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