Revert of Delete SkImageDecoder

include/core/SkImageDecoder.h

+/*
+ * 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.
+ */
+
+#ifndef SkImageDecoder_DEFINED
+#define SkImageDecoder_DEFINED
+
+#include "SkBitmap.h"
+#include "SkImage.h"
+#include "SkPngChunkReader.h"
+#include "SkRect.h"
+#include "SkRefCnt.h"
+#include "SkTRegistry.h"
+#include "SkTypes.h"
+
+class SkStream;
+class SkStreamRewindable;
+
+/** \class SkImageDecoder
+
+    DEPRECATED Please use SkImage::NewFromEncoded() or SkImageGenerator::NewFromEncoded().
+
+    Base class for decoding compressed images into a SkBitmap
+*/
+class SkImageDecoder : SkNoncopyable {
+public:
+    virtual ~SkImageDecoder();
+
+    // TODO (scroggo): Merge with SkEncodedFormat
+    enum Format {
+        kUnknown_Format,
+        kBMP_Format,
+        kGIF_Format,
+        kICO_Format,
+        kJPEG_Format,
+        kPNG_Format,
+        kWBMP_Format,
+        kWEBP_Format,
+        kPKM_Format,
+        kKTX_Format,
+        kASTC_Format,
+
+        kLastKnownFormat = kKTX_Format,
+    };
+
+    /** Return the format of image this decoder can decode. If this decoder can decode multiple
+        formats, kUnknown_Format will be returned.
+    */
+    virtual Format getFormat() const;
+
+    /** If planes or rowBytes is NULL, decodes the header and computes componentSizes
+        for memory allocation.
+        Otherwise, decodes the YUV planes into the provided image planes and
+        updates componentSizes to the final image size.
+        Returns whether the decoding was successful.
+    */
+    bool decodeYUV8Planes(SkStream* stream, SkISize componentSizes[3], void* planes[3],
+                          size_t rowBytes[3], SkYUVColorSpace*);
+
+    /** Return the format of the SkStreamRewindable or kUnknown_Format if it cannot be determined.
+        Rewinds the stream before returning.
+    */
+    static Format GetStreamFormat(SkStreamRewindable*);
+
+    /** Return a readable string of the Format provided.
+    */
+    static const char* GetFormatName(Format);
+
+    /** Return a readable string of the value returned by getFormat().
+    */
+    const char* getFormatName() const;
+
+    /** Whether the decoder should skip writing zeroes to output if possible.
+    */
+    bool getSkipWritingZeroes() const { return fSkipWritingZeroes; }
+
+    /** Set to true if the decoder should skip writing any zeroes when
+        creating the output image.
+        This is a hint that may not be respected by the decoder.
+        It should only be used if it is known that the memory to write
+        to has already been set to 0; otherwise the resulting image will
+        have garbage.
+        This is ideal for images that contain a lot of completely transparent
+        pixels, but may be a performance hit for an image that has only a
+        few transparent pixels.
+        The default is false.
+    */
+    void setSkipWritingZeroes(bool skip) { fSkipWritingZeroes = skip; }
+
+    /** Returns true if the decoder should try to dither the resulting image.
+        The default setting is true.
+    */
+    bool getDitherImage() const { return fDitherImage; }
+
+    /** Set to true if the the decoder should try to dither the resulting image.
+        The default setting is true.
+    */
+    void setDitherImage(bool dither) { fDitherImage = dither; }
+
+    /** Returns true if the decoder should try to decode the
+        resulting image to a higher quality even at the expense of
+        the decoding speed.
+    */
+    bool getPreferQualityOverSpeed() const { return fPreferQualityOverSpeed; }
+
+    /** Set to true if the the decoder should try to decode the
+        resulting image to a higher quality even at the expense of
+        the decoding speed.
+    */
+    void setPreferQualityOverSpeed(bool qualityOverSpeed) {
+        fPreferQualityOverSpeed = qualityOverSpeed;
+    }
+
+    /** Set to true to require the decoder to return a bitmap with unpremultiplied
+        colors. The default is false, meaning the resulting bitmap will have its
+        colors premultiplied.
+        NOTE: Passing true to this function may result in a bitmap which cannot
+        be properly used by Skia.
