1/*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "GrReducedClip.h"
9
10#include "GrAppliedClip.h"
11#include "GrClip.h"
12#include "GrColor.h"
13#include "GrContextPriv.h"
14#include "GrRenderTargetContext.h"
15#include "GrRenderTargetContextPriv.h"
16#include "GrDrawingManager.h"
17#include "GrFixedClip.h"
18#include "GrPathRenderer.h"
19#include "GrStencilSettings.h"
20#include "GrStyle.h"
21#include "GrUserStencilSettings.h"
22#include "SkClipOpPriv.h"
23
24typedef SkClipStack::Element Element;
25
26/**
27 * There are plenty of optimizations that could be added here. Maybe flips could be folded into
28 * earlier operations. Or would inserting flips and reversing earlier ops ever be a win? Perhaps
29 * for the case where the bounds are kInsideOut_BoundsType. We could restrict earlier operations
30 * based on later intersect operations, and perhaps remove intersect-rects. We could optionally
31 * take a rect in case the caller knows a bound on what is to be drawn through this clip.
32 */
33GrReducedClip::GrReducedClip(const SkClipStack& stack, const SkRect& queryBounds,
34                             int maxWindowRectangles) {
35    SkASSERT(!queryBounds.isEmpty());
36    fHasIBounds = false;
37
38    if (stack.isWideOpen()) {
39        fInitialState = InitialState::kAllIn;
40        return;
41    }
42
43    SkClipStack::BoundsType stackBoundsType;
44    SkRect stackBounds;
45    bool iior;
46    stack.getBounds(&stackBounds, &stackBoundsType, &iior);
47
48    if (stackBounds.isEmpty() || GrClip::IsOutsideClip(stackBounds, queryBounds)) {
49        bool insideOut = SkClipStack::kInsideOut_BoundsType == stackBoundsType;
50        fInitialState = insideOut ? InitialState::kAllIn : InitialState::kAllOut;
51        return;
52    }
53
54    if (iior) {
55        // "Is intersection of rects" means the clip is a single rect indicated by the stack bounds.
56        // This should only be true if aa/non-aa status matches among all elements.
57        SkASSERT(SkClipStack::kNormal_BoundsType == stackBoundsType);
58        SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart);
59        if (!iter.prev()->isAA() || GrClip::IsPixelAligned(stackBounds)) {
60            // The clip is a non-aa rect. This is the one spot where we can actually implement the
61            // clip (using fIBounds) rather than just telling the caller what it should be.
62            stackBounds.round(&fIBounds);
63            fHasIBounds = true;
64            fInitialState = fIBounds.isEmpty() ? InitialState::kAllOut : InitialState::kAllIn;
65            return;
66        }
67        if (GrClip::IsInsideClip(stackBounds, queryBounds)) {
68            fInitialState = InitialState::kAllIn;
69            return;
70        }
71
72        SkRect tightBounds;
73        SkAssertResult(tightBounds.intersect(stackBounds, queryBounds));
74        fIBounds = GrClip::GetPixelIBounds(tightBounds);
75        SkASSERT(!fIBounds.isEmpty()); // Empty should have been blocked by IsOutsideClip above.
76        fHasIBounds = true;
77
78        // Implement the clip with an AA rect element.
79        fElements.addToHead(stackBounds, kReplace_SkClipOp, true/*doAA*/);
80        fElementsGenID = stack.getTopmostGenID();
81        fRequiresAA = true;
82
83        fInitialState = InitialState::kAllOut;
84        return;
85    }
86
87    SkRect tighterQuery = queryBounds;
88    if (SkClipStack::kNormal_BoundsType == stackBoundsType) {
89        // Tighten the query by introducing a new clip at the stack's pixel boundaries. (This new
90        // clip will be enforced by the scissor through fIBounds.)
91        SkAssertResult(tighterQuery.intersect(GrClip::GetPixelBounds(stackBounds)));
92    }
93
94    fIBounds = GrClip::GetPixelIBounds(tighterQuery);
95    SkASSERT(!fIBounds.isEmpty()); // Empty should have been blocked by IsOutsideClip above.
96    fHasIBounds = true;
97
98    // Now that we have determined the bounds to use and filtered out the trivial cases, call the
99    // helper that actually walks the stack.
