GrClipStackClip.cpp revision 875218ebd816eb8931c64c5018ce2dc9bc8fd695 
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 "GrClipStackClip.h"
9
10#include "GrAppliedClip.h"
11#include "GrContextPriv.h"
12#include "GrDrawingManager.h"
13#include "GrRenderTargetContextPriv.h"
14#include "GrFixedClip.h"
15#include "GrGpuResourcePriv.h"
16#include "GrRenderTargetPriv.h"
17#include "GrStencilAttachment.h"
18#include "GrSWMaskHelper.h"
19#include "GrTextureProxy.h"
20#include "effects/GrConvexPolyEffect.h"
21#include "effects/GrRRectEffect.h"
22#include "effects/GrTextureDomain.h"
23#include "SkClipOpPriv.h"
24
25typedef SkClipStack::Element Element;
26typedef GrReducedClip::InitialState InitialState;
27typedef GrReducedClip::ElementList ElementList;
28
29static const int kMaxAnalyticElements = 4;
30const char GrClipStackClip::kMaskTestTag[] = "clip_mask";
31
32bool GrClipStackClip::quickContains(const SkRect& rect) const {
33    if (!fStack || fStack->isWideOpen()) {
34        return true;
35    }
36    return fStack->quickContains(rect.makeOffset(SkIntToScalar(fOrigin.x()),
37                                                 SkIntToScalar(fOrigin.y())));
38}
39
40bool GrClipStackClip::quickContains(const SkRRect& rrect) const {
41    if (!fStack || fStack->isWideOpen()) {
42        return true;
43    }
44    return fStack->quickContains(rrect.makeOffset(SkIntToScalar(fOrigin.fX),
45                                                  SkIntToScalar(fOrigin.fY)));
46}
47
48bool GrClipStackClip::isRRect(const SkRect& origRTBounds, SkRRect* rr, GrAA* aa) const {
49    if (!fStack) {
50        return false;
51    }
52    const SkRect* rtBounds = &origRTBounds;
53    SkRect tempRTBounds;
54    bool origin = fOrigin.fX || fOrigin.fY;
55    if (origin) {
56        tempRTBounds = origRTBounds;
57        tempRTBounds.offset(SkIntToScalar(fOrigin.fX), SkIntToScalar(fOrigin.fY));
58        rtBounds = &tempRTBounds;
59    }
60    bool isAA;
61    if (fStack->isRRect(*rtBounds, rr, &isAA)) {
62        *aa = GrBoolToAA(isAA);
63        if (origin) {
64            rr->offset(-SkIntToScalar(fOrigin.fX), -SkIntToScalar(fOrigin.fY));
65        }
66        return true;
67    }
68    return false;
69}
70
71void GrClipStackClip::getConservativeBounds(int width, int height, SkIRect* devResult,
72                                            bool* isIntersectionOfRects) const {
73    if (!fStack) {
74        devResult->setXYWH(0, 0, width, height);
75        if (isIntersectionOfRects) {
76            *isIntersectionOfRects = true;
77        }
78        return;
79    }
80    SkRect devBounds;
81    fStack->getConservativeBounds(-fOrigin.x(), -fOrigin.y(), width, height, &devBounds,
82                                  isIntersectionOfRects);
83    devBounds.roundOut(devResult);
84}
85
86////////////////////////////////////////////////////////////////////////////////
87// set up the draw state to enable the aa clipping mask.
88static sk_sp<GrFragmentProcessor> create_fp_for_mask(GrContext* context,
89                                                     sk_sp<GrTextureProxy> mask,
90                                                     const SkIRect &devBound) {
91    SkIRect domainTexels = SkIRect::MakeWH(devBound.width(), devBound.height());
92    return GrDeviceSpaceTextureDecalFragmentProcessor::Make(context, std::move(mask), domainTexels,
93                                                            {devBound.fLeft, devBound.fTop});
94}
95
96// Does the path in 'element' require SW rendering? If so, return true (and,
97// optionally, set 'prOut' to NULL. If not, return false (and, optionally, set
98// 'prOut' to the non-SW path renderer that will do the job).
