Prototype of RAW decoding in Skia.

src/codec/SkRawCodec.cpp

+/*
+ * Copyright 2016 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 "SkCodecPriv.h"
+#include "SkColorPriv.h"
+#include "SkData.h"
+#if !defined(GOOGLE3)
+#include "SkJpegCodec.h"
+#endif
+#include "SkRawCodec.h"
+#include "SkRefCnt.h"
+#include "SkStream.h"
+#include "SkStreamPriv.h"
+#include "SkSwizzler.h"
+#include "SkTemplates.h"
+#include "SkTypes.h"
+
+#include "dng_color_space.h"
+#include "dng_exceptions.h"
+#include "dng_host.h"
+#include "dng_info.h"
+#include "dng_memory.h"
+#include "dng_render.h"
+#include "dng_stream.h"
+
+#include "src/piex.h"
+
+#include <cmath>  // for std::round,floor,ceil
+#include <limits>
+
+namespace {
+
+// T must be unsigned type.
+template <class T>
+bool safe_add_to_size_t(T arg1, T arg2, size_t* result) {
+    SkASSERT(arg1 >= 0);
+    SkASSERT(arg2 >= 0);
+    if (arg1 >= 0 && arg2 <= std::numeric_limits<T>::max() - arg1) {
+        T sum = arg1 + arg2;
+        if (sum <= std::numeric_limits<size_t>::max()) {
+            *result = static_cast<size_t>(sum);
+            return true;
+        }
+    }
+    return false;
+}
+
+class SkDngMemoryAllocator : public dng_memory_allocator {
+public:
+    ~SkDngMemoryAllocator() override {}
+
+    dng_memory_block* Allocate(uint32 size) override {
+        // To avoid arbitary allocation requests which might lead to out-of-memory, limit the
+        // amount of memory that can be allocated at once. The memory limit is based on experiments
+        // and supposed to be sufficient for all valid DNG images.
+        if (size > 300 * 1024 * 1024) {  // 300 MB
+            ThrowMemoryFull();
+        }
+        return dng_memory_allocator::Allocate(size);
+    }
+};
+
+}  // namespace
+
+// Note: this class could throw exception if it is used as dng_stream.
+class SkRawStream : public dng_stream, public ::piex::StreamInterface {
+public:
+    // Note that this call will take the ownership of stream.
+    explicit SkRawStream(SkStream* stream)
+        : fStream(stream), fWholeStreamRead(false) {}
+
+    ~SkRawStream() override {}
+
+    /*
+     * Creates an SkMemoryStream from the offset with size.
+     * Note: for performance reason, this function is destructive to the SkRawStream. One should
+     *       abandon current object after the function call.
+     */
+    SkMemoryStream* transferBuffer(size_t offset, size_t size) {
+        SkAutoTUnref<SkData> data(SkData::NewUninitialized(size));
+        if (offset > fStreamBuffer.bytesWritten()) {
+            // If the offset is not buffered, read from fStream directly and skip the buffering.
+            const size_t skipLength = offset - fStreamBuffer.bytesWritten();
+            if (fStream->skip(skipLength) != skipLength) {
+                return nullptr;
+            }
+            const size_t bytesRead = fStream->read(data->writable_data(), size);
+            if (bytesRead < size) {
+                data.reset(SkData::NewSubset(data.get(), 0, bytesRead));
+            }
+        } else {
+            const size_t alreadyBuffered = SkTMin(fStreamBuffer.bytesWritten() - offset, size);
+            if (alreadyBuffered > 0 &&
+                !fStreamBuffer.read(data->writable_data(), offset, alreadyBuffered)) {
+                return nullptr;
+            }
+
+            const size_t remaining = size - alreadyBuffered;
+            if (remaining) {
+                auto* dst = static_cast<uint8_t*>(data->writable_data()) + alreadyBuffered;
+                const size_t bytesRead = fStream->read(dst, remaining);
+                size_t newSize;
+                if (bytesRead < remaining) {
+                    if (!safe_add_to_size_t(alreadyBuffered, bytesRead, &newSize)) {
