Revert of Extract most of the mutable state of SkShader into a separate Context object.

src/effects/gradients/SkGradientShader.cpp

Index: src/effects/gradients/SkGradientShader.cpp
diff --git a/src/effects/gradients/SkGradientShader.cpp b/src/effects/gradients/SkGradientShader.cpp
index 666204e0aed451ad0f236c4cb72c26a7fa7945be..2ebb9c71d9bdc8cafc169fc6fbb3e5e079c226bc 100644
--- a/src/effects/gradients/SkGradientShader.cpp
+++ b/src/effects/gradients/SkGradientShader.cpp
@@ -15,6 +15,8 @@
 SkGradientShaderBase::SkGradientShaderBase(const Descriptor& desc) {
     SkASSERT(desc.fCount > 1);
 
+    fCacheAlpha = 256;  // init to a value that paint.getAlpha() can't return
+
     fMapper = desc.fMapper;
     SkSafeRef(fMapper);
     fGradFlags = SkToU8(desc.fFlags);
@@ -23,6 +25,10 @@
     SkASSERT(SkShader::kTileModeCount == SK_ARRAY_COUNT(gTileProcs));
     fTileMode = desc.fTileMode;
     fTileProc = gTileProcs[desc.fTileMode];
+
+    fCache16 = fCache16Storage = NULL;
+    fCache32 = NULL;
+    fCache32PixelRef = NULL;
 
     /*  Note: we let the caller skip the first and/or last position.
         i.e. pos[0] = 0.3, pos[1] = 0.7
@@ -138,7 +144,13 @@
 }
 
 SkGradientShaderBase::SkGradientShaderBase(SkReadBuffer& buffer) : INHERITED(buffer) {
+    fCacheAlpha = 256;
+
     fMapper = buffer.readUnitMapper();
+
+    fCache16 = fCache16Storage = NULL;
+    fCache32 = NULL;
+    fCache32PixelRef = NULL;
 
     int colorCount = fColorCount = buffer.getArrayCount();
     if (colorCount > kColorStorageCount) {
@@ -174,6 +186,10 @@
 }
 
 SkGradientShaderBase::~SkGradientShaderBase() {
+    if (fCache16Storage) {
+        sk_free(fCache16Storage);
+    }
+    SkSafeUnref(fCache32PixelRef);
     if (fOrigColors != fStorage) {
         sk_free(fOrigColors);
     }
@@ -181,6 +197,7 @@
 }
 
 void SkGradientShaderBase::initCommon() {
+    fFlags = 0;
     unsigned colorAlpha = 0xFF;
     for (int i = 0; i < fColorCount; i++) {
         colorAlpha &= SkColorGetA(fOrigColors[i]);
@@ -207,50 +224,49 @@
     return fColorsAreOpaque;
 }
 
-SkGradientShaderBase::GradientShaderBaseContext::GradientShaderBaseContext(
-        const SkGradientShaderBase& shader, const SkBitmap& device,
-        const SkPaint& paint, const SkMatrix& matrix)
-    : INHERITED(shader, device, paint, matrix)
-    , fCache(shader.getCache(getPaintAlpha()))
-{
+bool SkGradientShaderBase::setContext(const SkBitmap& device,
+                                 const SkPaint& paint,
+                                 const SkMatrix& matrix) {
+    if (!this->INHERITED::setContext(device, paint, matrix)) {
+        return false;
+    }
+
     const SkMatrix& inverse = this->getTotalInverse();
 
-    fDstToIndex.setConcat(shader.fPtsToUnit, inverse);
-
+    fDstToIndex.setConcat(fPtsToUnit, inverse);
     fDstToIndexProc = fDstToIndex.getMapXYProc();
-    fDstToIndexClass = (uint8_t)SkShader::Context::ComputeMatrixClass(fDstToIndex);
+    fDstToIndexClass = (uint8_t)SkShader::ComputeMatrixClass(fDstToIndex);
 
     // now convert our colors in to PMColors
     unsigned paintAlpha = this->getPaintAlpha();
 
