1
2/*
3 * Copyright 2012 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#include "GrClipMaskManager.h"
10#include "GrAAConvexPathRenderer.h"
11#include "GrAAHairLinePathRenderer.h"
12#include "GrAARectRenderer.h"
13#include "GrDrawTargetCaps.h"
14#include "GrGpu.h"
15#include "GrPaint.h"
16#include "GrPathRenderer.h"
17#include "GrRenderTarget.h"
18#include "GrStencilBuffer.h"
19#include "GrSWMaskHelper.h"
20#include "effects/GrTextureDomain.h"
21#include "effects/GrConvexPolyEffect.h"
22#include "effects/GrRRectEffect.h"
23#include "SkRasterClip.h"
24#include "SkStrokeRec.h"
25#include "SkTLazy.h"
26
27#define GR_AA_CLIP 1
28
29typedef SkClipStack::Element Element;
30
31using namespace GrReducedClip;
32
33////////////////////////////////////////////////////////////////////////////////
34namespace {
35// set up the draw state to enable the aa clipping mask. Besides setting up the
36// stage matrix this also alters the vertex layout
37void setup_drawstate_aaclip(GrGpu* gpu,
38                            GrTexture* result,
39                            const SkIRect &devBound) {
40    GrDrawState* drawState = gpu->drawState();
41    SkASSERT(drawState);
42
43    SkMatrix mat;
44    // We want to use device coords to compute the texture coordinates. We set our matrix to be
45    // equal to the view matrix followed by an offset to the devBound, and then a scaling matrix to
46    // normalized coords. We apply this matrix to the vertex positions rather than local coords.
47    mat.setIDiv(result->width(), result->height());
48    mat.preTranslate(SkIntToScalar(-devBound.fLeft),
49                     SkIntToScalar(-devBound.fTop));
50    mat.preConcat(drawState->getViewMatrix());
51
52    SkIRect domainTexels = SkIRect::MakeWH(devBound.width(), devBound.height());
53    // This could be a long-lived effect that is cached with the alpha-mask.
54    drawState->addCoverageProcessor(
55        GrTextureDomainEffect::Create(result,
56                                      mat,
57                                      GrTextureDomain::MakeTexelDomain(result, domainTexels),
58                                      GrTextureDomain::kDecal_Mode,
59                                      GrTextureParams::kNone_FilterMode,
60                                      kPosition_GrCoordSet))->unref();
61}
62
63bool path_needs_SW_renderer(GrContext* context,
64                            GrGpu* gpu,
65                            const SkPath& origPath,
66                            const SkStrokeRec& stroke,
67                            bool doAA) {
68    // the gpu alpha mask will draw the inverse paths as non-inverse to a temp buffer
69    SkTCopyOnFirstWrite<SkPath> path(origPath);
70    if (path->isInverseFillType()) {
71        path.writable()->toggleInverseFillType();
72    }
73    // last (false) parameter disallows use of the SW path renderer
74    GrPathRendererChain::DrawType type = doAA ?
75                                         GrPathRendererChain::kColorAntiAlias_DrawType :
76                                         GrPathRendererChain::kColor_DrawType;
77
78    return NULL == context->getPathRenderer(*path, stroke, gpu, false, type);
79}
80
81}
82
83/*
84 * This method traverses the clip stack to see if the GrSoftwarePathRenderer
85 * will be used on any element. If so, it returns true to indicate that the
86 * entire clip should be rendered in SW and then uploaded en masse to the gpu.
87 */
88bool GrClipMaskManager::useSWOnlyPath(const ElementList& elements) {
89
90    // TODO: generalize this function so that when
91    // a clip gets complex enough it can just be done in SW regardless
92    // of whether it would invoke the GrSoftwarePathRenderer.
93    SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
94
95    for (ElementList::Iter iter(elements.headIter()); iter.get(); iter.next()) {
96        const Element* element = iter.get();
97        // rects can always be drawn directly w/o using the software path
98        // Skip rrects once we're drawing them directly.
99        if (Element::kRect_Type != element->getType()) {
100            SkPath path;
101            element->asPath(&path);
102            if (path_needs_SW_renderer(this->getContext(), fGpu, path, stroke, element->isAA())) {
103                return true;
104            }
105        }
106    }
107    return false;
108}
109
110bool GrClipMaskManager::installClipEffects(const ElementList& elements,
111                                           GrDrawState::AutoRestoreEffects* are,
112                                           const SkVector& clipToRTOffset,
113                                           const SkRect* drawBounds) {
114
115    GrDrawState* drawState = fGpu->drawState();
116    SkRect boundsInClipSpace;
117    if (drawBounds) {
118        boundsInClipSpace = *drawBounds;
119        boundsInClipSpace.offset(-clipToRTOffset.fX, -clipToRTOffset.fY);
120    }
121
122    are->set(drawState);
123    GrRenderTarget* rt = drawState->getRenderTarget();
124    ElementList::Iter iter(elements);
125
126    bool setARE = false;
127    bool failed = false;
128
129    while (iter.get()) {
130        SkRegion::Op op = iter.get()->getOp();
131        bool invert;
132        bool skip = false;
133        switch (op) {
134            case SkRegion::kReplace_Op:
135                SkASSERT(iter.get() == elements.head());
136                // Fallthrough, handled same as intersect.
137            case SkRegion::kIntersect_Op:
138                invert = false;
139                if (drawBounds && iter.get()->contains(boundsInClipSpace)) {
140                    skip = true;
141                }
142                break;
143            case SkRegion::kDifference_Op:
144                invert = true;
145                // We don't currently have a cheap test for whether a rect is fully outside an
146                // element's primitive, so don't attempt to set skip.
147                break;
148            default:
149                failed = true;
150                break;
151        }
152        if (failed) {
153            break;
154        }
155
156        if (!skip) {
157            GrPrimitiveEdgeType edgeType;
158            if (GR_AA_CLIP && iter.get()->isAA()) {
159                if (rt->isMultisampled()) {
160                    // Coverage based AA clips don't place nicely with MSAA.