+                        return nullptr;
+                    }
+                    data.reset(SkData::NewSubset(data.get(), 0, newSize));
+                }
+            }
+        }
+        return new SkMemoryStream(data);
+    }
+
+    // For PIEX
+    ::piex::Error GetData(const size_t offset, const size_t length,
+                          uint8* data) override {
+        if (offset == 0 && length == 0) {
+            return ::piex::Error::kOk;
+        }
+        size_t sum;
+        if (!safe_add_to_size_t(offset, length, &sum) || !this->bufferMoreData(sum)) {
+            return ::piex::Error::kFail;
+        }
+        if (!fStreamBuffer.read(data, offset, length)) {
+            return ::piex::Error::kFail;
+        }
+        return ::piex::Error::kOk;
+    }
+
+protected:
+    // For dng_stream
+    uint64 DoGetLength() override {
+        if (!this->bufferMoreData(kReadToEnd)) {  // read whole stream
+            ThrowReadFile();
+        }
+        return fStreamBuffer.bytesWritten();
+    }
+
+    // For dng_stream
+    void DoRead(void* data, uint32 count, uint64 offset) override {
+        if (count == 0 && offset == 0) {
+            return;
+        }
+        size_t sum;
+        if (!safe_add_to_size_t(static_cast<uint64>(count), offset, &sum) ||
+            !this->bufferMoreData(sum)) {
+            ThrowReadFile();
+        }
+
+        if (!fStreamBuffer.read(data, offset, count)) {
+            ThrowReadFile();
+        }
+    }
+
+private:
+    // Note: if the newSize == kReadToEnd (0), this function will read to the end of stream.
+    bool bufferMoreData(size_t newSize) {
+        if (newSize == kReadToEnd) {
+            if (fWholeStreamRead) {  // already read-to-end.
+                return true;
+            }
+
+            // TODO: optimize for the special case when the input is SkMemoryStream.
+            return SkStreamCopy(&fStreamBuffer, fStream.get());
+        }
+
+        if (newSize <= fStreamBuffer.bytesWritten()) {  // already buffered to newSize
+            return true;
+        }
+        if (fWholeStreamRead) {  // newSize is larger than the whole stream.
+            return false;
+        }
+
+        const size_t sizeToRead = newSize - fStreamBuffer.bytesWritten();
+        SkAutoTMalloc<uint8> tempBuffer(sizeToRead);
+        const size_t bytesRead = fStream->read(tempBuffer.get(), sizeToRead);
+        if (bytesRead != sizeToRead) {
+            return false;
+        }
+        return fStreamBuffer.write(tempBuffer.get(), bytesRead);
+    }
+
+    SkAutoTDelete<SkStream> fStream;
+    bool fWholeStreamRead;
+
+    SkDynamicMemoryWStream fStreamBuffer;
+
+    const size_t kReadToEnd = 0;
+};
+
+class SkDngImage {
+public:
+    static SkDngImage* NewFromStream(SkRawStream* stream) {
+        SkAutoTDelete<SkDngImage> dngImage(new SkDngImage(stream));
+        if (!dngImage->readDng()) {
+            return nullptr;
+        }
+
+        SkASSERT(dngImage->fNegative);
+        return dngImage.release();
+    }
+
+    /*
+     * Renders the DNG image to the size. The DNG SDK only allows scaling close to integer factors
+     * down to 80 pixels on the short edge. The rendered image will be close to the specified size,
+     * but there is no guarantee that any of the edges will match the requested size. E.g.
+     *   100% size:              4000 x 3000
+     *   requested size:         1600 x 1200
+     *   returned size could be: 2000 x 1500
+     */
+    dng_image* render(int width, int height) {
+        // render() takes ownership of fHost, fInfo and fNegative when available.
+        SkAutoTDelete<dng_host> host;
+        SkAutoTDelete<dng_info> info;
+        SkAutoTDelete<dng_negative> negative;