     fFlags = this->INHERITED::getFlags();
-    if (shader.fColorsAreOpaque && paintAlpha == 0xFF) {
+    if (fColorsAreOpaque && paintAlpha == 0xFF) {
         fFlags |= kOpaqueAlpha_Flag;
     }
     // we can do span16 as long as our individual colors are opaque,
     // regardless of the paint's alpha
-    if (shader.fColorsAreOpaque) {
+    if (fColorsAreOpaque) {
         fFlags |= kHasSpan16_Flag;
     }
-}
-
-SkGradientShaderBase::GradientShaderCache::GradientShaderCache(
-        U8CPU alpha, const SkGradientShaderBase& shader)
-    : fCacheAlpha(alpha)
-    , fShader(shader)
-    , fCache16Inited(false)
-    , fCache32Inited(false)
-{
-    // Only initialize the cache in getCache16/32.
-    fCache16 = NULL;
-    fCache32 = NULL;
-    fCache16Storage = NULL;
-    fCache32PixelRef = NULL;
-}
-
-SkGradientShaderBase::GradientShaderCache::~GradientShaderCache() {
-    sk_free(fCache16Storage);
-    SkSafeUnref(fCache32PixelRef);
+
+    this->setCacheAlpha(paintAlpha);
+    return true;
+}
+
+void SkGradientShaderBase::setCacheAlpha(U8CPU alpha) const {
+    // if the new alpha differs from the previous time we were called, inval our cache
+    // this will trigger the cache to be rebuilt.
+    // we don't care about the first time, since the cache ptrs will already be NULL
+    if (fCacheAlpha != alpha) {
+        fCache16 = NULL;            // inval the cache
+        fCache32 = NULL;            // inval the cache
+        fCacheAlpha = alpha;        // record the new alpha
+        // inform our subclasses
+        if (fCache32PixelRef) {
+            fCache32PixelRef->notifyPixelsChanged();
+        }
+    }
 }
 
 #define Fixed_To_Dot8(x)        (((x) + 0x80) >> 8)
@@ -259,8 +275,8 @@
     build a 16bit table as long as the original colors are opaque, even if the
     paint specifies a non-opaque alpha.
 */
-void SkGradientShaderBase::GradientShaderCache::Build16bitCache(
-        uint16_t cache[], SkColor c0, SkColor c1, int count) {
+void SkGradientShaderBase::Build16bitCache(uint16_t cache[], SkColor c0, SkColor c1,
+                                      int count) {
     SkASSERT(count > 1);
     SkASSERT(SkColorGetA(c0) == 0xFF);
     SkASSERT(SkColorGetA(c1) == 0xFF);
@@ -308,9 +324,8 @@
  */
 typedef uint32_t SkUFixed;
 
-void SkGradientShaderBase::GradientShaderCache::Build32bitCache(
-        SkPMColor cache[], SkColor c0, SkColor c1,
-        int count, U8CPU paintAlpha, uint32_t gradFlags) {
+void SkGradientShaderBase::Build32bitCache(SkPMColor cache[], SkColor c0, SkColor c1,
+                                      int count, U8CPU paintAlpha, uint32_t gradFlags) {
     SkASSERT(count > 1);
 
     // need to apply paintAlpha to our two endpoints
@@ -453,121 +468,97 @@
     return 0;
 }
 
-const uint16_t* SkGradientShaderBase::GradientShaderCache::getCache16() {
-    SkOnce(&fCache16Inited, &fCache16Mutex, SkGradientShaderBase::GradientShaderCache::initCache16,
-           this);
-    SkASSERT(fCache16);
+const uint16_t* SkGradientShaderBase::getCache16() const {
+    if (fCache16 == NULL) {
+        // double the count for dither entries
+        const int entryCount = kCache16Count * 2;
+        const size_t allocSize = sizeof(uint16_t) * entryCount;
+
+        if (fCache16Storage == NULL) { // set the storage and our working ptr
+            fCache16Storage = (uint16_t*)sk_malloc_throw(allocSize);
+        }
+        fCache16 = fCache16Storage;
+        if (fColorCount == 2) {
+            Build16bitCache(fCache16, fOrigColors[0], fOrigColors[1],
+                            kCache16Count);
+        } else {
+            Rec* rec = fRecs;
+            int prevIndex = 0;
+            for (int i = 1; i < fColorCount; i++) {
+                int nextIndex = SkFixedToFFFF(rec[i].fPos) >> kCache16Shift;
+                SkASSERT(nextIndex < kCache16Count);
+
+                if (nextIndex > prevIndex)
+                    Build16bitCache(fCache16 + prevIndex, fOrigColors[i-1], fOrigColors[i], nextIndex - prevIndex + 1);
+                prevIndex = nextIndex;
+            }
+        }
+
+        if (fMapper) {
+            fCache16Storage = (uint16_t*)sk_malloc_throw(allocSize);
+            uint16_t* linear = fCache16;         // just computed linear data
+            uint16_t* mapped = fCache16Storage;  // storage for mapped data
+            SkUnitMapper* map = fMapper;
+            for (int i = 0; i < kCache16Count; i++) {
+                int index = map->mapUnit16(bitsTo16(i, kCache16Bits)) >> kCache16Shift;
+                mapped[i] = linear[index];
+                mapped[i + kCache16Count] = linear[index + kCache16Count];
+            }
+            sk_free(fCache16);
+            fCache16 = fCache16Storage;
+        }
+    }
     return fCache16;
 }
 
