Revert of Revert of allow canvas to force conservative clips (for speed) (patchset #1 id:1 of https://codereview.chromium.org/554033003/)

Reason for revert:
May just rebaseline, plus want to see the results of the chrome tests, so re-trying this CL.

Original issue's description:
> Revert of allow canvas to force conservative clips (for speed) (patchset #7 id:120001 of https://codereview.chromium.org/541593005/)
>
> Reason for revert:
> multipicturedraw failed on nvprmsaa -- don't know why yet
>
> Original issue's description:
> > Allow SkCanvas to be initialized to force conservative rasterclips. This has the following effects:
> >
> > 1. Queries to the current clip will be conservatively large. This can mean the quickReject may return false more often.
> >
> > 2. The conservative clips mean less work is done.
> >
> > 3. Enabled by default for Gpu, Record, and NoSaveLayer canvases.
> >
> > 4. API is private for now.
> >
> > Committed: https://skia.googlesource.com/skia/+/27a5e656c3d6ef22f9cb34de18e1b960da3aa241
>
> TBR=robertphillips@google.com,bsalomon@google.com,mtklein@google.com,junov@google.com
> NOTREECHECKS=true
> NOTRY=true
>
> Committed: https://skia.googlesource.com/skia/+/6f09709519b79a1159f3826645f1c5fbc101ee11

R=robertphillips@google.com, bsalomon@google.com, mtklein@google.com, junov@google.com, reed@google.com
TBR=bsalomon@google.com, junov@google.com, mtklein@google.com, reed@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/560713002

12 files changed, 233 insertions, 166 deletions

diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index f514d18b5e..5088d7ded5 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -1265,11 +1265,6 @@ protected:
                         SkIRect* intersection,
                         const SkImageFilter* imageFilter = NULL);
 
-    // Called by child classes that override clipPath and clipRRect to only
-    // track fast conservative clip bounds, rather than exact clips.
-    void updateClipConservativelyUsingBounds(const SkRect&, SkRegion::Op,
-                                             bool inverseFilled);
-
     // notify our surface (if we have one) that we are about to draw, so it
     // can perform copy-on-write or invalidate any cached images
     void predrawNotify();
@@ -1309,13 +1304,22 @@ private:
     friend class SkDebugCanvas;     // needs experimental fAllowSimplifyClip
     friend class SkDeferredDevice;  // needs getTopDevice()
     friend class SkSurface_Raster;  // needs getDevice()
+    friend class SkRecorder;        // InitFlags
+    friend class SkNoSaveLayerCanvas;   // InitFlags
     
+    enum InitFlags {
+        kDefault_InitFlags                  = 0,
+        kConservativeRasterClip_InitFlag    = 1 << 0,
+    };
+    SkCanvas(int width, int height, InitFlags flags);
+    SkCanvas(SkBaseDevice*, InitFlags flags);
+
     // needs gettotalclip()
     friend SkCanvasState* SkCanvasStateUtils::CaptureCanvasState(SkCanvas*);
     
     SkBaseDevice* createLayerDevice(const SkImageInfo&);
 
-    SkBaseDevice* init(SkBaseDevice*);
+    SkBaseDevice* init(SkBaseDevice*, InitFlags);
 
     /**
      *  DEPRECATED
@@ -1365,6 +1369,7 @@ private:
     mutable bool   fCachedLocalClipBoundsDirty;
     bool fAllowSoftClip;
     bool fAllowSimplifyClip;
+    bool fConservativeRasterClip;
 
     const SkRect& getLocalClipBounds() const {
         if (fCachedLocalClipBoundsDirty) {
diff --git a/include/core/SkDevice.h b/include/core/SkDevice.h
index aad5bf4737..618431a2de 100644
--- a/include/core/SkDevice.h
+++ b/include/core/SkDevice.h
@@ -372,6 +372,8 @@ private:
     // TODO: move to SkBitmapDevice
     virtual void replaceBitmapBackendForRasterSurface(const SkBitmap&) {}
 
+    virtual bool forceConservativeRasterClip() const { return false; }
+
     // just called by SkCanvas when built as a layer
     void setOrigin(int x, int y) { fOrigin.set(x, y); }
     // just called by SkCanvas for saveLayer
diff --git a/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index 91fc2f0bb6..5545227129 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -152,6 +152,7 @@ private:
     virtual SkSurface* newSurface(const SkImageInfo&) SK_OVERRIDE;
 
     virtual SkImageFilter::Cache* getImageFilterCache() SK_OVERRIDE;
+    virtual bool forceConservativeRasterClip() const SK_OVERRIDE { return true; }
 
