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