Enabling ico decoding with use of png and bmp decoders

BUG=skia:3257

Review URL: https://codereview.chromium.org/1011343003

6 files changed, 503 insertions, 67 deletions

diff --git a/src/codec/SkCodec.cpp b/src/codec/SkCodec.cpp
index 12341f5929..0411e44069 100644
--- a/src/codec/SkCodec.cpp
+++ b/src/codec/SkCodec.cpp
@@ -8,6 +8,7 @@
 #include "SkCodec.h"
 #include "SkData.h"
 #include "SkCodec_libbmp.h"
+#include "SkCodec_libico.h"
 #include "SkCodec_libpng.h"
 #include "SkStream.h"
 
@@ -18,6 +19,7 @@ struct DecoderProc {
 
 static const DecoderProc gDecoderProcs[] = {
     { SkPngCodec::IsPng, SkPngCodec::NewFromStream },
+    { SkIcoCodec::IsIco, SkIcoCodec::NewFromStream },
     { SkBmpCodec::IsBmp, SkBmpCodec::NewFromStream }
 };
 
diff --git a/src/codec/SkCodec_libbmp.cpp b/src/codec/SkCodec_libbmp.cpp
index e9551cbb6f..ac6cf3a443 100644
--- a/src/codec/SkCodec_libbmp.cpp
+++ b/src/codec/SkCodec_libbmp.cpp
@@ -29,9 +29,6 @@ static bool conversion_possible(const SkImageInfo& dst,
             return src.alphaType() == dst.alphaType() ||
                     (kPremul_SkAlphaType == dst.alphaType() &&
                     kUnpremul_SkAlphaType == src.alphaType());
-        case kRGB_565_SkColorType:
-            return src.alphaType() == dst.alphaType() &&
-                    kOpaque_SkAlphaType == dst.alphaType();
         default:
             return false;
     }
@@ -88,11 +85,31 @@ bool SkBmpCodec::IsBmp(SkStream* stream) {
 /*
  *
  * Assumes IsBmp was called and returned true
- * Creates a bitmap decoder
+ * Creates a bmp decoder
  * Reads enough of the stream to determine the image format
  *
  */
 SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
+    return SkBmpCodec::NewFromStream(stream, false);
+}
+
+/*
+ *
+ * Creates a bmp decoder for a bmp embedded in ico
+ * Reads enough of the stream to determine the image format
+ *
+ */
+SkCodec* SkBmpCodec::NewFromIco(SkStream* stream) {
+    return SkBmpCodec::NewFromStream(stream, true);
+}
+
+/*
+ *
+ * Creates a bmp decoder
+ * Reads enough of the stream to determine the image format
+ *
+ */
+SkCodec* SkBmpCodec::NewFromStream(SkStream* stream, bool isIco) {
     // Header size constants
     static const uint32_t kBmpHeaderBytes = 14;
     static const uint32_t kBmpHeaderBytesPlusFour = kBmpHeaderBytes + 4;
@@ -106,37 +123,68 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
     static const uint32_t kBmpInfoV5Bytes = 124;
     static const uint32_t kBmpMaskBytes = 12;
 