     // sets the render target, clip, and matrix on GrContext. Use forceIdenity to override
     // SkDraw's matrix and draw in device coords.
diff --git a/include/utils/SkNoSaveLayerCanvas.h b/include/utils/SkNoSaveLayerCanvas.h
index 686f179901..56a09622a0 100644
--- a/include/utils/SkNoSaveLayerCanvas.h
+++ b/include/utils/SkNoSaveLayerCanvas.h
@@ -16,7 +16,8 @@
 // It also simplifies the clipping calls to only use rectangles.
 class SK_API SkNoSaveLayerCanvas : public SkCanvas {
 public:
-    SkNoSaveLayerCanvas(SkBaseDevice* device) : INHERITED(device) {}
+    SkNoSaveLayerCanvas(SkBaseDevice* device) : INHERITED(device, kConservativeRasterClip_InitFlag)
+    {}
 
 protected:
     virtual SaveLayerStrategy willSaveLayer(const SkRect* bounds, const SkPaint* paint,
@@ -25,21 +26,6 @@ protected:
         return kNoLayer_SaveLayerStrategy;
     }
 
-    // disable aa for speed
-    virtual void onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->INHERITED::onClipRect(rect, op, kHard_ClipEdgeStyle);
-    }
-
-    // for speed, just respect the bounds, and disable AA. May give us a few
-    // false positives and negatives.
-    virtual void onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->updateClipConservativelyUsingBounds(path.getBounds(), op,
-                                                  path.isInverseFillType());
-    }
-    virtual void onClipRRect(const SkRRect& rrect, SkRegion::Op op, ClipEdgeStyle) SK_OVERRIDE {
-        this->updateClipConservativelyUsingBounds(rrect.getBounds(), op, false);
-    }
-
 private:
     typedef SkCanvas INHERITED;
 };
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index 99786151ab..62d60da178 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -81,9 +81,12 @@ struct DeviceCM {
     const SkMatrix*     fMatrix;
     SkPaint*            fPaint; // may be null (in the future)
 
-    DeviceCM(SkBaseDevice* device, int x, int y, const SkPaint* paint, SkCanvas* canvas)
-            : fNext(NULL) {
-        if (device) {
+    DeviceCM(SkBaseDevice* device, int x, int y, const SkPaint* paint, SkCanvas* canvas,
+             bool conservativeRasterClip)
+        : fNext(NULL)
+        , fClip(conservativeRasterClip)
+    {
+        if (NULL != device) {
             device->ref();
             device->onAttachToCanvas(canvas);
         }
@@ -151,11 +154,10 @@ private:
 */
 class SkCanvas::MCRec {
 public:
-    SkMatrix        fMatrix;
     SkRasterClip    fRasterClip;
+    SkMatrix        fMatrix;
     SkDrawFilter*   fFilter;    // the current filter (or null)
-
-    DeviceCM*   fLayer;
+    DeviceCM*       fLayer;
     /*  If there are any layers in the stack, this points to the top-most
         one that is at or below this level in the stack (so we know what
         bitmap/device to draw into from this level. This value is NOT
@@ -164,22 +166,21 @@ public:
     */
     DeviceCM*   fTopLayer;
 
-    MCRec(const MCRec* prev) {
-        if (prev) {
-            fMatrix = prev->fMatrix;
-            fRasterClip = prev->fRasterClip;
-
-            fFilter = prev->fFilter;
-            SkSafeRef(fFilter);
-
-            fTopLayer = prev->fTopLayer;
-        } else {   // no prev
-            fMatrix.reset();
-            fFilter     = NULL;
-            fTopLayer   = NULL;
-        }
+    MCRec(bool conservativeRasterClip) : fRasterClip(conservativeRasterClip) {
+        fMatrix.reset();
+        fFilter     = NULL;
+        fLayer      = NULL;
+        fTopLayer   = NULL;
+        
+        // don't bother initializing fNext
+        inc_rec();
+    }
+    MCRec(const MCRec& prev) : fRasterClip(prev.fRasterClip) {
+        fMatrix = prev.fMatrix;
+        fFilter = SkSafeRef(prev.fFilter);
         fLayer = NULL;
-
+        fTopLayer = prev.fTopLayer;
+        
         // don't bother initializing fNext
         inc_rec();
     }
@@ -381,7 +382,8 @@ bool AutoDrawLooper::doNext(SkDrawFilter::Type drawType) {
 
