Make SkAndroidCodec support ico

BUG=skia:

Review URL: https://codereview.chromium.org/1472933002

7 files changed, 243 insertions, 75 deletions

diff --git a/src/codec/SkAndroidCodec.cpp b/src/codec/SkAndroidCodec.cpp
index cf6e253d97..c26b3eff9b 100644
--- a/src/codec/SkAndroidCodec.cpp
+++ b/src/codec/SkAndroidCodec.cpp
@@ -34,11 +34,9 @@ SkAndroidCodec* SkAndroidCodec::NewFromStream(SkStream* stream, SkPngChunkReader
         case kWBMP_SkEncodedFormat:
         case kBMP_SkEncodedFormat:
         case kGIF_SkEncodedFormat:
+        case kICO_SkEncodedFormat:
             return new SkSampledCodec(codec.detach());
         default:
-            // FIXME: SkSampledCodec is temporarily disabled for other formats
-            // while focusing on the formats that are supported by
-            // BitmapRegionDecoder.
             return nullptr;
     }
 }
diff --git a/src/codec/SkBmpCodec.cpp b/src/codec/SkBmpCodec.cpp
index 191c2ad800..aff54021a7 100644
--- a/src/codec/SkBmpCodec.cpp
+++ b/src/codec/SkBmpCodec.cpp
@@ -481,6 +481,8 @@ bool SkBmpCodec::ReadHeader(SkStream* stream, bool inIco, SkCodec** codecOut) {
         // Return the codec
         switch (inputFormat) {
             case kStandard_BmpInputFormat:
+                // We require streams to have a memory base for Bmp-in-Ico decodes.
+                SkASSERT(!inIco || nullptr != stream->getMemoryBase());
                 *codecOut = new SkBmpStandardCodec(imageInfo, stream, bitsPerPixel, numColors,
                         bytesPerColor, offset - bytesRead, rowOrder, inIco);
                 return true;
diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index fd4d6d18bc..5bbdcd25e2 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -27,6 +27,7 @@ SkBmpStandardCodec::SkBmpStandardCodec(const SkImageInfo& info, SkStream* stream
     , fSrcRowBytes(SkAlign4(compute_row_bytes(this->getInfo().width(), this->bitsPerPixel())))
     , fSrcBuffer(new uint8_t [fSrcRowBytes])
     , fInIco(inIco)
+    , fAndMaskRowBytes(fInIco ? SkAlign4(compute_row_bytes(this->getInfo().width(), 1)) : 0)
 {}
 
 /*
@@ -60,9 +61,6 @@ SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
         *rowsDecoded = rows;
         return kIncompleteInput;
     }
-    if (fInIco) {
-        return this->decodeIcoMask(dstInfo, dst, dstRowBytes);
-    }
     return kSuccess;
 }
 
@@ -227,9 +225,8 @@ SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
 /*
  * Performs the bitmap decoding for standard input format
  */
-int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo,
-                                               void* dst, size_t dstRowBytes,
-                                               const Options& opts) {
+int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
+        const Options& opts) {
     // Iterate over rows of the image
     const int height = dstInfo.height();
     for (int y = 0; y < height; y++) {
@@ -246,29 +243,77 @@ int SkBmpStandardCodec::decodeRows(const SkImageInfo& dstInfo,
         fSwizzler->swizzle(dstRow, fSrcBuffer.get());
     }
 