100    this->walkStack(stack, tighterQuery, maxWindowRectangles);
101
102    if (fWindowRects.count() < maxWindowRectangles) {
103        this->addInteriorWindowRectangles(maxWindowRectangles);
104    }
105}
106
107void GrReducedClip::walkStack(const SkClipStack& stack, const SkRect& queryBounds,
108                              int maxWindowRectangles) {
109    // walk backwards until we get to:
110    //  a) the beginning
111    //  b) an operation that is known to make the bounds all inside/outside
112    //  c) a replace operation
113
114    enum class InitialTriState {
115        kUnknown = -1,
116        kAllIn = (int)GrReducedClip::InitialState::kAllIn,
117        kAllOut = (int)GrReducedClip::InitialState::kAllOut
118    } initialTriState = InitialTriState::kUnknown;
119
120    // During our backwards walk, track whether we've seen ops that either grow or shrink the clip.
121    // TODO: track these per saved clip so that we can consider them on the forward pass.
122    bool embiggens = false;
123    bool emsmallens = false;
124
125    // We use a slightly relaxed set of query bounds for element containment tests. This is to
126    // account for floating point rounding error that may have occurred during coord transforms.
127    SkRect relaxedQueryBounds = queryBounds.makeInset(GrClip::kBoundsTolerance,
128                                                      GrClip::kBoundsTolerance);
129
130    SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart);
131    int numAAElements = 0;
132    while (InitialTriState::kUnknown == initialTriState) {
133        const Element* element = iter.prev();
134        if (nullptr == element) {
135            initialTriState = InitialTriState::kAllIn;
136            break;
137        }
138        if (SkClipStack::kEmptyGenID == element->getGenID()) {
139            initialTriState = InitialTriState::kAllOut;
140            break;
141        }
142        if (SkClipStack::kWideOpenGenID == element->getGenID()) {
143            initialTriState = InitialTriState::kAllIn;
144            break;
145        }
146
147        bool skippable = false;
148        bool isFlip = false; // does this op just flip the in/out state of every point in the bounds
149
150        switch (element->getOp()) {
151            case kDifference_SkClipOp:
152                // check if the shape subtracted either contains the entire bounds (and makes
153                // the clip empty) or is outside the bounds and therefore can be skipped.
154                if (element->isInverseFilled()) {
155                    if (element->contains(relaxedQueryBounds)) {
156                        skippable = true;
157                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
158                        initialTriState = InitialTriState::kAllOut;
159                        skippable = true;
160                    }
161                } else {
162                    if (element->contains(relaxedQueryBounds)) {
163                        initialTriState = InitialTriState::kAllOut;
164                        skippable = true;
165                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
166                        skippable = true;
167                    } else if (fWindowRects.count() < maxWindowRectangles && !embiggens &&
168                               !element->isAA() && Element::kRect_Type == element->getType()) {
169                        this->addWindowRectangle(element->getRect(), false);
170                        skippable = true;
171                    }
172                }
173                if (!skippable) {
174                    emsmallens = true;
175                }
176                break;
177            case kIntersect_SkClipOp:
178                // check if the shape intersected contains the entire bounds and therefore can
179                // be skipped or it is outside the entire bounds and therefore makes the clip
180                // empty.
181                if (element->isInverseFilled()) {
182                    if (element->contains(relaxedQueryBounds)) {
183                        initialTriState = InitialTriState::kAllOut;
184                        skippable = true;
185                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
186                        skippable = true;
187                    }
188                } else {
189                    if (element->contains(relaxedQueryBounds)) {
190                        skippable = true;
191                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
192                        initialTriState = InitialTriState::kAllOut;
193                        skippable = true;
194                    } else if (!embiggens && !element->isAA() &&
195                               Element::kRect_Type == element->getType()) {
196                        // fIBounds and queryBounds have already acccounted for this element via
197                        // clip stack bounds; here we just apply the non-aa rounding effect.
198                        SkIRect nonaaRect;
199                        element->getRect().round(&nonaaRect);
200                        if (!this->intersectIBounds(nonaaRect)) {
201                            return;
202                        }
203                        skippable = true;
204                    }
205                }
206                if (!skippable) {
207                    emsmallens = true;
208                }
209                break;
210            case kUnion_SkClipOp:
211                // If the union-ed shape contains the entire bounds then after this element
212                // the bounds is entirely inside the clip. If the union-ed shape is outside the
213                // bounds then this op can be skipped.