 ////////////////////////////////////////////////////////////////////////////
 
-SkBaseDevice* SkCanvas::init(SkBaseDevice* device) {
+SkBaseDevice* SkCanvas::init(SkBaseDevice* device, InitFlags flags) {
+    fConservativeRasterClip = SkToBool(flags & kConservativeRasterClip_InitFlag);
     fCachedLocalClipBounds.setEmpty();
     fCachedLocalClipBoundsDirty = true;
     fAllowSoftClip = true;
@@ -391,10 +393,14 @@ SkBaseDevice* SkCanvas::init(SkBaseDevice* device) {
     fCullCount = 0;
     fMetaData = NULL;
 
+    if (device && device->forceConservativeRasterClip()) {
+        fConservativeRasterClip = true;
+    }
+    
     fMCRec = (MCRec*)fMCStack.push_back();
-    new (fMCRec) MCRec(NULL);
+    new (fMCRec) MCRec(fConservativeRasterClip);
 
-    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, 0, 0, NULL, NULL));
+    fMCRec->fLayer = SkNEW_ARGS(DeviceCM, (NULL, 0, 0, NULL, NULL, fConservativeRasterClip));
     fMCRec->fTopLayer = fMCRec->fLayer;
 
     fSurfaceBase = NULL;
@@ -412,25 +418,54 @@ SkCanvas::SkCanvas()
 {
     inc_canvas();
 
-    this->init(NULL);
+    this->init(NULL, kDefault_InitFlags);
 }
 
+static SkBitmap make_nopixels(int width, int height) {
+    SkBitmap bitmap;
+    bitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
+    return bitmap;
+}
+
+class SkNoPixelsBitmapDevice : public SkBitmapDevice {
+public:
+    SkNoPixelsBitmapDevice(int width, int height) : INHERITED(make_nopixels(width, height)) {}
+
+private:
+    
+    typedef SkBitmapDevice INHERITED;
+};
+
 SkCanvas::SkCanvas(int width, int height)
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
+    
+    this->init(SkNEW_ARGS(SkNoPixelsBitmapDevice, (width, height)), kDefault_InitFlags)->unref();
+}
 
-    SkBitmap bitmap;
-    bitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
-    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)))->unref();
+SkCanvas::SkCanvas(int width, int height, InitFlags flags)
+    : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
+{
+    inc_canvas();
+    
+    this->init(SkNEW_ARGS(SkNoPixelsBitmapDevice, (width, height)), flags)->unref();
 }
 
-SkCanvas::SkCanvas(SkBaseDevice* device)
+SkCanvas::SkCanvas(SkBaseDevice* device, InitFlags flags)
     : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
 {
     inc_canvas();
+    
+    this->init(device, flags);
+}
 
-    this->init(device);
+SkCanvas::SkCanvas(SkBaseDevice* device)
+    : fMCStack(sizeof(MCRec), fMCRecStorage, sizeof(fMCRecStorage))
+{
+    inc_canvas();
+    
+    this->init(device, kDefault_InitFlags);
 }
 
 SkCanvas::SkCanvas(const SkBitmap& bitmap)
@@ -438,7 +473,7 @@ SkCanvas::SkCanvas(const SkBitmap& bitmap)
 {
     inc_canvas();
 
-    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)))->unref();
+    this->init(SkNEW_ARGS(SkBitmapDevice, (bitmap)), kDefault_InitFlags)->unref();
 }
 
 SkCanvas::~SkCanvas() {
@@ -734,7 +769,7 @@ int SkCanvas::internalSave() {
     int saveCount = this->getSaveCount(); // record this before the actual save
 
     MCRec* newTop = (MCRec*)fMCStack.push_back();
-    new (newTop) MCRec(fMCRec);    // balanced in restore()
+    new (newTop) MCRec(*fMCRec);    // balanced in restore()
     fMCRec = newTop;
 
     fClipStack.save();
@@ -866,7 +901,8 @@ int SkCanvas::internalSaveLayer(const SkRect* bounds, const SkPaint* paint, Save
     }
 
     device->setOrigin(ir.fLeft, ir.fTop);
-    DeviceCM* layer = SkNEW_ARGS(DeviceCM, (device, ir.fLeft, ir.fTop, paint, this));
+    DeviceCM* layer = SkNEW_ARGS(DeviceCM,
+                                 (device, ir.fLeft, ir.fTop, paint, this, fConservativeRasterClip));
     device->unref();
 