-void SkGradientShaderBase::GradientShaderCache::initCache16(GradientShaderCache* cache) {
-    // double the count for dither entries
-    const int entryCount = kCache16Count * 2;
-    const size_t allocSize = sizeof(uint16_t) * entryCount;
-
-    SkASSERT(NULL == cache->fCache16Storage);
-    cache->fCache16Storage = (uint16_t*)sk_malloc_throw(allocSize);
-    cache->fCache16 = cache->fCache16Storage;
-    if (cache->fShader.fColorCount == 2) {
-        Build16bitCache(cache->fCache16, cache->fShader.fOrigColors[0],
-                        cache->fShader.fOrigColors[1], kCache16Count);
-    } else {
-        Rec* rec = cache->fShader.fRecs;
-        int prevIndex = 0;
-        for (int i = 1; i < cache->fShader.fColorCount; i++) {
-            int nextIndex = SkFixedToFFFF(rec[i].fPos) >> kCache16Shift;
-            SkASSERT(nextIndex < kCache16Count);
-
-            if (nextIndex > prevIndex)
-                Build16bitCache(cache->fCache16 + prevIndex, cache->fShader.fOrigColors[i-1],
-                                cache->fShader.fOrigColors[i], nextIndex - prevIndex + 1);
-            prevIndex = nextIndex;
-        }
-    }
-
-    if (cache->fShader.fMapper) {
-        cache->fCache16Storage = (uint16_t*)sk_malloc_throw(allocSize);
-        uint16_t* linear = cache->fCache16;         // just computed linear data
-        uint16_t* mapped = cache->fCache16Storage;  // storage for mapped data
-        SkUnitMapper* map = cache->fShader.fMapper;
-        for (int i = 0; i < kCache16Count; i++) {
-            int index = map->mapUnit16(bitsTo16(i, kCache16Bits)) >> kCache16Shift;
-            mapped[i] = linear[index];
-            mapped[i + kCache16Count] = linear[index + kCache16Count];
-        }
-        sk_free(cache->fCache16);
-        cache->fCache16 = cache->fCache16Storage;
-    }
-}
-
-const SkPMColor* SkGradientShaderBase::GradientShaderCache::getCache32() {
-    SkOnce(&fCache32Inited, &fCache32Mutex, SkGradientShaderBase::GradientShaderCache::initCache32,
-           this);
-    SkASSERT(fCache32);
+const SkPMColor* SkGradientShaderBase::getCache32() const {
+    if (fCache32 == NULL) {
+        SkImageInfo info;
+        info.fWidth = kCache32Count;
+        info.fHeight = 4;   // for our 4 dither rows
+        info.fAlphaType = kPremul_SkAlphaType;
+        info.fColorType = kN32_SkColorType;
+
+        if (NULL == fCache32PixelRef) {
+            fCache32PixelRef = SkMallocPixelRef::NewAllocate(info, 0, NULL);
+        }
+        fCache32 = (SkPMColor*)fCache32PixelRef->getAddr();
+        if (fColorCount == 2) {
+            Build32bitCache(fCache32, fOrigColors[0], fOrigColors[1],
+                            kCache32Count, fCacheAlpha, fGradFlags);
+        } else {
+            Rec* rec = fRecs;
+            int prevIndex = 0;
+            for (int i = 1; i < fColorCount; i++) {
+                int nextIndex = SkFixedToFFFF(rec[i].fPos) >> kCache32Shift;
+                SkASSERT(nextIndex < kCache32Count);
+
+                if (nextIndex > prevIndex)
+                    Build32bitCache(fCache32 + prevIndex, fOrigColors[i-1],
+                                    fOrigColors[i], nextIndex - prevIndex + 1,
+                                    fCacheAlpha, fGradFlags);
+                prevIndex = nextIndex;
+            }
+        }
+
+        if (fMapper) {
+            SkMallocPixelRef* newPR = SkMallocPixelRef::NewAllocate(info, 0, NULL);
+            SkPMColor* linear = fCache32;           // just computed linear data
+            SkPMColor* mapped = (SkPMColor*)newPR->getAddr();    // storage for mapped data
+            SkUnitMapper* map = fMapper;
+            for (int i = 0; i < kCache32Count; i++) {
+                int index = map->mapUnit16((i << 8) | i) >> 8;
+                mapped[i + kCache32Count*0] = linear[index + kCache32Count*0];
+                mapped[i + kCache32Count*1] = linear[index + kCache32Count*1];
+                mapped[i + kCache32Count*2] = linear[index + kCache32Count*2];
+                mapped[i + kCache32Count*3] = linear[index + kCache32Count*3];
+            }
+            fCache32PixelRef->unref();
+            fCache32PixelRef = newPR;
+            fCache32 = (SkPMColor*)newPR->getAddr();
+        }
+    }
     return fCache32;
-}
-
-void SkGradientShaderBase::GradientShaderCache::initCache32(GradientShaderCache* cache) {
-    SkImageInfo info;
-    info.fWidth = kCache32Count;
-    info.fHeight = 4;   // for our 4 dither rows
-    info.fAlphaType = kPremul_SkAlphaType;
-    info.fColorType = kN32_SkColorType;
-
-    SkASSERT(NULL == cache->fCache32PixelRef);
-    cache->fCache32PixelRef = SkMallocPixelRef::NewAllocate(info, 0, NULL);
-    cache->fCache32 = (SkPMColor*)cache->fCache32PixelRef->getAddr();
-    if (cache->fShader.fColorCount == 2) {
-        Build32bitCache(cache->fCache32, cache->fShader.fOrigColors[0],
-                        cache->fShader.fOrigColors[1], kCache32Count, cache->fCacheAlpha,
-                        cache->fShader.fGradFlags);
-    } else {
-        Rec* rec = cache->fShader.fRecs;
-        int prevIndex = 0;
-        for (int i = 1; i < cache->fShader.fColorCount; i++) {
-            int nextIndex = SkFixedToFFFF(rec[i].fPos) >> kCache32Shift;
-            SkASSERT(nextIndex < kCache32Count);
-
-            if (nextIndex > prevIndex)
-                Build32bitCache(cache->fCache32 + prevIndex, cache->fShader.fOrigColors[i-1],
-                                cache->fShader.fOrigColors[i], nextIndex - prevIndex + 1,
-                                cache->fCacheAlpha, cache->fShader.fGradFlags);
-            prevIndex = nextIndex;
-        }
-    }
-
-    if (cache->fShader.fMapper) {
-        SkMallocPixelRef* newPR = SkMallocPixelRef::NewAllocate(info, 0, NULL);
-        SkPMColor* linear = cache->fCache32;           // just computed linear data
-        SkPMColor* mapped = (SkPMColor*)newPR->getAddr();    // storage for mapped data
-        SkUnitMapper* map = cache->fShader.fMapper;
-        for (int i = 0; i < kCache32Count; i++) {
-            int index = map->mapUnit16((i << 8) | i) >> 8;
-            mapped[i + kCache32Count*0] = linear[index + kCache32Count*0];
-            mapped[i + kCache32Count*1] = linear[index + kCache32Count*1];
-            mapped[i + kCache32Count*2] = linear[index + kCache32Count*2];
-            mapped[i + kCache32Count*3] = linear[index + kCache32Count*3];
-        }
-        cache->fCache32PixelRef->unref();
-        cache->fCache32PixelRef = newPR;
-        cache->fCache32 = (SkPMColor*)newPR->getAddr();
-    }
-}
-
-/*
- *  The gradient holds a cache for the most recent value of alpha. Successive
- *  callers with the same alpha value will share the same cache.
- */
-SkGradientShaderBase::GradientShaderCache* SkGradientShaderBase::getCache(U8CPU alpha) const {
-    SkAutoMutexAcquire ama(fCacheMutex);
-    if (!fCache || fCache->getAlpha() != alpha) {
-        fCache.reset(SkNEW_ARGS(GradientShaderCache, (alpha, *this)));
-    }
-    // Increment the ref counter inside the mutex to ensure the returned pointer is still valid.
-    // Otherwise, the pointer may have been overwritten on a different thread before the object's
-    // ref count was incremented.
-    fCache.get()->ref();
-    return fCache;
 }
 