99bool GrClipStackClip::PathNeedsSWRenderer(GrContext* context,
100                                          bool hasUserStencilSettings,
101                                          const GrRenderTargetContext* renderTargetContext,
102                                          const SkMatrix& viewMatrix,
103                                          const Element* element,
104                                          GrPathRenderer** prOut,
105                                          bool needsStencil) {
106    if (Element::kRect_Type == element->getType()) {
107        // rects can always be drawn directly w/o using the software path
108        // TODO: skip rrects once we're drawing them directly.
109        if (prOut) {
110            *prOut = nullptr;
111        }
112        return false;
113    } else {
114        // We shouldn't get here with an empty clip element.
115        SkASSERT(Element::kEmpty_Type != element->getType());
116
117        // the gpu alpha mask will draw the inverse paths as non-inverse to a temp buffer
118        SkPath path;
119        element->asPath(&path);
120        if (path.isInverseFillType()) {
121            path.toggleInverseFillType();
122        }
123
124        GrPathRendererChain::DrawType type =
125                needsStencil ? GrPathRendererChain::DrawType::kStencilAndColor
126                             : GrPathRendererChain::DrawType::kColor;
127
128        GrShape shape(path, GrStyle::SimpleFill());
129        GrPathRenderer::CanDrawPathArgs canDrawArgs;
130        canDrawArgs.fShaderCaps = context->caps()->shaderCaps();
131        canDrawArgs.fViewMatrix = &viewMatrix;
132        canDrawArgs.fShape = &shape;
133        if (!element->isAA()) {
134            canDrawArgs.fAAType = GrAAType::kNone;
135        } else if (renderTargetContext->isUnifiedMultisampled()) {
136            canDrawArgs.fAAType = GrAAType::kMSAA;
137        } else if (renderTargetContext->isStencilBufferMultisampled()){
138            canDrawArgs.fAAType = GrAAType::kMixedSamples;
139        } else {
140            canDrawArgs.fAAType = GrAAType::kCoverage;
141        }
142        canDrawArgs.fHasUserStencilSettings = hasUserStencilSettings;
143
144        // the 'false' parameter disallows use of the SW path renderer
145        GrPathRenderer* pr =
146            context->contextPriv().drawingManager()->getPathRenderer(canDrawArgs, false, type);
147        if (prOut) {
148            *prOut = pr;
149        }
150        return SkToBool(!pr);
151    }
152}
153
154/*
155 * This method traverses the clip stack to see if the GrSoftwarePathRenderer
156 * will be used on any element. If so, it returns true to indicate that the
157 * entire clip should be rendered in SW and then uploaded en masse to the gpu.
158 */
159bool GrClipStackClip::UseSWOnlyPath(GrContext* context,
160                                    bool hasUserStencilSettings,
161                                    const GrRenderTargetContext* renderTargetContext,
162                                    const GrReducedClip& reducedClip) {
163    // TODO: generalize this function so that when
164    // a clip gets complex enough it can just be done in SW regardless
165    // of whether it would invoke the GrSoftwarePathRenderer.
166
167    // Set the matrix so that rendered clip elements are transformed to mask space from clip
168    // space.