     layer->fNext = fMCRec->fTopLayer;
@@ -1286,7 +1322,7 @@ void SkCanvas::onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle edg
 
         fMCRec->fMatrix.mapRect(&r, rect);
         fClipStack.clipDevRect(r, op, kSoft_ClipEdgeStyle == edgeStyle);
-        fMCRec->fRasterClip.op(r, op, kSoft_ClipEdgeStyle == edgeStyle);
+        fMCRec->fRasterClip.op(r, this->getBaseLayerSize(), op, kSoft_ClipEdgeStyle == edgeStyle);
     } else {
         // since we're rotated or some such thing, we convert the rect to a path
         // and clip against that, since it can handle any matrix. However, to
@@ -1421,82 +1457,6 @@ void SkCanvas::onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle edg
     rasterclip_path(&fMCRec->fRasterClip, this, devPath, op, edgeStyle);
 }
 
-void SkCanvas::updateClipConservativelyUsingBounds(const SkRect& bounds, SkRegion::Op op,
-                                                   bool inverseFilled) {
-    // This is for updating the clip conservatively using only bounds
-    // information.
-    // Contract:
-    //    The current clip must contain the true clip. The true
-    //    clip is the clip that would have normally been computed
-    //    by calls to clipPath and clipRRect
-    // Objective:
-    //    Keep the current clip as small as possible without
-    //    breaking the contract, using only clip bounding rectangles
-    //    (for performance).
-
-    // N.B.: This *never* calls back through a virtual on canvas, so subclasses
-    // don't have to worry about getting caught in a loop. Thus anywhere
-    // we call a virtual method, we explicitly prefix it with
-    // SkCanvas:: to be sure to call the base-class.
-
-    if (inverseFilled) {
-        switch (op) {
-            case SkRegion::kIntersect_Op:
-            case SkRegion::kDifference_Op:
-                // These ops can only shrink the current clip. So leaving
-                // the clip unchanged conservatively respects the contract.
-                break;
-            case SkRegion::kUnion_Op:
-            case SkRegion::kReplace_Op:
-            case SkRegion::kReverseDifference_Op:
-            case SkRegion::kXOR_Op: {
-                    // These ops can grow the current clip up to the extents of
-                    // the input clip, which is inverse filled, so we just set
-                    // the current clip to the device bounds.
-                    SkRect deviceBounds;
-                    SkIRect deviceIBounds;
-                    this->getDevice()->getGlobalBounds(&deviceIBounds);
-                    deviceBounds = SkRect::Make(deviceIBounds);
-
-                    // set the clip in device space
-                    SkMatrix savedMatrix = this->getTotalMatrix();
-                    this->SkCanvas::setMatrix(SkMatrix::I());
-                    this->SkCanvas::onClipRect(deviceBounds, SkRegion::kReplace_Op,
-                                               kHard_ClipEdgeStyle);
-                    this->setMatrix(savedMatrix);
-                    break;
-            }
-            default:
-                SkASSERT(0); // unhandled op?
-        }
-    } else {
-        // Not inverse filled
-        switch (op) {
-            case SkRegion::kIntersect_Op:
-            case SkRegion::kUnion_Op:
-            case SkRegion::kReplace_Op:
-                this->SkCanvas::onClipRect(bounds, op, kHard_ClipEdgeStyle);
-                break;
-            case SkRegion::kDifference_Op:
-                // Difference can only shrink the current clip.
-                // Leaving clip unchanged conservatively fullfills the contract.
-                break;
-            case SkRegion::kReverseDifference_Op:
-                // To reverse, we swap in the bounds with a replace op.
-                // As with difference, leave it unchanged.
-                this->SkCanvas::onClipRect(bounds, SkRegion::kReplace_Op, kHard_ClipEdgeStyle);
-                break;
-            case SkRegion::kXOR_Op:
-                // Be conservative, based on (A XOR B) always included in (A union B),
-                // which is always included in (bounds(A) union bounds(B))
-                this->SkCanvas::onClipRect(bounds, SkRegion::kUnion_Op, kHard_ClipEdgeStyle);
-                break;
-            default:
-                SkASSERT(0); // unhandled op?
-        }
-    }
-}
-
 void SkCanvas::clipRegion(const SkRegion& rgn, SkRegion::Op op) {
     this->onClipRegion(rgn, op);
 }
@@ -1525,7 +1485,7 @@ void SkCanvas::validateClip() const {
 