-    // Read the first header and the size of the second header
-    SkAutoTDeleteArray<uint8_t> hBuffer(
-            SkNEW_ARRAY(uint8_t, kBmpHeaderBytesPlusFour));
-    if (stream->read(hBuffer.get(), kBmpHeaderBytesPlusFour) !=
-            kBmpHeaderBytesPlusFour) {
-        SkDebugf("Error: unable to read first bitmap header.\n");
-        return NULL;
-    }
-
     // The total bytes in the bmp file
-    // We only need to use this value for RLE decoding, so we will only check
-    // that it is valid in the RLE case.
-    const uint32_t totalBytes = get_int(hBuffer.get(), 2);
-
+    // We only need to use this value for RLE decoding, so we will only
+    // check that it is valid in the RLE case.
+    uint32_t totalBytes;
     // The offset from the start of the file where the pixel data begins
-    const uint32_t offset = get_int(hBuffer.get(), 10);
-    if (offset < kBmpHeaderBytes + kBmpOS2V1Bytes) {
-        SkDebugf("Error: invalid starting location for pixel data\n");
-        return NULL;
-    }
-
+    uint32_t offset;
     // The size of the second (info) header in bytes
-    // The size is the first field of the second header, so we have already
-    // read the first four infoBytes.
-    const uint32_t infoBytes = get_int(hBuffer.get(), 14);
-    if (infoBytes < kBmpOS2V1Bytes) {
-        SkDebugf("Error: invalid second header size.\n");
-        return NULL;
+    uint32_t infoBytes;
+
+    // Bmps embedded in Icos skip the first Bmp header
+    if (!isIco) {
+        // Read the first header and the size of the second header
+        SkAutoTDeleteArray<uint8_t> hBuffer(
+                SkNEW_ARRAY(uint8_t, kBmpHeaderBytesPlusFour));
+        if (stream->read(hBuffer.get(), kBmpHeaderBytesPlusFour) !=
+                kBmpHeaderBytesPlusFour) {
+            SkDebugf("Error: unable to read first bitmap header.\n");
+            return NULL;
+        }
+
+        totalBytes = get_int(hBuffer.get(), 2);
+        offset = get_int(hBuffer.get(), 10);
+        if (offset < kBmpHeaderBytes + kBmpOS2V1Bytes) {
+            SkDebugf("Error: invalid starting location for pixel data\n");
+            return NULL;
+        }
+
+        // The size of the second (info) header in bytes
+        // The size is the first field of the second header, so we have already
+        // read the first four infoBytes.
+        infoBytes = get_int(hBuffer.get(), 14);
+        if (infoBytes < kBmpOS2V1Bytes) {
+            SkDebugf("Error: invalid second header size.\n");
+            return NULL;
+        }
+    } else {
+        // This value is only used by RLE compression.  Bmp in Ico files do not
+        // use RLE.  If the compression field is incorrectly signaled as RLE,
+        // we will catch this and signal an error below.
+        totalBytes = 0;
+
+        // Bmps in Ico cannot specify an offset.  We will always assume that
+        // pixel data begins immediately after the color table.  This value
+        // will be corrected below.
+        offset = 0;
+
+        // Read the size of the second header
+        SkAutoTDeleteArray<uint8_t> hBuffer(
+                SkNEW_ARRAY(uint8_t, 4));
+        if (stream->read(hBuffer.get(), 4) != 4) {
+            SkDebugf("Error: unable to read size of second bitmap header.\n");
+            return NULL;
+        }
+        infoBytes = get_int(hBuffer.get(), 0);
+        if (infoBytes < kBmpOS2V1Bytes) {
+            SkDebugf("Error: invalid second header size.\n");
+            return NULL;
+        }
     }
+
+    // We already read the first four bytes of the info header to get the size
     const uint32_t infoBytesRemaining = infoBytes - 4;
-    hBuffer.free();
 
     // Read the second header
     SkAutoTDeleteArray<uint8_t> iBuffer(
@@ -243,6 +291,11 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
         height = -height;
         rowOrder = kTopDown_RowOrder;
     }
+    // The height field for bmp in ico is double the actual height because they
+    // contain an XOR mask followed by an AND mask
+    if (isIco) {
+        height /= 2;
+    }
     static const int kBmpMaxDim = 1 << 16;
     if (width < 0 || width >= kBmpMaxDim || height >= kBmpMaxDim) {
         // TODO: Decide if we want to support really large bmps.
@@ -344,16 +397,19 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
 