161                    failed = true;
162                    break;
163                }
164                edgeType =
165                        invert ? kInverseFillAA_GrProcessorEdgeType : kFillAA_GrProcessorEdgeType;
166            } else {
167                edgeType =
168                        invert ? kInverseFillBW_GrProcessorEdgeType : kFillBW_GrProcessorEdgeType;
169            }
170            SkAutoTUnref<GrFragmentProcessor> fp;
171            switch (iter.get()->getType()) {
172                case SkClipStack::Element::kPath_Type:
173                    fp.reset(GrConvexPolyEffect::Create(edgeType, iter.get()->getPath(),
174                        &clipToRTOffset));
175                    break;
176                case SkClipStack::Element::kRRect_Type: {
177                    SkRRect rrect = iter.get()->getRRect();
178                    rrect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
179                    fp.reset(GrRRectEffect::Create(edgeType, rrect));
180                    break;
181                }
182                case SkClipStack::Element::kRect_Type: {
183                    SkRect rect = iter.get()->getRect();
184                    rect.offset(clipToRTOffset.fX, clipToRTOffset.fY);
185                    fp.reset(GrConvexPolyEffect::Create(edgeType, rect));
186                    break;
187                }
188                default:
189                    break;
190            }
191            if (fp) {
192                if (!setARE) {
193                    are->set(fGpu->drawState());
194                    setARE = true;
195                }
196                fGpu->drawState()->addCoverageProcessor(fp);
197            } else {
198                failed = true;
199                break;
200            }
201        }
202        iter.next();
203    }
204
205    if (failed) {
206        are->set(NULL);
207    }
208
209    return !failed;
210}
211
212////////////////////////////////////////////////////////////////////////////////
213// sort out what kind of clip mask needs to be created: alpha, stencil,
214// scissor, or entirely software
215bool GrClipMaskManager::setupClipping(const GrClipData* clipDataIn,
216                                      GrDrawState::AutoRestoreEffects* are,
217                                      const SkRect* devBounds) {
218    fCurrClipMaskType = kNone_ClipMaskType;
219
220    ElementList elements(16);
221    int32_t genID;
222    InitialState initialState;
223    SkIRect clipSpaceIBounds;
224    bool requiresAA;
225
226    GrDrawState* drawState = fGpu->drawState();
227
228    const GrRenderTarget* rt = drawState->getRenderTarget();
229    // GrDrawTarget should have filtered this for us
230    SkASSERT(rt);
231
232    bool ignoreClip = !drawState->isClipState() || clipDataIn->fClipStack->isWideOpen();
233
234    if (!ignoreClip) {
235        SkIRect clipSpaceRTIBounds = SkIRect::MakeWH(rt->width(), rt->height());
236        clipSpaceRTIBounds.offset(clipDataIn->fOrigin);
237        ReduceClipStack(*clipDataIn->fClipStack,
238                        clipSpaceRTIBounds,
239                        &elements,
240                        &genID,
241                        &initialState,
242                        &clipSpaceIBounds,
243                        &requiresAA);
244        if (elements.isEmpty()) {
245            if (kAllIn_InitialState == initialState) {
246                ignoreClip = clipSpaceIBounds == clipSpaceRTIBounds;
247            } else {
248                return false;
249            }
250        }
251    }
252
253    if (ignoreClip) {
254        fGpu->disableScissor();
255        this->setGpuStencil();
256        return true;
257    }
258
259    // An element count of 4 was chosen because of the common pattern in Blink of:
260    //   isect RR
261    //   diff  RR
262    //   isect convex_poly
263    //   isect convex_poly
264    // when drawing rounded div borders. This could probably be tuned based on a
265    // configuration's relative costs of switching RTs to generate a mask vs
266    // longer shaders.
267    if (elements.count() <= 4) {
268        SkVector clipToRTOffset = { SkIntToScalar(-clipDataIn->fOrigin.fX),
269                                    SkIntToScalar(-clipDataIn->fOrigin.fY) };
270        if (elements.isEmpty() ||
271            (requiresAA && this->installClipEffects(elements, are, clipToRTOffset, devBounds))) {
272            SkIRect scissorSpaceIBounds(clipSpaceIBounds);
273            scissorSpaceIBounds.offset(-clipDataIn->fOrigin);
274            if (NULL == devBounds ||
275                !SkRect::Make(scissorSpaceIBounds).contains(*devBounds)) {
276                fGpu->enableScissor(scissorSpaceIBounds);
277            } else {
278                fGpu->disableScissor();
279            }
280            this->setGpuStencil();
281            return true;
282        }
283    }
284
285#if GR_AA_CLIP
286    // If MSAA is enabled we can do everything in the stencil buffer.
287    if (0 == rt->numSamples() && requiresAA) {
288        GrTexture* result = NULL;
289
290        if (this->useSWOnlyPath(elements)) {
291            // The clip geometry is complex enough that it will be more efficient to create it
292            // entirely in software
293            result = this->createSoftwareClipMask(genID,
294                                                  initialState,
295                                                  elements,
296                                                  clipSpaceIBounds);
297        } else {
298            result = this->createAlphaClipMask(genID,
299                                               initialState,
300                                               elements,
301                                               clipSpaceIBounds);
302        }
303
304        if (result) {
305            // The mask's top left coord should be pinned to the rounded-out top left corner of
306            // clipSpace bounds. We determine the mask's position WRT to the render target here.