     SkIRect ir;
     ir.set(0, 0, device->width(), device->height());
-    SkRasterClip tmpClip(ir);
+    SkRasterClip tmpClip(ir, fConservativeRasterClip);
 
     SkClipStack::B2TIter                iter(fClipStack);
     const SkClipStack::Element* element;
@@ -1569,7 +1529,6 @@ bool SkCanvas::isClipRect() const {
 }
 
 bool SkCanvas::quickReject(const SkRect& rect) const {
-
     if (!rect.isFinite())
         return true;
 
diff --git a/src/core/SkDeviceLooper.cpp b/src/core/SkDeviceLooper.cpp
index 9346465dfc..a8350cc027 100644
--- a/src/core/SkDeviceLooper.cpp
+++ b/src/core/SkDeviceLooper.cpp
@@ -10,9 +10,10 @@
 SkDeviceLooper::SkDeviceLooper(const SkBitmap& base,
                                const SkRasterClip& rc,
                                const SkIRect& bounds, bool aa)
-: fBaseBitmap(base)
-, fBaseRC(rc)
-, fDelta(aa ? kAA_Delta : kBW_Delta)
+    : fBaseBitmap(base)
+    , fBaseRC(rc)
+    , fSubsetRC(rc.isForceConservativeRects())
+    , fDelta(aa ? kAA_Delta : kBW_Delta)
 {
     // sentinels that next() has not yet been called, and so our mapper functions
     // should not be called either.
diff --git a/src/core/SkPictureRecord.cpp b/src/core/SkPictureRecord.cpp
index b17169183a..cae8420e95 100644
--- a/src/core/SkPictureRecord.cpp
+++ b/src/core/SkPictureRecord.cpp
@@ -788,7 +788,7 @@ size_t SkPictureRecord::recordClipRect(const SkRect& rect, SkRegion::Op op, bool
 
 void SkPictureRecord::onClipRRect(const SkRRect& rrect, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
     this->recordClipRRect(rrect, op, kSoft_ClipEdgeStyle == edgeStyle);
-    this->updateClipConservativelyUsingBounds(rrect.getBounds(), op, false);
+    this->INHERITED::onClipRRect(rrect, op, edgeStyle);
 }
 
 size_t SkPictureRecord::recordClipRRect(const SkRRect& rrect, SkRegion::Op op, bool doAA) {
@@ -810,9 +810,7 @@ size_t SkPictureRecord::recordClipRRect(const SkRRect& rrect, SkRegion::Op op, b
 void SkPictureRecord::onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
     int pathID = this->addPathToHeap(path);
     this->recordClipPath(pathID, op, kSoft_ClipEdgeStyle == edgeStyle);
-
-    this->updateClipConservativelyUsingBounds(path.getBounds(), op,
-                                              path.isInverseFillType());
+    this->INHERITED::onClipPath(path, op, edgeStyle);
 }
 
 size_t SkPictureRecord::recordClipPath(int pathID, SkRegion::Op op, bool doAA) {
diff --git a/src/core/SkRasterClip.cpp b/src/core/SkRasterClip.cpp
index dab91d8f4c..f820c5a0a4 100644
--- a/src/core/SkRasterClip.cpp
+++ b/src/core/SkRasterClip.cpp
@@ -6,18 +6,12 @@
  */
 
 #include "SkRasterClip.h"
-
-
-SkRasterClip::SkRasterClip() {
-    fIsBW = true;
-    fIsEmpty = true;
-    fIsRect = false;
-    SkDEBUGCODE(this->validate();)
-}
+#include "SkPath.h"
 
 SkRasterClip::SkRasterClip(const SkRasterClip& src) {
     AUTO_RASTERCLIP_VALIDATE(src);
 
+    fForceConservativeRects = src.fForceConservativeRects;
     fIsBW = src.fIsBW;
     if (fIsBW) {
         fBW = src.fBW;
@@ -30,13 +24,22 @@ SkRasterClip::SkRasterClip(const SkRasterClip& src) {
     SkDEBUGCODE(this->validate();)
 }
 
-SkRasterClip::SkRasterClip(const SkIRect& bounds) : fBW(bounds) {
+SkRasterClip::SkRasterClip(const SkIRect& bounds, bool forceConservativeRects) : fBW(bounds) {
+    fForceConservativeRects = forceConservativeRects;
     fIsBW = true;
     fIsEmpty = this->computeIsEmpty();  // bounds might be empty, so compute
     fIsRect = !fIsEmpty;
     SkDEBUGCODE(this->validate();)
 }
 