     // Most versions of bmps should be rendered as opaque.  Either they do
     // not have an alpha channel, or they expect the alpha channel to be
-    // ignored.  V4+ bmp files introduce an alpha mask and allow the creator
+    // ignored.  V3+ bmp files introduce an alpha mask and allow the creator
     // of the image to use the alpha channels.  However, many of these images
-    // leave the alpha channel blank and expect to be rendered as opaque.  For
-    // this reason, we set the alpha type to kUnknown for V4+ bmps and figure
-    // out the alpha type during the decode.
+    // leave the alpha channel blank and expect to be rendered as opaque.  This
+    // is the case for almost all V3 images, so we render these as opaque.  For
+    // V4+, we will use the alpha channel, and fix the image later if it turns
+    // out to be fully transparent.
+    // As an exception, V3 bmp-in-ico may use an alpha mask.
     SkAlphaType alphaType = kOpaque_SkAlphaType;
-    if (kInfoV4_BitmapHeaderType == headerType ||
+    if ((kInfoV3_BitmapHeaderType == headerType && isIco) ||
+            kInfoV4_BitmapHeaderType == headerType ||
             kInfoV5_BitmapHeaderType == headerType) {
         // Header types are matched based on size.  If the header is
-        // V4+, we are guaranteed to be able to read at least this size.
+        // V3+, we are guaranteed to be able to read at least this size.
         SkASSERT(infoBytesRemaining > 52);
         inputMasks.alpha = get_int(iBuffer.get(), 48);
         if (inputMasks.alpha != 0) {
@@ -362,6 +418,11 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
     }
     iBuffer.free();
 
+    // Additionally, 32 bit bmp-in-icos use the alpha channel
+    if (isIco && 32 == bitsPerPixel) {
+        alphaType = kUnpremul_SkAlphaType;
+    }
+
     // Check for valid bits per pixel input
     switch (bitsPerPixel) {
         // In addition to more standard pixel compression formats, bmp supports
@@ -406,7 +467,7 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
 
     // Calculate the number of bytes read so far
     const uint32_t bytesRead = kBmpHeaderBytes + infoBytes + maskBytes;
-    if (offset < bytesRead) {
+    if (!isIco && offset < bytesRead) {
         SkDebugf("Error: pixel data offset less than header size.\n");
         return NULL;
     }
@@ -420,7 +481,7 @@ SkCodec* SkBmpCodec::NewFromStream(SkStream* stream) {
     return SkNEW_ARGS(SkBmpCodec, (imageInfo, stream, bitsPerPixel,
                                    inputFormat, masks.detach(), numColors,
                                    bytesPerColor, offset - bytesRead,
-                                   rowOrder, RLEBytes));
+                                   rowOrder, RLEBytes, isIco));
 }
 
 /*
@@ -433,7 +494,7 @@ SkBmpCodec::SkBmpCodec(const SkImageInfo& info, SkStream* stream,
                        uint16_t bitsPerPixel, BitmapInputFormat inputFormat,
                        SkMasks* masks, uint32_t numColors,
                        uint32_t bytesPerColor, uint32_t offset,
-                       RowOrder rowOrder, size_t RLEBytes)
+                       RowOrder rowOrder, size_t RLEBytes, bool isIco)
     : INHERITED(info, stream)
     , fBitsPerPixel(bitsPerPixel)
     , fInputFormat(inputFormat)
@@ -444,6 +505,8 @@ SkBmpCodec::SkBmpCodec(const SkImageInfo& info, SkStream* stream,
     , fOffset(offset)
     , fRowOrder(rowOrder)
     , fRLEBytes(RLEBytes)
+    , fIsIco(isIco)
+
 {}
 
 /*
@@ -459,11 +522,11 @@ SkCodec::Result SkBmpCodec::onGetPixels(const SkImageInfo& dstInfo,
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
-    if (dstInfo.dimensions() != this->getOriginalInfo().dimensions()) {
+    if (dstInfo.dimensions() != this->getInfo().dimensions()) {
         SkDebugf("Error: scaling not supported.\n");
         return kInvalidScale;
     }
-    if (!conversion_possible(dstInfo, this->getOriginalInfo())) {
+    if (!conversion_possible(dstInfo, this->getInfo())) {
         SkDebugf("Error: cannot convert input type to output type.\n");
         return kInvalidConversion;
     }
@@ -553,26 +616,29 @@ SkCodec::Result SkBmpCodec::onGetPixels(const SkImageInfo& dstInfo,
         }
     }
 