214                if (element->isInverseFilled()) {
215                    if (element->contains(relaxedQueryBounds)) {
216                        skippable = true;
217                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
218                        initialTriState = InitialTriState::kAllIn;
219                        skippable = true;
220                    }
221                } else {
222                    if (element->contains(relaxedQueryBounds)) {
223                        initialTriState = InitialTriState::kAllIn;
224                        skippable = true;
225                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
226                        skippable = true;
227                    }
228                }
229                if (!skippable) {
230                    embiggens = true;
231                }
232                break;
233            case kXOR_SkClipOp:
234                // If the bounds is entirely inside the shape being xor-ed then the effect is
235                // to flip the inside/outside state of every point in the bounds. We may be
236                // able to take advantage of this in the forward pass. If the xor-ed shape
237                // doesn't intersect the bounds then it can be skipped.
238                if (element->isInverseFilled()) {
239                    if (element->contains(relaxedQueryBounds)) {
240                        skippable = true;
241                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
242                        isFlip = true;
243                    }
244                } else {
245                    if (element->contains(relaxedQueryBounds)) {
246                        isFlip = true;
247                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
248                        skippable = true;
249                    }
250                }
251                if (!skippable) {
252                    emsmallens = embiggens = true;
253                }
254                break;
255            case kReverseDifference_SkClipOp:
256                // When the bounds is entirely within the rev-diff shape then this behaves like xor
257                // and reverses every point inside the bounds. If the shape is completely outside
258                // the bounds then we know after this element is applied that the bounds will be
259                // all outside the current clip.B
260                if (element->isInverseFilled()) {
261                    if (element->contains(relaxedQueryBounds)) {
262                        initialTriState = InitialTriState::kAllOut;
263                        skippable = true;
264                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
265                        isFlip = true;
266                    }
267                } else {
268                    if (element->contains(relaxedQueryBounds)) {
269                        isFlip = true;
270                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
271                        initialTriState = InitialTriState::kAllOut;
272                        skippable = true;
273                    }
274                }
275                if (!skippable) {
276                    emsmallens = embiggens = true;
277                }
278                break;
279
280            case kReplace_SkClipOp:
281                // Replace will always terminate our walk. We will either begin the forward walk
282                // at the replace op or detect here than the shape is either completely inside
283                // or completely outside the bounds. In this latter case it can be skipped by
284                // setting the correct value for initialTriState.
285                if (element->isInverseFilled()) {
286                    if (element->contains(relaxedQueryBounds)) {
287                        initialTriState = InitialTriState::kAllOut;
288                        skippable = true;
289                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
290                        initialTriState = InitialTriState::kAllIn;
291                        skippable = true;
292                    }
293                } else {
294                    if (element->contains(relaxedQueryBounds)) {
295                        initialTriState = InitialTriState::kAllIn;
296                        skippable = true;
297                    } else if (GrClip::IsOutsideClip(element->getBounds(), queryBounds)) {
298                        initialTriState = InitialTriState::kAllOut;
299                        skippable = true;
300                    } else if (!embiggens && !element->isAA() &&
301                               Element::kRect_Type == element->getType()) {
302                        // fIBounds and queryBounds have already acccounted for this element via
303                        // clip stack bounds; here we just apply the non-aa rounding effect.
304                        SkIRect nonaaRect;
305                        element->getRect().round(&nonaaRect);
306                        if (!this->intersectIBounds(nonaaRect)) {
307                            return;
308                        }
309                        initialTriState = InitialTriState::kAllIn;
310                        skippable = true;
311                    }
312                }
313                if (!skippable) {
314                    initialTriState = InitialTriState::kAllOut;
315                    embiggens = emsmallens = true;
316                }
317                break;
318            default:
319                SkDEBUGFAIL("Unexpected op.");
320                break;
321        }
322        if (!skippable) {
323            if (0 == fElements.count()) {
324                // This will be the last element. Record the stricter genID.