+        if (!fHost || !fInfo || !fNegative) {
+            if (!this->readDng()) {
+                return nullptr;
+            }
+        } else {
+            host.reset(fHost.release());
+            info.reset(fInfo.release());
+            negative.reset(fNegative.release());
+        }
+
+        // DNG SDK preserves the aspect ratio, so it only needs to know the longer dimension.
+        const int preferredSize = SkTMax(width, height);
+        try {
+            host->SetPreferredSize(preferredSize);
+            host->ValidateSizes();
+
+            negative->ReadStage1Image(*host, *fStream, *info);
+
+            if (info->fMaskIndex != -1) {
+                negative->ReadTransparencyMask(*host, *fStream, *info);
+            }
+
+            negative->ValidateRawImageDigest(*host);
+            if (negative->IsDamaged()) {
+                return nullptr;
+            }
+
+            const int32 kMosaicPlane = -1;
+            negative->BuildStage2Image(*host);
+            negative->BuildStage3Image(*host, kMosaicPlane);
+
+            dng_render render(*host, *negative);
+            render.SetFinalSpace(dng_space_sRGB::Get());
+            render.SetFinalPixelType(ttByte);
+
+            dng_point stage3_size = negative->Stage3Image()->Size();
+            render.SetMaximumSize(SkTMax(stage3_size.h, stage3_size.v));
+
+            return render.Render();
+        } catch (...) {
+            return nullptr;
+        }
+    }
+
+    const SkImageInfo& getImageInfo() const {
+        return fImageInfo;
+    }
+
+    bool isXtransImage() const {
+        return fIsXtransImage;
+    }
+
+private:
+    bool readDng() {
+        // Due to the limit of DNG SDK, we need to reset host and info.
+        fHost.reset(new dng_host(&fAllocator));
+        fInfo.reset(new dng_info);
+        try {
+            fHost->ValidateSizes();
+            fInfo->Parse(*fHost, *fStream);
+            fInfo->PostParse(*fHost);
+            if (!fInfo->IsValidDNG()) {
+                return false;
+            }
+
+            fNegative.reset(fHost->Make_dng_negative());
+            fNegative->Parse(*fHost, *fStream, *fInfo);
+            fNegative->PostParse(*fHost, *fStream, *fInfo);
+            fNegative->SynchronizeMetadata();
+
+            fImageInfo = SkImageInfo::Make(fNegative->DefaultCropSizeH().As_real64(),
+                                           fNegative->DefaultCropSizeV().As_real64(),
+                                           kN32_SkColorType, kOpaque_SkAlphaType);
+            fIsXtransImage = fNegative->GetMosaicInfo() != nullptr 
+                ? (fNegative->GetMosaicInfo()->fCFAPatternSize.v == 6
+                   && fNegative->GetMosaicInfo()->fCFAPatternSize.h == 6)
+                : false;
+            return true;
+        } catch (...) {
+            fNegative.reset(nullptr);
+            return false;
+        }
+    }
+
+    SkDngImage(SkRawStream* stream)
+        : fStream(stream) {}
+
+    SkDngMemoryAllocator fAllocator;
+    SkAutoTDelete<SkRawStream> fStream;
+    SkAutoTDelete<dng_host> fHost;
+    SkAutoTDelete<dng_info> fInfo;
+    SkAutoTDelete<dng_negative> fNegative;
+
+    SkImageInfo fImageInfo;
+    bool fIsXtransImage;
+};
+
+/*
+ * Tries to handle the image with PIEX. If PIEX returns kOk and finds the preview image, create a
+ * SkJpegCodec. If PIEX returns kFail, then the file is invalid, return nullptr. In other cases,
+ * fallback to create SkRawCodec for DNG images.
+ */
+SkCodec* SkRawCodec::NewFromStream(SkStream* stream) {
+    SkAutoTDelete<SkRawStream> rawStream(new SkRawStream(stream));
+    ::piex::PreviewImageData imageData;
+    // FIXME: ::piex::GetPreviewImageData() calls read (or whatever function it calls) frequently