307            SkIRect rtSpaceMaskBounds = clipSpaceIBounds;
308            rtSpaceMaskBounds.offset(-clipDataIn->fOrigin);
309            are->set(fGpu->drawState());
310            setup_drawstate_aaclip(fGpu, result, rtSpaceMaskBounds);
311            fGpu->disableScissor();
312            this->setGpuStencil();
313            return true;
314        }
315        // if alpha clip mask creation fails fall through to the non-AA code paths
316    }
317#endif // GR_AA_CLIP
318
319    // Either a hard (stencil buffer) clip was explicitly requested or an anti-aliased clip couldn't
320    // be created. In either case, free up the texture in the anti-aliased mask cache.
321    // TODO: this may require more investigation. Ganesh performs a lot of utility draws (e.g.,
322    // clears, InOrderDrawBuffer playbacks) that hit the stencil buffer path. These may be
323    // "incorrectly" clearing the AA cache.
324    fAACache.reset();
325
326    // use the stencil clip if we can't represent the clip as a rectangle.
327    SkIPoint clipSpaceToStencilSpaceOffset = -clipDataIn->fOrigin;
328    this->createStencilClipMask(genID,
329                                initialState,
330                                elements,
331                                clipSpaceIBounds,
332                                clipSpaceToStencilSpaceOffset);
333
334    // This must occur after createStencilClipMask. That function may change the scissor. Also, it
335    // only guarantees that the stencil mask is correct within the bounds it was passed, so we must
336    // use both stencil and scissor test to the bounds for the final draw.
337    SkIRect scissorSpaceIBounds(clipSpaceIBounds);
338    scissorSpaceIBounds.offset(clipSpaceToStencilSpaceOffset);
339    fGpu->enableScissor(scissorSpaceIBounds);
340    this->setGpuStencil();
341    return true;
342}
343
344#define VISUALIZE_COMPLEX_CLIP 0
345
346#if VISUALIZE_COMPLEX_CLIP
347    #include "SkRandom.h"
348    SkRandom gRandom;
349    #define SET_RANDOM_COLOR drawState->setColor(0xff000000 | gRandom.nextU());
350#else
351    #define SET_RANDOM_COLOR
352#endif
353
354namespace {
355
356////////////////////////////////////////////////////////////////////////////////
357// set up the OpenGL blend function to perform the specified
358// boolean operation for alpha clip mask creation
359void setup_boolean_blendcoeffs(GrDrawState* drawState, SkRegion::Op op) {
360
361    switch (op) {
362        case SkRegion::kReplace_Op:
363            drawState->setBlendFunc(kOne_GrBlendCoeff, kZero_GrBlendCoeff);
364            break;
365        case SkRegion::kIntersect_Op:
366            drawState->setBlendFunc(kDC_GrBlendCoeff, kZero_GrBlendCoeff);
367            break;
368        case SkRegion::kUnion_Op:
369            drawState->setBlendFunc(kOne_GrBlendCoeff, kISC_GrBlendCoeff);
370            break;
371        case SkRegion::kXOR_Op:
372            drawState->setBlendFunc(kIDC_GrBlendCoeff, kISC_GrBlendCoeff);
373            break;
374        case SkRegion::kDifference_Op:
375            drawState->setBlendFunc(kZero_GrBlendCoeff, kISC_GrBlendCoeff);
376            break;
377        case SkRegion::kReverseDifference_Op:
378            drawState->setBlendFunc(kIDC_GrBlendCoeff, kZero_GrBlendCoeff);
379            break;
380        default:
381            SkASSERT(false);
382            break;
383    }
384}
385
386}
387
388////////////////////////////////////////////////////////////////////////////////
389bool GrClipMaskManager::drawElement(GrTexture* target,
390                                    const SkClipStack::Element* element,
391                                    GrPathRenderer* pr) {
392    GrDrawState* drawState = fGpu->drawState();
393
394    drawState->setRenderTarget(target->asRenderTarget());
395
396    // TODO: Draw rrects directly here.
397    switch (element->getType()) {
398        case Element::kEmpty_Type:
399            SkDEBUGFAIL("Should never get here with an empty element.");
400            break;
401        case Element::kRect_Type:
402            // TODO: Do rects directly to the accumulator using a aa-rect GrProcessor that covers
403            // the entire mask bounds and writes 0 outside the rect.
404            if (element->isAA()) {
405                getContext()->getAARectRenderer()->fillAARect(fGpu,
406                                                              fGpu,
407                                                              element->getRect(),
408                                                              SkMatrix::I(),
409                                                              element->getRect());
410            } else {
411                fGpu->drawSimpleRect(element->getRect());
412            }
413            return true;
414        default: {
415            SkPath path;
416            element->asPath(&path);
417            if (path.isInverseFillType()) {
418                path.toggleInverseFillType();
419            }
420            SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
421            if (NULL == pr) {
422                GrPathRendererChain::DrawType type;
423                type = element->isAA() ? GrPathRendererChain::kColorAntiAlias_DrawType :
424                                         GrPathRendererChain::kColor_DrawType;
425                pr = this->getContext()->getPathRenderer(path, stroke, fGpu, false, type);
426            }
427            if (NULL == pr) {
428                return false;
429            }
430            pr->drawPath(path, stroke, fGpu, element->isAA());
431            break;
432        }
433    }
434    return true;
435}
436
437bool GrClipMaskManager::canStencilAndDrawElement(GrTexture* target,
438                                                 const SkClipStack::Element* element,
439                                                 GrPathRenderer** pr) {
440    GrDrawState* drawState = fGpu->drawState();
441    drawState->setRenderTarget(target->asRenderTarget());
442
443    if (Element::kRect_Type == element->getType()) {
444        return true;
445    } else {
446        // We shouldn't get here with an empty clip element.