-    // Check that we have not read past the pixel array offset
-    if(fOffset < colorBytes) {
-        // This may occur on OS 2.1 and other old versions where the color
-        // table defaults to max size, and the bmp tries to use a smaller color
-        // table.  This is invalid, and our decision is to indicate an error,
-        // rather than try to guess the intended size of the color table.
-        SkDebugf("Error: pixel data offset less than color table size.\n");
-        return false;
-    }
+    // Bmp-in-Ico files do not use an offset to indicate where the pixel data
+    // begins.  Pixel data always begins immediately after the color table.
+    if (!fIsIco) {
+        // Check that we have not read past the pixel array offset
+        if(fOffset < colorBytes) {
+            // This may occur on OS 2.1 and other old versions where the color
+            // table defaults to max size, and the bmp tries to use a smaller
+            // color table.  This is invalid, and our decision is to indicate
+            // an error, rather than try to guess the intended size of the
+            // color table.
+            SkDebugf("Error: pixel data offset less than color table size.\n");
+            return false;
+        }
 
-    // After reading the color table, skip to the start of the pixel array
-    if (stream()->skip(fOffset - colorBytes) != fOffset - colorBytes) {
-        SkDebugf("Error: unable to skip to image data.\n");
-        return false;
+        // After reading the color table, skip to the start of the pixel array
+        if (stream()->skip(fOffset - colorBytes) != fOffset - colorBytes) {
+            SkDebugf("Error: unable to skip to image data.\n");
+            return false;
+        }
     }
 
     // Set the color table and return true on success
-    if (maxColors > 0) {
-        fColorTable.reset(SkNEW_ARGS(SkColorTable, (colorTable, maxColors)));
-    }
+    fColorTable.reset(SkNEW_ARGS(SkColorTable, (colorTable, maxColors)));
     return true;
 }
 
@@ -989,7 +1055,6 @@ SkCodec::Result SkBmpCodec::decode(const SkImageInfo& dstInfo,
     // SkSwizzler does not support.  Firstly, all bmp images that contain
     // alpha are masked by the alpha mask.  Secondly, many fully transparent
     // bmp images are intended to be opaque.  Here, we make those corrections.
-    // Modifying alpha is safe because colors are stored unpremultiplied.
     /*
     SkPMColor* dstRow = (SkPMColor*) dst;
     if (SkSwizzler::kBGRA == config) {
@@ -1006,6 +1071,41 @@ SkCodec::Result SkBmpCodec::decode(const SkImageInfo& dstInfo,
     }
     */
 
+    // Finally, apply the AND mask for bmp-in-ico images
+    if (fIsIco) {
+        // The AND mask is always 1 bit per pixel
+        const size_t rowBytes = SkAlign4(compute_row_bytes(width, 1));
+
+        SkPMColor* dstPtr = (SkPMColor*) dst;
+        for (int y = 0; y < height; y++) {
+            // The srcBuffer will at least be large enough
+            if (stream()->read(srcBuffer.get(), rowBytes) != rowBytes) {
+                SkDebugf("Warning: incomplete AND mask for bmp-in-ico.\n");
+                return kIncompleteInput;
+            }
+
+            int row;
+            if (kBottomUp_RowOrder == fRowOrder) {
+                row = height - y - 1;
+            } else {
+                row = y;
+            }
+
+            SkPMColor* dstRow =
+                    SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);
+
+            for (int x = 0; x < width; x++) {
+                int quotient;
+                int modulus;
+                SkTDivMod(x, 8, &quotient, &modulus);
+                uint32_t shift = 7 - modulus;
+                uint32_t alphaBit =
+                        (srcBuffer.get()[quotient] >> shift) & 0x1;
+                dstRow[x] &= alphaBit - 1;
+            }
+        }
+    }
+
     // Finished decoding the entire image
     return kSuccess;
 }
diff --git a/src/codec/SkCodec_libbmp.h b/src/codec/SkCodec_libbmp.h
index fb23716f77..4dda117d5a 100644
--- a/src/codec/SkCodec_libbmp.h
+++ b/src/codec/SkCodec_libbmp.h
@@ -7,7 +7,6 @@
 