-    // Finished decoding the entire image
+    if (fInIco) {
+        const int startScanline = this->currScanline();
+        if (startScanline < 0) {
+            // We are not performing a scanline decode.
+            // Just decode the entire ICO mask and return.
+            decodeIcoMask(this->stream(), dstInfo, dst, dstRowBytes);
+            return height;
+        }
+
+        // In order to perform a scanline ICO decode, we must be able
+        // to skip ahead in the stream in order to apply the AND mask
+        // to the requested scanlines.
+        // We will do this by taking advantage of the fact that
+        // SkIcoCodec always uses a SkMemoryStream as its underlying
+        // representation of the stream.
+        const void* memoryBase = this->stream()->getMemoryBase();
+        SkASSERT(nullptr != memoryBase);
+        SkASSERT(this->stream()->hasLength());
+        SkASSERT(this->stream()->hasPosition());
+
+        const size_t length = this->stream()->getLength();
+        const size_t currPosition = this->stream()->getPosition();
+
+        // Calculate how many bytes we must skip to reach the AND mask.
+        const int remainingScanlines = this->getInfo().height() - startScanline - height;
+        const size_t bytesToSkip = remainingScanlines * fSrcRowBytes +
+                startScanline * fAndMaskRowBytes;
+        const size_t subStreamStartPosition = currPosition + bytesToSkip;
+        if (subStreamStartPosition >= length) {
+            // FIXME: How can we indicate that this decode was actually incomplete?
+            return height;
+        }
+
+        // Create a subStream to pass to decodeIcoMask().  It is useful to encapsulate
+        // the memory base into a stream in order to safely handle incomplete images
+        // without reading out of bounds memory.
+        const void* subStreamMemoryBase = SkTAddOffset<const void>(memoryBase,
+                subStreamStartPosition);
+        const size_t subStreamLength = length - subStreamStartPosition;
+        // This call does not transfer ownership of the subStreamMemoryBase.
+        SkMemoryStream subStream(subStreamMemoryBase, subStreamLength, false);
+
+        // FIXME: If decodeIcoMask does not succeed, is there a way that we can
+        //        indicate the decode was incomplete?
+        decodeIcoMask(&subStream, dstInfo, dst, dstRowBytes);
+    }
+
     return height;
 }
 
-// TODO (msarett): This function will need to be modified in order to perform row by row decodes
-//                 when the Ico scanline decoder is implemented.
-SkCodec::Result SkBmpStandardCodec::decodeIcoMask(const SkImageInfo& dstInfo,
+void SkBmpStandardCodec::decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo,
         void* dst, size_t dstRowBytes) {
     // BMP in ICO have transparency, so this cannot be 565, and this mask
     // prevents us from using kIndex8. The below code depends on the output
     // being an SkPMColor.
     SkASSERT(dstInfo.colorType() == kN32_SkColorType);
 
-    // The AND mask is always 1 bit per pixel
-    const int width = this->getInfo().width();
-    const size_t rowBytes = SkAlign4(compute_row_bytes(width, 1));
+    // If we are sampling, make sure that we only mask the sampled pixels.
+    // We do not need to worry about sampling in the y-dimension because that
+    // should be handled by SkSampledCodec.
+    const int sampleX = fSwizzler->sampleX();
+    const int sampledWidth = get_scaled_dimension(this->getInfo().width(), sampleX);
+    const int srcStartX = get_start_coord(sampleX);
+
 
     SkPMColor* dstPtr = (SkPMColor*) dst;
     for (int y = 0; y < dstInfo.height(); y++) {
         // The srcBuffer will at least be large enough
-        if (stream()->read(fSrcBuffer.get(), rowBytes) != rowBytes) {
+        if (stream->read(fSrcBuffer.get(), fAndMaskRowBytes) != fAndMaskRowBytes) {
             SkCodecPrintf("Warning: incomplete AND mask for bmp-in-ico.\n");
-            return kIncompleteInput;
+            return;
         }
 
         int row = this->getDstRow(y, dstInfo.height());
@@ -276,17 +321,17 @@ SkCodec::Result SkBmpStandardCodec::decodeIcoMask(const SkImageInfo& dstInfo,
         SkPMColor* dstRow =
                 SkTAddOffset<SkPMColor>(dstPtr, row * dstRowBytes);
 
-        for (int x = 0; x < width; x++) {
+        int srcX = srcStartX;
+        for (int dstX = 0; dstX < sampledWidth; dstX++) {
             int quotient;
             int modulus;
-            SkTDivMod(x, 8, &quotient, &modulus);
+            SkTDivMod(srcX, 8, &quotient, &modulus);
             uint32_t shift = 7 - modulus;
-            uint32_t alphaBit =
-                    (fSrcBuffer.get()[quotient] >> shift) & 0x1;
-            dstRow[x] &= alphaBit - 1;
+            uint32_t alphaBit = (fSrcBuffer.get()[quotient] >> shift) & 0x1;
+            dstRow[dstX] &= alphaBit - 1;
+            srcX += sampleX;
         }
     }
-    return kSuccess;
 }
 
 uint32_t SkBmpStandardCodec::onGetFillValue(SkColorType colorType, SkAlphaType alphaType) const {
diff --git a/src/codec/SkBmpStandardCodec.h b/src/codec/SkBmpStandardCodec.h
index d687eaad28..7f23616a60 100644
--- a/src/codec/SkBmpStandardCodec.h
+++ b/src/codec/SkBmpStandardCodec.h
@@ -75,7 +75,12 @@ private:
     int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
             const Options& opts) override;
 
