = result->headIter().get(); |
| } |
| } |
| } |
| if (NULL != requiresAA) { |
| *requiresAA = numAAElements > 0; |
| } |
| } |
| } // namespace GrReducedClip |