 #include "SkCodec.h"
 #include "SkColorTable.h"
-#include "SkEncodedFormat.h"
 #include "SkImageInfo.h"
 #include "SkMaskSwizzler.h"
 #include "SkStream.h"
@@ -36,7 +35,7 @@ public:
 
     /*
      *
-     * Checks the start of the stream to see if the image is a bitmap
+     * Checks the start of the stream to see if the image is a bmp
      *
      */
     static bool IsBmp(SkStream*);
@@ -44,17 +43,25 @@ public:
     /*
      *
      * Assumes IsBmp was called and returned true
-     * Creates a bitmap decoder
+     * Creates a bmp decoder
      * Reads enough of the stream to determine the image format
      *
      */
     static SkCodec* NewFromStream(SkStream*);
 
+    /*
+     *
+     * Creates a bmp decoder for a bmp embedded in ico
+     * Reads enough of the stream to determine the image format
+     *
+     */
+    static SkCodec* NewFromIco(SkStream*);
+
 protected:
 
     /*
      *
-     * Initiates the bitmap decode
+     * Initiates the bmp decode
      *
      */
     virtual Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
@@ -62,11 +69,12 @@ protected:
                                int*) SK_OVERRIDE;
 
     SkEncodedFormat onGetEncodedFormat() const SK_OVERRIDE { return kBMP_SkEncodedFormat; }
+
 private:
 
     /*
      *
-     * Used to define the input format of the bitmap
+     * Used to define the input format of the bmp
      *
      */
     enum BitmapInputFormat {
@@ -85,6 +93,14 @@ private:
 
     /*
      *
+     * Creates a bmp decoder
+     * Reads enough of the stream to determine the image format
+     *
+     */
+    static SkCodec* NewFromStream(SkStream*, bool isIco);
+
+    /*
+     *
      * Performs the bitmap decoding for bit masks input format
      *
      */
@@ -149,7 +165,8 @@ private:
     SkBmpCodec(const SkImageInfo& srcInfo, SkStream* stream,
                uint16_t bitsPerPixel, BitmapInputFormat format,
                SkMasks* masks, uint32_t numColors, uint32_t bytesPerColor,
-               uint32_t offset, RowOrder rowOrder, size_t RLEByes);
+               uint32_t offset, RowOrder rowOrder, size_t RLEBytes,
+               bool isIco);
 
     // Fields
     const uint16_t                      fBitsPerPixel;
@@ -161,6 +178,7 @@ private:
     const uint32_t                      fOffset;
     const RowOrder                      fRowOrder;
     const size_t                        fRLEBytes;
+    const bool                          fIsIco;
 