169    SkMatrix translate;
170    translate.setTranslate(SkIntToScalar(-reducedClip.left()), SkIntToScalar(-reducedClip.top()));
171
172    for (ElementList::Iter iter(reducedClip.elements()); iter.get(); iter.next()) {
173        const Element* element = iter.get();
174
175        SkClipOp op = element->getOp();
176        bool invert = element->isInverseFilled();
177        bool needsStencil = invert ||
178                            kIntersect_SkClipOp == op || kReverseDifference_SkClipOp == op;
179
180        if (PathNeedsSWRenderer(context, hasUserStencilSettings,
181                                renderTargetContext, translate, element, nullptr, needsStencil)) {
182            return true;
183        }
184    }
185    return false;
186}
187
188static bool get_analytic_clip_processor(const ElementList& elements,
189                                        bool abortIfAA,
190                                        const SkVector& clipToRTOffset,
191                                        const SkRect& drawBounds,
192                                        sk_sp<GrFragmentProcessor>* resultFP) {
193    SkRect boundsInClipSpace;
194    boundsInClipSpace = drawBounds.makeOffset(-clipToRTOffset.fX, -clipToRTOffset.fY);
195    SkASSERT(elements.count() <= kMaxAnalyticElements);
196    SkSTArray<kMaxAnalyticElements, sk_sp<GrFragmentProcessor>> fps;
197    ElementList::Iter iter(elements);
198    while (iter.get()) {
199        SkClipOp op = iter.get()->getOp();
200        bool invert;
201        bool skip = false;
202        switch (op) {
203            case kReplace_SkClipOp:
204                SkASSERT(iter.get() == elements.head());
205                // Fallthrough, handled same as intersect.
206            case kIntersect_SkClipOp:
207                invert = false;
208                if (iter.get()->contains(boundsInClipSpace)) {
209                    skip = true;
210                }
211                break;
212            case kDifference_SkClipOp:
213                invert = true;
214                // We don't currently have a cheap test for whether a rect is fully outside an
215                // element's primitive, so don't attempt to set skip.
216                break;
217            default:
218                return false;
219        }
220        if (!skip) {
221            GrPrimitiveEdgeType edgeType;
222            if (iter.get()->isAA()) {
223                if (abortIfAA) {
224                    return false;
225                }
226                edgeType =
227                    invert ? kInverseFillAA_GrProcessorEdgeType : kFillAA_GrProcessorEdgeType;
228            } else {
229                edgeType =
230                    invert ? kInverseFillBW_GrProcessorEdgeType : kFillBW_GrProcessorEdgeType;
231            }
232
233            switch (iter.get()->getType()) {
234                case SkClipStack::Element::kPath_Type:
235                    fps.emplace_back(GrConvexPolyEffect::Make(edgeType, iter.get()->getPath(),
236                                                              &clipToRTOffset));
237                    break;
238                case SkClipStack::Element::kRRect_Type: {
239                    SkRRect rrect = iter.get()->getRRect();
240                    rrect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
241                    fps.emplace_back(GrRRectEffect::Make(edgeType, rrect));
242                    break;
243                }
244                case SkClipStack::Element::kRect_Type: {
245                    SkRect rect = iter.get()->getRect();
246                    rect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
247                    fps.emplace_back(GrConvexPolyEffect::Make(edgeType, rect));
248                    break;
249                }
250                default:
251                    break;
252            }
253            if (!fps.back()) {
254                return false;
255            }
256        }
257        iter.next();
258    }
259
260    *resultFP = nullptr;
261    if (fps.count()) {
262        *resultFP = GrFragmentProcessor::RunInSeries(fps.begin(), fps.count());
263    }
264    return true;
265}
266
267////////////////////////////////////////////////////////////////////////////////
268// sort out what kind of clip mask needs to be created: alpha, stencil,
269// scissor, or entirely software
270bool GrClipStackClip::apply(GrContext* context, GrRenderTargetContext* renderTargetContext,
271                            bool useHWAA, bool hasUserStencilSettings, GrAppliedClip* out) const {