+SkRasterClip::SkRasterClip(bool forceConservativeRects) {
+    fForceConservativeRects = forceConservativeRects;
+    fIsBW = true;
+    fIsEmpty = true;
+    fIsRect = false;
+    SkDEBUGCODE(this->validate();)
+}
+
 SkRasterClip::~SkRasterClip() {
     SkDEBUGCODE(this->validate();)
 }
@@ -70,9 +73,84 @@ bool SkRasterClip::setRect(const SkIRect& rect) {
     return fIsRect;
 }
 
+/////////////////////////////////////////////////////////////////////////////////////
+
+bool SkRasterClip::setConservativeRect(const SkRect& r, const SkIRect& clipR, bool isInverse) {
+    SkIRect ir;
+    r.roundOut(&ir);
+
+    SkRegion::Op op;
+    if (isInverse) {
+        op = SkRegion::kDifference_Op;
+    } else {
+        op = SkRegion::kIntersect_Op;
+    }
+    fBW.setRect(clipR);
+    fBW.op(ir, op);
+    return this->updateCacheAndReturnNonEmpty();
+}
+
+/////////////////////////////////////////////////////////////////////////////////////
+
+enum MutateResult {
+    kDoNothing_MutateResult,
+    kReplaceClippedAgainstGlobalBounds_MutateResult,
+    kContinue_MutateResult,
+};
+
+static MutateResult mutate_conservative_op(SkRegion::Op* op, bool inverseFilled) {
+    if (inverseFilled) {
+        switch (*op) {
+            case SkRegion::kIntersect_Op:
+            case SkRegion::kDifference_Op:
+                // These ops can only shrink the current clip. So leaving
+                // the clip unchanged conservatively respects the contract.
+                return kDoNothing_MutateResult;
+            case SkRegion::kUnion_Op:
+            case SkRegion::kReplace_Op:
+            case SkRegion::kReverseDifference_Op:
+            case SkRegion::kXOR_Op: {
+                // These ops can grow the current clip up to the extents of
+                // the input clip, which is inverse filled, so we just set
+                // the current clip to the device bounds.
+                *op = SkRegion::kReplace_Op;
+                return kReplaceClippedAgainstGlobalBounds_MutateResult;
+            }
+        }
+    } else {
+        // Not inverse filled
+        switch (*op) {
+            case SkRegion::kIntersect_Op:
+            case SkRegion::kUnion_Op:
+            case SkRegion::kReplace_Op:
+                return kContinue_MutateResult;
+            case SkRegion::kDifference_Op:
+                // Difference can only shrink the current clip.
+                // Leaving clip unchanged conservatively fullfills the contract.
+                return kDoNothing_MutateResult;
+            case SkRegion::kReverseDifference_Op:
+                // To reverse, we swap in the bounds with a replace op.
+                // As with difference, leave it unchanged.
+                *op = SkRegion::kReplace_Op;
+                return kContinue_MutateResult;
+            case SkRegion::kXOR_Op:
+                // Be conservative, based on (A XOR B) always included in (A union B),
+                // which is always included in (bounds(A) union bounds(B))
+                *op = SkRegion::kUnion_Op;
+                return kContinue_MutateResult;
+        }
+    }
+    SkFAIL("should not get here");
+    return kDoNothing_MutateResult;
+}
+
 bool SkRasterClip::setPath(const SkPath& path, const SkRegion& clip, bool doAA) {
     AUTO_RASTERCLIP_VALIDATE(*this);
 