     typedef SkCodec INHERITED;
 };
diff --git a/src/codec/SkCodec_libico.cpp b/src/codec/SkCodec_libico.cpp
new file mode 100644
index 0000000000..2adfa9cfde
--- /dev/null
+++ b/src/codec/SkCodec_libico.cpp
@@ -0,0 +1,254 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCodec_libbmp.h"
+#include "SkCodec_libico.h"
+#include "SkCodec_libpng.h"
+#include "SkCodecPriv.h"
+#include "SkColorPriv.h"
+#include "SkData.h"
+#include "SkStream.h"
+#include "SkTDArray.h"
+#include "SkTSort.h"
+
+/*
+ * Checks the start of the stream to see if the image is an Ico or Cur
+ */
+bool SkIcoCodec::IsIco(SkStream* stream) {
+    const char icoSig[] = { '\x00', '\x00', '\x01', '\x00' };
+    const char curSig[] = { '\x00', '\x00', '\x02', '\x00' };
+    char buffer[sizeof(icoSig)];
+    return stream->read(buffer, sizeof(icoSig)) == sizeof(icoSig) &&
+            (!memcmp(buffer, icoSig, sizeof(icoSig)) ||
+            !memcmp(buffer, curSig, sizeof(curSig)));
+}
+
+/*
+ * Assumes IsIco was called and returned true
+ * Creates an Ico decoder
+ * Reads enough of the stream to determine the image format
+ */
+SkCodec* SkIcoCodec::NewFromStream(SkStream* stream) {
+    // Header size constants
+    static const uint32_t kIcoDirectoryBytes = 6;
+    static const uint32_t kIcoDirEntryBytes = 16;
+
+    // Read the directory header
+    SkAutoTDeleteArray<uint8_t> dirBuffer(
+            SkNEW_ARRAY(uint8_t, kIcoDirectoryBytes));
+    if (stream->read(dirBuffer.get(), kIcoDirectoryBytes) !=
+            kIcoDirectoryBytes) {
+        SkDebugf("Error: unable to read ico directory header.\n");
+        return NULL;
+    }
+
+    // Process the directory header
+    const uint16_t numImages = get_short(dirBuffer.get(), 4);
+    if (0 == numImages) {
+        SkDebugf("Error: No images embedded in ico.\n");
+        return NULL;
+    }
+
+    // Ensure that we can read all of indicated directory entries
+    SkAutoTDeleteArray<uint8_t> entryBuffer(
+            SkNEW_ARRAY(uint8_t, numImages*kIcoDirEntryBytes));
+    if (stream->read(entryBuffer.get(), numImages*kIcoDirEntryBytes) !=
+            numImages*kIcoDirEntryBytes) {
+        SkDebugf("Error: unable to read ico directory entries.\n");
+        return NULL;
+    }
+
+    // This structure is used to represent the vital information about entries
+    // in the directory header.  We will obtain this information for each
+    // directory entry.
+    struct Entry {
+        uint32_t offset;
+        uint32_t size;
+    };
+    SkAutoTDeleteArray<Entry> directoryEntries(SkNEW_ARRAY(Entry, numImages));
+
+    // Iterate over directory entries
+    for (uint32_t i = 0; i < numImages; i++) {
+        // The directory entry contains information such as width, height,
+        // bits per pixel, and number of colors in the color palette.  We will
+        // ignore these fields since they are repeated in the header of the
+        // embedded image.  In the event of an inconsistency, we would always
+        // defer to the value in the embedded header anyway.
+
+        // Specifies the size of the embedded image, including the header
+        uint32_t size = get_int(entryBuffer.get(), 8 + i*kIcoDirEntryBytes);
+
+        // Specifies the offset of the embedded image from the start of file.
+        // It does not indicate the start of the pixel data, but rather the
+        // start of the embedded image header.
+        uint32_t offset = get_int(entryBuffer.get(), 12 + i*kIcoDirEntryBytes);
+
+        // Save the vital fields
+        directoryEntries.get()[i].offset = offset;
+        directoryEntries.get()[i].size = size;
+    }
+
+    // It is "customary" that the embedded images will be stored in order of
+    // increasing offset.  However, the specification does not indicate that
+    // they must be stored in this order, so we will not trust that this is the
+    // case.  Here we sort the embedded images by increasing offset.
+    struct EntryLessThan {
+        bool operator() (Entry a, Entry b) const {
+            return a.offset < b.offset;
+        }
+    };
+    EntryLessThan lessThan;
+    SkTQSort(directoryEntries.get(), directoryEntries.get() + numImages - 1,
+            lessThan);