-    Result decodeIcoMask(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
+    /*
+     * @param stream This may be a pointer to the stream owned by the parent SkCodec
+     *               or a sub-stream of the stream owned by the parent SkCodec.
+     *               Either way, this stream is unowned.
+     */
+    void decodeIcoMask(SkStream* stream, const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
 
     SkAutoTUnref<SkColorTable>          fColorTable;     // owned
     const uint32_t                      fNumColors;
@@ -85,6 +90,7 @@ private:
     const size_t                        fSrcRowBytes;
     SkAutoTDeleteArray<uint8_t>         fSrcBuffer;
     const bool                          fInIco;
+    const size_t                        fAndMaskRowBytes; // only used for fInIco decodes
 
     typedef SkBmpCodec INHERITED;
 };
diff --git a/src/codec/SkCodec_libico.cpp b/src/codec/SkCodec_libico.cpp
index 8c5a1b3412..e1314d7121 100644
--- a/src/codec/SkCodec_libico.cpp
+++ b/src/codec/SkCodec_libico.cpp
@@ -15,6 +15,43 @@
 #include "SkTDArray.h"
 #include "SkTSort.h"
 
+static bool ico_conversion_possible(const SkImageInfo& dstInfo) {
+    // We only support kN32_SkColorType.
+    // This makes sense for BMP-in-ICO.  The presence of an AND
+    // mask (which changes colors and adds transparency) means that
+    // we cannot use k565 or kIndex8.
+    // FIXME: For PNG-in-ICO, we could technically support whichever
+    //        color types that the png supports.
+    if (kN32_SkColorType != dstInfo.colorType()) {
+        return false;
+    }
+
+    // We only support transparent alpha types.  This is necessary for
+    // BMP-in-ICOs since there will be an AND mask.
+    // FIXME: For opaque PNG-in-ICOs, we should be able to support kOpaque.
+    return kPremul_SkAlphaType == dstInfo.alphaType() ||
+            kUnpremul_SkAlphaType == dstInfo.alphaType();
+}
+
+static SkImageInfo fix_embedded_alpha(const SkImageInfo& dstInfo, SkAlphaType embeddedAlpha) {
+    // FIXME (msarett): ICO is considered non-opaque, even if the embedded BMP
+    // incorrectly claims it has no alpha.
+    switch (embeddedAlpha) {
+        case kPremul_SkAlphaType:
+        case kUnpremul_SkAlphaType:
+            // Use the requested alpha type if the embedded codec supports alpha.
+            embeddedAlpha = dstInfo.alphaType();
+            break;
+        case kOpaque_SkAlphaType:
+            // If the embedded codec claims it is opaque, decode as if it is opaque.
+            break;
+        default:
+            SkASSERT(false);
+            break;
+    }
+    return dstInfo.makeAlphaType(embeddedAlpha);
+}
+
 /*
  * Checks the start of the stream to see if the image is an Ico or Cur
  */
@@ -197,6 +234,7 @@ SkIcoCodec::SkIcoCodec(const SkImageInfo& info,
                        SkTArray<SkAutoTDelete<SkCodec>, true>* codecs)
     : INHERITED(info, nullptr)
     , fEmbeddedCodecs(codecs)
+    , fCurrScanlineCodec(nullptr)
 {}
 
 /*
@@ -226,15 +264,21 @@ SkISize SkIcoCodec::onGetScaledDimensions(float desiredScale) const {
     return fEmbeddedCodecs->operator[](minIndex)->getInfo().dimensions();
 }
 
-bool SkIcoCodec::onDimensionsSupported(const SkISize& dim) {
+int SkIcoCodec::chooseCodec(const SkISize& requestedSize, int startIndex) {
+    SkASSERT(startIndex >= 0);
+
     // FIXME: Cache the index from onGetScaledDimensions?
-    for (int32_t i = 0; i < fEmbeddedCodecs->count(); i++) {
-        if (fEmbeddedCodecs->operator[](i)->getInfo().dimensions() == dim) {
-            return true;
+    for (int i = startIndex; i < fEmbeddedCodecs->count(); i++) {
+        if (fEmbeddedCodecs->operator[](i)->getInfo().dimensions() == requestedSize) {
+            return i;
         }
     }
 