325                fElementsGenID = element->getGenID();
326            }
327
328            // if it is a flip, change it to a bounds-filling rect
329            if (isFlip) {
330                SkASSERT(kXOR_SkClipOp == element->getOp() ||
331                         kReverseDifference_SkClipOp == element->getOp());
332                fElements.addToHead(SkRect::Make(fIBounds), kReverseDifference_SkClipOp, false);
333            } else {
334                Element* newElement = fElements.addToHead(*element);
335                if (newElement->isAA()) {
336                    ++numAAElements;
337                }
338                // Intersecting an inverse shape is the same as differencing the non-inverse shape.
339                // Replacing with an inverse shape is the same as setting initialState=kAllIn and
340                // differencing the non-inverse shape.
341                bool isReplace = kReplace_SkClipOp == newElement->getOp();
342                if (newElement->isInverseFilled() &&
343                    (kIntersect_SkClipOp == newElement->getOp() || isReplace)) {
344                    newElement->invertShapeFillType();
345                    newElement->setOp(kDifference_SkClipOp);
346                    if (isReplace) {
347                        SkASSERT(InitialTriState::kAllOut == initialTriState);
348                        initialTriState = InitialTriState::kAllIn;
349                    }
350                }
351            }
352        }
353    }
354
355    if ((InitialTriState::kAllOut == initialTriState && !embiggens) ||
356        (InitialTriState::kAllIn == initialTriState && !emsmallens)) {
357        fElements.reset();
358        numAAElements = 0;
359    } else {
360        Element* element = fElements.headIter().get();
361        while (element) {
362            bool skippable = false;
363            switch (element->getOp()) {
364                case kDifference_SkClipOp:
365                    // subtracting from the empty set yields the empty set.
366                    skippable = InitialTriState::kAllOut == initialTriState;
367                    break;
368                case kIntersect_SkClipOp:
369                    // intersecting with the empty set yields the empty set
370                    if (InitialTriState::kAllOut == initialTriState) {
371                        skippable = true;
372                    } else {
373                        // We can clear to zero and then simply draw the clip element.
374                        initialTriState = InitialTriState::kAllOut;
375                        element->setOp(kReplace_SkClipOp);
376                    }
377                    break;
378                case kUnion_SkClipOp:
379                    if (InitialTriState::kAllIn == initialTriState) {
380                        // unioning the infinite plane with anything is a no-op.
381                        skippable = true;
382                    } else {
383                        // unioning the empty set with a shape is the shape.
384                        element->setOp(kReplace_SkClipOp);
385                    }
386                    break;
387                case kXOR_SkClipOp:
388                    if (InitialTriState::kAllOut == initialTriState) {
389                        // xor could be changed to diff in the kAllIn case, not sure it's a win.
390                        element->setOp(kReplace_SkClipOp);
391                    }
392                    break;
393                case kReverseDifference_SkClipOp:
394                    if (InitialTriState::kAllIn == initialTriState) {
395                        // subtracting the whole plane will yield the empty set.
396                        skippable = true;
397                        initialTriState = InitialTriState::kAllOut;
398                    } else {
399                        // this picks up flips inserted in the backwards pass.
400                        skippable = element->isInverseFilled() ?
401                            GrClip::IsOutsideClip(element->getBounds(), queryBounds) :
402                            element->contains(relaxedQueryBounds);
403                        if (skippable) {
404                            initialTriState = InitialTriState::kAllIn;
405                        } else {
406                            element->setOp(kReplace_SkClipOp);
407                        }
408                    }
409                    break;
410                case kReplace_SkClipOp:
411                    skippable = false; // we would have skipped it in the backwards walk if we
412                                       // could've.