+
+    // Now will construct a candidate codec for each of the embedded images
+    uint32_t bytesRead = kIcoDirectoryBytes + numImages * kIcoDirEntryBytes;
+    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> codecs(
+            SkNEW_ARGS((SkTArray<SkAutoTDelete<SkCodec>, true>), (numImages)));
+    for (uint32_t i = 0; i < numImages; i++) {
+        uint32_t offset = directoryEntries.get()[i].offset;
+        uint32_t size = directoryEntries.get()[i].size;
+        
+        // Ensure that the offset is valid
+        if (offset < bytesRead) {
+            SkDebugf("Warning: invalid ico offset.\n");
+            continue;
+        }
+
+        // If we cannot skip, assume we have reached the end of the stream and
+        // stop trying to make codecs
+        if (stream->skip(offset - bytesRead) != offset - bytesRead) {
+            SkDebugf("Warning: could not skip to ico offset.\n");
+            break;
+        }
+        bytesRead = offset;
+
+        // Create a new stream for the embedded codec
+        SkAutoTUnref<SkData> data(SkData::NewFromStream(stream, size));
+        if (NULL == data.get()) {
+            SkDebugf("Warning: could not create embedded stream.\n");
+            break;
+        }
+        SkAutoTDelete<SkMemoryStream>
+                embeddedStream(SkNEW_ARGS(SkMemoryStream, (data.get())));
+        bytesRead += size;
+
+        // Check if the embedded codec is bmp or png and create the codec
+        const bool isPng = SkPngCodec::IsPng(embeddedStream);
+        SkAssertResult(embeddedStream->rewind());
+        SkCodec* codec = NULL;
+        if (isPng) {
+            codec = SkPngCodec::NewFromStream(embeddedStream.detach());
+        } else {
+            codec = SkBmpCodec::NewFromIco(embeddedStream.detach());
+        }
+
+        // Save a valid codec
+        if (NULL != codec) {
+            codecs->push_back().reset(codec);
+        }
+    }
+
+    // Recognize if there are no valid codecs
+    if (0 == codecs->count()) {
+        SkDebugf("Error: could not find any valid embedded ico codecs.\n");
+        return NULL;
+    }
+
+    // Use the largest codec as a "suggestion" for image info
+    uint32_t maxSize = 0;
+    uint32_t maxIndex = 0;
+    for (int32_t i = 0; i < codecs->count(); i++) {
+        SkImageInfo info = codecs->operator[](i)->getInfo();
+        uint32_t size = info.width() * info.height();
+        if (size > maxSize) {
+            maxSize = size;
+            maxIndex = i;
+        }
+    }
+    SkImageInfo info = codecs->operator[](maxIndex)->getInfo();
+
+    // Note that stream is owned by the embedded codec, the ico does not need
+    // direct access to the stream.
+    return SkNEW_ARGS(SkIcoCodec, (info, codecs.detach()));
+}
+
+/*
+ * Creates an instance of the decoder
+ * Called only by NewFromStream
+ */
+SkIcoCodec::SkIcoCodec(const SkImageInfo& info,
+                       SkTArray<SkAutoTDelete<SkCodec>, true>* codecs)
+    : INHERITED(info, NULL)
+    , fEmbeddedCodecs(codecs)
+{}
+
+/*
+ * Chooses the best dimensions given the desired scale
+ */
+SkISize SkIcoCodec::onGetScaledDimensions(float desiredScale) const { 
+    // We set the dimensions to the largest candidate image by default.
+    // Regardless of the scale request, this is the largest image that we
+    // will decode.
+    if (desiredScale >= 1.0) {
+        return this->getInfo().dimensions();
+    }
+
+    int origWidth = this->getInfo().width();
+    int origHeight = this->getInfo().height();
+    float desiredSize = desiredScale * origWidth * origHeight;
+    // At least one image will have smaller error than this initial value
+    float minError = ((float) (origWidth * origHeight)) - desiredSize + 1.0f;
+    int32_t minIndex = -1;
+    for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
+        int width = fEmbeddedCodecs->operator[](i)->getInfo().width();
+        int height = fEmbeddedCodecs->operator[](i)->getInfo().height();
+        float error = SkTAbs(((float) (width * height)) - desiredSize);
+        if (error < minError) {
+            minError = error;
+            minIndex = i;
+        }
+    }
+    SkASSERT(minIndex >= 0);
+