447        SkASSERT(Element::kEmpty_Type != element->getType());
448        SkPath path;
449        element->asPath(&path);
450        if (path.isInverseFillType()) {
451            path.toggleInverseFillType();
452        }
453        SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
454        GrPathRendererChain::DrawType type = element->isAA() ?
455            GrPathRendererChain::kStencilAndColorAntiAlias_DrawType :
456            GrPathRendererChain::kStencilAndColor_DrawType;
457        *pr = this->getContext()->getPathRenderer(path, stroke, fGpu, false, type);
458        return SkToBool(*pr);
459    }
460}
461
462void GrClipMaskManager::mergeMask(GrTexture* dstMask,
463                                  GrTexture* srcMask,
464                                  SkRegion::Op op,
465                                  const SkIRect& dstBound,
466                                  const SkIRect& srcBound) {
467    GrDrawState::AutoViewMatrixRestore avmr;
468    GrDrawState* drawState = fGpu->drawState();
469    SkAssertResult(avmr.setIdentity(drawState));
470    GrDrawState::AutoRestoreEffects are(drawState);
471
472    drawState->setRenderTarget(dstMask->asRenderTarget());
473
474    setup_boolean_blendcoeffs(drawState, op);
475
476    SkMatrix sampleM;
477    sampleM.setIDiv(srcMask->width(), srcMask->height());
478
479    drawState->addColorProcessor(
480        GrTextureDomainEffect::Create(srcMask,
481                                      sampleM,
482                                      GrTextureDomain::MakeTexelDomain(srcMask, srcBound),
483                                      GrTextureDomain::kDecal_Mode,
484                                      GrTextureParams::kNone_FilterMode))->unref();
485    fGpu->drawSimpleRect(SkRect::Make(dstBound));
486}
487
488// get a texture to act as a temporary buffer for AA clip boolean operations
489// TODO: given the expense of createTexture we may want to just cache this too
490void GrClipMaskManager::getTemp(int width, int height, GrAutoScratchTexture* temp) {
491    if (temp->texture()) {
492        // we've already allocated the temp texture
493        return;
494    }
495
496    GrTextureDesc desc;
497    desc.fFlags = kRenderTarget_GrTextureFlagBit|kNoStencil_GrTextureFlagBit;
498    desc.fWidth = width;
499    desc.fHeight = height;
500    desc.fConfig = kAlpha_8_GrPixelConfig;
501
502    temp->set(this->getContext(), desc);
503}
504
505////////////////////////////////////////////////////////////////////////////////
506// Return the texture currently in the cache if it exists. Otherwise, return NULL
507GrTexture* GrClipMaskManager::getCachedMaskTexture(int32_t elementsGenID,
508                                                   const SkIRect& clipSpaceIBounds) {
509    bool cached = fAACache.canReuse(elementsGenID, clipSpaceIBounds);
510    if (!cached) {
511        return NULL;
512    }
513
514    return fAACache.getLastMask();
515}
516
517////////////////////////////////////////////////////////////////////////////////
518// Allocate a texture in the texture cache. This function returns the texture
519// allocated (or NULL on error).
520GrTexture* GrClipMaskManager::allocMaskTexture(int32_t elementsGenID,
521                                               const SkIRect& clipSpaceIBounds,
522                                               bool willUpload) {
523    // Since we are setting up the cache we should free up the
524    // currently cached mask so it can be reused.
525    fAACache.reset();
526
527    GrTextureDesc desc;
528    desc.fFlags = willUpload ? kNone_GrTextureFlags : kRenderTarget_GrTextureFlagBit;
529    desc.fWidth = clipSpaceIBounds.width();
530    desc.fHeight = clipSpaceIBounds.height();
531    desc.fConfig = kRGBA_8888_GrPixelConfig;
532    if (willUpload || this->getContext()->isConfigRenderable(kAlpha_8_GrPixelConfig, false)) {
533        // We would always like A8 but it isn't supported on all platforms
534        desc.fConfig = kAlpha_8_GrPixelConfig;
535    }
536
537    fAACache.acquireMask(elementsGenID, desc, clipSpaceIBounds);
538    return fAACache.getLastMask();
539}
540
541////////////////////////////////////////////////////////////////////////////////
542// Create a 8-bit clip mask in alpha
543GrTexture* GrClipMaskManager::createAlphaClipMask(int32_t elementsGenID,
544                                                  InitialState initialState,
545                                                  const ElementList& elements,
546                                                  const SkIRect& clipSpaceIBounds) {
547    SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
548
549    // First, check for cached texture
550    GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
551    if (result) {
552        fCurrClipMaskType = kAlpha_ClipMaskType;
553        return result;
554    }
555
556    // There's no texture in the cache. Let's try to allocate it then.
557    result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, false);
558    if (NULL == result) {
559        fAACache.reset();
560        return NULL;
561    }
562
563    // The top-left of the mask corresponds to the top-left corner of the bounds.
564    SkVector clipToMaskOffset = {
565        SkIntToScalar(-clipSpaceIBounds.fLeft),
566        SkIntToScalar(-clipSpaceIBounds.fTop)
567    };
568    // The texture may be larger than necessary, this rect represents the part of the texture
569    // we populate with a rasterization of the clip.
570    SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
571
572    // Set the matrix so that rendered clip elements are transformed to mask space from clip space.
573    SkMatrix translate;
574    translate.setTranslate(clipToMaskOffset);
575    GrDrawTarget::AutoGeometryAndStatePush agasp(fGpu, GrDrawTarget::kReset_ASRInit, &translate);
576
577    GrDrawState* drawState = fGpu->drawState();
578
579    // We're drawing a coverage mask and want coverage to be run through the blend function.
580    drawState->enableState(GrDrawState::kCoverageDrawing_StateBit);
581
582    // The scratch texture that we are drawing into can be substantially larger than the mask. Only
583    // clear the part that we care about.
584    fGpu->clear(&maskSpaceIBounds,
585                kAllIn_InitialState == initialState ? 0xffffffff : 0x00000000,
586                true,
587                result->asRenderTarget());
588
589    // When we use the stencil in the below loop it is important to have this clip installed.
590    // The second pass that zeros the stencil buffer renders the rect maskSpaceIBounds so the first
591    // pass must not set values outside of this bounds or stencil values outside the rect won't be
592    // cleared.