413                    break;
414                default:
415                    SkDEBUGFAIL("Unexpected op.");
416                    break;
417            }
418            if (!skippable) {
419                break;
420            } else {
421                if (element->isAA()) {
422                    --numAAElements;
423                }
424                fElements.popHead();
425                element = fElements.headIter().get();
426            }
427        }
428    }
429    fRequiresAA = numAAElements > 0;
430
431    SkASSERT(InitialTriState::kUnknown != initialTriState);
432    fInitialState = static_cast<GrReducedClip::InitialState>(initialTriState);
433}
434
435static bool element_is_pure_subtract(SkClipOp op) {
436    SkASSERT(static_cast<int>(op) >= 0);
437    return static_cast<int>(op) <= static_cast<int>(kIntersect_SkClipOp);
438
439    GR_STATIC_ASSERT(0 == static_cast<int>(kDifference_SkClipOp));
440    GR_STATIC_ASSERT(1 == static_cast<int>(kIntersect_SkClipOp));
441}
442
443void GrReducedClip::addInteriorWindowRectangles(int maxWindowRectangles) {
444    SkASSERT(fWindowRects.count() < maxWindowRectangles);
445    // Walk backwards through the element list and add window rectangles to the interiors of
446    // "difference" elements. Quit if we encounter an element that may grow the clip.
447    ElementList::Iter iter(fElements, ElementList::Iter::kTail_IterStart);
448    for (; iter.get() && element_is_pure_subtract(iter.get()->getOp()); iter.prev()) {
449        const Element* element = iter.get();
450        if (kDifference_SkClipOp != element->getOp()) {
451            continue;
452        }
453
454        if (Element::kRect_Type == element->getType()) {
455            SkASSERT(element->isAA());
456            this->addWindowRectangle(element->getRect(), true);
457            if (fWindowRects.count() >= maxWindowRectangles) {
458                return;
459            }
460            continue;
461        }
462
463        if (Element::kRRect_Type == element->getType()) {
464            // For round rects we add two overlapping windows in the shape of a plus.
465            const SkRRect& clipRRect = element->getRRect();
466            SkVector insetTL = clipRRect.radii(SkRRect::kUpperLeft_Corner);
467            SkVector insetBR = clipRRect.radii(SkRRect::kLowerRight_Corner);
468            if (SkRRect::kComplex_Type == clipRRect.getType()) {
469                const SkVector& insetTR = clipRRect.radii(SkRRect::kUpperRight_Corner);
470                const SkVector& insetBL = clipRRect.radii(SkRRect::kLowerLeft_Corner);
471                insetTL.fX = SkTMax(insetTL.x(), insetBL.x());
472                insetTL.fY = SkTMax(insetTL.y(), insetTR.y());
473                insetBR.fX = SkTMax(insetBR.x(), insetTR.x());
474                insetBR.fY = SkTMax(insetBR.y(), insetBL.y());
475            }
476            const SkRect& bounds = clipRRect.getBounds();
477            if (insetTL.x() + insetBR.x() >= bounds.width() ||
478                insetTL.y() + insetBR.y() >= bounds.height()) {
479                continue; // The interior "plus" is empty.
480            }
481
482            SkRect horzRect = SkRect::MakeLTRB(bounds.left(), bounds.top() + insetTL.y(),
483                                               bounds.right(), bounds.bottom() - insetBR.y());
484            this->addWindowRectangle(horzRect, element->isAA());
485            if (fWindowRects.count() >= maxWindowRectangles) {
486                return;
487            }
488
489            SkRect vertRect = SkRect::MakeLTRB(bounds.left() + insetTL.x(), bounds.top(),
490                                               bounds.right() - insetBR.x(), bounds.bottom());
491            this->addWindowRectangle(vertRect, element->isAA());
492            if (fWindowRects.count() >= maxWindowRectangles) {
493                return;
494            }
495            continue;
496        }
497    }
498}
499
500inline void GrReducedClip::addWindowRectangle(const SkRect& elementInteriorRect, bool elementIsAA) {
501    SkIRect window;
502    if (!elementIsAA) {
503        elementInteriorRect.round(&window);
504    } else {
505        elementInteriorRect.roundIn(&window);
506    }
507    if (!window.isEmpty()) { // Skip very thin windows that round to zero or negative dimensions.
