remove alphatype from colortable

the owning bitmap is (already) responsible for knowing the alphatype

BUG=skia:
R=djsollen@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/611093002

5 files changed, 25 insertions, 47 deletions

diff --git a/src/core/SkColorTable.cpp b/src/core/SkColorTable.cpp
index 2607f9ae0f..f2eab61483 100644
--- a/src/core/SkColorTable.cpp
+++ b/src/core/SkColorTable.cpp
@@ -13,44 +13,36 @@
 #include "SkStream.h"
 #include "SkTemplates.h"
 
-// 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;
-    int count = src.count();
-    fCount = SkToU16(count);
-    fColors = reinterpret_cast<SkPMColor*>(
-                                    sk_malloc_throw(count * sizeof(SkPMColor)));
-    memcpy(fColors, src.fColors, count * sizeof(SkPMColor));
+void SkColorTable::init(const SkPMColor colors[], int count) {
+    SkASSERT((unsigned)count <= 256);
 
+    f16BitCache = NULL;
+    fCount = count;
+    fColors = reinterpret_cast<SkPMColor*>(sk_malloc_throw(count * sizeof(SkPMColor)));
+    
+    memcpy(fColors, colors, count * sizeof(SkPMColor));
+    
     SkDEBUGCODE(fColorLockCount = 0;)
     SkDEBUGCODE(f16BitCacheLockCount = 0;)
 }
 
-SkColorTable::SkColorTable(const SkPMColor colors[], int count, SkAlphaType at)
-    : f16BitCache(NULL), fAlphaType(SkToU8(at))
-{
-    SkASSERT(0 == count || colors);
+// 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() {
+    this->init(src.fColors, src.fCount);
+}
 
+SkColorTable::SkColorTable(const SkPMColor colors[], int count) {
+    SkASSERT(0 == count || colors);
     if (count < 0) {
         count = 0;
     } 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));
-
-    SkDEBUGCODE(fColorLockCount = 0;)
-    SkDEBUGCODE(f16BitCacheLockCount = 0;)
+    this->init(colors, count);
 }
 
-SkColorTable::~SkColorTable()
-{
+SkColorTable::~SkColorTable() {
     SkASSERT(fColorLockCount == 0);
     SkASSERT(f16BitCacheLockCount == 0);
 
@@ -73,9 +65,6 @@ static inline void build_16bitcache(uint16_t dst[], const SkPMColor src[],
 }
 
 const uint16_t* SkColorTable::lock16BitCache() {
-    // Assert that we're opaque, since our 16-bit cache will be sort of useless
-    // if there is alpha (which we're throwing away)
-    SkASSERT(this->isOpaque());
     if (NULL == f16BitCache) {
         f16BitCache = (uint16_t*)sk_malloc_throw(fCount * sizeof(uint16_t));
         build_16bitcache(f16BitCache, fColors, fCount);
@@ -92,7 +81,10 @@ SkColorTable::SkColorTable(SkReadBuffer& buffer) {
     SkDEBUGCODE(fColorLockCount = 0;)
     SkDEBUGCODE(f16BitCacheLockCount = 0;)
 
-    fAlphaType = SkToU8(buffer.readUInt());
+    if (buffer.isVersionLT(SkReadBuffer::kRemoveColorTableAlpha_Version)) {
+        /*fAlphaType = */buffer.readUInt();
+    }
+
     fCount = buffer.getArrayCount();
     size_t allocSize = fCount * sizeof(SkPMColor);
     SkDEBUGCODE(bool success = false;)
@@ -110,6 +102,5 @@ SkColorTable::SkColorTable(SkReadBuffer& buffer) {
 }
 
 void SkColorTable::writeToBuffer(SkWriteBuffer& buffer) const {
-    buffer.writeUInt(fAlphaType);
     buffer.writeColorArray(fColors, fCount);
 }
diff --git a/src/core/SkReadBuffer.h b/src/core/SkReadBuffer.h
index a5b983095b..b073847528 100644
--- a/src/core/SkReadBuffer.h
+++ b/src/core/SkReadBuffer.h
@@ -49,6 +49,7 @@ public:
         kImageFilterUniqueID_Version       = 31,
         kRemoveAndroidPaintOpts_Version    = 32,
         kFlattenCreateProc_Version         = 33,
+        kRemoveColorTableAlpha_Version     = 36,
     };
 
     /**
diff --git a/src/images/SkImageDecoder_libgif.cpp b/src/images/SkImageDecoder_libgif.cpp
index 745f4e11f1..81071c9515 100644
--- a/src/images/SkImageDecoder_libgif.cpp
+++ b/src/images/SkImageDecoder_libgif.cpp
@@ -332,7 +332,6 @@ bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
                 // Declare colorPtr here for scope.
                 SkPMColor colorPtr[256]; // storage for worst-case
                 const ColorMapObject* cmap = find_colormap(gif);
-                SkAlphaType alphaType = kOpaque_SkAlphaType;
                 if (cmap != NULL) {
                     SkASSERT(cmap->ColorCount == (1 << (cmap->BitsPerPixel)));
                     colorCount = cmap->ColorCount;
@@ -355,16 +354,13 @@ bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
                 transpIndex = find_transpIndex(temp_save, colorCount);
                 if (transpIndex >= 0) {
                     colorPtr[transpIndex] = SK_ColorTRANSPARENT; // ram in a transparent SkPMColor
-                    alphaType = kPremul_SkAlphaType;
                     fillIndex = transpIndex;
                 } else if (fillIndex >= colorCount) {
                     // gif->SBackGroundColor should be less than colorCount.
                     fillIndex = 0;  // If not, fix it.
                 }
 
-                SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable,
-                                                  (colorPtr, colorCount,
-                                                   alphaType)));
+                SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable, (colorPtr, colorCount)));
                 if (!this->allocPixelRef(bm, ctable)) {
                     return error_return(*bm, "allocPixelRef");
                 }
diff --git a/src/images/SkImageDecoder_libpng.cpp b/src/images/SkImageDecoder_libpng.cpp
index dd1d1c8a98..7911a293f6 100644
--- a/src/images/SkImageDecoder_libpng.cpp
+++ b/src/images/SkImageDecoder_libpng.cpp
@@ -709,17 +709,7 @@ bool SkPNGImageDecoder::decodePalette(png_structp png_ptr, png_infop info_ptr,
         *colorPtr = colorPtr[-1];
     }
 
-    SkAlphaType alphaType = kOpaque_SkAlphaType;
-    if (reallyHasAlpha) {
-        if (this->getRequireUnpremultipliedColors()) {
-            alphaType = kUnpremul_SkAlphaType;
-        } else {
-            alphaType = kPremul_SkAlphaType;
-        }
-    }
-
-    *colorTablep = SkNEW_ARGS(SkColorTable,
-                              (colorStorage, colorCount, alphaType));
+    *colorTablep = SkNEW_ARGS(SkColorTable, (colorStorage, colorCount));
     *reallyHasAlphap = reallyHasAlpha;
     return true;
 }
diff --git a/src/images/SkImageDecoder_wbmp.cpp b/src/images/SkImageDecoder_wbmp.cpp
index ddb7c3df02..0bf138940d 100644
--- a/src/images/SkImageDecoder_wbmp.cpp
+++ b/src/images/SkImageDecoder_wbmp.cpp
@@ -119,7 +119,7 @@ bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
     }
 
     const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE };
-    SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2, kOpaque_SkAlphaType));
+    SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2));
     SkAutoUnref   aur(ct);
 
     if (!this->allocPixelRef(decodedBitmap, ct)) {