272    if (!fStack || fStack->isWideOpen()) {
273        return true;
274    }
275
276    SkRect devBounds = SkRect::MakeIWH(renderTargetContext->width(),
277                                       renderTargetContext->height());
278    if (!devBounds.intersect(out->clippedDrawBounds())) {
279        return false;
280    }
281
282    const SkScalar clipX = SkIntToScalar(fOrigin.x()),
283                   clipY = SkIntToScalar(fOrigin.y());
284
285    SkRect clipSpaceDevBounds = devBounds.makeOffset(clipX, clipY);
286    const GrReducedClip reducedClip(*fStack, clipSpaceDevBounds,
287                                    renderTargetContext->priv().maxWindowRectangles());
288
289    if (reducedClip.hasIBounds() &&
290        !GrClip::IsInsideClip(reducedClip.ibounds(), clipSpaceDevBounds)) {
291        SkIRect scissorSpaceIBounds(reducedClip.ibounds());
292        scissorSpaceIBounds.offset(-fOrigin);
293        out->addScissor(scissorSpaceIBounds);
294    }
295
296    if (!reducedClip.windowRectangles().empty()) {
297        out->addWindowRectangles(reducedClip.windowRectangles(), fOrigin,
298                                 GrWindowRectsState::Mode::kExclusive);
299    }
300
301    if (reducedClip.elements().isEmpty()) {
302        return InitialState::kAllIn == reducedClip.initialState();
303    }
304
305#ifdef SK_DEBUG
306    SkASSERT(reducedClip.hasIBounds());
307    SkIRect rtIBounds = SkIRect::MakeWH(renderTargetContext->width(),
308                                        renderTargetContext->height());
309    SkIRect clipIBounds = reducedClip.ibounds().makeOffset(-fOrigin.x(), -fOrigin.y());
310    SkASSERT(rtIBounds.contains(clipIBounds)); // Mask shouldn't be larger than the RT.
311#endif
312
313    // An element count of 4 was chosen because of the common pattern in Blink of:
314    //   isect RR
315    //   diff  RR
316    //   isect convex_poly
317    //   isect convex_poly
318    // when drawing rounded div borders. This could probably be tuned based on a
319    // configuration's relative costs of switching RTs to generate a mask vs
320    // longer shaders.
321    if (reducedClip.elements().count() <= kMaxAnalyticElements) {
322        // When there are multiple samples we want to do per-sample clipping, not compute a
323        // fractional pixel coverage.
324        bool disallowAnalyticAA = renderTargetContext->isStencilBufferMultisampled();
325        if (disallowAnalyticAA && !renderTargetContext->numColorSamples()) {
326            // With a single color sample, any coverage info is lost from color once it hits the
327            // color buffer anyway, so we may as well use coverage AA if nothing else in the pipe
328            // is multisampled.
329            disallowAnalyticAA = useHWAA || hasUserStencilSettings;
330        }
331        sk_sp<GrFragmentProcessor> clipFP;
332        if (reducedClip.requiresAA() &&
333            get_analytic_clip_processor(reducedClip.elements(), disallowAnalyticAA,
334                                        {-clipX, -clipY}, devBounds, &clipFP)) {
335            out->addCoverageFP(std::move(clipFP));
336            return true;
337        }
338    }
339
340    // If the stencil buffer is multisampled we can use it to do everything.
341    if (!renderTargetContext->isStencilBufferMultisampled() && reducedClip.requiresAA()) {
342        sk_sp<GrTextureProxy> result;
343        if (UseSWOnlyPath(context, hasUserStencilSettings, renderTargetContext, reducedClip)) {
344            // The clip geometry is complex enough that it will be more efficient to create it
345            // entirely in software
346            result = this->createSoftwareClipMask(context, reducedClip);
347        } else {
348            result = this->createAlphaClipMask(context, reducedClip);
349        }
350
351        if (result) {
352            // The mask's top left coord should be pinned to the rounded-out top left corner of
353            // clipSpace bounds. We determine the mask's position WRT to the render target here.
354            SkIRect rtSpaceMaskBounds = reducedClip.ibounds();
355            rtSpaceMaskBounds.offset(-fOrigin);
356            out->addCoverageFP(create_fp_for_mask(context, std::move(result), rtSpaceMaskBounds));
357            return true;
358        }
359        // if alpha clip mask creation fails fall through to the non-AA code paths
360    }
361
362    GrRenderTarget* rt = renderTargetContext->accessRenderTarget();
363    if (!rt) {
364        return true;
365    }
366
367    // use the stencil clip if we can't represent the clip as a rectangle.