+    return fEmbeddedCodecs->operator[](minIndex)->getInfo().dimensions();
+}
+
+/*
+ * Initiates the Ico decode
+ */
+SkCodec::Result SkIcoCodec::onGetPixels(const SkImageInfo& dstInfo,
+                                        void* dst, size_t dstRowBytes,
+                                        const Options& opts, SkPMColor* ct,
+                                        int* ptr) {
+    // We return invalid scale if there is no candidate image with matching
+    // dimensions.
+    Result result = kInvalidScale;
+    for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
+        // If the dimensions match, try to decode
+        if (dstInfo.dimensions() ==
+                fEmbeddedCodecs->operator[](i)->getInfo().dimensions()) {
+
+            // Perform the decode
+            result = fEmbeddedCodecs->operator[](i)->getPixels(dstInfo,
+                    dst, dstRowBytes, &opts, ct, ptr);
+
+            // On a fatal error, keep trying to find an image to decode
+            if (kInvalidConversion == result || kInvalidInput == result ||
+                    kInvalidScale == result) {
+                SkDebugf("Warning: Attempt to decode candidate ico failed.\n");
+                continue;
+            }
+
+            // On success or partial success, return the result
+            return result;
+        }
+    }
+
+    SkDebugf("Error: No matching candidate image in ico.\n");
+    return result;
+}
diff --git a/src/codec/SkCodec_libico.h b/src/codec/SkCodec_libico.h
new file mode 100644
index 0000000000..778bcd2c54
--- /dev/null
+++ b/src/codec/SkCodec_libico.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCodec.h"
+#include "SkImageInfo.h"
+#include "SkStream.h"
+#include "SkTypes.h"
+
+/*
+ * This class implements the decoding for bmp images
+ */
+class SkIcoCodec : public SkCodec {
+public:
+
+    /*
+     * Checks the start of the stream to see if the image is a Ico or Cur
+     */
+    static bool IsIco(SkStream*);
+
+    /*
+     * Assumes IsIco was called and returned true
+     * Creates an Ico decoder
+     * Reads enough of the stream to determine the image format
+     */
+    static SkCodec* NewFromStream(SkStream*);
+
+protected:
+
+    /*
+     * Chooses the best dimensions given the desired scale
+     */
+    SkISize onGetScaledDimensions(float desiredScale) const SK_OVERRIDE;
+
+    /*
+     * Initiates the Ico decode
+     */
+    Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
+                       size_t dstRowBytes, const Options&, SkPMColor*, int*)
+                       SK_OVERRIDE;
+
+    SkEncodedFormat onGetEncodedFormat() const SK_OVERRIDE {
+        return kICO_SkEncodedFormat;
+    }
+
+private:
+
+    /*
+     * Constructor called by NewFromStream
+     * @param embeddedCodecs codecs for the embedded images, takes ownership
+     */
+    SkIcoCodec(const SkImageInfo& srcInfo,
+               SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
+
+    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>>
+            fEmbeddedCodecs; // owned
+
+    typedef SkCodec INHERITED;
+};
diff --git a/src/codec/SkCodec_libpng.cpp b/src/codec/SkCodec_libpng.cpp
index 57653e74df..e113a0e1b6 100644
--- a/src/codec/SkCodec_libpng.cpp
+++ b/src/codec/SkCodec_libpng.cpp
@@ -368,10 +368,10 @@ SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void*
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
-    if (requestedInfo.dimensions() != this->getOriginalInfo().dimensions()) {
+    if (requestedInfo.dimensions() != this->getInfo().dimensions()) {
         return kInvalidScale;
     }
-    if (!conversion_possible(requestedInfo, this->getOriginalInfo())) {
+    if (!conversion_possible(requestedInfo, this->getInfo())) {
         return kInvalidConversion;
     }
 
@@ -424,7 +424,7 @@ SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void*
         // told png to upscale.
         SkASSERT(PNG_COLOR_TYPE_GRAY == pngColorType);
         sc = SkSwizzler::kGray;
-    } else if (this->getOriginalInfo().alphaType() == kOpaque_SkAlphaType) {
+    } else if (this->getInfo().alphaType() == kOpaque_SkAlphaType) {
         sc = SkSwizzler::kRGBX;
     } else {
         sc = SkSwizzler::kRGBA;