593    GrDrawTarget::AutoClipRestore acr(fGpu, maskSpaceIBounds);
594    drawState->enableState(GrDrawState::kClip_StateBit);
595
596    GrAutoScratchTexture temp;
597    // walk through each clip element and perform its set op
598    for (ElementList::Iter iter = elements.headIter(); iter.get(); iter.next()) {
599        const Element* element = iter.get();
600        SkRegion::Op op = element->getOp();
601        bool invert = element->isInverseFilled();
602
603        if (invert || SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
604            GrPathRenderer* pr = NULL;
605            bool useTemp = !this->canStencilAndDrawElement(result, element, &pr);
606            GrTexture* dst;
607            // This is the bounds of the clip element in the space of the alpha-mask. The temporary
608            // mask buffer can be substantially larger than the actually clip stack element. We
609            // touch the minimum number of pixels necessary and use decal mode to combine it with
610            // the accumulator.
611            SkIRect maskSpaceElementIBounds;
612
613            if (useTemp) {
614                if (invert) {
615                    maskSpaceElementIBounds = maskSpaceIBounds;
616                } else {
617                    SkRect elementBounds = element->getBounds();
618                    elementBounds.offset(clipToMaskOffset);
619                    elementBounds.roundOut(&maskSpaceElementIBounds);
620                }
621
622                this->getTemp(maskSpaceIBounds.fRight, maskSpaceIBounds.fBottom, &temp);
623                if (NULL == temp.texture()) {
624                    fAACache.reset();
625                    return NULL;
626                }
627                dst = temp.texture();
628                // clear the temp target and set blend to replace
629                fGpu->clear(&maskSpaceElementIBounds,
630                            invert ? 0xffffffff : 0x00000000,
631                            true,
632                            dst->asRenderTarget());
633                setup_boolean_blendcoeffs(drawState, SkRegion::kReplace_Op);
634
635            } else {
636                // draw directly into the result with the stencil set to make the pixels affected
637                // by the clip shape be non-zero.
638                dst = result;
639                GR_STATIC_CONST_SAME_STENCIL(kStencilInElement,
640                                             kReplace_StencilOp,
641                                             kReplace_StencilOp,
642                                             kAlways_StencilFunc,
643                                             0xffff,
644                                             0xffff,
645                                             0xffff);
646                drawState->setStencil(kStencilInElement);
647                setup_boolean_blendcoeffs(drawState, op);
648            }
649
650            drawState->setAlpha(invert ? 0x00 : 0xff);
651
652            if (!this->drawElement(dst, element, pr)) {
653                fAACache.reset();
654                return NULL;
655            }
656
657            if (useTemp) {
658                // Now draw into the accumulator using the real operation and the temp buffer as a
659                // texture
660                this->mergeMask(result,
661                                temp.texture(),
662                                op,
663                                maskSpaceIBounds,
664                                maskSpaceElementIBounds);
665            } else {
666                // Draw to the exterior pixels (those with a zero stencil value).
667                drawState->setAlpha(invert ? 0xff : 0x00);
668                GR_STATIC_CONST_SAME_STENCIL(kDrawOutsideElement,
669                                             kZero_StencilOp,
670                                             kZero_StencilOp,
671                                             kEqual_StencilFunc,
672                                             0xffff,
673                                             0x0000,
674                                             0xffff);
675                drawState->setStencil(kDrawOutsideElement);
676                fGpu->drawSimpleRect(clipSpaceIBounds);
677                drawState->disableStencil();
678            }
679        } else {
680            // all the remaining ops can just be directly draw into the accumulation buffer
681            drawState->setAlpha(0xff);
682            setup_boolean_blendcoeffs(drawState, op);
683            this->drawElement(result, element);
684        }
685    }
686
687    fCurrClipMaskType = kAlpha_ClipMaskType;
688    return result;
689}
690
691////////////////////////////////////////////////////////////////////////////////
692// Create a 1-bit clip mask in the stencil buffer. 'devClipBounds' are in device
693// (as opposed to canvas) coordinates
694bool GrClipMaskManager::createStencilClipMask(int32_t elementsGenID,
695                                              InitialState initialState,
696                                              const ElementList& elements,
697                                              const SkIRect& clipSpaceIBounds,
698                                              const SkIPoint& clipSpaceToStencilOffset) {
699
700    SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
701
702    GrDrawState* drawState = fGpu->drawState();
703    SkASSERT(drawState->isClipState());
704
705    GrRenderTarget* rt = drawState->getRenderTarget();
706    SkASSERT(rt);
707
708    // TODO: dynamically attach a SB when needed.
709    GrStencilBuffer* stencilBuffer = rt->getStencilBuffer();
710    if (NULL == stencilBuffer) {
711        return false;
712    }
713
714    if (stencilBuffer->mustRenderClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset)) {
715
716        stencilBuffer->setLastClip(elementsGenID, clipSpaceIBounds, clipSpaceToStencilOffset);
717
718        // Set the matrix so that rendered clip elements are transformed from clip to stencil space.
719        SkVector translate = {
720            SkIntToScalar(clipSpaceToStencilOffset.fX),
721            SkIntToScalar(clipSpaceToStencilOffset.fY)
722        };
723        SkMatrix matrix;
724        matrix.setTranslate(translate);
725        GrDrawTarget::AutoGeometryAndStatePush agasp(fGpu, GrDrawTarget::kReset_ASRInit, &matrix);
726        drawState = fGpu->drawState();
727
728        drawState->setRenderTarget(rt);
729
730        // We set the current clip to the bounds so that our recursive draws are scissored to them.