508        fWindowRects.addWindow(window);
509    }
510}
511
512inline bool GrReducedClip::intersectIBounds(const SkIRect& irect) {
513    SkASSERT(fHasIBounds);
514    if (!fIBounds.intersect(irect)) {
515        fHasIBounds = false;
516        fWindowRects.reset();
517        fElements.reset();
518        fRequiresAA = false;
519        fInitialState = InitialState::kAllOut;
520        return false;
521    }
522    return true;
523}
524
525////////////////////////////////////////////////////////////////////////////////
526// Create a 8-bit clip mask in alpha
527
528static bool stencil_element(GrRenderTargetContext* rtc,
529                            const GrFixedClip& clip,
530                            const GrUserStencilSettings* ss,
531                            const SkMatrix& viewMatrix,
532                            const SkClipStack::Element* element) {
533    GrAA aa = GrBoolToAA(element->isAA());
534    switch (element->getType()) {
535        case Element::kEmpty_Type:
536            SkDEBUGFAIL("Should never get here with an empty element.");
537            break;
538        case Element::kRect_Type:
539            return rtc->priv().drawAndStencilRect(clip, ss,
540                                                  (SkRegion::Op)element->getOp(),
541                                                  element->isInverseFilled(), aa, viewMatrix,
542                                                  element->getRect());
543            break;
544        default: {
545            SkPath path;
546            element->asPath(&path);
547            if (path.isInverseFillType()) {
548                path.toggleInverseFillType();
549            }
550
551            return rtc->priv().drawAndStencilPath(clip, ss, (SkRegion::Op)element->getOp(),
552                                                  element->isInverseFilled(), aa, viewMatrix, path);
553            break;
554        }
555    }
556
557    return false;
558}
559
560static void draw_element(GrRenderTargetContext* rtc,
561                         const GrClip& clip,  // TODO: can this just always be WideOpen?
562                         GrPaint&& paint,
563                         GrAA aa,
564                         const SkMatrix& viewMatrix,
565                         const SkClipStack::Element* element) {
566    // TODO: Draw rrects directly here.
567    switch (element->getType()) {
568        case Element::kEmpty_Type:
569            SkDEBUGFAIL("Should never get here with an empty element.");
570            break;
571        case Element::kRect_Type:
572            rtc->drawRect(clip, std::move(paint), aa, viewMatrix, element->getRect());
573            break;
574        default: {
575            SkPath path;
576            element->asPath(&path);
577            if (path.isInverseFillType()) {
578                path.toggleInverseFillType();
579            }
580
581            rtc->drawPath(clip, std::move(paint), aa, viewMatrix, path, GrStyle::SimpleFill());
582            break;
583        }
584    }
585}
586
587bool GrReducedClip::drawAlphaClipMask(GrRenderTargetContext* rtc) const {
588    // The texture may be larger than necessary, this rect represents the part of the texture
589    // we populate with a rasterization of the clip.
590    GrFixedClip clip(SkIRect::MakeWH(fIBounds.width(), fIBounds.height()));
591
592    if (!fWindowRects.empty()) {
593        clip.setWindowRectangles(fWindowRects.makeOffset(-fIBounds.left(), -fIBounds.top()),
594                                 GrWindowRectsState::Mode::kExclusive);
595    }
596
597    // The scratch texture that we are drawing into can be substantially larger than the mask. Only
598    // clear the part that we care about.
599    GrColor initialCoverage = InitialState::kAllIn == this->initialState() ? -1 : 0;
600    rtc->priv().clear(clip, initialCoverage, true);
601
602    // Set the matrix so that rendered clip elements are transformed to mask space from clip space.
603    SkMatrix translate;
604    translate.setTranslate(SkIntToScalar(-fIBounds.left()), SkIntToScalar(-fIBounds.top()));
605
606    // walk through each clip element and perform its set op
607    for (ElementList::Iter iter(fElements); iter.get(); iter.next()) {
608        const Element* element = iter.get();
609        SkRegion::Op op = (SkRegion::Op)element->getOp();
610        GrAA aa = GrBoolToAA(element->isAA());
611        bool invert = element->isInverseFilled();
612        if (invert || SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
613            // draw directly into the result with the stencil set to make the pixels affected
614            // by the clip shape be non-zero.
615            static constexpr GrUserStencilSettings kStencilInElement(
616                 GrUserStencilSettings::StaticInit<
617                     0xffff,
618                     GrUserStencilTest::kAlways,
619                     0xffff,
620                     GrUserStencilOp::kReplace,
621                     GrUserStencilOp::kReplace,
622                     0xffff>()
623            );
624            if (!stencil_element(rtc, clip, &kStencilInElement, translate, element)) {
625                return false;
626            }
627
628            // Draw to the exterior pixels (those with a zero stencil value).
