Revert "change SkColorTable to be immutable"

src/core/SkColorTable.cpp

Index: src/core/SkColorTable.cpp
diff --git a/src/core/SkColorTable.cpp b/src/core/SkColorTable.cpp
index c117443954f5d532cef4bf40372d7e37aaae8d08..e1ebf9202dc33f51e07c9c98024fff8f41a2c960 100644
--- a/src/core/SkColorTable.cpp
+++ b/src/core/SkColorTable.cpp
@@ -14,11 +14,27 @@
 
 SK_DEFINE_INST_COUNT(SkColorTable)
 
+SkColorTable::SkColorTable(int count)
+    : f16BitCache(NULL), fFlags(0)
+{
+    if (count < 0)
+        count = 0;
+    else if (count > 256)
+        count = 256;
+
+    fCount = SkToU16(count);
+    fColors = (SkPMColor*)sk_malloc_throw(count * sizeof(SkPMColor));
+    memset(fColors, 0, count * sizeof(SkPMColor));
+
+    SkDEBUGCODE(fColorLockCount = 0;)
+    SkDEBUGCODE(f16BitCacheLockCount = 0;)
+}
+
 // As copy constructor is hidden in the class hierarchy, we need to call
 // default constructor explicitly to suppress a compiler warning.
 SkColorTable::SkColorTable(const SkColorTable& src) : INHERITED() {
     f16BitCache = NULL;
-    fAlphaType = src.fAlphaType;
+    fFlags = src.fFlags;
     int count = src.count();
     fCount = SkToU16(count);
     fColors = reinterpret_cast<SkPMColor*>(
@@ -29,22 +45,20 @@ SkColorTable::SkColorTable(const SkColorTable& src) : INHERITED() {
     SkDEBUGCODE(f16BitCacheLockCount = 0;)
 }
 
-SkColorTable::SkColorTable(const SkPMColor colors[], int count, SkAlphaType at)
-    : f16BitCache(NULL), fAlphaType(SkToU8(at))
+SkColorTable::SkColorTable(const SkPMColor colors[], int count)
+    : f16BitCache(NULL), fFlags(0)
 {
-    SkASSERT(0 == count || NULL != colors);
-
-    if (count < 0) {
+    if (count < 0)
         count = 0;
-    } else if (count > 256) {
+    else if (count > 256)
         count = 256;
-    }
 
     fCount = SkToU16(count);
     fColors = reinterpret_cast<SkPMColor*>(
                                     sk_malloc_throw(count * sizeof(SkPMColor)));
 
-    memcpy(fColors, colors, count * sizeof(SkPMColor));
+    if (colors)
+        memcpy(fColors, colors, count * sizeof(SkPMColor));
 
     SkDEBUGCODE(fColorLockCount = 0;)
     SkDEBUGCODE(f16BitCacheLockCount = 0;)
@@ -59,30 +73,69 @@ SkColorTable::~SkColorTable()
     sk_free(f16BitCache);
 }
 
-void SkColorTable::unlockColors() {
+void SkColorTable::setFlags(unsigned flags)
+{
+    fFlags = SkToU8(flags);
+}
+
+void SkColorTable::unlockColors(bool changed)
+{
     SkASSERT(fColorLockCount != 0);
     SkDEBUGCODE(sk_atomic_dec(&fColorLockCount);)
+    if (changed)
+        this->inval16BitCache();
+}
+
+void SkColorTable::inval16BitCache()
+{
+    SkASSERT(f16BitCacheLockCount == 0);
+    if (f16BitCache)
+    {
+        sk_free(f16BitCache);
+        f16BitCache = NULL;
+    }
 }
 
 #include "SkColorPriv.h"
 
-static inline void build_16bitcache(uint16_t dst[], const SkPMColor src[],
-                                    int count) {
-    while (--count >= 0) {
+static inline void build_16bitcache(uint16_t dst[], const SkPMColor src[], int count)
+{
+    while (--count >= 0)
         *dst++ = SkPixel32ToPixel16_ToU16(*src++);
-    }
 }
 
-const uint16_t* SkColorTable::lock16BitCache() {
-    if (this->isOpaque() && NULL == f16BitCache) {
-        f16BitCache = (uint16_t*)sk_malloc_throw(fCount * sizeof(uint16_t));
-        build_16bitcache(f16BitCache, fColors, fCount);
+const uint16_t* SkColorTable::lock16BitCache()
+{
+    if (fFlags & kColorsAreOpaque_Flag)
+    {
+        if (f16BitCache == NULL) // build the cache
+        {
+            f16BitCache = (uint16_t*)sk_malloc_throw(fCount * sizeof(uint16_t));
+            build_16bitcache(f16BitCache, fColors, fCount);
+        }
+    }
+    else    // our colors have alpha, so no cache
+    {
+        this->inval16BitCache();
+        if (f16BitCache)
+        {
+            sk_free(f16BitCache);
+            f16BitCache = NULL;
+        }
     }
 
     SkDEBUGCODE(f16BitCacheLockCount += 1);
     return f16BitCache;
 }
 
+void SkColorTable::setIsOpaque(bool isOpaque) {
+    if (isOpaque) {
+        fFlags |= kColorsAreOpaque_Flag;
+    } else {
+        fFlags &= ~kColorsAreOpaque_Flag;
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkColorTable::SkColorTable(SkFlattenableReadBuffer& buffer) {
@@ -90,7 +143,7 @@ SkColorTable::SkColorTable(SkFlattenableReadBuffer& buffer) {
     SkDEBUGCODE(fColorLockCount = 0;)
     SkDEBUGCODE(f16BitCacheLockCount = 0;)
 
-    fAlphaType = SkToU8(buffer.readUInt());
+    fFlags = buffer.readUInt();
     fCount = buffer.getArrayCount();
     fColors = (SkPMColor*)sk_malloc_throw(fCount * sizeof(SkPMColor));
     SkDEBUGCODE(const uint32_t countRead =) buffer.readColorArray(fColors);
@@ -101,6 +154,6 @@ SkColorTable::SkColorTable(SkFlattenableReadBuffer& buffer) {
 }
 
 void SkColorTable::flatten(SkFlattenableWriteBuffer& buffer) const {
-    buffer.writeUInt(fAlphaType);
+    buffer.writeUInt(fFlags);
     buffer.writeColorArray(fColors, fCount);
 }