731        SkIRect stencilSpaceIBounds(clipSpaceIBounds);
732        stencilSpaceIBounds.offset(clipSpaceToStencilOffset);
733        GrDrawTarget::AutoClipRestore acr(fGpu, stencilSpaceIBounds);
734        drawState->enableState(GrDrawState::kClip_StateBit);
735
736#if !VISUALIZE_COMPLEX_CLIP
737        drawState->enableState(GrDrawState::kNoColorWrites_StateBit);
738#endif
739
740        int clipBit = stencilBuffer->bits();
741        SkASSERT((clipBit <= 16) && "Ganesh only handles 16b or smaller stencil buffers");
742        clipBit = (1 << (clipBit-1));
743
744        fGpu->clearStencilClip(rt, stencilSpaceIBounds, kAllIn_InitialState == initialState);
745
746        // walk through each clip element and perform its set op
747        // with the existing clip.
748        for (ElementList::Iter iter(elements.headIter()); iter.get(); iter.next()) {
749            const Element* element = iter.get();
750            bool fillInverted = false;
751            // enabled at bottom of loop
752            drawState->disableState(GrGpu::kModifyStencilClip_StateBit);
753            // if the target is MSAA then we want MSAA enabled when the clip is soft
754            if (rt->isMultisampled()) {
755                drawState->setState(GrDrawState::kHWAntialias_StateBit, element->isAA());
756            }
757
758            // This will be used to determine whether the clip shape can be rendered into the
759            // stencil with arbitrary stencil settings.
760            GrPathRenderer::StencilSupport stencilSupport;
761
762            SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
763
764            SkRegion::Op op = element->getOp();
765
766            GrPathRenderer* pr = NULL;
767            SkPath clipPath;
768            if (Element::kRect_Type == element->getType()) {
769                stencilSupport = GrPathRenderer::kNoRestriction_StencilSupport;
770                fillInverted = false;
771            } else {
772                element->asPath(&clipPath);
773                fillInverted = clipPath.isInverseFillType();
774                if (fillInverted) {
775                    clipPath.toggleInverseFillType();
776                }
777                pr = this->getContext()->getPathRenderer(clipPath,
778                                                         stroke,
779                                                         fGpu,
780                                                         false,
781                                                         GrPathRendererChain::kStencilOnly_DrawType,
782                                                         &stencilSupport);
783                if (NULL == pr) {
784                    return false;
785                }
786            }
787
788            int passes;
789            GrStencilSettings stencilSettings[GrStencilSettings::kMaxStencilClipPasses];
790
791            bool canRenderDirectToStencil =
792                GrPathRenderer::kNoRestriction_StencilSupport == stencilSupport;
793            bool canDrawDirectToClip; // Given the renderer, the element,
794                                      // fill rule, and set operation can
795                                      // we render the element directly to
796                                      // stencil bit used for clipping.
797            canDrawDirectToClip = GrStencilSettings::GetClipPasses(op,
798                                                                   canRenderDirectToStencil,
799                                                                   clipBit,
800                                                                   fillInverted,
801                                                                   &passes,
802                                                                   stencilSettings);
803
804            // draw the element to the client stencil bits if necessary
805            if (!canDrawDirectToClip) {
806                GR_STATIC_CONST_SAME_STENCIL(gDrawToStencil,
807                                             kIncClamp_StencilOp,
808                                             kIncClamp_StencilOp,
809                                             kAlways_StencilFunc,
810                                             0xffff,
811                                             0x0000,
812                                             0xffff);
813                SET_RANDOM_COLOR
814                if (Element::kRect_Type == element->getType()) {
815                    *drawState->stencil() = gDrawToStencil;
816                    fGpu->drawSimpleRect(element->getRect());
817                } else {
818                    if (!clipPath.isEmpty()) {
819                        if (canRenderDirectToStencil) {
820                            *drawState->stencil() = gDrawToStencil;
821                            pr->drawPath(clipPath, stroke, fGpu, false);
822                        } else {
823                            pr->stencilPath(clipPath, stroke, fGpu);
824                        }
825                    }
826                }
827            }
828
829            // now we modify the clip bit by rendering either the clip
830            // element directly or a bounding rect of the entire clip.
831            drawState->enableState(GrGpu::kModifyStencilClip_StateBit);
832            for (int p = 0; p < passes; ++p) {
833                *drawState->stencil() = stencilSettings[p];
834                if (canDrawDirectToClip) {
835                    if (Element::kRect_Type == element->getType()) {
836                        SET_RANDOM_COLOR
837                        fGpu->drawSimpleRect(element->getRect());
838                    } else {
839                        SET_RANDOM_COLOR
840                        pr->drawPath(clipPath, stroke, fGpu, false);
841                    }
842                } else {
843                    SET_RANDOM_COLOR
844                    // The view matrix is setup to do clip space -> stencil space translation, so
845                    // draw rect in clip space.
846                    fGpu->drawSimpleRect(SkRect::Make(clipSpaceIBounds));
847                }
848            }
849        }
850    }
851    // set this last because recursive draws may overwrite it back to kNone.
852    SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
853    fCurrClipMaskType = kStencil_ClipMaskType;
854    return true;
855}
856
857
858// mapping of clip-respecting stencil funcs to normal stencil funcs
859// mapping depends on whether stencil-clipping is in effect.
860static const GrStencilFunc
861    gSpecialToBasicStencilFunc[2][kClipStencilFuncCount] = {
862    {// Stencil-Clipping is DISABLED,  we are effectively always inside the clip
863        // In the Clip Funcs
864        kAlways_StencilFunc,          // kAlwaysIfInClip_StencilFunc
865        kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
866        kLess_StencilFunc,            // kLessIfInClip_StencilFunc
867        kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
868        // Special in the clip func that forces user's ref to be 0.
869        kNotEqual_StencilFunc,        // kNonZeroIfInClip_StencilFunc
870                                      // make ref 0 and do normal nequal.
871    },
872    {// Stencil-Clipping is ENABLED
873        // In the Clip Funcs
874        kEqual_StencilFunc,           // kAlwaysIfInClip_StencilFunc
875                                      // eq stencil clip bit, mask
876                                      // out user bits.