+    if (fForceConservativeRects) {
+        return this->setConservativeRect(path.getBounds(), clip.getBounds(), path.isInverseFillType());
+    }
+
     if (this->isBW() && !doAA) {
         (void)fBW.setPath(path, clip);
     } else {
@@ -90,7 +168,22 @@ bool SkRasterClip::op(const SkPath& path, const SkISize& size, SkRegion::Op op,
     // base is used to limit the size (and therefore memory allocation) of the
     // region that results from scan converting devPath.
     SkRegion base;
-    
+
+    if (fForceConservativeRects) {
+        SkIRect ir;
+        switch (mutate_conservative_op(&op, path.isInverseFillType())) {
+            case kDoNothing_MutateResult:
+                return !this->isEmpty();
+            case kReplaceClippedAgainstGlobalBounds_MutateResult:
+                ir = SkIRect::MakeSize(size);
+                break;
+            case kContinue_MutateResult:
+                path.getBounds().roundOut(&ir);
+                break;
+        }
+        return this->op(ir, op);
+    }
+
     if (SkRegion::kIntersect_Op == op) {
         // since we are intersect, we can do better (tighter) with currRgn's
         // bounds, than just using the device. However, if currRgn is complex,
@@ -102,7 +195,7 @@ bool SkRasterClip::op(const SkPath& path, const SkISize& size, SkRegion::Op op,
             return this->setPath(path, this->bwRgn(), doAA);
         } else {
             base.setRect(this->getBounds());
-            SkRasterClip clip;
+            SkRasterClip clip(fForceConservativeRects);
             clip.setPath(path, base, doAA);
             return this->op(clip, op);
         }
@@ -112,7 +205,7 @@ bool SkRasterClip::op(const SkPath& path, const SkISize& size, SkRegion::Op op,
         if (SkRegion::kReplace_Op == op) {
             return this->setPath(path, base, doAA);
         } else {
-            SkRasterClip clip;
+            SkRasterClip clip(fForceConservativeRects);
             clip.setPath(path, base, doAA);
             return this->op(clip, op);
         }
@@ -182,9 +275,24 @@ static bool nearly_integral(SkScalar x) {
     return x - SkScalarFloorToScalar(x) < domain;
 }
 
-bool SkRasterClip::op(const SkRect& r, SkRegion::Op op, bool doAA) {
+bool SkRasterClip::op(const SkRect& r, const SkISize& size, SkRegion::Op op, bool doAA) {
     AUTO_RASTERCLIP_VALIDATE(*this);
 
+    if (fForceConservativeRects) {
+        SkIRect ir;
+        switch (mutate_conservative_op(&op, false)) {
+            case kDoNothing_MutateResult:
+                return !this->isEmpty();
+            case kReplaceClippedAgainstGlobalBounds_MutateResult:
+                ir = SkIRect::MakeSize(size);
+                break;
+            case kContinue_MutateResult:
+                r.roundOut(&ir);
+                break;
+        }
+        return this->op(ir, op);
+    }
+    
     if (fIsBW && doAA) {
         // check that the rect really needs aa, or is it close enought to
         // integer boundaries that we can just treat it as a BW rect?
@@ -251,7 +359,9 @@ const SkRegion& SkRasterClip::forceGetBW() {
 
 void SkRasterClip::convertToAA() {
     AUTO_RASTERCLIP_VALIDATE(*this);
-
+    
+    SkASSERT(!fForceConservativeRects);
+    
     SkASSERT(fIsBW);
     fAA.setRegion(fBW);
     fIsBW = false;
diff --git a/src/core/SkRasterClip.h b/src/core/SkRasterClip.h
index ec38990a0c..8a0681805c 100644
--- a/src/core/SkRasterClip.h
+++ b/src/core/SkRasterClip.h
@@ -13,11 +13,13 @@
 
 class SkRasterClip {
 public:
-    SkRasterClip();
-    SkRasterClip(const SkIRect&);
+    SkRasterClip(bool forceConservativeRects = false);
+    SkRasterClip(const SkIRect&, bool forceConservativeRects = false);
     SkRasterClip(const SkRasterClip&);
     ~SkRasterClip();
 
+    bool isForceConservativeRects() const { return fForceConservativeRects; }
+
     bool isBW() const { return fIsBW; }
     bool isAA() const { return !fIsBW; }
     const SkRegion& bwRgn() const { SkASSERT(fIsBW); return fBW; }
@@ -41,7 +43,7 @@ public:
 
     bool op(const SkIRect&, SkRegion::Op);
     bool op(const SkRegion&, SkRegion::Op);
-    bool op(const SkRect&, SkRegion::Op, bool doAA);
+    bool op(const SkRect&, const SkISize&, SkRegion::Op, bool doAA);
     bool op(const SkPath&, const SkISize&, SkRegion::Op, bool doAA);
     
     void translate(int dx, int dy, SkRasterClip* dst) const;
@@ -75,6 +77,7 @@ public:
 private:
     SkRegion    fBW;
     SkAAClip    fAA;
+    bool        fForceConservativeRects;
     bool        fIsBW;
     // these 2 are caches based on querying the right obj based on fIsBW
     bool        fIsEmpty;
@@ -107,6 +110,7 @@ private:
     bool setPath(const SkPath& path, const SkRegion& clip, bool doAA);
     bool setPath(const SkPath& path, const SkIRect& clip, bool doAA);
     bool op(const SkRasterClip&, SkRegion::Op);
+    bool setConservativeRect(const SkRect& r, const SkIRect& clipR, bool isInverse);
 };
 