 /*
@@ -581,14 +572,14 @@
 void SkGradientShaderBase::getGradientTableBitmap(SkBitmap* bitmap) const {
     // our caller assumes no external alpha, so we ensure that our cache is
     // built with 0xFF
-    GradientShaderCache* cache = this->getCache(0xFF);
+    this->setCacheAlpha(0xFF);
 
     // don't have a way to put the mapper into our cache-key yet
     if (fMapper) {
-        // force our cache32pixelref to be built
-        (void)cache->getCache32();
+        // force our cahce32pixelref to be built
+        (void)this->getCache32();
         bitmap->setConfig(SkImageInfo::MakeN32Premul(kCache32Count, 1));
-        bitmap->setPixelRef(cache->getCache32PixelRef());
+        bitmap->setPixelRef(fCache32PixelRef);
         return;
     }
 
@@ -627,9 +618,9 @@
 
     if (!gCache->find(storage.get(), size, bitmap)) {
         // force our cahce32pixelref to be built
-        (void)cache->getCache32();
+        (void)this->getCache32();
         bitmap->setConfig(SkImageInfo::MakeN32Premul(kCache32Count, 1));
-        bitmap->setPixelRef(cache->getCache32PixelRef());
+        bitmap->setPixelRef(fCache32PixelRef);
 
         gCache->add(storage.get(), size, *bitmap);
     }