add setPreserveSrcDepth to replace PrefTable API for android

src/images/SkImageDecoder.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
 #include "SkBitmap.h"
 #include "SkImagePriv.h"
 #include "SkPixelRef.h"
 #include "SkStream.h"
 #include "SkTemplates.h"
 #include "SkCanvas.h"
 
 SkImageDecoder::SkImageDecoder()
     : fPeeker(NULL)
 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
     , fChooser(NULL)
 #endif
     , fAllocator(NULL)
     , fSampleSize(1)
     , fDefaultPref(kUnknown_SkColorType)
+    , fPreserveSrcDepth(false)
     , fDitherImage(true)
 #ifdef SK_SUPPORT_LEGACY_BITMAP_CONFIG
     , fUsePrefTable(false)
 #endif
     , fSkipWritingZeroes(false)
     , fPreferQualityOverSpeed(false)
     , fRequireUnpremultipliedColors(false) {
 }
 
 SkImageDecoder::~SkImageDecoder() {
@@ skipping 14 matching lines @@
 #endif
     other->setAllocator(fAllocator);
     other->setSampleSize(fSampleSize);
 #ifdef SK_SUPPORT_LEGACY_BITMAP_CONFIG
     if (fUsePrefTable) {
         other->setPrefConfigTable(fPrefTable);
     } else {
         other->fDefaultPref = fDefaultPref;
     }
 #endif
+    other->setPreserveSrcDepth(fPreserveSrcDepth);
     other->setDitherImage(fDitherImage);
     other->setSkipWritingZeroes(fSkipWritingZeroes);
     other->setPreferQualityOverSpeed(fPreferQualityOverSpeed);
     other->setRequireUnpremultipliedColors(fRequireUnpremultipliedColors);
 }
 
 SkImageDecoder::Format SkImageDecoder::getFormat() const {
     return kUnknown_Format;
 }
 
@@ skipping 80 matching lines @@
     fUsePrefTable = true;
     fPrefTable = prefTable;
 }
 #endif
 
 // TODO: use colortype in fPrefTable, fDefaultPref so we can stop using SkBitmapConfigToColorType()
 //
 SkColorType SkImageDecoder::getPrefColorType(SrcDepth srcDepth, bool srcHasAlpha) const {
     SkColorType ct = fDefaultPref;
 #ifdef SK_SUPPORT_LEGACY_BITMAP_CONFIG
-
     if (fUsePrefTable) {
         // Until we kill or change the PrefTable, we have to go into Config land for a moment.
         SkBitmap::Config config = SkBitmap::kNo_Config;
         switch (srcDepth) {
             case kIndex_SrcDepth:
                 config = srcHasAlpha ? fPrefTable.fPrefFor_8Index_YesAlpha_src
                                      : fPrefTable.fPrefFor_8Index_NoAlpha_src;
                 break;
             case k8BitGray_SrcDepth:
                 config = fPrefTable.fPrefFor_8Gray_src;
                 break;
             case k32Bit_SrcDepth:
                 config = srcHasAlpha ? fPrefTable.fPrefFor_8bpc_YesAlpha_src
                                      : fPrefTable.fPrefFor_8bpc_NoAlpha_src;
                 break;
         }
         // now return to SkColorType land
         ct = SkBitmapConfigToColorType(config);
     }
 #endif
+    if (fPreserveSrcDepth) {
+        switch (srcDepth) {
+            case kIndex_SrcDepth:
+                ct = kIndex_8_SkColorType;
+                break;
+            case k8BitGray_SrcDepth:
+                ct = kN32_SkColorType;
+                break;
+            case k32Bit_SrcDepth:
+                ct = kN32_SkColorType;
+                break;
+        }
+    }
     return ct;
 }
 
 bool SkImageDecoder::decode(SkStream* stream, SkBitmap* bm, SkColorType pref, Mode mode) {
     // we reset this to false before calling onDecode
     fShouldCancelDecode = false;
     // assign this, for use by getPrefColorType(), in case fUsePrefTable is false
     fDefaultPref = pref;
 
     // pass a temporary bitmap, so that if we return false, we are assured of
@@ skipping 112 matching lines @@
             if (kUnknown_Format == *format) {
                 if (stream->rewind()) {
                     *format = GetStreamFormat(stream);
                 }
             }
         }
         delete codec;
     }
     return success;
 }