[scroggo, 2016/01/21 17:57:43]

Instead of "read (or whatever function it calls)", I think the function it calls
is "GetData()"? Please say that instead.

[yujieqin, 2016/01/21 18:06:12]

Sure thing, done.

+    // with small amounts, resulting in many calls to bufferMoreData. Could we make this more
+    // efficient by requesting more than needed?

[scroggo, 2016/01/21 17:57:43]

Sorry, I know this is what I suggested, but I think it could still be clearer:

"... efficient by grouping smaller requests together."

[yujieqin, 2016/01/21 18:06:11]

Thanks for the suggestion. :)

+    if (::piex::IsRaw(rawStream.get())) {
+        ::piex::Error error = ::piex::GetPreviewImageData(rawStream.get(), &imageData);
+
+        if (error == ::piex::Error::kOk && imageData.preview_length > 0) {
+#if !defined(GOOGLE3)
+            // transferBuffer() is destructive to the rawStream. Abandon the rawStream after this
+            // function call.
+            // FIXME: one may avoid the copy of memoryStream and use the buffered rawStream.
+            SkMemoryStream* memoryStream =
+                    rawStream->transferBuffer(imageData.preview_offset, imageData.preview_length);
+            return memoryStream ? SkJpegCodec::NewFromStream(memoryStream) : nullptr;
+#else
+            return nullptr;
+#endif
+        } else if (error == ::piex::Error::kFail) {
+            return nullptr;
+        }
+    }
+
+    SkAutoTDelete<SkDngImage> dngImage(SkDngImage::NewFromStream(rawStream.release()));
+    if (!dngImage) {
+        return nullptr;
+    }
+
+    return new SkRawCodec(dngImage.release());
+}
+
+SkCodec::Result SkRawCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
+                                        size_t dstRowBytes, const Options& options,
+                                        SkPMColor ctable[], int* ctableCount,
+                                        int* rowsDecoded) {
+    if (!conversion_possible(requestedInfo, this->getInfo())) {
+        SkCodecPrintf("Error: cannot convert input type to output type.\n");
+        return kInvalidConversion;
+    }
+
+    SkAutoTDelete<SkSwizzler> swizzler(SkSwizzler::CreateSwizzler(
+            SkSwizzler::kRGB, nullptr, requestedInfo, options));
+    SkASSERT(swizzler);
+
+    const int width = requestedInfo.width();
+    const int height = requestedInfo.height();
+    SkAutoTDelete<dng_image> image(fDngImage->render(width, height));
+    if (!image) {
+        return kInvalidInput;
+    }
+
+    // Because the DNG SDK can not guarantee to render to requested size, we allow a small
+    // difference. Only the overlapping region will be converted.
+    const float maxDiffRatio = 1.03f;
+    const dng_point& imageSize = image->Size();
+    if (imageSize.h / width > maxDiffRatio || imageSize.h < width ||
+        imageSize.v / height > maxDiffRatio || imageSize.v < height) {
+        return SkCodec::kInvalidScale;
+    }
+
+    void* dstRow = dst;
+    uint8_t srcRow[width * 3];
+
+    dng_pixel_buffer buffer;
+    buffer.fData = &srcRow[0];
+    buffer.fPlane = 0;
+    buffer.fPlanes = 3;
+    buffer.fColStep = buffer.fPlanes;
+    buffer.fPlaneStep = 1;
+    buffer.fPixelType = ttByte;
+    buffer.fPixelSize = sizeof(uint8_t);
+    buffer.fRowStep = sizeof(srcRow);
+
+    for (int i = 0; i < height; ++i) {
+        buffer.fArea = dng_rect(i, 0, i + 1, width);
+
+        try {
+            image->Get(buffer, dng_image::edge_zero);
+        } catch (...) {
+            *rowsDecoded = i;
+            return kIncompleteInput; 
+        }
+
+        swizzler->swizzle(dstRow, &srcRow[0]);
+        dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
+    }
+    return kSuccess;
+}
+
+SkISize SkRawCodec::onGetScaledDimensions(float desiredScale) const {
+    SkASSERT(desiredScale <= 1.f);
+    const SkISize dim = this->getInfo().dimensions();
+
+    // Limits the minimum size to be 80 on the short edge.
+    const float shortEdge = SkTMin(dim.fWidth, dim.fHeight);
+    if (desiredScale < 80.f / shortEdge) {
+        desiredScale = 80.f / shortEdge;
+    }
+
+    // For Xtrans images, the integer-factor scaling does not support the half-size scaling case
+    // (stronger downscalings are fine). In this case, returns the factor "3" scaling instead.
+    if (fDngImage->isXtransImage() && desiredScale > 1.f / 3.f && desiredScale < 1.f) {
+        desiredScale = 1.f / 3.f;
+    }
+
+    // Round to integer-factors.
+    const float finalScale = std::floor(1.f/ desiredScale);
+    return SkISize::Make(std::floor(dim.fWidth / finalScale),
+                         std::floor(dim.fHeight / finalScale));
+}
+
+bool SkRawCodec::onDimensionsSupported(const SkISize& dim) {
+    const SkISize fullDim = this->getInfo().dimensions();
+    const float fullShortEdge = SkTMin(fullDim.fWidth, fullDim.fHeight);
+    const float shortEdge = SkTMin(dim.fWidth, dim.fHeight);
+
+    SkISize sizeFloor = this->onGetScaledDimensions(1.f / std::floor(fullShortEdge / shortEdge));
+    SkISize sizeCeil = this->onGetScaledDimensions(1.f / std::ceil(fullShortEdge / shortEdge));
+    return sizeFloor == dim || sizeCeil == dim;
+}
+
+SkRawCodec::~SkRawCodec() {}
+
+SkRawCodec::SkRawCodec(SkDngImage* dngImage)
+    : INHERITED(dngImage->getImageInfo(), nullptr)
+    , fDngImage(dngImage) {}