629            static constexpr GrUserStencilSettings kDrawOutsideElement(
630                 GrUserStencilSettings::StaticInit<
631                     0x0000,
632                     GrUserStencilTest::kEqual,
633                     0xffff,
634                     GrUserStencilOp::kZero,
635                     GrUserStencilOp::kZero,
636                     0xffff>()
637            );
638            if (!rtc->priv().drawAndStencilRect(clip, &kDrawOutsideElement, op, !invert, GrAA::kNo,
639                                                translate, SkRect::Make(fIBounds))) {
640                return false;
641            }
642        } else {
643            // all the remaining ops can just be directly draw into the accumulation buffer
644            GrPaint paint;
645            paint.setCoverageSetOpXPFactory(op, false);
646
647            draw_element(rtc, clip, std::move(paint), aa, translate, element);
648        }
649    }
650
651    return true;
652}
653
654////////////////////////////////////////////////////////////////////////////////
655// Create a 1-bit clip mask in the stencil buffer.
656
657class StencilClip final : public GrClip {
658public:
659    StencilClip(const SkIRect& scissorRect) : fFixedClip(scissorRect) {}
660    const GrFixedClip& fixedClip() const { return fFixedClip; }
661
662    void setWindowRectangles(const GrWindowRectangles& windows, GrWindowRectsState::Mode mode) {
663        fFixedClip.setWindowRectangles(windows, mode);
664    }
665
666private:
667    bool quickContains(const SkRect&) const override {
668        return false;
669    }
670    void getConservativeBounds(int width, int height, SkIRect* bounds, bool* iior) const override {
671        fFixedClip.getConservativeBounds(width, height, bounds, iior);
672    }
673    bool isRRect(const SkRect& rtBounds, SkRRect* rr, GrAA*) const override {
674        return false;
675    }
676    bool apply(GrContext* context, GrRenderTargetContext* renderTargetContext, bool useHWAA,
677               bool hasUserStencilSettings, GrAppliedClip* out, SkRect* bounds) const override {
678        if (!fFixedClip.apply(context, renderTargetContext, useHWAA, hasUserStencilSettings, out,
679                              bounds)) {
680            return false;
681        }
682        out->addStencilClip();
683        return true;
684    }
685
686    GrFixedClip fFixedClip;
687
688    typedef GrClip INHERITED;
689};
690
691bool GrReducedClip::drawStencilClipMask(GrContext* context,
692                                        GrRenderTargetContext* renderTargetContext) const {
693    // We set the current clip to the bounds so that our recursive draws are scissored to them.
694    StencilClip stencilClip(fIBounds);
695
696    if (!fWindowRects.empty()) {
697        stencilClip.setWindowRectangles(fWindowRects, GrWindowRectsState::Mode::kExclusive);
698    }
699
700    bool initialState = InitialState::kAllIn == this->initialState();
701    renderTargetContext->priv().clearStencilClip(stencilClip.fixedClip(), initialState);
702
703    // walk through each clip element and perform its set op with the existing clip.
704    for (ElementList::Iter iter(fElements); iter.get(); iter.next()) {
705        const Element* element = iter.get();
706        GrAAType aaType = GrAAType::kNone;
707        if (element->isAA() && renderTargetContext->isStencilBufferMultisampled()) {
708            aaType = GrAAType::kMSAA;
709        }
710
711        bool fillInverted = false;
712
713        // This will be used to determine whether the clip shape can be rendered into the
714        // stencil with arbitrary stencil settings.