877
878        kEqual_StencilFunc,           // kEqualIfInClip_StencilFunc
879                                      // add stencil bit to mask and ref
880
881        kLess_StencilFunc,            // kLessIfInClip_StencilFunc
882        kLEqual_StencilFunc,          // kLEqualIfInClip_StencilFunc
883                                      // for both of these we can add
884                                      // the clip bit to the mask and
885                                      // ref and compare as normal
886        // Special in the clip func that forces user's ref to be 0.
887        kLess_StencilFunc,            // kNonZeroIfInClip_StencilFunc
888                                      // make ref have only the clip bit set
889                                      // and make comparison be less
890                                      // 10..0 < 1..user_bits..
891    }
892};
893
894namespace {
895// Sets the settings to clip against the stencil buffer clip while ignoring the
896// client bits.
897const GrStencilSettings& basic_apply_stencil_clip_settings() {
898    // stencil settings to use when clip is in stencil
899    GR_STATIC_CONST_SAME_STENCIL_STRUCT(gSettings,
900        kKeep_StencilOp,
901        kKeep_StencilOp,
902        kAlwaysIfInClip_StencilFunc,
903        0x0000,
904        0x0000,
905        0x0000);
906    return *GR_CONST_STENCIL_SETTINGS_PTR_FROM_STRUCT_PTR(&gSettings);
907}
908}
909
910void GrClipMaskManager::setGpuStencil() {
911    // We make two copies of the StencilSettings here (except in the early
912    // exit scenario. One copy from draw state to the stack var. Then another
913    // from the stack var to the gpu. We could make this class hold a ptr to
914    // GrGpu's fStencilSettings and eliminate the stack copy here.
915
916    const GrDrawState& drawState = fGpu->getDrawState();
917
918    // use stencil for clipping if clipping is enabled and the clip
919    // has been written into the stencil.
920    GrClipMaskManager::StencilClipMode clipMode;
921    if (this->isClipInStencil() && drawState.isClipState()) {
922        clipMode = GrClipMaskManager::kRespectClip_StencilClipMode;
923        // We can't be modifying the clip and respecting it at the same time.
924        SkASSERT(!drawState.isStateFlagEnabled(
925                    GrGpu::kModifyStencilClip_StateBit));
926    } else if (drawState.isStateFlagEnabled(
927                    GrGpu::kModifyStencilClip_StateBit)) {
928        clipMode = GrClipMaskManager::kModifyClip_StencilClipMode;
929    } else {
930        clipMode = GrClipMaskManager::kIgnoreClip_StencilClipMode;
931    }
932
933    GrStencilSettings settings;
934    // The GrGpu client may not be using the stencil buffer but we may need to
935    // enable it in order to respect a stencil clip.
936    if (drawState.getStencil().isDisabled()) {
937        if (GrClipMaskManager::kRespectClip_StencilClipMode == clipMode) {
938            settings = basic_apply_stencil_clip_settings();
939        } else {
940            fGpu->disableStencil();
941            return;
942        }
943    } else {
944        settings = drawState.getStencil();
945    }
946
947    // TODO: dynamically attach a stencil buffer
948    int stencilBits = 0;
949    GrStencilBuffer* stencilBuffer =
950        drawState.getRenderTarget()->getStencilBuffer();
951    if (stencilBuffer) {
952        stencilBits = stencilBuffer->bits();
953    }
954
955    SkASSERT(fGpu->caps()->stencilWrapOpsSupport() || !settings.usesWrapOp());
956    SkASSERT(fGpu->caps()->twoSidedStencilSupport() || !settings.isTwoSided());
957    this->adjustStencilParams(&settings, clipMode, stencilBits);
958    fGpu->setStencilSettings(settings);
959}
960
961void GrClipMaskManager::adjustStencilParams(GrStencilSettings* settings,
962                                            StencilClipMode mode,
963                                            int stencilBitCnt) {
964    SkASSERT(stencilBitCnt > 0);
965
966    if (kModifyClip_StencilClipMode == mode) {
967        // We assume that this clip manager itself is drawing to the GrGpu and
968        // has already setup the correct values.
969        return;
970    }
971
972    unsigned int clipBit = (1 << (stencilBitCnt - 1));
973    unsigned int userBits = clipBit - 1;
974
975    GrStencilSettings::Face face = GrStencilSettings::kFront_Face;
976    bool twoSided = fGpu->caps()->twoSidedStencilSupport();
977
978    bool finished = false;
979    while (!finished) {
980        GrStencilFunc func = settings->func(face);
981        uint16_t writeMask = settings->writeMask(face);
982        uint16_t funcMask = settings->funcMask(face);
983        uint16_t funcRef = settings->funcRef(face);
984
985        SkASSERT((unsigned) func < kStencilFuncCount);
986
987        writeMask &= userBits;
988
989        if (func >= kBasicStencilFuncCount) {
990            int respectClip = kRespectClip_StencilClipMode == mode;
991            if (respectClip) {
992                // The GrGpu class should have checked this
993                SkASSERT(this->isClipInStencil());
994                switch (func) {
995                    case kAlwaysIfInClip_StencilFunc:
996                        funcMask = clipBit;
997                        funcRef = clipBit;
998                        break;
999                    case kEqualIfInClip_StencilFunc:
1000                    case kLessIfInClip_StencilFunc:
1001                    case kLEqualIfInClip_StencilFunc:
1002                        funcMask = (funcMask & userBits) | clipBit;
1003                        funcRef  = (funcRef  & userBits) | clipBit;
1004                        break;
1005                    case kNonZeroIfInClip_StencilFunc:
1006                        funcMask = (funcMask & userBits) | clipBit;
1007                        funcRef = clipBit;
1008                        break;
1009                    default:
1010                        SkFAIL("Unknown stencil func");
1011                }
1012            } else {
1013                funcMask &= userBits;
1014                funcRef &= userBits;
1015            }
1016            const GrStencilFunc* table =
1017                gSpecialToBasicStencilFunc[respectClip];
1018            func = table[func - kBasicStencilFuncCount];
1019            SkASSERT(func >= 0 && func < kBasicStencilFuncCount);
1020        } else {
1021            funcMask &= userBits;
1022            funcRef &= userBits;
1023        }
1024
1025        settings->setFunc(face, func);
1026        settings->setWriteMask(face, writeMask);
1027        settings->setFuncMask(face, funcMask);
1028        settings->setFuncRef(face, funcRef);
1029
1030        if (GrStencilSettings::kFront_Face == face) {
1031            face = GrStencilSettings::kBack_Face;
1032            finished = !twoSided;
1033        } else {
1034            finished = true;
1035        }
1036    }
1037    if (!twoSided) {
1038        settings->copyFrontSettingsToBack();
1039    }
1040}
1041
1042////////////////////////////////////////////////////////////////////////////////
1043GrTexture* GrClipMaskManager::createSoftwareClipMask(int32_t elementsGenID,
1044                                                     GrReducedClip::InitialState initialState,
1045                                                     const GrReducedClip::ElementList& elements,
1046                                                     const SkIRect& clipSpaceIBounds) {
1047    SkASSERT(kNone_ClipMaskType == fCurrClipMaskType);
1048
1049    GrTexture* result = this->getCachedMaskTexture(elementsGenID, clipSpaceIBounds);
1050    if (result) {
1051        return result;
1052    }
1053
1054    // The mask texture may be larger than necessary. We round out the clip space bounds and pin
1055    // the top left corner of the resulting rect to the top left of the texture.