-    return false;
+    return -1;
+}
+
+bool SkIcoCodec::onDimensionsSupported(const SkISize& dim) {
+    return this->chooseCodec(dim, 0) >= 0;
 }
 
 /*
@@ -249,54 +293,89 @@ SkCodec::Result SkIcoCodec::onGetPixels(const SkImageInfo& dstInfo,
         return kUnimplemented;
     }
 
-    if (!valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
+    if (!ico_conversion_possible(dstInfo)) {
         return kInvalidConversion;
     }
 
-    // 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++) {
-        SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](i);
-        // If the dimensions match, try to decode
-        if (dstInfo.dimensions() == embeddedCodec->getInfo().dimensions()) {
-
-            // Perform the decode
-            // FIXME (msarett): ICO is considered non-opaque, even if the embedded BMP
-            // incorrectly claims it has no alpha.
-            SkAlphaType embeddedAlpha = embeddedCodec->getInfo().alphaType();
-            switch (embeddedAlpha) {
-                case kPremul_SkAlphaType:
-                case kUnpremul_SkAlphaType:
-                    // Use the requested alpha type if the embedded codec supports alpha.
-                    embeddedAlpha = dstInfo.alphaType();
-                    break;
-                case kOpaque_SkAlphaType:
-                    // If the embedded codec claims it is opaque, decode as if it is opaque.
-                    break;
-                default:
-                    SkASSERT(false);
-                    break;
-            }
-            SkImageInfo info = dstInfo.makeAlphaType(embeddedAlpha);
-            result = embeddedCodec->getPixels(info, dst, dstRowBytes, &opts, colorTable,
-                    colorCount);
-            // The embedded codec will handle filling incomplete images, so we will indicate
-            // that all of the rows are initialized.
-            *rowsDecoded = info.height();
-
-            // On a fatal error, keep trying to find an image to decode
-            if (kInvalidConversion == result || kInvalidInput == result ||
-                    kInvalidScale == result) {
-                SkCodecPrintf("Warning: Attempt to decode candidate ico failed.\n");
-                continue;
-            }
-
-            // On success or partial success, return the result
+    int index = 0;
+    SkCodec::Result result = kInvalidScale;
+    while (true) {
+        index = this->chooseCodec(dstInfo.dimensions(), index);
+        if (index < 0) {
+            break;
+        }
+
+        SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index);
+        SkImageInfo decodeInfo = fix_embedded_alpha(dstInfo, embeddedCodec->getInfo().alphaType());
+        SkASSERT(decodeInfo.colorType() == kN32_SkColorType);
+        result = embeddedCodec->getPixels(decodeInfo, dst, dstRowBytes, &opts, colorTable,
+                colorCount);
+
+        switch (result) {
+            case kSuccess:
+            case kIncompleteInput:
+                // The embedded codec will handle filling incomplete images, so we will indicate
+                // that all of the rows are initialized.
+                *rowsDecoded = decodeInfo.height();
+                return result;
+            default:
+                // Continue trying to find a valid embedded codec on a failed decode.
+                break;
+        }
+
+        index++;
+    }
+
+    SkCodecPrintf("Error: No matching candidate image in ico.\n");
+    return result;
+}
+
+SkCodec::Result SkIcoCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
+        const SkCodec::Options& options, SkPMColor colorTable[], int* colorCount) {
+    if (!ico_conversion_possible(dstInfo)) {
+        return kInvalidConversion;
+    }
+
+    int index = 0;
+    SkCodec::Result result = kInvalidScale;
+    while (true) {
+        index = this->chooseCodec(dstInfo.dimensions(), index);
+        if (index < 0) {
+            break;
+        }
+
+        SkCodec* embeddedCodec = fEmbeddedCodecs->operator[](index);
+        SkImageInfo decodeInfo = fix_embedded_alpha(dstInfo, embeddedCodec->getInfo().alphaType());
+        result = embeddedCodec->startScanlineDecode(decodeInfo, &options, colorTable, colorCount);
+        if (kSuccess == result) {
+            fCurrScanlineCodec = embeddedCodec;
             return result;
         }
+
+        index++;
     }
 
