Supply separate flags for onBuildTileIndex

src/images/SkImageDecoder_libpng.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 "SkImageEncoder.h"
 #include "SkColor.h"
@@ skipping 34 matching lines @@
 #define DEFAULT_FOR_SUPPRESS_PNG_IMAGE_DECODER_WARNINGS false
 #else  // !defined(SK_DEBUG)
 #define DEFAULT_FOR_SUPPRESS_PNG_IMAGE_DECODER_WARNINGS true
 #endif  // defined(SK_DEBUG)
 SK_CONF_DECLARE(bool, c_suppressPNGImageDecoderWarnings,
                 "images.png.suppressDecoderWarnings",
                 DEFAULT_FOR_SUPPRESS_PNG_IMAGE_DECODER_WARNINGS,
                 "Suppress most PNG warnings when calling image decode "
                 "functions.");
 
-
+#if defined(SK_BUILD_FOR_ANDROID) && !defined(SK_PNG_NO_INDEX_SUPPORTED)
+#define SK_PNG_INDEX_SUPPORTED
+#endif
 
 class SkPNGImageIndex {
 public:
     // Takes ownership of stream.
     SkPNGImageIndex(SkStreamRewindable* stream, png_structp png_ptr, png_infop info_ptr)
         : fStream(stream)
         , fPng_ptr(png_ptr)
         , fInfo_ptr(info_ptr)
         , fColorType(kUnknown_SkColorType) {
         SkASSERT(stream != nullptr);
@@ skipping 15 matching lines @@
     SkPNGImageDecoder() {
         fImageIndex = nullptr;
     }
     Format getFormat() const override {
         return kPNG_Format;
     }
 
     virtual ~SkPNGImageDecoder() { delete fImageIndex; }
 
 protected:
-#ifdef SK_BUILD_FOR_ANDROID
+#ifdef SK_PNG_INDEX_SUPPORTED
     bool onBuildTileIndex(SkStreamRewindable *stream, int *width, int *height) override;
     bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& region) override;
 #endif
     Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
 
 private:
     SkPNGImageIndex* fImageIndex;
 
     bool onDecodeInit(SkStream* stream, png_structp *png_ptrp, png_infop *info_ptrp);
     bool decodePalette(png_structp png_ptr, png_infop info_ptr, int bitDepth,
@@ skipping 23 matching lines @@
 };
 
 static void sk_read_fn(png_structp png_ptr, png_bytep data, png_size_t length) {
     SkStream* sk_stream = (SkStream*) png_get_io_ptr(png_ptr);
     size_t bytes = sk_stream->read(data, length);
     if (bytes != length) {
         png_error(png_ptr, "Read Error!");
     }
 }
 
-#ifdef SK_BUILD_FOR_ANDROID
+#ifdef SK_PNG_INDEX_SUPPORTED
 static void sk_seek_fn(png_structp png_ptr, png_uint_32 offset) {
     SkStreamRewindable* sk_stream = (SkStreamRewindable*) png_get_io_ptr(png_ptr);
     if (!sk_stream->rewind()) {
         png_error(png_ptr, "Failed to rewind stream!");
     }
     (void)sk_stream->skip(offset);
 }
 #endif
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
@@ skipping 109 matching lines @@
     */
     if (setjmp(png_jmpbuf(png_ptr))) {
         png_destroy_read_struct(&png_ptr, &info_ptr, png_infopp_NULL);
         return false;
     }
 
     /* If you are using replacement read functions, instead of calling
     * png_init_io() here you would call:
     */
     png_set_read_fn(png_ptr, (void *)sk_stream, sk_read_fn);
-#ifdef SK_BUILD_FOR_ANDROID
+#ifdef SK_PNG_INDEX_SUPPORTED
     png_set_seek_fn(png_ptr, sk_seek_fn);
 #endif
     /* where user_io_ptr is a structure you want available to the callbacks */
     /* If we have already read some of the signature */
 //  png_set_sig_bytes(png_ptr, 0 /* sig_read */ );
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
     // hookup our peeker so we can see any user-chunks the caller may be interested in
     png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0);
     if (this->getPeeker()) {
@@ skipping 443 matching lines @@
     SkPMColor lastColor = index > 0 ? colorPtr[-1] : SkPackARGB32(0xFF, 0, 0, 0);
     for (; index < colorCount; index++) {
         *colorPtr++ = lastColor;
     }
 
     *colorTablep = new SkColorTable(colorStorage, colorCount);
     *reallyHasAlphap = reallyHasAlpha;
     return true;
 }
 
-#ifdef SK_BUILD_FOR_ANDROID
+#ifdef SK_PNG_INDEX_SUPPORTED
 
 bool SkPNGImageDecoder::onBuildTileIndex(SkStreamRewindable* sk_stream, int *width, int *height) {
     SkAutoTDelete<SkStreamRewindable> streamDeleter(sk_stream);
     png_structp png_ptr;
     png_infop   info_ptr;
 
     if (!onDecodeInit(sk_stream, &png_ptr, &info_ptr)) {
         return false;
     }
 
@@ skipping 541 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? new SkPNGImageEncoder : nullptr;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libpng_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_png);
 static SkImageEncoder_EncodeReg gEReg(sk_libpng_efactory);