change SkColorTable to be immutable

BUG=
R=scroggo@google.com

Review URL: https://codereview.chromium.org/25353002

git-svn-id: http://skia.googlecode.com/svn/trunk@11676 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 26 insertions, 14 deletions

diff --git a/src/images/SkImageDecoder_libgif.cpp b/src/images/SkImageDecoder_libgif.cpp
index 08f37efced..ab0fbdaf3f 100644
--- a/src/images/SkImageDecoder_libgif.cpp
+++ b/src/images/SkImageDecoder_libgif.cpp
@@ -248,10 +248,13 @@ bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
                 if (NULL == cmap) {
                     return error_return(gif, *bm, "null cmap");
                 }
-
                 colorCount = cmap->ColorCount;
-                SkAutoTMalloc<SkPMColor> colorStorage(colorCount);
-                SkPMColor* colorPtr = colorStorage.get();
+                if (colorCount > 256) {
+                    colorCount = 256;   // our kIndex8 can't support more
+                }
+
+                SkPMColor colorPtr[256]; // storage for worst-case
+                SkAlphaType alphaType = kOpaque_SkAlphaType;
                 for (int index = 0; index < colorCount; index++) {
                     colorPtr[index] = SkPackARGB32(0xFF,
                                                    cmap->Colors[index].Red,
@@ -263,10 +266,12 @@ bool SkGIFImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* bm, Mode mode) {
                 bool reallyHasAlpha = transpIndex >= 0;
                 if (reallyHasAlpha) {
                     colorPtr[transpIndex] = SK_ColorTRANSPARENT; // ram in a transparent SkPMColor
+                    alphaType = kPremul_SkAlphaType;
                 }
 
-                SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable, (colorPtr, colorCount)));
-                ctable->setIsOpaque(!reallyHasAlpha);
+                SkAutoTUnref<SkColorTable> ctable(SkNEW_ARGS(SkColorTable,
+                                                  (colorPtr, colorCount,
+                                                   alphaType)));
                 if (!this->allocPixelRef(bm, ctable)) {
                     return error_return(gif, *bm, "allocPixelRef");
                 }
diff --git a/src/images/SkImageDecoder_libpng.cpp b/src/images/SkImageDecoder_libpng.cpp
index 4e4106aede..951083b0f4 100644
--- a/src/images/SkImageDecoder_libpng.cpp
+++ b/src/images/SkImageDecoder_libpng.cpp
@@ -648,8 +648,6 @@ bool SkPNGImageDecoder::decodePalette(png_structp png_ptr, png_infop info_ptr,
     png_colorp palette;
     png_bytep trans;
     int numTrans;
-    bool reallyHasAlpha = false;
-    SkColorTable* colorTable = NULL;
 
     png_get_PLTE(png_ptr, info_ptr, &palette, &numPalette);
 
@@ -660,17 +658,16 @@ bool SkPNGImageDecoder::decodePalette(png_structp png_ptr, png_infop info_ptr,
         the colortable by 1 (if its < 256) and duplicate the last color into that slot.
     */
     int colorCount = numPalette + (numPalette < 256);
+    SkPMColor colorStorage[256];    // worst-case storage
+    SkPMColor* colorPtr = colorStorage;
 
-    colorTable = SkNEW_ARGS(SkColorTable, (colorCount));
-
-    SkPMColor* colorPtr = colorTable->lockColors();
     if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
         png_get_tRNS(png_ptr, info_ptr, &trans, &numTrans, NULL);
         *hasAlphap = (numTrans > 0);
     } else {
         numTrans = 0;
-        colorTable->setFlags(colorTable->getFlags() | SkColorTable::kColorsAreOpaque_Flag);
     }
+
     // check for bad images that might make us crash
     if (numTrans > numPalette) {
         numTrans = numPalette;
@@ -692,7 +689,7 @@ bool SkPNGImageDecoder::decodePalette(png_structp png_ptr, png_infop info_ptr,
         *colorPtr++ = proc(*trans++, palette->red, palette->green, palette->blue);
         palette++;
     }
-    reallyHasAlpha |= (transLessThanFF < 0);
+    bool reallyHasAlpha = (transLessThanFF < 0);
 
     for (; index < numPalette; index++) {
         *colorPtr++ = SkPackARGB32(0xFF, palette->red, palette->green, palette->blue);
@@ -703,8 +700,18 @@ bool SkPNGImageDecoder::decodePalette(png_structp png_ptr, png_infop info_ptr,
     if (numPalette < 256) {
         *colorPtr = colorPtr[-1];
     }
-    colorTable->unlockColors(true);
-    *colorTablep = colorTable;
+
+    SkAlphaType alphaType = kOpaque_SkAlphaType;
+    if (reallyHasAlpha) {
+        if (this->getRequireUnpremultipliedColors()) {
+            alphaType = kUnpremul_SkAlphaType;
+        } else {
+            alphaType = kPremul_SkAlphaType;
+        }
+    }
+
+    *colorTablep = SkNEW_ARGS(SkColorTable,
+                              (colorStorage, colorCount, alphaType));
     *reallyHasAlphap = reallyHasAlpha;
     return true;
 }