add colortable support to imagegenerator

src/images/SkDecodingImageGenerator.cpp

Index: src/images/SkDecodingImageGenerator.cpp
diff --git a/src/images/SkDecodingImageGenerator.cpp b/src/images/SkDecodingImageGenerator.cpp
index b3924a7daa4d2b342cb6ea29f333ce93aa4b7390..1f0f706edeef17fef2862b4195d2bfc7e536ecdc 100644
--- a/src/images/SkDecodingImageGenerator.cpp
+++ b/src/images/SkDecodingImageGenerator.cpp
@@ -23,12 +23,6 @@ bool equal_modulo_alpha(const SkImageInfo& a, const SkImageInfo& b) {
 class DecodingImageGenerator : public SkImageGenerator {
 public:
     virtual ~DecodingImageGenerator();
-    virtual SkData* refEncodedData() SK_OVERRIDE;
-    // This implementaion of getInfo() always returns true.
-    virtual bool getInfo(SkImageInfo* info) SK_OVERRIDE;
-    virtual bool getPixels(const SkImageInfo& info,
-                           void* pixels,
-                           size_t rowBytes) SK_OVERRIDE;
 
     SkData*                fData;
     SkStreamRewindable*    fStream;
@@ -41,6 +35,18 @@ public:
                            const SkImageInfo& info,
                            int sampleSize,
                            bool ditherImage);
+
+protected:
+    virtual SkData* onRefEncodedData() SK_OVERRIDE;
+    virtual bool onGetInfo(SkImageInfo* info) SK_OVERRIDE {
+        *info = fInfo;
+        return true;
+    }
+    virtual bool onGetPixels(const SkImageInfo& info,
+                             void* pixels, size_t rowBytes,
+                             SkPMColor ctable[], int* ctableCount) SK_OVERRIDE;
+
+private:
     typedef SkImageGenerator INHERITED;
 };
 
@@ -123,14 +129,7 @@ DecodingImageGenerator::~DecodingImageGenerator() {
     fStream->unref();
 }
 
-bool DecodingImageGenerator::getInfo(SkImageInfo* info) {
-    if (info != NULL) {
-        *info = fInfo;
-    }
-    return true;
-}
-
-SkData* DecodingImageGenerator::refEncodedData() {
+SkData* DecodingImageGenerator::onRefEncodedData() {
     // This functionality is used in `gm --serialize`
     // Does not encode options.
     if (fData != NULL) {
@@ -151,22 +150,15 @@ SkData* DecodingImageGenerator::refEncodedData() {
     return SkSafeRef(fData);
 }
 
-bool DecodingImageGenerator::getPixels(const SkImageInfo& info,
-                                         void* pixels,
-                                         size_t rowBytes) {
-    if (NULL == pixels) {
-        return false;
-    }
+bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info,
+                                         void* pixels, size_t rowBytes,
+                                         SkPMColor ctableEntries[], int* ctableCount) {
     if (fInfo != info) {
         // The caller has specified a different info.  This is an
         // error for this kind of SkImageGenerator.  Use the Options
         // to change the settings.
         return false;
     }
-    if (info.minRowBytes() > rowBytes) {
-        // The caller has specified a bad rowBytes.
-        return false;
-    }
 
     SkAssertResult(fStream->rewind());
     SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
@@ -202,6 +194,20 @@ bool DecodingImageGenerator::getPixels(const SkImageInfo& info,
     } else {
         SkASSERT(check_alpha(info.alphaType(), bitmap.alphaType()));
     }
+
+    if (kIndex_8_SkColorType == info.colorType()) {
+        if (kIndex_8_SkColorType != bitmap.colorType()) {
+            return false;   // they asked for Index8, but we didn't receive that from decoder
+        }
+        SkColorTable* ctable = bitmap.getColorTable();
+        if (NULL == ctable) {
+            return false;
+        }
+        const int count = ctable->count();
+        memcpy(ctableEntries, ctable->lockColors(), count * sizeof(SkPMColor));
+        ctable->unlockColors();
+        *ctableCount = count;
+    }
     return true;
 }
 
@@ -214,11 +220,6 @@ SkImageGenerator* CreateDecodingImageGenerator(
         const SkDecodingImageGenerator::Options& opts) {
     SkASSERT(stream);
     SkAutoTUnref<SkStreamRewindable> autoStream(stream);  // always unref this.
-    if (opts.fUseRequestedColorType &&
-        (kIndex_8_SkColorType == opts.fRequestedColorType)) {
-        // We do not support indexed color with SkImageGenerators,
-        return NULL;
-    }
     SkAssertResult(autoStream->rewind());
     SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(autoStream));
     if (NULL == decoder.get()) {
@@ -227,24 +228,16 @@ SkImageGenerator* CreateDecodingImageGenerator(
     SkBitmap bitmap;
     decoder->setSampleSize(opts.fSampleSize);
     decoder->setRequireUnpremultipliedColors(opts.fRequireUnpremul);
-    if (!decoder->decode(stream, &bitmap,
-                         SkImageDecoder::kDecodeBounds_Mode)) {
+    if (!decoder->decode(stream, &bitmap, SkImageDecoder::kDecodeBounds_Mode)) {
         return NULL;
     }
-    if (bitmap.config() == SkBitmap::kNo_Config) {
+    if (kUnknown_SkColorType == bitmap.colorType()) {
         return NULL;
     }
 
     SkImageInfo info = bitmap.info();
 
-    if (!opts.fUseRequestedColorType) {
-        // Use default
-        if (kIndex_8_SkColorType == bitmap.colorType()) {
-            // We don't support kIndex8 because we don't support
-            // colortables in this workflow.
-            info.fColorType = kN32_SkColorType;
-        }
-    } else {
+    if (opts.fUseRequestedColorType && (opts.fRequestedColorType != info.colorType())) {
         if (!bitmap.canCopyTo(opts.fRequestedColorType)) {
             SkASSERT(bitmap.colorType() != opts.fRequestedColorType);
             return NULL;  // Can not translate to needed config.