+    */
+    void setRequireUnpremultipliedColors(bool request) {
+        fRequireUnpremultipliedColors = request;
+    }
+
+    /** Returns true if the decoder will only return bitmaps with unpremultiplied
+        colors.
+    */
+    bool getRequireUnpremultipliedColors() const { return fRequireUnpremultipliedColors; }
+
+    SkPngChunkReader* getPeeker() const { return fPeeker; }
+    SkPngChunkReader* setPeeker(SkPngChunkReader*);
+
+    /**
+     *  By default, the codec will try to comply with the "pref" colortype
+     *  that is passed to decode() or decodeSubset(). However, this can be called
+     *  to override that, causing the codec to try to match the src depth instead
+     *  (as shown below).
+     *
+     *      src_8Index  -> kIndex_8_SkColorType
+     *      src_8Gray   -> kN32_SkColorType
+     *      src_8bpc    -> kN32_SkColorType
+     */
+    void setPreserveSrcDepth(bool preserve) {
+        fPreserveSrcDepth = preserve;
+    }
+
+    SkBitmap::Allocator* getAllocator() const { return fAllocator; }
+    SkBitmap::Allocator* setAllocator(SkBitmap::Allocator*);
+
+    // sample-size, if set to > 1, tells the decoder to return a smaller than
+    // original bitmap, sampling 1 pixel for every size pixels. e.g. if sample
+    // size is set to 3, then the returned bitmap will be 1/3 as wide and high,
+    // and will contain 1/9 as many pixels as the original.
+    // Note: this is a hint, and the codec may choose to ignore this, or only
+    // approximate the sample size.
+    int getSampleSize() const { return fSampleSize; }
+    void setSampleSize(int size);
+
+    /** Reset the sampleSize to its default of 1
+     */
+    void resetSampleSize() { this->setSampleSize(1); }
+
+    /** Decoding is synchronous, but for long decodes, a different thread can
+        call this method safely. This sets a state that the decoders will
+        periodically check, and if they see it changed to cancel, they will
+        cancel. This will result in decode() returning false. However, there is
+        no guarantee that the decoder will see the state change in time, so
+        it is possible that cancelDecode() will be called, but will be ignored
+        and decode() will return true (assuming no other problems were
+        encountered).
+
+        This state is automatically reset at the beginning of decode().
+     */
+    void cancelDecode() {
+        // now the subclass must query shouldCancelDecode() to be informed
+        // of the request
+        fShouldCancelDecode = true;
+    }
+
+    /** Passed to the decode method. If kDecodeBounds_Mode is passed, then
+        only the bitmap's info need be set. If kDecodePixels_Mode
+        is passed, then the bitmap must have pixels or a pixelRef.
+    */
+    enum Mode {
+        kDecodeBounds_Mode, //!< only return info in bitmap
+        kDecodePixels_Mode  //!< return entire bitmap (including pixels)
+    };
+
+    /** Result of a decode. If read as a boolean, a partial success is
+        considered a success (true).
+    */
+    enum Result {
+        kFailure        = 0,    //!< Image failed to decode. bitmap will be
+                                //   unchanged.
+        kPartialSuccess = 1,    //!< Part of the image decoded. The rest is
+                                //   filled in automatically
+        kSuccess        = 2     //!< The entire image was decoded, if Mode is
+                                //   kDecodePixels_Mode, or the bounds were
+                                //   decoded, in kDecodeBounds_Mode.
+    };
+
+    /** Given a stream, decode it into the specified bitmap.
+        If the decoder can decompress the image, it calls bitmap.setInfo(),
+        and then if the Mode is kDecodePixels_Mode, call allocPixelRef(),
+        which will allocated a pixelRef. To access the pixel memory, the codec
+        needs to call lockPixels/unlockPixels on the
+        bitmap. It can then set the pixels with the decompressed image.
+    *   If the image cannot be decompressed, return kFailure. After the
+    *   decoding, the function converts the decoded colortype in bitmap
+    *   to pref if possible. Whether a conversion is feasible is
+    *   tested by Bitmap::canCopyTo(pref).
+
+        If an SkBitmap::Allocator is installed via setAllocator, it will be
+        used to allocate the pixel memory. A clever allocator can be used
+        to allocate the memory from a cache, volatile memory, or even from
+        an existing bitmap's memory.