368    if (!context->resourceProvider()->attachStencilAttachment(rt)) {
369        SkDebugf("WARNING: failed to attach stencil buffer for clip mask. Clip will be ignored.\n");
370        return true;
371    }
372
373    // This relies on the property that a reduced sub-rect of the last clip will contain all the
374    // relevant window rectangles that were in the last clip. This subtle requirement will go away
375    // after clipping is overhauled.
376    if (renderTargetContext->priv().mustRenderClip(reducedClip.elementsGenID(),
377                                                   reducedClip.ibounds(), fOrigin)) {
378        reducedClip.drawStencilClipMask(context, renderTargetContext, fOrigin);
379        renderTargetContext->priv().setLastClip(reducedClip.elementsGenID(), reducedClip.ibounds(),
380                                                fOrigin);
381    }
382    out->addStencilClip();
383    return true;
384}
385
386////////////////////////////////////////////////////////////////////////////////
387// Create a 8-bit clip mask in alpha
388
389static void create_clip_mask_key(int32_t clipGenID, const SkIRect& bounds, GrUniqueKey* key) {
390    static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
391    GrUniqueKey::Builder builder(key, kDomain, 3, GrClipStackClip::kMaskTestTag);
392    builder[0] = clipGenID;
393    // SkToS16 because image filters outset layers to a size indicated by the filter, which can
394    // sometimes result in negative coordinates from clip space.
395    builder[1] = SkToS16(bounds.fLeft) | (SkToS16(bounds.fRight) << 16);
396    builder[2] = SkToS16(bounds.fTop) | (SkToS16(bounds.fBottom) << 16);
397}
398
399static void add_invalidate_on_pop_message(const SkClipStack& stack, int32_t clipGenID,
400                                          const GrUniqueKey& clipMaskKey) {
401    SkClipStack::Iter iter(stack, SkClipStack::Iter::kTop_IterStart);
402    while (const Element* element = iter.prev()) {
403        if (element->getGenID() == clipGenID) {
404            std::unique_ptr<GrUniqueKeyInvalidatedMessage> msg(
405                    new GrUniqueKeyInvalidatedMessage(clipMaskKey));
406            element->addResourceInvalidationMessage(std::move(msg));
407            return;
408        }
409    }
410    SkDEBUGFAIL("Gen ID was not found in stack.");
411}
412
413// MDB TODO (caching): this side-steps the issue of texture proxies cached by unique ID
414sk_sp<GrTextureProxy> GrClipStackClip::createAlphaClipMask(GrContext* context,
415                                                           const GrReducedClip& reducedClip) const {
416    GrResourceProvider* resourceProvider = context->resourceProvider();
417    GrUniqueKey key;
418    create_clip_mask_key(reducedClip.elementsGenID(), reducedClip.ibounds(), &key);
419
420    sk_sp<GrTexture> texture(resourceProvider->findAndRefTextureByUniqueKey(key));
421    if (texture) {
422        return GrSurfaceProxy::MakeWrapped(std::move(texture));
423    }
424
425    sk_sp<GrRenderTargetContext> rtc(context->makeRenderTargetContextWithFallback(
426                                                                             SkBackingFit::kApprox,
427                                                                             reducedClip.width(),
428                                                                             reducedClip.height(),
429                                                                             kAlpha_8_GrPixelConfig,
430                                                                             nullptr));
431    if (!rtc) {
432        return nullptr;
433    }
434
435    if (!reducedClip.drawAlphaClipMask(rtc.get())) {
436        return nullptr;
437    }
438
439    sk_sp<GrTextureProxy> result(rtc->asTextureProxyRef());
440    if (!result) {
441        return nullptr;
442    }
443
444    GrTexture* tex = result->instantiate(context->textureProvider());
445    if (!tex) {
446        return nullptr;
447    }
448
449    tex->resourcePriv().setUniqueKey(key);
450    add_invalidate_on_pop_message(*fStack, reducedClip.elementsGenID(), key);
451
452    return result;
453}
454
455// MDB TODO (caching): This side-steps the caching of texture proxies by unique ID
456sk_sp<GrTextureProxy> GrClipStackClip::createSoftwareClipMask(
457                                                          GrContext* context,
458                                                          const GrReducedClip& reducedClip) const {
459    GrUniqueKey key;
460    create_clip_mask_key(reducedClip.elementsGenID(), reducedClip.ibounds(), &key);
461
462    sk_sp<GrTexture> texture(context->textureProvider()->findAndRefTextureByUniqueKey(key));
463    if (texture) {
464        return GrSurfaceProxy::MakeWrapped(std::move(texture));
465    }
466
467    // The mask texture may be larger than necessary. We round out the clip space bounds and pin
468    // the top left corner of the resulting rect to the top left of the texture.