1056    SkIRect maskSpaceIBounds = SkIRect::MakeWH(clipSpaceIBounds.width(), clipSpaceIBounds.height());
1057
1058    GrSWMaskHelper helper(this->getContext());
1059
1060    SkMatrix matrix;
1061    matrix.setTranslate(SkIntToScalar(-clipSpaceIBounds.fLeft),
1062                        SkIntToScalar(-clipSpaceIBounds.fTop));
1063    helper.init(maskSpaceIBounds, &matrix, false);
1064
1065    helper.clear(kAllIn_InitialState == initialState ? 0xFF : 0x00);
1066
1067    SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
1068
1069    for (ElementList::Iter iter(elements.headIter()) ; iter.get(); iter.next()) {
1070
1071        const Element* element = iter.get();
1072        SkRegion::Op op = element->getOp();
1073
1074        if (SkRegion::kIntersect_Op == op || SkRegion::kReverseDifference_Op == op) {
1075            // Intersect and reverse difference require modifying pixels outside of the geometry
1076            // that is being "drawn". In both cases we erase all the pixels outside of the geometry
1077            // but leave the pixels inside the geometry alone. For reverse difference we invert all
1078            // the pixels before clearing the ones outside the geometry.
1079            if (SkRegion::kReverseDifference_Op == op) {
1080                SkRect temp = SkRect::Make(clipSpaceIBounds);
1081                // invert the entire scene
1082                helper.draw(temp, SkRegion::kXOR_Op, false, 0xFF);
1083            }
1084
1085            SkPath clipPath;
1086            element->asPath(&clipPath);
1087            clipPath.toggleInverseFillType();
1088            helper.draw(clipPath, stroke, SkRegion::kReplace_Op, element->isAA(), 0x00);
1089
1090            continue;
1091        }
1092
1093        // The other ops (union, xor, diff) only affect pixels inside
1094        // the geometry so they can just be drawn normally
1095        if (Element::kRect_Type == element->getType()) {
1096            helper.draw(element->getRect(), op, element->isAA(), 0xFF);
1097        } else {
1098            SkPath path;
1099            element->asPath(&path);
1100            helper.draw(path, stroke, op, element->isAA(), 0xFF);
1101        }
1102    }
1103
1104    // Allocate clip mask texture
1105    result = this->allocMaskTexture(elementsGenID, clipSpaceIBounds, true);
1106    if (NULL == result) {
1107        fAACache.reset();
1108        return NULL;
1109    }
1110    helper.toTexture(result);
1111
1112    fCurrClipMaskType = kAlpha_ClipMaskType;
1113    return result;
1114}
1115
1116////////////////////////////////////////////////////////////////////////////////
1117void GrClipMaskManager::purgeResources() {
1118    fAACache.purgeResources();
1119}
1120
1121void GrClipMaskManager::setGpu(GrGpu* gpu) {
1122    fGpu = gpu;
1123    fAACache.setContext(gpu->getContext());
1124}
1125
1126void GrClipMaskManager::adjustPathStencilParams(GrStencilSettings* settings) {
1127    const GrDrawState& drawState = fGpu->getDrawState();
1128    GrClipMaskManager::StencilClipMode clipMode;
1129    if (this->isClipInStencil() && drawState.isClipState()) {
1130        clipMode = GrClipMaskManager::kRespectClip_StencilClipMode;
1131        // We can't be modifying the clip and respecting it at the same time.
1132        SkASSERT(!drawState.isStateFlagEnabled(
1133                    GrGpu::kModifyStencilClip_StateBit));
1134    } else if (drawState.isStateFlagEnabled(
1135                    GrGpu::kModifyStencilClip_StateBit)) {
1136        clipMode = GrClipMaskManager::kModifyClip_StencilClipMode;
1137    } else {
1138        clipMode = GrClipMaskManager::kIgnoreClip_StencilClipMode;
1139    }
1140
1141    // TODO: dynamically attach a stencil buffer
1142    int stencilBits = 0;
1143    GrStencilBuffer* stencilBuffer =
1144        drawState.getRenderTarget()->getStencilBuffer();
1145    if (stencilBuffer) {
1146        stencilBits = stencilBuffer->bits();
1147        this->adjustStencilParams(settings, clipMode, stencilBits);
1148    }
1149}
1150