+
+        If an SkPngChunkReader is installed via setPeeker, it may be used to
+        peek into meta data during the decode.
+    */
+    Result decode(SkStream*, SkBitmap* bitmap, SkColorType pref, Mode);
+    Result decode(SkStream* stream, SkBitmap* bitmap, Mode mode) {
+        return this->decode(stream, bitmap, kUnknown_SkColorType, mode);
+    }
+
+    /** Given a stream, this will try to find an appropriate decoder object.
+        If none is found, the method returns NULL.
+
+        DEPRECATED Please use SkImage::NewFromEncoded() or SkImageGenerator::NewFromEncoded().
+    */
+    static SkImageDecoder* Factory(SkStreamRewindable*);
+
+    /** Decode the image stored in the specified file, and store the result
+        in bitmap. Return true for success or false on failure.
+
+        @param pref Prefer this colortype.
+
+        @param format On success, if format is non-null, it is set to the format
+                      of the decoded file. On failure it is ignored.
+
+        DEPRECATED Do not use.
+    */
+    static bool DecodeFile(const char file[], SkBitmap* bitmap, SkColorType pref, Mode,
+                           Format* format = NULL);
+    static bool DecodeFile(const char file[], SkBitmap* bitmap) {
+        return DecodeFile(file, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL);
+    }
+
+    /** Decode the image stored in the specified memory buffer, and store the
+        result in bitmap. Return true for success or false on failure.
+
+        @param pref Prefer this colortype.
+
+        @param format On success, if format is non-null, it is set to the format
+                       of the decoded buffer. On failure it is ignored.
+
+        DEPRECATED Please use SkImage::NewFromEncoded() or SkImageGenerator::NewFromEncoded().
+     */
+    static bool DecodeMemory(const void* buffer, size_t size, SkBitmap* bitmap, SkColorType pref,
+                             Mode, Format* format = NULL);
+    static bool DecodeMemory(const void* buffer, size_t size, SkBitmap* bitmap){
+        return DecodeMemory(buffer, size, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL);
+    }
+
+    /** Decode the image stored in the specified SkStreamRewindable, and store the result
+        in bitmap. Return true for success or false on failure.
+
+        @param pref Prefer this colortype.
+
+        @param format On success, if format is non-null, it is set to the format
+                      of the decoded stream. On failure it is ignored.
+
+        DEPRECATED Please use SkImage::NewFromEncoded() or SkImageGenerator::NewFromEncoded().
+     */
+    static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap, SkColorType pref, Mode,
+                             Format* format = NULL);
+    static bool DecodeStream(SkStreamRewindable* stream, SkBitmap* bitmap) {
+        return DecodeStream(stream, bitmap, kUnknown_SkColorType, kDecodePixels_Mode, NULL);
+    }
+
+protected:
+    // must be overridden in subclasses. This guy is called by decode(...)
+    virtual Result onDecode(SkStream*, SkBitmap* bitmap, Mode) = 0;
+
+    /** If planes or rowBytes is NULL, decodes the header and computes componentSizes
+        for memory allocation.
+        Otherwise, decodes the YUV planes into the provided image planes and
+        updates componentSizes to the final image size.
+        Returns whether the decoding was successful.
+    */
+    virtual bool onDecodeYUV8Planes(SkStream*, SkISize[3] /*componentSizes*/,
+                                    void*[3] /*planes*/, size_t[3] /*rowBytes*/,
+                                    SkYUVColorSpace*) {
+        return false;
+    }
+
+    /**
+     *  Copy all fields on this decoder to the other decoder. Used by subclasses
+     *  to decode a subimage using a different decoder, but with the same settings.
+     */
+    void copyFieldsToOther(SkImageDecoder* other);
+
+    /** Can be queried from within onDecode, to see if the user (possibly in
+        a different thread) has requested the decode to cancel. If this returns
+        true, your onDecode() should stop and return false.
+        Each subclass needs to decide how often it can query this, to balance
+        responsiveness with performance.
+
+        Calling this outside of onDecode() may return undefined values.
+     */
+
+public:
+    bool shouldCancelDecode() const { return fShouldCancelDecode; }
+
+protected:
+    SkImageDecoder();
+
+    /**
+     *  Return the default preference being used by the current or latest call to decode.