 class SkAutoRasterClipValidate : SkNoncopyable {
diff --git a/src/core/SkRecorder.cpp b/src/core/SkRecorder.cpp
index 86578a53b8..f6c16d1c30 100644
--- a/src/core/SkRecorder.cpp
+++ b/src/core/SkRecorder.cpp
@@ -11,7 +11,7 @@
 
 // SkCanvas will fail in mysterious ways if it doesn't know the real width and height.
 SkRecorder::SkRecorder(SkRecord* record, int width, int height)
-    : SkCanvas(width, height)
+    : SkCanvas(width, height, SkCanvas::kConservativeRasterClip_InitFlag)
     , fRecord(record)
     , fSaveLayerCount(0) {}
 
@@ -280,12 +280,12 @@ void SkRecorder::onClipRect(const SkRect& rect, SkRegion::Op op, ClipEdgeStyle e
 }
 
 void SkRecorder::onClipRRect(const SkRRect& rrect, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
-    INHERITED(updateClipConservativelyUsingBounds, rrect.getBounds(), op, false);
+    INHERITED(onClipRRect, rrect, op, edgeStyle);
     APPEND(ClipRRect, this->devBounds(), rrect, op, edgeStyle == kSoft_ClipEdgeStyle);
 }
 
 void SkRecorder::onClipPath(const SkPath& path, SkRegion::Op op, ClipEdgeStyle edgeStyle) {
-    INHERITED(updateClipConservativelyUsingBounds, path.getBounds(), op, path.isInverseFillType());
+    INHERITED(onClipPath, path, op, edgeStyle);
     APPEND(ClipPath, this->devBounds(), delay_copy(path), op, edgeStyle == kSoft_ClipEdgeStyle);
 }
 
diff --git a/tests/AAClipTest.cpp b/tests/AAClipTest.cpp
index 776cd5267a..64e378455a 100644
--- a/tests/AAClipTest.cpp
+++ b/tests/AAClipTest.cpp
@@ -371,6 +371,7 @@ static bool operator==(const SkRasterClip& a, const SkRasterClip& b) {
 
 static void did_dx_affect(skiatest::Reporter* reporter, const SkScalar dx[],
                           size_t count, bool changed) {
+    const SkISize baseSize = SkISize::Make(10, 10);
     SkIRect ir = { 0, 0, 10, 10 };
 
     for (size_t i = 0; i < count; ++i) {
@@ -381,11 +382,11 @@ static void did_dx_affect(skiatest::Reporter* reporter, const SkScalar dx[],
         SkRasterClip rc1(ir);
         SkRasterClip rc2(ir);
 
-        rc0.op(r, SkRegion::kIntersect_Op, false);
+        rc0.op(r, baseSize, SkRegion::kIntersect_Op, false);
         r.offset(dx[i], 0);
-        rc1.op(r, SkRegion::kIntersect_Op, true);
+        rc1.op(r, baseSize, SkRegion::kIntersect_Op, true);
         r.offset(-2*dx[i], 0);
-        rc2.op(r, SkRegion::kIntersect_Op, true);
+        rc2.op(r, baseSize, SkRegion::kIntersect_Op, true);
 
         REPORTER_ASSERT(reporter, changed != (rc0 == rc1));
         REPORTER_ASSERT(reporter, changed != (rc0 == rc2));
diff --git a/tests/PictureTest.cpp b/tests/PictureTest.cpp
index 05aec092c3..3bc91d78a7 100644
--- a/tests/PictureTest.cpp
+++ b/tests/PictureTest.cpp
@@ -1570,8 +1570,8 @@ static void test_clip_bound_opt(skiatest::Reporter* reporter) {
     path2.addOval(rect3);
     SkIRect clipBounds;
     SkPictureRecorder recorder;
-    // Minimalist test set for 100% code coverage of
-    // SkPictureRecord::updateClipConservativelyUsingBounds
+
+    // Testing conservative-raster-clip that is enabled by PictureRecord
     {
         SkCanvas* canvas = recorder.beginRecording(10, 10);
         canvas->clipPath(invPath, SkRegion::kIntersect_Op);