469    SkIRect maskSpaceIBounds = SkIRect::MakeWH(reducedClip.width(), reducedClip.height());
470
471    GrSWMaskHelper helper;
472
473    // Set the matrix so that rendered clip elements are transformed to mask space from clip
474    // space.
475    SkMatrix translate;
476    translate.setTranslate(SkIntToScalar(-reducedClip.left()), SkIntToScalar(-reducedClip.top()));
477
478    if (!helper.init(maskSpaceIBounds, &translate)) {
479        return nullptr;
480    }
481    helper.clear(InitialState::kAllIn == reducedClip.initialState() ? 0xFF : 0x00);
482
483    for (ElementList::Iter iter(reducedClip.elements()); iter.get(); iter.next()) {
484        const Element* element = iter.get();
485        SkClipOp op = element->getOp();
486        GrAA aa = GrBoolToAA(element->isAA());
487
488        if (kIntersect_SkClipOp == op || kReverseDifference_SkClipOp == op) {
489            // Intersect and reverse difference require modifying pixels outside of the geometry
490            // that is being "drawn". In both cases we erase all the pixels outside of the geometry
491            // but leave the pixels inside the geometry alone. For reverse difference we invert all
492            // the pixels before clearing the ones outside the geometry.
493            if (kReverseDifference_SkClipOp == op) {
494                SkRect temp = SkRect::Make(reducedClip.ibounds());
495                // invert the entire scene
496                helper.drawRect(temp, SkRegion::kXOR_Op, GrAA::kNo, 0xFF);
497            }
498            SkPath clipPath;
499            element->asPath(&clipPath);
500            clipPath.toggleInverseFillType();
501            GrShape shape(clipPath, GrStyle::SimpleFill());
502            helper.drawShape(shape, SkRegion::kReplace_Op, aa, 0x00);
503            continue;
504        }
505
506        // The other ops (union, xor, diff) only affect pixels inside
507        // the geometry so they can just be drawn normally
508        if (Element::kRect_Type == element->getType()) {
509            helper.drawRect(element->getRect(), (SkRegion::Op)op, aa, 0xFF);
510        } else {
511            SkPath path;
512            element->asPath(&path);
513            GrShape shape(path, GrStyle::SimpleFill());
514            helper.drawShape(shape, (SkRegion::Op)op, aa, 0xFF);
515        }
516    }
517
518    sk_sp<GrTextureProxy> result(helper.toTexture(context, SkBackingFit::kApprox));
519
520    GrTexture* tex = result->instantiate(context->textureProvider());
521    if (!tex) {
522        return nullptr;
523    }
524
525    tex->resourcePriv().setUniqueKey(key);
526    add_invalidate_on_pop_message(*fStack, reducedClip.elementsGenID(), key);
527    return result;
528}
529