715        GrPathRenderer::StencilSupport stencilSupport;
716
717        SkRegion::Op op = (SkRegion::Op)element->getOp();
718
719        GrPathRenderer* pr = nullptr;
720        SkPath clipPath;
721        if (Element::kRect_Type == element->getType()) {
722            stencilSupport = GrPathRenderer::kNoRestriction_StencilSupport;
723            fillInverted = false;
724        } else {
725            element->asPath(&clipPath);
726            fillInverted = clipPath.isInverseFillType();
727            if (fillInverted) {
728                clipPath.toggleInverseFillType();
729            }
730
731            GrShape shape(clipPath, GrStyle::SimpleFill());
732            GrPathRenderer::CanDrawPathArgs canDrawArgs;
733            canDrawArgs.fShaderCaps = context->caps()->shaderCaps();
734            canDrawArgs.fViewMatrix = &SkMatrix::I();
735            canDrawArgs.fShape = &shape;
736            canDrawArgs.fAAType = aaType;
737            canDrawArgs.fHasUserStencilSettings = false;
738
739            GrDrawingManager* dm = context->contextPriv().drawingManager();
740            pr = dm->getPathRenderer(canDrawArgs, false, GrPathRendererChain::DrawType::kStencil,
741                                     &stencilSupport);
742            if (!pr) {
743                return false;
744            }
745        }
746
747        bool canRenderDirectToStencil =
748            GrPathRenderer::kNoRestriction_StencilSupport == stencilSupport;
749        bool drawDirectToClip; // Given the renderer, the element,
750                               // fill rule, and set operation should
751                               // we render the element directly to
752                               // stencil bit used for clipping.
753        GrUserStencilSettings const* const* stencilPasses =
754            GrStencilSettings::GetClipPasses(op, canRenderDirectToStencil, fillInverted,
755                                             &drawDirectToClip);
756
757        // draw the element to the client stencil bits if necessary
758        if (!drawDirectToClip) {
759            static constexpr GrUserStencilSettings kDrawToStencil(
760                 GrUserStencilSettings::StaticInit<
761                     0x0000,
762                     GrUserStencilTest::kAlways,
763                     0xffff,
764                     GrUserStencilOp::kIncMaybeClamp,
765                     GrUserStencilOp::kIncMaybeClamp,
766                     0xffff>()
767            );
768            if (Element::kRect_Type == element->getType()) {
769                renderTargetContext->priv().stencilRect(stencilClip.fixedClip(), &kDrawToStencil,
770                                                        aaType, SkMatrix::I(), element->getRect());
771            } else {
772                if (!clipPath.isEmpty()) {
773                    GrShape shape(clipPath, GrStyle::SimpleFill());
774                    if (canRenderDirectToStencil) {
775                        GrPaint paint;
776                        paint.setXPFactory(GrDisableColorXPFactory::Get());
777
778                        GrPathRenderer::DrawPathArgs args{context,
779                                                          std::move(paint),
780                                                          &kDrawToStencil,
781                                                          renderTargetContext,
782                                                          &stencilClip.fixedClip(),
783                                                          &SkMatrix::I(),
784                                                          &shape,
785                                                          aaType,
786                                                          false};
787                        pr->drawPath(args);
788                    } else {
789                        GrPathRenderer::StencilPathArgs args;
790                        args.fContext = context;
791                        args.fRenderTargetContext = renderTargetContext;
792                        args.fClip = &stencilClip.fixedClip();
793                        args.fViewMatrix = &SkMatrix::I();
794                        args.fAAType = aaType;
795                        args.fShape = &shape;
796                        pr->stencilPath(args);
797                    }
798                }
799            }
800        }
801
802        // now we modify the clip bit by rendering either the clip
803        // element directly or a bounding rect of the entire clip.
804        for (GrUserStencilSettings const* const* pass = stencilPasses; *pass; ++pass) {
805            if (drawDirectToClip) {
806                if (Element::kRect_Type == element->getType()) {
807                    renderTargetContext->priv().stencilRect(stencilClip, *pass, aaType,
808                                                            SkMatrix::I(), element->getRect());
809                } else {
810                    GrShape shape(clipPath, GrStyle::SimpleFill());
811                    GrPaint paint;
812                    paint.setXPFactory(GrDisableColorXPFactory::Get());
813                    GrPathRenderer::DrawPathArgs args{context,
814                                                      std::move(paint),
815                                                      *pass,
816                                                      renderTargetContext,
817                                                      &stencilClip,
818                                                      &SkMatrix::I(),
819                                                      &shape,
820                                                      aaType,
821                                                      false};
822                    pr->drawPath(args);
823                }
824            } else {
825                // The view matrix is setup to do clip space -> stencil space translation, so
826                // draw rect in clip space.
827                renderTargetContext->priv().stencilRect(stencilClip, *pass, aaType, SkMatrix::I(),
828                                                        SkRect::Make(fIBounds));
829            }
830        }
831    }
832    return true;
833}
834