     SkCodecPrintf("Error: No matching candidate image in ico.\n");
     return result;
 }
+
+int SkIcoCodec::onGetScanlines(void* dst, int count, size_t rowBytes) {
+    SkASSERT(fCurrScanlineCodec);
+    return fCurrScanlineCodec->getScanlines(dst, count, rowBytes);
+}
+
+bool SkIcoCodec::onSkipScanlines(int count) {
+    SkASSERT(fCurrScanlineCodec);
+    return fCurrScanlineCodec->skipScanlines(count);
+}
+
+SkCodec::SkScanlineOrder SkIcoCodec::onGetScanlineOrder() const {
+    // FIXME: This function will possibly return the wrong value if it is called
+    //        before startScanlineDecode().
+    return fCurrScanlineCodec ? fCurrScanlineCodec->getScanlineOrder() :
+            INHERITED::onGetScanlineOrder();
+}
+
+SkSampler* SkIcoCodec::getSampler(bool createIfNecessary) {
+    return fCurrScanlineCodec ? fCurrScanlineCodec->getSampler(createIfNecessary) : nullptr;
+}
diff --git a/src/codec/SkCodec_libico.h b/src/codec/SkCodec_libico.h
index 92675f4d74..a1d99b884d 100644
--- a/src/codec/SkCodec_libico.h
+++ b/src/codec/SkCodec_libico.h
@@ -47,17 +47,45 @@ protected:
         return kICO_SkEncodedFormat;
     }
 
+    SkScanlineOrder onGetScanlineOrder() const override;
+
 private:
 
+    Result onStartScanlineDecode(const SkImageInfo& dstInfo, const SkCodec::Options& options,
+            SkPMColor inputColorPtr[], int* inputColorCount) override;
+
+    int onGetScanlines(void* dst, int count, size_t rowBytes) override;
+
+    bool onSkipScanlines(int count) override;
+
+    SkSampler* getSampler(bool createIfNecessary) override;
+
+    /*
+     * Searches fEmbeddedCodecs for a codec that matches requestedSize.
+     * The search starts at startIndex and ends when an appropriate codec
+     * is found, or we have reached the end of the array.
+     *
+     * @return the index of the matching codec or -1 if there is no
+     *         matching codec between startIndex and the end of
+     *         the array.
+     */
+    int chooseCodec(const SkISize& requestedSize, int startIndex);
+
     /*
      * Constructor called by NewFromStream
      * @param embeddedCodecs codecs for the embedded images, takes ownership
      */
-    SkIcoCodec(const SkImageInfo& srcInfo,
-               SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
+    SkIcoCodec(const SkImageInfo& srcInfo, SkTArray<SkAutoTDelete<SkCodec>, true>* embeddedCodecs);
+
+    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> fEmbeddedCodecs; // owned
 
-    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>>
-            fEmbeddedCodecs; // owned
+    // Only used by the scanline decoder.  onStartScanlineDecode() will set
+    // fCurrScanlineCodec to one of the fEmbeddedCodecs, if it can find a
+    // codec of the appropriate size.  We will use fCurrScanlineCodec for
+    // subsequent calls to onGetScanlines() or onSkipScanlines().
+    // fCurrScanlineCodec is owned by this class, but should not be an
+    // SkAutoTDelete.  It will be deleted by the destructor of fEmbeddedCodecs.
+    SkCodec* fCurrScanlineCodec;
 
     typedef SkCodec INHERITED;
 };
diff --git a/src/codec/SkSwizzler.h b/src/codec/SkSwizzler.h
index 7f5bbc6209..bdb10a1416 100644
--- a/src/codec/SkSwizzler.h
+++ b/src/codec/SkSwizzler.h
@@ -163,6 +163,16 @@ public:
         SkSampler::Fill(fillInfo, dst, rowBytes, colorOrIndex, zeroInit);
     }
 
+    /**
+     *  If fSampleX > 1, the swizzler is sampling every fSampleX'th pixel and
+     *  discarding the rest.
+     *
+     *  This getter is currently used by SkBmpStandardCodec for Bmp-in-Ico decodes.
+     *  Ideally, the subclasses of SkCodec would have no knowledge of sampling, but
+     *  this allows us to apply a transparency mask to pixels after swizzling.
+     */
+    int sampleX() const { return fSampleX; }
+
 private:
 
     /**