+     */
+    SkColorType getDefaultPref() { return fDefaultPref; }
+
+    /*  Helper for subclasses. Call this to allocate the pixel memory given the bitmap's info.
+        Returns true on success. This method handles checking for an optional Allocator.
+    */
+    bool allocPixelRef(SkBitmap*, SkColorTable*) const;
+
+    /**
+     *  The raw data of the src image.
+     */
+    enum SrcDepth {
+        // Color-indexed.
+        kIndex_SrcDepth,
+        // Grayscale in 8 bits.
+        k8BitGray_SrcDepth,
+        // 8 bits per component. Used for 24 bit if there is no alpha.
+        k32Bit_SrcDepth,
+    };
+    /** The subclass, inside onDecode(), calls this to determine the colorType of
+        the returned bitmap. SrcDepth and hasAlpha reflect the raw data of the
+        src image. This routine returns the caller's preference given
+        srcDepth and hasAlpha, or kUnknown_SkColorType if there is no preference.
+     */
+    SkColorType getPrefColorType(SrcDepth, bool hasAlpha) const;
+
+private:
+    SkPngChunkReader*       fPeeker;
+    SkBitmap::Allocator*    fAllocator;
+    int                     fSampleSize;
+    SkColorType             fDefaultPref;   // use if fUsePrefTable is false
+    bool                    fPreserveSrcDepth;
+    bool                    fDitherImage;
+    bool                    fSkipWritingZeroes;
+    mutable bool            fShouldCancelDecode;
+    bool                    fPreferQualityOverSpeed;
+    bool                    fRequireUnpremultipliedColors;
+};
+
+/** Calling newDecoder with a stream returns a new matching imagedecoder
+    instance, or NULL if none can be found. The caller must manage its ownership
+    of the stream as usual, calling unref() when it is done, as the returned
+    decoder may have called ref() (and if so, the decoder is responsible for
+    balancing its ownership when it is destroyed).
+ */
+class SkImageDecoderFactory : public SkRefCnt {
+public:
+    
+
+    virtual SkImageDecoder* newDecoder(SkStreamRewindable*) = 0;
+
+private:
+    typedef SkRefCnt INHERITED;
+};
+
+class SkDefaultImageDecoderFactory : SkImageDecoderFactory {
+public:
+    // calls SkImageDecoder::Factory(stream)
+    virtual SkImageDecoder* newDecoder(SkStreamRewindable* stream) {
+        return SkImageDecoder::Factory(stream);
+    }
+};
+
+// This macro declares a global (i.e., non-class owned) creation entry point
+// for each decoder (e.g., CreateJPEGImageDecoder)
+#define DECLARE_DECODER_CREATOR(codec)          \
+    SkImageDecoder *Create ## codec ();
+
+// This macro defines the global creation entry point for each decoder. Each
+// decoder implementation that registers with the decoder factory must call it.
+#define DEFINE_DECODER_CREATOR(codec) \
+    SkImageDecoder* Create##codec() { return new Sk##codec; }
+
+// All the decoders known by Skia. Note that, depending on the compiler settings,
+// not all of these will be available
+DECLARE_DECODER_CREATOR(BMPImageDecoder);
+DECLARE_DECODER_CREATOR(GIFImageDecoder);
+DECLARE_DECODER_CREATOR(ICOImageDecoder);
+DECLARE_DECODER_CREATOR(JPEGImageDecoder);
+DECLARE_DECODER_CREATOR(PNGImageDecoder);
+DECLARE_DECODER_CREATOR(WBMPImageDecoder);
+DECLARE_DECODER_CREATOR(WEBPImageDecoder);
+DECLARE_DECODER_CREATOR(PKMImageDecoder);
+DECLARE_DECODER_CREATOR(KTXImageDecoder);
+DECLARE_DECODER_CREATOR(ASTCImageDecoder);
+
+// Typedefs to make registering decoder and formatter callbacks easier.
+// These have to be defined outside SkImageDecoder. :(
+typedef SkTRegistry<SkImageDecoder*(*)(SkStreamRewindable*)>        SkImageDecoder_DecodeReg;
+typedef SkTRegistry<SkImageDecoder::Format(*)(SkStreamRewindable*)> SkImageDecoder_FormatReg;
+
+#endif